Clinical trial NCT04821830
Conditions: Parkinson Disease
Keywords: Parkinson's Disease
Sponsor: University of Michigan
Start date: 2020-02-12; Completion date: 2024-04-25
Enrollment: 19 participants; Allocation: NON_RANDOMIZED; Intervention model: SINGLE_GROUP

Brief summary:
Parkinson disease (PD) is a common disorder in which reduced speed of movement results from inadequate brain production of the chemical dopamine. The most effective treatment for PD is the drug levo-dopa, which partially replaces brain dopamine. Despite decades of successful use, how levo-dopa improves speed of movement in PD is not understood. This observational study recruits participants who have been prescribed levo-dopa by their treating physicians. Before their first dose, immediately after their first dose and later, when their dose has been stabilized, they will engage with the research team to participate in a few simple experiments to measure speed, grip strength, tremor, and stability (on and off of treatment). The purpose of these experiments is to understand how levo-dopa treatment in Parkinson disease enhances movement speed. An important but not understood component of levo-dopa action, the Long Duration Response (LDR), lasts for days to weeks. A basic function of dopamine signaling in the brain is modulation of motivation - the coupling between effort and action values. These experiments will determine if the LDR is associated with relative normalization of motivation function in the brain. The motivation behavior of recently diagnosed PD participants will be examined before and after treatment with levo-dopa to determine if the magnitude of the LDR is correlated with improvements in motivation behavior.

Detailed description:
Dopamine replacement therapy (DRT) is the standard symptomatic treatment for early to moderate Parkinson disease (PD). In early to moderate PD, the most important DRT component is the Long Duration Response (LDR), a pharmacodynamic effect that builds up over the course of days-weeks and can be induced by dopamine agonists. Despite its effectiveness, DRT actions are poorly understood and the basis of the LDR is unknown. As the LDR wanes in advancing disease, PD patients develop troublesome motor fluctuations and increasing disability. Improved understanding of the LDR has the potential to prolong the duration of its effects and could have a significant positive effect on clinical practice.

The kinetics of the LDR suggest long-term plastic changes in striatal function. Recent studies of striatal dopamine actions in PD subjects and experimental animals indicate that striatal dopaminergic neurotransmission regulates "vigor," the force, velocity, or amplitude of actions. Vigor is closely allied to the concept that striatal dopaminergic neurotransmission mediates motivation, which involves the assessment of act utility and the appropriate scaling of actions to perceived rewards. Recent theoretical and experimental results suggest that tonic striatal dopamine signaling, mimicked by dopamine agonist administration, is a key determinant of movement vigor. Convergent clinical pharmacologic and experimental data lead to a strong hypothesis that the LDR results from chronic DRT partially restoring motivational coupling of effort to perceived reward and movement vigor. Prior experiments examining vigor in PD subjects did not take the LDR into account, resulting in incomplete examinations of the role of vigor deficits in PD.

Recent non-human primate work on the control and vigor of saccadic eye movements indicates the existence of basal ganglia circuit changes that stably encode motor action values for prolonged periods. Striatal dopaminergic neurotransmission is critical for establishing this remarkably stable form of value-action coupling. This phenomenon is a plausible circuit level mechanism underlying the LDR.

Our long-term goal is to understand the clinically relevant actions of DRT. The primary objective of our proposal is to test the hypothesis that the LDR results from partial restoration of normal action vigor by reinstating the link between motivation and effort. Our secondary objective is to explore potential mechanisms underlying the LDR. The rationale for these experiments is that better understanding of the LDR, a clinically crucial component of DRT action, will lead to improved symptomatic therapy.

We will study recently diagnosed PD subjects. All subjects will undergo standard evaluations of clinical, cognitive, and motivational features. Subjects will perform incentive motivation tasks assessing movement vigor in response to monetary incentives. Two complementary tasks, one based on modulation of movement velocity and one based on modulation of grip strength, will be employed. To assess whether the recently described stable action-value coupling for saccades is relevant to the LDR, subjects will perform a task that measures saccadic eye movement vigor in response to stable value signals learned prior to LDR induction. Subjects will perform all tasks before and after LDR induction in both the "practical off" and post-acute treatment states.

Specific Aim 1: To use incentive motivation tasks to evaluate the coupling between motivation and movement vigor in recently treated PD subjects before and after LDR induction.

Hypothesis 1A: LDR induction will result in partial restoration of movement vigor in response to monetary incentives in PD subjects in the "practical off" state.

Hypothesis 1B: The magnitude of partially restored movement vigor in response to monetary incentives will correlate with reduced bradykinesia in PD subjects in the "practical off" state.

Hypothesis 1C: Identical effects will be found with an incentive motivation task based on movement amplitude and one based on grip strength.

Specific Aim 2: To use a saccadic eye movement task to assess saccadic eye movement vigor in response to stable value signals in recently treated PD subjects before and after LDR induction.

Hypothesis 2: LDR induction will result in partial restoration of saccadic eye movement vigor in response to previously learned stable value signals in PD subjects in the "practical off" state.

Validation of our hypotheses would have considerable impact by identifying a specific functional process underlying the LDR and a potential mechanism of the LDR. This will facilitate research into LDR mechanisms, provide a rational basis for developing valid animal models of the LDR, and open a new path towards improved symptomatic management of PD.

Arms: arm 1: Participants will undergo evaluation of the relationship between the LDR and movement vigor. All participants will undergo standard evaluation with standard clinical rating scales and three outcome measures: Tapping Speed Task; Joystick Movement Task; and completion of MDS-UPDRS.

carbidopa/levodopa, as prescribed by treating physician: There will be 4 measurement states: at baseline prior to chronic treatment initiation (OFF-No LDR); at baseline after a standard, acute oral dose (25/250 carbidopa/L-dopa), referenced in the protocol, but prescribed and provided by their prescribing physician as standard of care initial dosage (ON-No LDR); 2 months after initiation of chronic, stable L-dopa treatment (amounts and sequences as prescribed by treating physicians) but with no L-dopa for 10-12 hours prior to evaluation (Practical OFF- LDR); and after resuming subjects' usual physician-prescribed L-dopa dose (ON-LDR). arm 2: Participants will undergo evaluation of the relationship between the LDR and movement vigor. All participants will undergo standard evaluation with standard clinical rating scales and the outcome measure: Grip Strength Task - Measurement of Incentive-Outcome Coupling - Movement Vigor.

carbidopa/levodopa, as prescribed by treating physician: There will be 4 measurement states: at baseline prior to chronic treatment initiation (OFF-No LDR); at baseline after a standard, acute oral dose (25/250 carbidopa/L-dopa), referenced in the protocol, but prescribed and provided by their prescribing physician as standard of care initial dosage (ON-No LDR); 2 months after initiation of chronic, stable L-dopa treatment (amounts and sequences as prescribed by treating physicians) but with no L-dopa for 10-12 hours prior to evaluation (Practical OFF- LDR); and after resuming subjects' usual physician-prescribed L-dopa dose (ON-LDR).
Interventions: intervention 1: carbidopa/levodopa, as prescribed by treating physician
Intervention descriptions: intervention 1: There will be 4 measurement states:

at baseline prior to chronic treatment initiation (OFF-No LDR); at baseline after a standard, acute oral dose (25/250 carbidopa/L-dopa), referenced in the protocol, but prescribed and provided by their prescribing physician as standard of care initial dosage (ON-No LDR); 2 months after initiation of chronic, stable L-dopa treatment (amounts and sequences as prescribed by treating physicians) but with no L-dopa for 10-12 hours prior to evaluation (Practical OFF- LDR); and after resuming subjects' usual physician-prescribed L-dopa dose (ON-LDR).

Protocol documents:
Prot_SAP_000.pdf: 
1 
 
 
 
 
 
 
Study Protocol and Statistical Analysis Plan 
 
 
 
 
Official title: Vigor and the LDR in Parkinson Disease 
 
NCT number: NCT04821830 
 
IRB Approval Date: 10/25/2019 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 


2 
 
Vigor and the LDR in Parkinson Disease 
PI: Roger L. Albin, MD; Co-I: Taraz Lee, PhD 
 
A. Abstract: 
 
Dopamine replacement therapy (DRT) is the standard and very effective symptomatic treatment for early to 
moderate Parkinson disease (PD). The most important DRT component is the Long Duration Response 
(LDR), a pharmacodynamic effect that builds up over the course of weeks. DRT actions are poorly understood 
and the basis of the LDR is unknown. As the LDR wanes in advancing disease, PD patients develop 
troublesome motor fluctuations and increasing disability. LDR kinetics suggest long-term plastic changes in 
striatal function. Studies of striatal dopamine actions indicate that striatal dopaminergic neurotransmission 
regulates “vigor;” modulation of the velocity, amplitude, force, or frequency of movements. Vigor is closely 
allied with the concept that striatal dopaminergic neurotransmission mediates motivation; assessment of act 
utility and appropriate scaling of actions to perceived rewards. Recent theoretical and experimental results 
suggest that tonic striatal dopamine signaling is a key determinant of movement vigor. Convergent clinical 
pharmacologic and experimental data lead to a strong hypothesis that the LDR results from chronic DRT 
partially restoring movement vigor. This model of the LDR requires stable “records” of action values. Recent 
non-human primate work on saccadic eye movement vigor indicates the existence of striatal dopaminergic 
neurotransmission stably encoding motor behavior values for prolonged periods – a potential mechanism for 
the LDR. Prior experiments examining vigor in PD did not take the LDR into account, resulting in incomplete 
examinations of the role of vigor deficits in PD. Our long-term goal is to understand the clinically relevant 
actions of DRT. The primary objective of our proposal is to test the hypothesis that the LDR results from 
partial restoration of normal movement vigor-motivation. Our secondary objective is to evaluate a potential 
mechanism underlying the LDR. The rationale for these experiments is that better understanding of the LDR, 
a clinically crucial component of DRT action, will lead to improved symptomatic therapy. We will study 
recently diagnosed PD subjects. All subjects will undergo standard evaluations of clinical, cognitive, and 
motivational features.  Subjects will perform incentive motivation tasks assessing movement vigor – 
motivation coupling to assess    our primary hypothesis. A task assessing saccadic eye movement vigor in 
response to stable value signals   will be employed to evaluate our secondary hypothesis. They will perform 
all tasks before and after LDR induction in both the “practical off” and post-acute treatment states. Validation 
of our hypotheses would have considerable impact by identifying the functional process underlying the LDR 
and providing information for uncovering the mechanisms of the LDR. This would facilitate research into LDR 
mechanisms, provide a rational basis for developing valid animal models of the LDR, and open a new path 
towards improved symptomatic management of PD. 
 
B. Specific Aims 
Dopamine replacement therapy (DRT) is the standard symptomatic treatment for early to moderate Parkinson 
disease (PD). In early to moderate PD, the most important DRT component is the Long Duration Response 
(LDR), a pharmacodynamic effect that builds up over the course of days-weeks and can be induced by 
dopamine agonists. Despite its effectiveness, DRT actions are poorly understood and the basis of the LDR is 
unknown.  As the LDR wanes in advancing disease, PD patients develop troublesome motor fluctuations and 
increasing disability. Improved understanding of the LDR has the potential to prolong the duration of its 
effects and could have a significant positive effect on clinical practice. 
 
The kinetics of the LDR suggest long-term plastic changes in striatal function. Recent studies of striatal 
dopamine actions in PD subjects and experimental animals indicate that striatal dopaminergic 
neurotransmission regulates “vigor,” the force, velocity, or amplitude of actions.  Vigor is closely allied to the 
concept that striatal dopaminergic neurotransmission mediates motivation, which involves the assessment of 
act utility and the appropriate scaling of actions to perceived rewards. Recent theoretical and experimental 
results suggest that tonic striatal dopamine signaling, mimicked by dopamine agonist administration, is a key 
determinant of movement vigor.  Convergent clinical pharmacologic and experimental data lead to a strong 
hypothesis that the LDR results from chronic DRT partially restoring motivational coupling of effort to 
perceived reward and movement vigor.  Prior experiments examining vigor in PD subjects did not take the 
LDR into account, resulting in incomplete examinations of the role of vigor deficits in PD. 


3 
 
Recent non-human primate work on the control and vigor of saccadic eye movements indicates the existence 
of basal ganglia circuit changes that stably encode motor action values for prolonged periods.  Striatal 
dopaminergic neurotransmission is critical for establishing this remarkably stable form of value-action 
coupling. This phenomenon is a plausible circuit level mechanism underlying the LDR. 
Our long-term goal is to understand the clinically relevant actions of DRT. The primary objective of our 
proposal is to test the hypothesis that the LDR results from partial restoration of normal action vigor by 
reinstating the link between motivation and effort. Our secondary objective is to explore potential 
mechanisms underlying the LDR. The rationale for these experiments is that better understanding of the 
LDR, a clinically crucial component of DRT action, will lead to improved symptomatic therapy. 
 
We will study recently diagnosed PD subjects. All subjects will undergo standard evaluations of clinical, 
cognitive, and motivational features. Subjects will perform incentive motivation tasks assessing movement 
vigor in response to monetary incentives. Two complementary tasks, one based on modulation of movement 
velocity and one based on modulation of grip strength, will be employed.   To assess whether the recently 
described stable action-value coupling for saccades is relevant to the LDR, subjects will perform a task that 
measures saccadic eye movement vigor in response to stable value signals learned prior to LDR induction. 
Subjects will perform all tasks before and after LDR induction in both the “practical off” and post-acute 
treatment states. 
Specific Aim 1: To use incentive motivation tasks to evaluate the coupling between motivation and movement 
vigor in recently treated PD subjects before and after LDR induction. 
Hypothesis 1A:  LDR induction will result in partial restoration of movement vigor in response to monetary 
incentives in PD subjects in the “practical off” state. 
Hypothesis 1B: The magnitude of partially restored movement vigor in response to monetary incentives will 
correlate with reduced bradykinesia in PD subjects in the “practical off” state. 
Hypothesis 1C:  Identical effects will be found with an incentive motivation task based on movement 
amplitude and one based on grip strength. 
Specific Aim 2: To use a saccadic eye movement task to assess saccadic eye movement vigor in 
response to stable value signals in recently treated PD subjects before and after LDR induction. 
Hypothesis 2:  LDR induction will result in partial restoration of saccadic eye movement vigor in response to 
previously learned stable value signals in PD subjects in the “practical off” state. 
Validation of our hypotheses would have considerable impact by identifying a specific functional process 
underlying the LDR and a potential mechanism of the LDR. This will facilitate research into LDR mechanisms, 
provide a rational basis for developing valid animal models of the LDR, and open a new path towards improved 
symptomatic management of PD. 
 
C. Research Strategy 
 
The Long Duration Response in Parkinson disease:  Parkinson disease (PD) is the second most common 
neurodegenerative disorder, affecting approximately 1 million Americans. PD is defined by a constellation of 
motor features – bradykinesia, rigidity, resting tremor, and postural instability. Bradykinesia, which includes 
slowed movements and progressive decrements of movement speed and amplitude with movement 
repetition, is regarded as the core deficit of PD.1   Motor dysfunction in PD results from reduced striatal 
dopamine (DA) signaling accompanying degeneration of the DAergic nigrostriatal projection. 
DA replacement therapy (DRT) is the cornerstone of PD treatment and is generally very effective in mild to 
moderate PD. The most effective and commonly used treatment is the DA precursor L-dopa.  Synthetic DA 
agonists, with longer half-lives, are used for monotherapy and as adjunctive agents.  These are primarily D2 
receptor selective agents, are less potent, and exhibit significantly higher rates of serious side effects. 
There are 2 major components of patient response to L-dopa treatment – the Short Duration Response 
(SDR) and the Long Duration Response (LDR).2-4   L-dopa has a half-life of approximately 1 hour in blood. 
With typical oral administration schedules (3-4x/day), plasma L-dopa levels are very low at the end of dose 
intervals. The SDR begins quickly, lasts minutes to hours, and then declines, with clinical effects 
approximately paralleling plasma L-dopa levels. The LDR is sustained improvement following chronic 


4 
 
treatment which builds up over days to weeks and declines over similar intervals with treatment suspension. 
The LDR is the major component of treatment response in early PD and is responsible for the fact that many 
early phase PD patients experience little or no decrement in performance if they miss L-dopa doses. 
Pharmacodynamic modeling studies suggest that the half-life of the LDR is approximately 8 days, with 
plausible suggestions of longer half- lives.5,6 
 
The LDR wanes with disease progression with increasing importance of the SDR.7,8   This results in motor 
fluctuations, including wearing off of drug effect and dyskinesias. Patients require increasing L-dopa doses, 
frequent regimen adjustments, and adjunctive agents. There is significantly increased incidence of 
troublesome medication side-effects.  Many need Deep Brain 
Stimulation (DBS) surgery to obtain adequate quality of life. 
 
Initial hypotheses about LDR mechanisms suggested that its existence reflected a brain “buffer” compartment 
taking up and storing L-dopa and/or DA for subsequent release. This hypothesis was falsified by several 
experiments demonstrating that DA agonists can initiate and sustain the LDR.5.9-11   In addition, LDR kinetics 
are identical in patients with Dopa Responsive Dystonia, a rare disorder of deficient DA synthesis highly 
responsive to L-dopa treatment.12   These individuals have normal nigrostriatal terminals and normal DA 
storage capacity. 
 
The mechanism(s) underlying the LDR are unknown as there have been no subsequent studies investigating 
the underpinnings of the LDR. 
 
Phasic Dopamine Signaling Does Not Explain the LDR: Striatal DA actions have been the focus of intense 
study over the past generation. Striatal DAergic neurotransmission is described as mediating a number of 
important processes, including reinforcement learning, habit formation, action selection, action vigor, and 
motivation (for discussion of vigor and motivation, see Approach below).  The best characterized aspect of 
striatal DA signaling is its role in reinforcement learning.  Considerable evidence indicates that rapid (100-300 
msec), phasic bursting of nigrostriatal neurons, resulting in discrete boluses of striatal DA, provides a Reward 
Prediction Error signal for reinforcement learning.13-15   Observed originally in seminal non-human primate 
experiments by Wolfram Schultz, studies of this aspect of striatal DAergic signaling dominate the literature on 
striatal DA actions. 
 
As pointed out by Schultz and others, restoration of phasic nigrostriatal DA signaling is unlikely to occur with L- 
dopa treatment and cannot account for the effects of L-dopa treatment in PD.2,16,17   At onset of symptomatic 
PD, patients have already experienced massive, >60% loss, of motor striatum nigrostriatal terminals.18 
Accompanying nigrostriatal terminal degeneration is loss of dopamine transporters (DAT) located uniquely on 
DAergic terminals.  DAT activity is the primary mechanism for clearing DA from the synaptic cleft. Massive 
nigrostriatal terminal loss results in both diminished DA release and increased DA extracellular residence time, 
degrading phasic DA signaling.19,20   Other components of striatal DA signaling must account for the 
effectiveness of L-dopa in PD.  Schultz suggested that some form(s) of tonic striatal DA signaling accounts for 
L-dopa effectiveness.16   LDR kinetics suggests long-term plastic changes in striatal DA actions. 
 
Approach Overview: Our primary objective is to test the hypothesis that the LDR results from partial 
restoration of a critical aspect of striatal DA signaling: mediation of vigor and motivation (Specific Aim 1). 
Confirmation of our hypothesis would connect the LDR to a fundamental feature of striatal DA action. The 
burgeoning preclinical and human experimental literature in this area would provide a solid foundation for 
mechanistic studies of the LDR. Our secondary objective is to evaluate a potential LDR circuit level 
mechanism (Specific Aim 2). 
 
The proposed work is based on collaboration between investigators with strongly complementary expertise. 
Dr. Albin is a Movement Disorder neurologist and experienced PD clinical researcher. Dr. Lee is a Cognitive 
Neuroscientist focused on the interactions between cognitive control, motivation, and action. We engaged 
expert collaborative consultants for critical aspects of the proposed experiments.  Dr. Joshua Dudman 
(HHMI- Janelia Farms) is a leading expert on striatal dopamine signaling and vigor modulation. Dr. 
Dudman developed the movement amplitude task deployed for SA1, a human adaptation of the task his lab 


5 
 
used in influential murine experiments demonstrating DAergic modulation of movement vigor.  Dr. Brian 
Anderson (Texas A&M) is an expert on the task deployed for SA2.  Drs. Dudman and Anderson agreed to 
advise us on implementation of these tasks and data interpretation (see attached LOS). 
Specific Aim 1: To use incentive motivation tasks to evaluate the coupling between motivation and 
movement vigor in recently treated PD subjects before and after LDR induction. 
Hypothesis 1A:  LDR induction will result in partial restoration of movement vigor in response to monetary 
incentives in PD subjects in the “practical off” state. 
Hypothesis 1B: The magnitude of partially restored movement vigor in response to monetary incentives will 
correlate with reduced bradykinesia in PD subjects in the “practical off” state. 
Hypothesis 1C:  Identical effects will be found with an incentive motivation task based on movement 
amplitude and one based on grip strength. 
 
Rationale: A substantial body of data indicates that striatal DAergic neurotransmission mediates vigor – the 
speed, amplitude, force, or frequency of actions.21-25   These different aspects of vigor have in common 
modultion of effort, ultimately the degree of energy expenditure required to accomplish actions.  Vigor 
modulation is closely linked to the motivational role of striatal DAergic neurotransmission. Salamone and 
others argue persuasively that striatal DAergic neurotransmission is critical for efficient effort allocation by 
proportioning actions to perceived rewards – the fundamental process of motivation.21-23   Several studies 
implicate aberrant movement vigor modulation as the underlying mechanism of PD bradykinesia. An 
influential experiment by Mazzoni et al. indicates that PD subjects exhibit aberrant estimation of effort-reward 
tradeoffs of movements.26   These results were replicated by several groups using a variety of paradigms to 
assess movement vigor in PD subjects.27-29   These paradigms generally isolate modulation of movement 
velocity, force (e.g., grip strength), or amplitude as outcome measures. These outcome variables all reflect 
effort and in most paradigms, the chosen outcome variable (e.g., amplitude of reaching) is co-linear with 
other potential outcome variables (e.g., force of reaching). 
 
Consistent with Schultz’s suggestion that some form of tonic striatal DA action is critical for treatment of PD, 
LDR induction by dopamine agonists suggests tonic striatal DA signaling in the LDR. Theoretical and recent 
experimental evidence indicates that tonic striatal DA signaling is an important mediator of vigor.  Niv et al. 
elaborated a model of reinforcement learning in which subjects make choices about action selection and vigor 
with the goal of maximizing the net value of rewards per unit time.30   Faster or more intense movements are 
more costly.30,31   Optimal performance requires an effort-reward (cost-benefit) analysis including the costs of 
action vigor. Simulations with this model recapitulate results of typical animal experiments examining 
response vigor.  In this model, a mechanism is needed to provide a long-term account of the prior average 
rate of rewards. Niv et al. predicted that tonic striatal dopamine signaling provides the necessary history of 
prior rate of reward.  Zhuang and colleagues tested this hypothesis with partial DAT knockdown (pDATKD) 
mice.32,33 These mice manifest chronic, moderate elevation of striatal DA but exhibit normal nigrostriatal 
neuron phasic activity and normal reinforcement learning.  pDATKD mice work more vigorously than control 
mice for equivalent rewards, exhibiting distorted effort-reward coupling. Panigraphi et al. examined forelimb 
movement vigor in MitoPark mice, a model of adult-onset, selective nigrostriatal neuron degeneration with 
slowly progressive bradykinesia.34   In clever experiments, they demonstrated normal reward contingency 
learning but impaired ability to scale forelimb movements appropriately. Panigraphi et al. also demonstrated 
significant improvements in MitoPark mice movement vigor with L-dopa treatment. Remarkably, improved 
movement vigor did not occur with acute treatment, but only with weeks of daily treatment, a possible LDR 
analogue. 
Converging theoretical work, preclinical experiments, and clinical experiments suggest that DRT improves 
bradykinesia via partial restoration of normal striatal vigor modulation and that the LDR is the manifestation of 
improved vigor modulation via partially restored tonic dopamine signaling. There is, however, a critical gap in 
the chain of data.  None of the human experiments adequately controlled for DRT treatment effects. The 
Mazzoni et al. study was performed in chronically treated PD subjects.26   Several other experiments 
evaluated PD subjects during DRT and after withholding DRT for 10-12 hours (the “practical off” state) and 
obtained analogous results.28,29   These experiments report reduced vigor modulation in the “practical off” 
state. The PD subjects in these studies were inevitably beneficiaries of the LDR, confounding comparison of 


6 
 
performance of PD subjects evaluated in the “practical off” state with control subject performances.  
Rigorous evaluation of the concept that PD bradykinesia results from aberrant modulation of vigor requires 
human experiments that control for LDR effects. A well designed experiment will assess whether the LDR is 
correlated with improved vigor, as predicted by our hypothesis. 
 
Procedures: 
a) We will study newly diagnosed PD subjects recruited from the Movement Disorders clinics at the 
University of Michigan. We see approximately 1300 PD patients annually.  Subjects must meet Movement 
Disorder Society (MDS) criteria for PD.1   Only H&Y1-2 subjects will be enrolled.  Exclusion criteria include 
significant cognitive impairment (Montreal Cognitive Assessment score <24), significant depression 
(Geriatric Depression Scale [GDS] >5), stimulant use, dopamine agonist treatment, or confounding other 
neurologic or medical disorders. Subjects will be characterized at each testing condition with standard 
scales: Parkinsonism – MDS- Unified Parkinson Disease Rating Scale (UPDRS); Mood – GDS; Apathy – 
Lille Apathy Rating Scale; Cognition – a short battery of selected domain specific tests used previously.35   
Bradykinesia will be quantified with a tapping task used extensively by Nutt et al. in prior LDR studies (see 
section c below).7,8 
 
b) Subjects will be studied at pre-treatment baseline and 2-3 months after L-dopa treatment initiation and 
regimen stabilization. We will only enroll drug-naïve subjects about to start treatment with L-dopa.  
Subjects will be studied in OFF and ON acute treatment states at baseline and after LDR induction. There 
will be 4 measurement states: at baseline prior to chronic treatment initiation (OFF-No LDR); at baseline 
after a standard, acute oral dose (25/250 carbidopa/L-dopa) of L-dopa (ON-No LDR), 2 months after initiation 
of chronic, stable L-dopa treatment but with no L-dopa for 10-12 hours prior to evaluation (Practical OFF– 
LDR), and after subjects’ usual L-dopa dose (ON-LDR) (Table 1). 
Table 1: 
 
Practical ON and OFF state measurements will be counterbalanced across individuals. We will recruit both 
male and female PD subjects, though we expect more male subjects as PD is more common in men. This is 
a within subjects design and randomization per se is not used. Blinding of study conditions is not feasible.  
It would be potentially interesting to include a placebo LDR induction arm, but denying PD subjects effective 
treatment is not ethical. Data analysis will be blinded. It would also be interesting to include a normal subject 
arm, but this is ethically problematic as it would involve chronic L-dopa treatment. If, however, we obtain 
results confirming our hypotheses, we will explore inclusion of normal controls in the next phase of 
experiments. 
 
c) LDR magnitude will be measured by reduction of bradykinesia between the initial OFF-No LDR state and the 
Practical OFF-LDR state. Comparisons of the On-No LDR state and OFF-No LDR state, and the Practical 
OFF-LDR and ON-LDR states will measure the SDR.  As a measure of bradykinesia, we will use the well-
validated tapping task used by Nutt et al. in their experiments defining LDR kinetics.7,8   With the hand most 
affected by PD, subjects are instructed to alternately tap 2 manual counters spaced 20 cm apart as rapidly as 
possible for 1 minute.  Subjects will practice several times until they feel comfortable  with the task. They will 
perform 5 trials spaced ~3-4 minutes apart with the initial trial discarded to reduce variation secondary to 
anxiety.  Results of the remaining 4 trials will be averaged       to generate a tapping speed (taps/min) for each 
subject in each condition. This is very similar to the approach used by Nutt et al. (JG Nutt, personal 
communication). 
d) Vigor modulation will be evaluated with two separate incentive motivation tasks; one based on modulation 
of movement amplitude and one based on modulation of grip strength. The latter is similar to a task used 
previously in PD subjects by Schmidt et al.36   It is implemented in the Lee laboratory.  This task was chosen 
because it is relatively easy to use and implement, is compatible with functional neuroimaging, and results in 
PD subjects were replicated using a very similar task by Chong et al.28   Briefly, subjects will be tasked with 
modulating their grip strength in response to monetary incentives. With the hand most affected by          PD 
OFF-No LDR 
Baseline - Treatment Naïve Subject 
ON-No LDR 
Baseline - Treatment Naïve Subject After Acute L-Dopa 
OFF-LDR 
Chronically Treated – “Practical Off” State 
ON-LDR 
Chronically Treated – After Usual L-Dopa 


7 
 
symptoms, they will be asked to squeeze a hand dynamometer at the outset of the experiment to measure 
the strength of their maximum voluntary contraction (MVC).  All grip strength targets will be scaled to this  
value.  Subsequently, subjects will undergo a series of trials in which they will be presented with an incentive 
cue that indicates the level of reward for that trial. They will be informed that on each of these trials they will 
earn a percentage of the incentive shown that is directly proportional to how hard they squeeze on that trial. 
While healthy individuals generally increase grip strength with increasing incentive values on this task, 
previous work has shown that PD patients are impaired in their ability to modulate their grip strength in this                
way.  To ensure that any deficits found are due to motivational vigor and not simply a reflection of impaired 
muscle power, we will incorporate control trials in which PD subjects are instructed to increase grip strength 
to similar target levels of force without monetary incentives. 
We will use a variant of the mouse task used in Panigrahi et al.34 This task was inspired by tasks used in 
human PD studies.26,27 A spring loaded joystick that returns to a center position if no force is applied is used. 
Application of force to the joystick displaces it from the center and is monitored to detect the real-time 
trajectory of the movement. A water reward is delivered 1 second after the joystick passes a specified 
amplitude threshold.  For human equivalent tasks, a flexible range of manipulanda (varying the force 
requirements) and flexible visuomotor feedback during training and/or testing are deployed. Varying force 
requirements for reward measure reward-effort coupling.  Use of 2 incentive motivation tasks is 
complementary and provides a more stringent test of our hypothesis.  As these tasks are different measures 
of movement vigor modulation, we should obtain similar and strongly correlated results. Confirmation of our 
hypothesis with the amplitude modulation task will provide reassurance that we are studying the same vigor 
modulation phenomenon studied in basic investigations. The grip strength modulation task is better suited to 
functional imaging experiments and will be a valuable platform for future experiments. 
e) Analysis Plan:  Hypothesis 1A; Our primary comparisons will be performance on the incentive motivation 
tasks before and after LDR induction. We predict that improved performance on the incentive motivation 
tasks will be apparent between the OFF-No LDR and Practical OFF-LDR conditions but not in comparisons 
between the other conditions. Data will be analyzed via 2-Way Repeated Measures ANOVA followed by 
post-hoc tests with incentive level and treatment condition as the factors and multiple comparison 
adjustments. Based on the Schmidt et al. data36, we estimate that achieving power of 0.9 at an effect size of 
η2 = 0.15 requires complete data from 16 subjects.  Based on experience with complex, serial imaging 
studies, we project a 10% dropout rate (~2 subjects). To compensate for dropouts, we will recruit 20 
subjects.  Hypothesis 1B; We will correlate changes in performance on the incentive motivation task with the 
change in tapping rates with Pearson or Spearman correlation tests. Hypothesis 1C: We will correlate the 
results of the amplitude modulation based and grip strength based incentive motivation tasks with Pearson or 
Spearman correlation tests. 
Interpretations and Potential Problems:  If our predictions are correct, we will validate the connection between 
the LDR and partial restoration of vigor modulation. Falsifying this hypothesis will be equally valuable as it 
would direct research on the LDR towards different features of striatal DA action. We may, for example, find a 
relationship between the SDR and improved vigor modulation, which would direct research towards the 
mechanisms of the SDR.  As discussed above, prior experiments evaluating vigor modulation in PD have not 
taken the LDR into account. We may find no clear relationship between vigor modulation and bradykinesia. 
This would be important as it would cast doubt on the widely accepted concept that PD bradykinesia is the 
consequence of altered vigor modulation, and potentially re-direct research in this field. 
Subject recruitment is a potential obstacle to study completion. Our clinics follow ~1300 PD subjects with 
~200 new PD patient visits per year. Our group successfully recruited for trials requiring untreated PD 
patients such as STEADY-PD and SURE-PD.  Our group expanded this past summer with the addition of 2 
faculty  Movement Disorder specialists primarily committed to clinical practice. Treatment with dopamine 
agonists is an exclusion criterion and will not affect recruitment. Our Movement Disorders group is 
conservative in terms      of treatment recommendations and the overwhelming majority of our patients initiate 
therapy with L-dopa monotherapy.  If recruitment lags, we will recruit through the Michigan Parkinson 
Foundation, the major lay PD organization in Michigan with 71 affiliated support groups and a mailing-email 
list of ~15,000 (see attached LOS). These experiments are straightforward, using simple behavioral tasks.  A 
potential problem is that some patients experience nausea with initial L-dopa treatment, which could 


8 
 
complicate the ON-No LDR assessment. We will reduce the possibility of nausea by 48 hour pretreatment 
with the peripheral decarboxylase inhibitor carbidopa.  Another potential problem is enrollment of subjects 
with one of the PD mimics (Multiple System Atrophy, etc.).  An advantage of our design is that we will be 
evaluating subjects after treatment initiation, allowing us to gauge treatment responses. Subjects not 
improving with L-dopa treatment, defined by the MDS criteria of > 30% improvement in MDS-UPDRSIII score, 
will be excluded. 
Specific Aim 2: To use a saccadic eye movement task to assess saccadic eye movement vigor in 
response to stable value signals in recently treated PD subjects before and after LDR induction. 
Hypothesis 2:  LDR induction will result in partial restoration of saccadic eye movement vigor in response to 
previously learned stable value signals in PD subjects in the “practical off” state. 
 
Rationale: The long half-life of the LDR indicates that it is based on long-term DA mediated striatal plasticity. 
The computational model of Niv et al. suggests that accurate vigor modulation requires a striatal DA signaling 
“recording” the long-term prior average value of rewards.  Rodent and non-human primate lesion experiments 
suggest that the striatum mediates estimates of prior reward histories.37,38   Studying saccadic eye movements 
in non-human primates, Hikosaka and colleagues described a basal ganglia mechanism stably encoding 
values of visual stimuli to modulate the vigor of saccadic eye movements.39,40   Hikosaka et al. presented 
animals with a large set of fractal images, training them to associate a subset with rewards. Weeks to months 
later and in unrewarded conditions, animals are exposed to groups of fractal images containing some images 
associated previously with rewards.  Saccadic eye movement vigor was measured. Images associated 
previously with rewards evoked greater saccadic vigor.  In detailed physiologic experiments, Hikosaka et al. 
established that activity of DAergic nigrostriatal neurons projecting to the caudate nucleus tail are critical for 
this phenomenon. This demonstration of long-term stable action-value association has features required of 
a DAergic mechanism “recording” reward history and underpinning vigor modulation. 
If this phenomenon underpins vigor modulation, then DRT partial restoration of DAergic signaling in this 
circuit is a plausible substrate for the LDR. LDR induction is predicted to improve saccadic eye movement 
vigor in tasks analogous to that used by Hikosaka et al. 
Procedures:  Subject recruitment, characterization, and test conditions are as described in Specific Aim 1. 
It is not feasible to train PD subjects on hundreds of fractal images. We will use an analogous task validated 
well in humans; value driven attentional oculomotor capture (VDAOC).41-43 A probabilistic learning task is used 
to train subjects to associate a salient visual stimulus (color) with reward. In a test phase, the previously 
rewarded stimulus is presented in task-irrelevant context as a distractor.  Saccades to the test phase target 
and distractor are assessed, including percentage of saccades to distractor or target, saccade latency, and 
saccade duration.  Previously rewarded distractor stimuli capture initial saccades and the magnitude of 
VDAOC is assessed. This task is accompanied by striatal dopamine release.44   Subjects are trained in a 
single session and attentional capture is remarkably durable; it persists in test phase experiments months 
after a single training session.45 To duplicate the approach used by Hikosaka et al., PD subjects will be 
trained on reward-color association prior to initiation of L-dopa therapy.  VDAOC will be measured in 4 
measurement states described above (Table 1).  Saccades will be evaluated with an Eyelink tracker with a 
sampling rate of 250 Hz. If we again assume a modest effect size of η2 = 0.15, 16 subjects will be sufficient to 
achieve a power of 0.9. To guard against dropouts, we will target enrolling 20 subjects.  Data analysis 
approach will be similar to that proposed for Specific Aim 1. 
Interpretations and Potential Problems:  Straightforward interpretation of this experiment presupposes 
validation of our hypothesis that LDR induction is associated with improved modulation of vigor as tested in 
Specific Aim 1 experiments. Assuming validation of our primary hypothesis, we predict that LDR induction 
will be associated with improved saccadic eye movement vigor (VDOAC magnitude). The analysis approach 
will be similar to that used for Specific Aim 1 experiments. The primary comparison will be between 
saccadic      vigor in OFF-No LDR and Practical OFF-LDR conditions.  If LDR induction is associated with 
improved saccadic vigor in the context of successful Specific Aim 1 experiments, we will have evidence 
supporting the hypothesis that the stable striatal DAergic signaling described by Hikosaka’s group underpins 
the LDR.  This would be an excellent point of departure for future experiments on LDR mechanisms. This 
experiment will have value even if we falsify Hypothesis 1.  Regardless of the outcome of the SA1 


9 
 
experiments, success with this experiment would support the existence in humans of the interesting and 
potentially important phenomenon described by Hikosaka et al. in monkeys. It’s possible that we might 
validate Hypothesis 1 but falsify Hypothesis 2. That result would certainly point away from the mechanism 
described by Hikosaka et al. as underlying the LDR. An alternative interpretation then would be that the 
dopamine deficient (PD) state    impairs value encoding. This could be evaluated in subsequent experiments 
in which different colors are associated with reward in different training sessions during each of our 
measurement conditions. 
Potential obstacles and responses to problems associated with this experiment are those outlined above for 
Specific Aim 1 experiments. This task has not been used in a patient population and a more prolonged 
training phase may be needed. Initial experiments will assess this potential issue. 
D. Recruitment and Retention: 
 
Subjects will include 30-40 with Parkinson disease (PD). For experiments for SA1 and SA2, our power 
estimates indicate that 16 participants will be adequate for each experiment. We project recruiting 20 subjects 
for each experiment to compensate for possible dropouts. A number of subjects will participate in both SA1 and 
SA2 experiments. 
 
Subjects will be recruited from the UMHS Movement Disorders Clinics. The UMHS Movement Disorders clinic 
follows a population of about 1300 clinically well-defined patients with PD, and evaluates approximately 200 
new PD patients per year.  Dr. Albin, Co-Director of the UMHS Movement Disorders clinic, will be in charge 
of subject recruitment. The UM Movement Disorders group is one of the largest in the nation with 13 faculty 
and actively involved in clinical research. We successfully recruit simultaneously for major clinical trials such 
as STEADY-PD and other clinical research projects involving complex protocols such a multiple imaging 
studies. Movement Disorders group faculty work closely on recruitment with all members of the group 
committed to assisting with recruitment of study subjects. We have a weekly email notification of studies 
actively recruiting and a well established system for directing patients identified in clinics as potential 
research subjects to the attention of study coordinators. The Movement Disorders group is expanded this 
past summer with the addition of 2 additional, primarily clinical, faculty. We also have 2 clinical fellows. 
 
In addition, we will apply to the UM IRB for a waiver of consent for screening and recruitment purposes only. 
Our study coordinator (SC) will use the electronic medical record (EMR) to screen all subjects scheduled for 
clinic visits and will maintain a password-protected screening log. The SC will contact possibly eligible 
subjects by phone in advance of their Neurology clinic appointment—so that subjects can discuss the study 
with their physician and so that our team can be available at that time to answer any questions—and will 
introduce them to the study, the ardor and nature of the study procedures, and to review inclusion/exclusion 
criteria. Subjects who are interested in participating will be scheduled for a baseline testing visit. 
 
If recruitment lags, we will recruit regionally through the Michigan Parkinson Foundation (MPF; see attached 
letter of support).  MPF is the major service organization for PD in Michigan.  It supports dozens of local 
chapters and has a newsletter with circulation in the thousands. 
 
Retention is clearly critical in studies of this type. Our experience with complex studies is reassuring.  For 
multiple PET imaging studies our group has performed, often involving anywhere from 2 – 4 PET studies 
(plus MRI imaging) and serial evaluations, including follow-up PET studies, we have had little difficulty with 
retention. Dropout rates are <10%. Our study plan budgets for potential dropouts. To enhance retention, our 
SC will contact subjects via phone on a regular basis throughout the period from study entry to completion. 
This type of personal contact is usually effective in maintaining study participation. We will provide 
reimbursement for travel expenses and a modest volunteer fee on study completion. 
 
Inclusion Criteria: PD diagnosis will be based on the recent Movement Disorder Society criteria.  
a) PD subjects >45 years and <81 will be studied. 
b) H&Y1-2 (early PD) subjects will be recruited. 
c) Only subjects about to initiate treatment with L-dopa preparations will be enrolled.  
 


10 
 
Exclusion Criteria: 
a) The presence of other neurologic disease or neurologic findings on examination. 
b) Cognitive Impairment: Montreal Cognitive Assessment (MoCA) score <24. 
c) Depression: Geriatric Depression Scale (GDS) score >5. 
d) Use of dopamine agonists or stimulants. 
e) Evidence of a stroke or mass lesion on prior structural brain imaging (CT or MRI). 
f) Evidence of any confounding medical or psychiatric problem that would preclude task participation. 
 
Sources of Materials: 
Information gathered specifically for this research project includes test results from clinical test scales, 
standardized neuropsychological measures and from experimental cognitive tests, neurobehavioral rating 
scales, clinical motor data, questionnaires, standardized interview, and data derived from structural and 
functional MRI. 
 
Potential Risks: 
Confidentiality of Research Information: The research data to be collected from subjects will consist of 
confidential information relating to clinical, neuropsychological, mood, neuroanatomical, and neurochemical 
functions. These research data are not intended for entry into the subjects’ clinical medical records. 
However, the data remain potentially discoverable. This may lead to violation of privacy and embarrassment 
of the subject. 
 
Clinical and Behavioral Testing: Risks in regard to the behavioral assessment are limited to fatigue, frustration 
and momentary embarrassment that may occur when one experiences difficulty disclosing information or 
during task performance.  The overnight “off” state may result in discomfort and transient worsening of 
parkinsonism symptoms.   
 
Adequacy of Protection Against Risks: 
 
Recruitment and Informed Consent: 
Subjects will be recruited from the UM Movement Disorders clinic and by advertisement. Individuals willing to 
participate will be scheduled for the research procedures at which time the nature and risks of the procedures 
will again be review d with the subjects and a written informed consent form will be obtained by one of the 
study investigators. One copy of the signed consent form will be given to the subject, one will be placed in the 
patient’s medical record and a third will be kept in the patient’s study binder kept at the patient’s research site. 
Study visits will be conducted in Dr. Lee’s laboratory in East Hall at the University of Michigan. 
 
Protection Against Risk: 
Confidentiality of Research Information: The possibility of unintended disclosure of medical or research data is 
minimal, but not entirely impossible. We will employ stringent safeguards against unintended and inappropriate 
discovery and dissemination of personal medical and research data in our subjects by a multi-layered 
approach. All data bearing potential subject identifiers will reside solely in locked files in the offices of the study 
investigators. Original data collection documents will be maintained in secure files under the control of the 
investigators. Entries regarding details of the research project and its results will not be submitted to clinical 
medical databases. Electronic databases in the project will employ subject codes that cannot be linked directly 
to participants without a “key”, possessed only by the study investigators in a secure location, and maintained 
separately from the databases. Databases will be housed on protected UM servers. Personal information   
that would directly identify study subjects will not be used in any publications or presentations resulting        
from this research study, unless separate written permission is given by the subject (or proxy). Any superfluous 
records will be shredded. 
Clinical and Behavioral Testing: Care will be taken to minimize distress. The study protocol is designed with 
the minimum number of procedures and tasks, so as to minimize participant burden.  Subjects will be 
addressed in a courteous manner that does not infringe the patient’s dignity. These individuals are 
prepared to respond to patient anxiety, concern and other behavioral changes as appropriate to the 
situation. Offering breaks and 


11 
 
reassuring subjects will further minimize risks when necessary.  All study visits will occur in the morning.  
Subjects studied in the overnight “off state” will take their medication as soon as study procedures are 
concluled.   
 
E. Safety Monitoring: 
 
Review of study procedures and adverse effects will be performed on a monthly basis. The PI will be 
responsible for monitoring any break in confidentiality and for reporting any adverse events following 
University of Michigan IRB guidelines. For purposes of this study, an AE is defined as any unfavorable or 
unintended change in structure, function, signs, or symptoms temporally associated with participation in this 
study, whether or not a causal relationship with the study has been established. Clinically significant 
abnormalities may be considered an AE if deemed appropriate by the PI. Unexpected worsening of a pre-
existing condition is also considered an AE, as is the discovery of an abnormal finding during physical exam 
that was not included in the medical history. Breaches of confidentiality will be considered related to the 
research whenever they occur and will be reported. Withdrawals from the study and the reason for these 
withdrawals will also be reported. 
 
The PI and Co-I are in daily contact with the project research staff testing the participants, scoring and entering 
data, and will monitor their procedures to ensure that confidentiality is maintained. The PI will ensure that the 
IRB is notified of any adverse event following the IRB guidelines. Expected and unexpected serious (including 
fatal) adverse reactions and major unresolved disputes between the research investigator(s) and the research 
participant or between research investigator(s) will be expeditiously reported to the IRB of the University of 
Michigan. At the time of renewal, the IRB will be provided with a summary indicating the frequency of the 
monitoring, cumulative adverse event data, information regarding participant safety or ethics changes, 
confidentiality issues, benefit-to-risk changes and recommendations on continuing, changing or terminating the 
study. 
 
For independent oversight, Dr. Kelvin Chou, a Movement Disorder neurologist with considerable trial 
experience, will act as a DSMB. Dr. Chou will meet with the study team to review the protocol prior to study 
initiation, 6 months after study initiation, and then yearly. Dr. Chou will receive a study charter that empowers 
him to recommend significant study changes, including study termination. All AEs will be immediately 
communicated to Dr. Chou for review. 
 
Definitions: 
An Adverse Event is any undesirable experience occurring in a subject during a clinical trial, whether or not 
considered related to the investigational protocol. For reporting purposes, we will distinguish among pre-existing 
conditions and trial-emergent adverse events. 
Pre-Existing Conditions (i.e., undesirable experiences, signs, or symptoms that begin prior to Study Procedures) 
will not be reported as adverse events unless they worsen in intensity or frequency after study entry (i.e., satisfy 
definition of Trial-Emergent, below). 
Trial-Emergent Adverse Events are undesirable experiences, signs or symptoms that begin or worsen in intensity 
or frequency after the Screening Visit, and prior to administration of study drug at the Imaging Visit. These will 
be reported as adverse events. 
Serious Adverse Event: A serious adverse event is an adverse event that is fatal or life-threatening, or results in 
hospitalization, prolongation of hospitalization, persistent or significant disability/incapacity, or a congenital 
anomaly/birth defect. A life-threatening adverse event is an adverse event that, in the view of the investigators, 
places the subject at immediate risk of death from the reaction, as it occurred. 
Unexpected Adverse Event: An unexpected adverse event is an experience not previously reported or an 
adverse event that occurs with specificity, severity or frequency that is not consistent with the investigator’s prior 
experience with the research methods. 
Relationship to Research Protocol: The assessment of the relationship of an adverse event to the study protocol 
(none, remote, possible, and probable) is a clinical decision based on all available information at the time of 
resolution or stabilization. The following definitions of the relationship between the study procedures and the 
adverse event (including serious adverse events) will be considered: 


12 
 
Remote (unlikely, doubtful, improbable): The time course of the study procedure(s) and the occurrence or 
worsening of the adverse event makes a causal relationship unlikely and another cause is probable. 
 
Possible: The time course of the study procedure(s) and the occurrence or worsening of the adverse event is 
consistent with a causal relationship, but another cause cannot be ruled out. OR The time course of the study 
procedure(s) and the occurrence or worsening of the adverse event is not consistent with a causal relationship 
but no alternative cause can be identified.  If the Investigators are unable to assess causality, the adverse event 
will be considered “Possible” by definition and not “Remote.”  
Probable: The time course of the study procedure(s) and the occurrence or worsening of the adverse event is 
consistent with a causal relationship, and no other cause can be identified. 
Intensity/Severity of an Adverse Event: In addition to assessing the relationship of the administration of the 
investigational product/procedure to adverse events, an assessment is required of the intensity (severity) of the 
event. The following classifications will be used: 
Mild: A mild adverse event is usually transient in nature and generally does not interfere with normal activities. 
Moderate: A moderate adverse event is sufficiently discomforting to interfere with normal activities. 
Severe: A severe adverse event is incapacitating and prevents normal activities. However, a severe event is not 
necessarily a serious event.  Nor must a serious event necessarily be severe. 
 
References 
1)         Postuma RB, Berg D, Stern M, et al. MDS clinical diagnostic criteria for Parkinson's disease.   
Mov Disord 2015;30:1591-601. PMID: 26474316 
2) 
Albin RL, Leventhal DK. The missing, the short, and the long: L-dopa responses and 
dopamine actions. Ann Neurol 2017;82:4-19. PMID: 28543679 
3) 
Anderson E, Nutt J. The long-duration response to levodopa: phenomenology, potential 
mechanisms and clinical implications. Parkinsonism Relat Disord 2011;17:587–592. PMID: 
21530536 
4) 
Nutt JG, Holford NH. The response to levodopa in Parkinson's disease: imposing pharmacological 
law and order. Ann Neurol 1996;39:561–573. PMID: 8619540 
5) 
Hauser RA, Holford NH. Quantitative description of loss of clinical benefit following withdrawal of 
levodopa-carbidopa and bromocriptine in early Parkinson's disease. Mov Disord 2002;17:961–
968. PMID: 12360545 
6) 
Holford NH, Chan PL, Nutt JG, et al. Disease progression and pharmacodynamics in Parkinson 
disease—evidence for functional protection with levodopa and other treatments. J 
Pharmacokinet Pharmacodyn2006;33:281–311. PMID: 16625427 
7) 
Nutt JG, Carter JH, Lea ES, Sexton GJ. Evolution of the response to levodopa during the first 4 
years of therapy. Ann Neurol 2002;51:686–693. PMID: 12112073 
8) 
Nutt JG, Woodward WR, Carter JH, Gancher ST. Effect of long-term therapy on the 
pharmacodynamics of levodopa. Relation to on-off phenomenon. Arch Neurol 1992;49:1123–1130. 
PMID: 1444877 
9) 
Nutt JG, Carter JH. Apomorphine can sustain the long-duration response to L-DOPA in 
fluctuating PD. Neurology 2000;54:247–250. PMID: 10636162 
10) 
Barbato L, Stocchi F, Monge A, et al. The long-duration action of levodopa may be due to 
a postsynaptic effect. Clin Neuropharmacol 1997;20:394–401. PMID: 9331515 
11) 
Stocchi F, Vacca L, Berardelli A, et al. Long-duration effect and the postsynaptic compartment: 
study using a dopamine agonist with a short half-life. Mov Disord 2001;16:301–305. PMID: 
11295785 
12) 
Nutt JG, Nygaard TG. Response to levodopa treatment in dopa-responsive dystonia. Arch 
Neurol 2001;58:905–910. PMID: 11405805 
13) 
Schultz W. Neuronal reward and decision signals: from theories to data. Physiol Rev 2015;95:853–
951. PMID: 26109341 
14) 
Glimcher PW. Understanding dopamine and reinforcement learning: the dopamine reward 
prediction error hypothesis. Proc Natl Acad Sci U S A 2011;108:15647–15654. PMID: 21389268 
15) 
Keiflin R, Janak PH. Dopamine prediction errors in reward learning and addiction: from theory to 
neural circuitry. Neuron 2015;88:247–263. PMID: 26494275 


13 
 
16) 
Schultz W. Multiple dopamine functions at different time courses. Ann Rev Neurosci 2007;30:259–
288. PMID: 17600522 
17) 
Schultz W. Reward prediction error. Curr Biol 2017;27:R369-R371. PMID: 28535383 
18) 
Bohnen NI, Albin RL, Koeppe RA, et al. Positron emission tomography of monoaminergic 
vesicular binding in aging and Parkinson disease. J Cereb Blood Flow Metab 2006;26:1198–
1212. PMID: 16421508 
19) 
Garris PA, Walker QD, Wightman RM. Dopamine release and uptake rates both decrease in the 
partially denervated striatum in proportion to the loss of dopamine terminals. Brain Res 
1997;753:225– 234. PMID: 9125407 
20) 
Janezic S, Threlfell S, Dodson PD, et al. Deficits in dopaminergic transmission precede neuron loss 
and dysfunction in a new Parkinson model. Proc Natl Acad Sci U S A 2013;110:E4016–E4025. 
PMID: 24082145 
21) 
Salamone JD, Correa M, Farrar AM, et al. Dopamine, behavioral economics, and effort. Front 
Behav Neurosci 2009;3:13. PMID: 19826615 
22) 
Salamone JD, Correa M. The mysterious motivational functions of mesolimbic dopamine. 
Neuron 2012;76:470–485. PMID: 23141060 
23) 
Beeler JA, Frazier CR, Zhuang X. Putting desire on a budget: dopamine and energy 
expenditure, reconciling reward and resources. Front Integr Neurosci 2012;6:49. PMID: 
22833718 
24) 
Yttri EA, Dudman JT. A Proposed Circuit Computation in Basal Ganglia: History-Dependent Gain. 
Mov Disord 2018;33:704-716. PMID: 29575303 
25) 
Dudman JT, Krakauer JW. The basal ganglia: from motor commands to the control of vigor. Curr 
Opin Neurobiol 2016;37:158-166. PMID: 27012960 
26) 
Mazzoni P, Hristova A, Krakauer JW. Why don't we move faster? Parkinson's disease, 
movement vigor, and implicit motivation. J Neurosci 2007;27:7105–7116. PMID: 17611263 
27) 
Baraduc P, Thobois S, Gan J, et al. A common optimization principle for motor execution in 
healthy subjects and parkinsonian patients. J Neurosci 2013;33:665–677. PMID: 23303945 
28) 
Chong TT, Bonnelle V, Manohar S, et al. Dopamine enhances willingness to exert effort for reward 
in Parkinson's disease. Cortex 2015;69:40–46. PMID: 25967086 
29) 
Gepshtein S, Li X, Snider J, et al. Dopamine function and the efficiency of human movement. J 
Cogn Neurosci 2014;26:645–665. PMID: 24144250 
30) 
Niv Y, Daw ND, Joel D, Dayan P. Tonic dopamine: opportunity costs and the control of 
response vigor. Psychopharmacology (Berl) 2007;191:507–520. PMID: 17031711 
31) 
Shadmehr R, Huang HJ, Ahmed AA. A representation of effort in decision making and motor 
control. Curr Biol 2016;26:1929-34. PMID: 27374338 
32) 
Cagniard B, Beeler JA, Britt JP, et al. Dopamine scales performance in the absence of 
new learning. Neuron 2006;51:541–547. PMID: 16950153 
33) 
Beeler JA, Daw N, Frazier CR, Zhuang X. Tonic dopamine modulates exploitation of 
reward learning. Front Behav Neurosci 2010;4:170. PMID: 21120145 
34) 
Panigrahi B, Martin KA, Li Y, et al. Dopamine is required for the neural representation and control 
of movement vigor. Cell 2015;162:1418–1430. PMID: 26359992 
35) 
Petrou M, Bohnen NI, Müller ML, Koeppe RA, Albin RL, Frey KA. Aβ-amyloid deposition in patients 
with Parkinson disease at risk for development of dementia. Neurology 2012;79:1161-1167. PMID: 
22933741 
36) 
Schmidt L, d'Arc BF, Lafargue G, et al. Disconnecting force from money: effects of basal 
ganglia damage on incentive motivation. Brain 2008;131:1303-1310. PMID: 18344560 
37) 
Muranishi M, Inokawa H, Yamada H, et al. Inactivation of the putamen selectively impairs 
reward history-based action selection. Exp Brain Res 2011;209:235–246. PMID: 21298425 
38) 
Wang AY, Miura K, Uchida N. The dorsomedial striatum encodes net expected return, critical 
for energizing performance vigor. Nat Neurosci 2013;16:639–647. PMID: 23584742 
39) 
Hikosaka O, Ghazizadeh A, Griggs W, Amita H. Parallel basal ganglia circuits for decision making. 
J Neural Transm (Vienna) 2017 Feb 2. doi: 10.1007/s00702-017-1691-1. PMID: 28155134 
40) 
Kim HF, Ghazizadeh A, Hikosaka O. Dopamine Neurons Encoding Long-Term Memory of Object 
Value for Habitual Behavior. Cell 2015;163:1165-1175. PMID: 26590420 


14 
 
41) 
Anderson BA, Laurent PA, Yantis S. Value-driven attentional capture. Proc Natl Acad Sci 
USA 2011;108:10367-10371. PMID: 21646524 
42) 
Anderson BA, Yantis S. Vlaue-driven attentional and oculomotor capture during goal-
directed, unconstrained viewing. Atten Percept Psychophys 2012;74:1644-1653. PMID: 
22810561 
43) 
Theeuwes J, Belopolsky AV. Reward grabs the eye: Oculomotor capture by rewarding stimuli. Vis 
Res 2012;74:80-85. PMID: 22902641 
44) 
Anderson BA, Kuwabara H, Wong DF, et al. The Role of Dopamine in Value-Based 
Attentional Orienting. Curr Biol 2016 ;26:550-555. PMID: 26877079 
45) 
Anderson BA, Yantis S. Persistence of value-driven attentional capture. J Exp Psych Hum 
Percept Perform 2013;39:6-9. PMID: 23181684 
46) 
da Silva JA, Tecuapetla F, Paixão V, Costa RM. Dopamine neuron activity before action initiation 
gates and invigorates future movements. Nature 2018;554:244-248. PMID: 29420469 
47) 
Thura D, Cisek P. The Basal Ganglia Do Not Select Reach Targets but Control the Urgency 
of Commitment. Neuron 2017;95:1160-1170.e5. PMID: 28823728 
48) 
Gadagkar V, Puzerey PA, Chen R, Baird-Daniel E, Farhang AR, Goldberg JH. Dopamine 
neurons encode performance error in singing birds. Science 2016;354:1278-1282. PMID: 27940871 
 
 

ICF_001.pdf: 
Vigor and the LDR in Parkinson Disease 
 
NCT04821830    
 
Date of IRB Approval: December 13, 2023 


Page 1 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
UNIVERSITY OF MICHIGAN
CONSENT TO BE PART OF A RESEARCH STUDY
1.  KEY INFORMATION ABOUT THE RESEARCHERS AND THIS STUDY  
Study title:   Vigor and the LDR in Parkinson disease
Company or agency sponsoring the study:  
National Institute of Neurologic Disease and Stroke-National Institutes of Health
Names, degrees, and affiliations of the principal investigator and study coordinator (if applicable):
Principal Investigator:  Roger L. Albin, MD
Study Coordinator: Teresa Scerbak, BS, CCRP
1.1 Key Study Information
You may be eligible to take part in a research study.  This form contains important information that will help 
you decide whether to join the study.  Take the time to carefully review this information.  You should talk to 
the researchers about the study and ask them any questions you have.  You may also wish to talk to others 
such as your family, friends, or other doctors about joining this study.  If you decide to join the study, you will 
be asked to sign this form before you can start study-related activities.  Before you do, be sure you understand 
what the research study is about.
A research study is different from the regular medical care you receive from your doctor.  Research studies 
hope to make discoveries and learn new information about diseases and how to treat them.  You should 
consider the reasons why you might want to join a research study or why it is not the best decision for you at 
this time.  
Research studies do not always offer the possibility of treating your disease or condition.  Research studies also 
have different kinds of risks and risk levels, depending on the type of the study.  You may also need to think 
about other requirements for being in the study.  For example, some studies require you to travel to scheduled 
visits at the study site in Ann Arbor or elsewhere. This may require you to arrange travel, change work 
schedules, find child care, or make other plans.  In your decision to participate in this study, consider all of 
these matters carefully.  
This is aimed at understanding how the most common treatment for Parkinson disease works in the brain. 
There can be risks associated with joining any research study.  The type of risk may impact whether you decide 
to join the study.  For this study, some of these risks may include short periods of nausea or fatigue.  More 
detailed information will be provided later in this document.
This study may not offer any benefit to you now but may benefit others in the future by leading to improved 
treatments of Parkinson disease.  More information will be provided later in this document.
We expect the amount of time you will participate in the study will be 4 days for Experiment 1, 5 days for 
Experiment 2 or 9 days if you choose to participate in both studies, over the course of 2 years.
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 2 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
You can decide not to be in this study.  Alternatives to joining this study include continuing your routine care.
Even if you decide to join the study now, you are free to leave at any time if you change your mind.
More information about this study continues in Section 2 of this document.
2. PURPOSE OF THIS STUDY
2.1 Study purpose: 
Parkinson disease is a common disorder in which reduced speed of movement results from inadequate brain 
production of the chemical dopamine.  The most effective treatment for Parkinson disease is the drug levo-
dopa, which partially replaces brain dopamine.  Despite decades of successful use, the ways levo-dopa 
improves speed of movement in Parkinson disease is not understood.  There is a very important component of 
levo-dopa action, the Long Duration Response (LDR), that lasts for days to weeks.  We do not understand how 
the LDR works.  The purpose of these experiments is to understand how levo-dopa treatment in Parkinson 
disease enhances movement speed.  Understanding how the levo-dopa treatment produces the LDR may lead 
to improved treatment of Parkinson disease.
3. WHO MAY PARTICIPATE IN THE STUDY
Taking part in this study is completely voluntary.  You do not have to participate if you don't want to.  You may 
also leave the study at any time.  If you leave the study before it is finished, there will be no penalty to you, 
and you will not lose any benefits to which you are otherwise entitled. 
3.1 Who can take part in this study?
To be eligible to participate:

Diagnosis of Parkinson Disease

Previously Untreated or treated for <4 weeks

Age >45 and <91

Mild to Moderate Parkinson disease  (Hoehn & Yahr Stages I-II)

About to start treatment with a L-Dopa preparation (Sinemet)
Subjects with any of the following are not eligible to participate in this study:

The presence of other neurologic disease or findings on examination

Depression: Geriatric Depression Scale score >11

Use of dopamine agonists or stimulants

Evidence of a stroke or mass lesion on prior structural brain imaging (MRI or CT)

Evidence of any confounding medical or psychiatric problem that would preclude task participation.

Participants with cognitive impairment that might impair their capacity to provide informed consent.

Evidence of color vision deficiency (experiment 2 only)
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 3 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
3.2 How many people are expected to take part in this study?
Approximately 40 participants will take part in this study. If the study research site, the research sponsor, or 
you believe that going in to the study center might put you at risk of exposure to the novel coronavirus 
(COVID-19), then some of the procedures usually done at study visits may be done over the phone.
4.  INFORMATION ABOUT STUDY PARTICIPATION
4.1 What will happen to me in this study?
  
Participation in this study involves testing your ability to perform movements under different conditions.  
These evaluations are performed at 4 times, 2 times before the start of your routine treatment for Parkinson 
disease and 2 times after the start of your routine treatment for Parkinson disease.  There are 2 experiments.  
Participants may take part in either one or both of these experiments.
Experiment 1 (see Table 1 below for Visit Schedule):  
Standard Clinical Evaluation:  At each study visit, all participants will undergo a standard clinical evaluation 
consisting of a physical examination by one of our physicians to assess severity of Parkinson disease, and a 
simple task to evaluate your speed of movement.  You will be asked to alternatively tap two counters spaced 
about 1.5 feet apart as fast as you can.  You will fill out questionnaires to assess aspects of mood and your 
thinking. These evaluations will take about 1.5 hours. 
Movement Tasks: 
You will be asked to perform 2 tasks assessing control of speed of movement.  In the first task, you will be 
asked to squeeze a hand-held grip strength monitor in proportion to an offered small monetary reward.  There 
will be a number of trials in which you are offered varying reward amounts.  How hard you squeeze the grip 
strength monitor will be recorded in each trial.  In the second task, you will move a joystick against varying 
resistance, again in proportion to a small monetary reward.  Your speed and force of movement will be 
recorded.  These tasks will take about 1.5 hours.
There will be 4 study visits for Experiment 1 (see Table 1 below for Visit Schedule).  The first and second visits 
(baseline visits) will take place prior to your starting treatment for your Parkinson disease.  The third and 
fourth visits (follow-up visits) will occur 2-3 months after you start treatment and when you have been on a 
stable dose of your Parkinson disease medication for weeks.

Visit 1:  For the Baseline Visit 1 session, you will not have taken any Parkinson disease medication.

Visit 2:  Baseline Visit 2 will take place within 2 weeks of Baseline Visit 1.  For this Visit, you will take a 
standard dose of the preferred medication for Parkinson disease – carbidopa/levodopa 25/250 – wait 
approximately 1 hour and repeat the evaluations and tasks.  First time use of carbidopa/levodopa 
occasionally produces nausea or lightheadedness.  To reduce the chance of these side-effects 
occurring, we will ask you to take carbidopa for the prior 24 hours.

Visit 3:  Follow-up Visit 1 will be identical to the Baseline Visit with 1 exception.  You will be asked not 
to take your usual Parkinson disease medication the morning of the Follow-up Visit.  You will resume 
your usual Parkinson disease medications after the evaluations and tasks are complete.
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 4 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023

Visit 4:  Follow-up Visit 2 will take place within 2 weeks of Follow-up Visit 1.  It will be identical to 
Follow-up Visit 1 except that you will take your usual Parkinson disease medications on your usual 
schedule.
Experiment 1: Table of Visits
Visit Evaluations
Visit 1
Visit 2
Visit 3
Visit 4
Examination
X
X
X
X
Cognitive Tests
X
X
X
X
Mood Questions
X
X
X
X
Tapping Task
X
X
X
X
Grip Strength 
Task
X
X
X
X
Joystick Task
X
X
X
X
Experiment 1: Visit Schedule
Visit Component 
Time Requirement
Clinical History; Neurologic Examination; 
Evaluation PD Severity; Tapping Task
0.5 Hour
Questionnaires for Thinking and Mood
1 Hour
Movement Tasks
1.5 Hour
Experiment 2:    
Standard Clinical Evaluation:  At each study visit, all participants will undergo a standard clinical evaluation 
consisting of a physical examination by one of our physicians and answer questions to assess severity of 
Parkinson disease. These evaluations will take about 30 minutes. In addition to the standard clinical evaluation, 
at the training visit, participants will be asked to complete questionnaires to assess aspects of your thinking 
and mood and look at a series of images designed to detect red-green color deficiencies. These tasks will take 
about 1 hour.  
Eye Movement Task:  This task has 2 components; a training component and a test component.  
In the training component, you will be asked to look at a computer screen and move your focus of vision as 
quickly as possible from the center of the computer screen to visual targets around the screen.  You will be 
rewarded for moving your vision towards some targets but not others.  In the test component, you will be 
presented with the visual targets and asked to look quickly at some but not others.  Where you look and how 
fast you move your vision from the center of the screen to the targets will be recorded.  Both training and test 
sessions will take about 1 hour. 
Movement Task: You will be asked to perform a task to assess control of speed of movement. In this task, you 
will move a joystick against varying resistance, in proportion to a small monetary reward.  Your speed and 
force of movement will be recorded.  This task will take about 30 minutes.
There will be 5 study visits for Experiment 2.  The first, training visit, will take place before you start treatment 
for your Parkinson disease.  The second and third visits will be test visits.  They will take place before you start 
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 5 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
treatment for your Parkinson disease.  The third and fourth visits will occur 2-3 months after you start 
treatment and when you have been on a stable dose of your Parkinson disease medication for weeks.

Training Visit:  You will undergo training at this visit.

Test Visit 1:  For the First Test Visit, you will not have taken any Parkinson disease medication.

Test Visit 2:  Test Visit 2 will take place within 2 weeks of Test Visit 1.  For this Visit, you will take a 
standard dose of the preferred medication for Parkinson disease – carbidopa/levodopa 25/250 – wait 
approximately 1 hour and repeat the evaluations and tasks.  First time use of carbidopa/levodopa 
occasionally produces nausea or lightheadedness.  To reduce the chance of these side-effects 
occurring, we will ask you to take carbidopa for the prior 24 hours.

Test Visit 3:  The Third Test Visit will be identical to the First Test Visit with 1 exception.  You will be 
asked to take your Parkinson disease medication on your usual schedule or not to take your 
medication the morning of the Third Test Visit. The researcher will let you know whether you should 
take your Parkinson disease medication or not. If you are asked to not take your Parkinson disease 
medication the morning of your visit, you will resume your usual Parkinson disease medications after 
the evaluations and tasks are complete.

Test Visit 4:  Follow-up Visit 2 will take place within 2 weeks of Follow-up Visit 1.  It will be identical to 
Follow-up Visit 1 with 1 exception.  You will be asked to take your Parkinson disease medication on 
your usual schedule or not to take your medication the morning of the Fourth Test Visit. The 
researcher will let you know whether you should take your medication or not.  If you are asked to not 
take your Parkinson disease medication the morning of your visit, you will resume your usual 
Parkinson disease medications after the evaluations and tasks are complete.
Experiment 2: Table of Visits
Visit Evaluations
Training Visit
Visit 1
Visit 2
Visit 3
Visit 4
Examination
X
X
X
X
X
Cognitive Tests
X
Mood Questions
X
Color Vision 
Test
X
Joystick Task
X
X
X
X
Eye Movement 
Task
X (Training)
X
X
X
X
Experiment 2: Visit Schedule
Visit Component 
Time Requirement
Clinical History; Neurologic Examination; 
Evaluation PD Severity
0.5 Hour
Questionnaires for Thinking and Mood
1 Hour
Movement Task 
0.5 Hour 
Eye Movement Task
1 Hour
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 6 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
Participants in Experiment 1 may also participate in Experiment 2.  
As a subject participating in this research study, you have certain responsibilities that may apply to this study, 
such as ensuring that you arrive at all of your scheduled appointments, take your study medication as directed, 
and report any adverse reactions you may have during the study. 
Coronavirus (COVID-19) Procedures
It is possible you will not be able to go in to the study center for a scheduled visit because of the Coronavirus. If 
this happens, the study doctor may ask you to complete some of the visit procedures over the phone instead 
of face-to-face.
4.2 How much of my time will be needed to take part in this study?  
Experiment 1 will consist of 4 study visits approximately 2-3 months apart.  Each study visit will take 
approximately 3 hours.  
Experiment 2 will consist of 5 study visits, with the second and third visits approximately 2-3 months apart. The 
training visit will take approximately 3.5 hours. Each remaining study visit will take approximately 3 hours.
4.3 When will my participation in the study be over? 
Study participation will end after all testing is complete.  However, you may withdraw from the study at any 
point in time. 
4.4 What will happen with my information and/or biospecimens used in this study?
Your collected information may be shared with the National Institute of Neurologic Disease and Stroke – 
National Institutes of Health.
With appropriate permissions, your collected information may also be shared with other researchers, here, or 
around the world, or with companies.
Your identifiable private information may be stripped of identifiers and used for future research studies or 
distributed to another researcher for future research studies without additional informed consent. 
5.  INFORMATION ABOUT STUDY RISKS AND BENEFITS
5.1 What risks will I face by taking part in the study?  What will the researchers do to protect me against 
these risks?
The known or expected risks are:

Confidentiality of Research Information: The research data to be collected from subjects will consist of 
confidential information relating to clinical, neuropsychological, mood, neuroanatomical, and 
neurochemical functions. These research data are not intended for entry into the subjects’ clinical 
medical records. However, the data remain potentially discoverable. This may lead to violation of 
privacy and embarrassment of the subject.  This is rare (<1% of participants).  

Clinical and Behavioral Testing: Risks in regard to the behavioral assessment are limited to fatigue, 
frustration and momentary embarrassment that may occur when one experiences difficulty disclosing 
information or during task performance.  This is uncommon (<10% of participants).  Risks of 
undergoing the motor testing in the (overnight) dopaminergic “off” state may result in some 
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 7 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
discomfort and the possibility of worsened parkinsonian motor symptoms the morning of the research 
testing assessment (infrequent). Temporary withdrawal of dopaminergic medication will be required 
for >12 hours (overnight) prior to testing in the morning of the 3rd or 4th visit. There may be discomfort 
or transient worsening of Parkinson symptoms when participants are tested on a day when they 
withhold their their usual PD medications.  In our experience, this is not common (<10% of 
participants).  If you feel the need to take your regular PD medications at any point because of 
discomfort or for any other medical reason, please let us know and we can make sure that you get 
your regular medication at that time. 

Initial Use of Levodopa:  Initial use of carbidopa/levodopa is sometimes accompanied by nausea or 
lightheadedness. This is uncommon (<10% of participants).
The researchers will try to minimize these risks by:

Confidentiality of Research Information: The possibility of unintended disclosure of medical or 
research data is minimal, but not entirely impossible. We will employ stringent safeguards against 
unintended and inappropriate discovery and dissemination of personal medical and research data in 
our subjects by a multi-layered approach. All data bearing potential subject identifiers will reside solely 
in locked files in the offices of the study investigators. Original data collection documents will be 
maintained in secure files under the control of the investigators. Entries regarding details of the 
research project and its results will not be submitted to clinical medical databases. Electronic 
databases in the project will employ subject codes that cannot be linked directly to participants 
without a “key”, possessed only by the study investigators in a secure location, and maintained 
separately from the databases. Databases will be housed on protected UM servers. Personal 
information that would directly identify study subjects will not be used in any publications or 
presentations resulting from this research study, unless separate written permission is given by the 
subject (or proxy). Any superfluous records will be shredded.

Clinical and Behavioral Testing: Care will be taken to minimize distress. Subjects will be addressed in a 
courteous manner that does not infringe the patient’s dignity. These individuals are prepared to 
respond to patient anxiety, concern and other behavioral changes as appropriate to the situation. 
Offering breaks and reassuring subjects will further minimize risks when necessary.  The off-state 
testing at the 3rd  visit (Experiment 1) or 4th visit (Experiment 2) will occur soon after the subjects arrive 
on the testing day so that they may be allowed to take their dopaminergic medications immediately 
afterwards. Any subjects that need to take their medications and reschedule the study visit will be able 
to do so any point should they like.

Initial Levodopa Treatment:  To reduce the risk of nausea or lightheadedness with initial Levodopa use, 
you will be asked to take carbidopa, a routine component of the standard treatment for Parkinson 
disease, for 24 hours prior to your Baseline (Experiment 1) or First Test (Experiment 2) Study Visit.  
See Section 9 of this document for more information on how the study team will protect your confidentiality 
and privacy.
As with any research study, there may be additional risks that are unknown or unexpected.
5.2 What happens if I get hurt, become sick, or have other problems as a result of this research?
The researchers have taken steps to minimize the risks of this study.  You will be directly monitored during all 
study visits.  Even so, you may still have problems or side effects, even when the researchers are careful to 
avoid them. Please tell the researchers listed in Section 10 about any injuries, side effects, or other problems 
that you have during this study.  You should also tell your regular doctors.
If you become ill, are hurt or injured, or feel you are experiencing a medical emergency at any point during or 
after the study, immediately dial 911 or visit your nearest emergency room. First aid and emergency care is 
readily available and will be provided to you by the University of Michigan Health System in case any 
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 8 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
complications, adverse effects, or health threatening events may arise during the course of testing.  If at a later 
point in the time you believe the study has made you sick or caused you injury, contact one of the people 
listed in section 10 of this document (Contact Information) after seeking care from your doctor or the 
emergency room.
5.3 If I take part in this study, can I also participate in other studies?
Being in more than one research study at the same time, or even at different times, may increase the risks to 
you.  It may also affect the results of the studies.  You should not take part in more than one study without 
approval from the researchers involved in each study.  
5.4 How could I benefit if I take part in this study?  How could others benefit?  
You may not receive any personal benefits from being in this study. However, others may benefit from the 
knowledge gained from this study.  Results from this study may be useful in improving treatment of Parkinson 
disease. 
5.5 Will the researchers tell me if they learn of new information that could change my willingness to stay in 
this study?
Yes, the researchers will tell you if they learn of important new information that may change your willingness 
to stay in this study. If new information is provided to you after you have joined the study, it is possible that 
you may be asked to sign a new consent form that includes the new information.
6.  ALTERNATIVES TO PARTICIPATING IN THE STUDY
6.1 If I decide not to take part in this study, what other options do I have?
You do not have to participate in this study. You may discontinue your participation from the study at any time 
without penalty. Taking part in the research is not a treatment or part of your routine medical care.
7.  ENDING THE STUDY
7.1 If I want to stop participating in the study, what should I do?
You are free to leave the study at any time.  If you leave the study before it is finished, there will be no penalty 
to you. You will not lose any benefits to which you may otherwise be entitled.  If you choose to tell the 
researchers why you are leaving the study, your reasons for leaving may be kept as part of the study record. If 
you decide to leave the study before it is finished, please tell one of the persons listed in Section 10 “Contact 
Information”.
7.2 Could there be any harm to me if I decide to leave the study before it is finished? 
There is no harm in leaving the study before it is finished. However, if you decide to leave the study during 
some of the procedures we may ask you to stay until it is deemed safe to leave.
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 9 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
7.3 Could the researchers take me out of the study even if I want to continue to participate?
Yes. There are many reasons why the researchers may need to end your participation in the study.  Some 
examples are:

The researcher believes that it is not in your best interest to stay in the study.

You become ineligible to participate.

Your condition changes and you need treatment that is not allowed while you are taking part in the 
study.

You do not follow instructions from the researchers.

The study is suspended or canceled.
8.  FINANCIAL INFORMATION
8.1 Who will pay for the costs of the study?  Will I or my health plan be billed for any costs of the study?  
There are no costs or billing for this study. 
You or your health plan will pay for all the things you would have paid for even if you were not in the study, 
like: 

Health care given during the study as part of your regular care 

Items or services needed to give you study drugs or devices 

Monitoring for side effects or other problems 

Deductibles or co-pays for these items or services. 
If you do not have a health plan, or if you think your health plan may not cover these costs during the study, 
please talk to the researchers listed in Section 10 below or call your health plan’s medical reviewer. 
There is the potential that the research evaluations may have caused you anxiety or worries about your health. 
You may need or want to investigate these health concerns further for an appropriate diagnosis. However, any 
procedures or tests should be obtained separately if your doctor believes that you require those tests for your 
diagnosis. These additional studies and appropriate treatment, if necessary, will not be paid for by this study. 
The study team has given you instructions about this research study. It is important that you follow these 
instructions carefully. If you get sick, have a medical complication, or are injured as a result of your being in the 
study, page Dr. Albin immediately, at 734-936-6267. The doctor will either treat you or send you to another 
doctor for treatment. 
By signing this form, you do not give up your right to seek payment if you are harmed as a result of being in 
this study. 
8.2 Will I be paid or given anything for taking part in this study?
Yes.  To compensate for travel expenses, you will receive $50 at the first study visit, regardless of whether you 
complete the study. For completing either Experiment 1 or Experiment 2, you will receive an additional $150.  
For completing both experiments, you will receive an additional $250.  The total compensation possible for 
participation in both Experiments 1 and 2 is $300.  
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 10 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
Study Payment Schedule
Study Component
Compensation
Study Enrollment
$50
Complete Experiment 1 or Experiment 2
$150
Complete Both Experiment 1 and Experiment 2
$250
8.3 Who could profit or financially benefit from the study results?
Neither the researchers conducting the study nor the University of Michigan will have financial profit from the 
study results.
9. CONFIDENTIALITY OF SUBJECT RECORDS AND AUTHORIZATION TO RELEASE YOUR PROTECTED HEALTH 
INFORMATION
The information below describes how the confidentiality of your research records will be protected in this 
study, and any sub-studies described in this document.  
9.1 How will the researchers protect my information? 
Your research records will be stored in a secure location to which only the investigators have access. All 
research records will be stored under code numbers, without attached names or other identifying information. 
The “key” linking these records to subject names will be stored in a separate, locked (electronic) file.  Your 
research records will not be part of your medical records.
A description of this clinical trial will be available on www.ClinicalTrials.gov (http://www.clinicaltrials.gov/), as 
required by US law. This website will not include information that can identify you. At most, the website will 
include a summary of the results. You can search this website at any time.
This research is covered by a Certificate of Confidentiality from the National Institutes of Health. The 
researchers with this Certificate may not disclose or use information, documents, or biospecimens that may 
identify you in any federal, state, or local civil, criminal, administrative, legislative, or other action, suit, or 
proceeding, or be used as evidence, for example, if there is a court subpoena, unless you have consented for 
this use. Information, documents, or biospecimens protected by this Certificate cannot be disclosed to anyone 
else who is not connected with the research except, if there is a federal, state, or local law that requires 
disclosure (such as to report child abuse or communicable diseases but not for federal, state, or local civil, 
criminal, administrative, legislative, or other proceedings, see below); if you have consented to the disclosure, 
including for your medical treatment; or if it is used for other scientific research, as allowed by federal 
regulations protecting research subjects. 
The Certificate cannot be used to refuse a request for information from personnel of the United States federal 
or state government agency sponsoring the project that is needed for auditing or program evaluation by the 
SPONSOR which is funding this project or for information that must be disclosed in order to meet the 
requirements of the federal Food and Drug Administration (FDA).  You should understand that a Certificate of 
Confidentiality does not prevent you from voluntarily releasing information about yourself or your 
involvement in this research. If you want your research information released to an insurer, medical care 
provider, or any other person not connected with the research, you must provide consent to allow the 
researchers to release it.
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 11 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
The Certificate of Confidentiality will not be used to prevent disclosure as required by federal, state, or local 
law of [list what will be reported, such as child abuse and neglect, or harm to self or others]. 
The Certificate of Confidentiality will not be used to prevent disclosure for any purpose you have consented to 
in this informed consent document.
9.2 What protected health information (PHI) about me could be seen by the researchers or by other people?  
Why?  Who might see it?
Signing this form gives the researchers your permission to obtain, use, and share information about you for 
this study, and is required in order for you to take part in the study.  
Medical information and billing records are protected by the privacy regulations of the federal Health 
Insurance Portability and Accountability Act of 1996 (HIPAA).  This type of information is called protected 
health information (PHI).  PHI about you may be obtained from any hospital, doctor, and other health care 
provider involved in your care, including:

Hospital/doctor's office records, including test results (X-rays, blood tests, urine tests, etc.)

Mental health care records (except psychotherapy notes not kept with your medical records)

Alcohol/substance abuse treatment records

HIV/AIDS status

Sexually transmitted disease and/or other communicable disease status

Genetic counseling/genetic testing records

Health plan/health insurance records

All records relating to your condition, the treatment you have received, and your response to the 
treatment

Billing information

Demographic information

Personal identifiers

Other information
There are many reasons why information about you may be used or seen by the researchers or others during 
or after this study.  Examples include:

The researchers may need the information to make sure you can take part in the study.  

The researchers may need the information to check your test results or look for side effects. 

University, Food and Drug Administration (FDA) and/or other government officials, auditors, and/or 
the IRB may need the information to make sure that the study is done in a safe and proper manner.   

Study sponsors or funders, or safety monitors or committees, may need the information to: 
o
Make sure the study is done safely and properly
o
Learn more about side effects 
o
Analyze the results of the study 

The researchers may need to use the information to create a databank of information about your 
condition or its treatment. 

If you receive any payments for taking part in this study, the University of Michigan accounting 
department may need your name, address, Social Security number, payment amount, and related 
information for tax reporting purposes.
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 12 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023

Federal or State law may require the study team to give information to government agencies. For 
example, to prevent harm to you or others, or for public health reasons. 
The results of this study could be published in an article, but would not include any information that would let 
others know who you are. 
9.3 What happens to information about me after the study is over or if I cancel my permission to use my 
PHI?
As a rule, the researchers will not continue to use or disclose information about you, but will keep it secure 
until it is destroyed.  Sometimes, it may be necessary for information about you to continue to be used or 
disclosed, even after you have canceled your permission or the study is over.
Examples of reasons for this include:

To avoid losing study results that have already included your information 

To provide limited information for research, education, or other activities. (This information would not 
include your name, social security number, or anything else that could let others know who you are.) 

To help University and government officials make sure that the study was conducted properly
As long as your information is kept within the University of Michigan Health System, it is protected by the 
Health System’s privacy policies.  For more information about these policies, ask for a copy of the University of 
Michigan “Notice of Privacy Practices”.  This information is also available on the web at 
http://www.uofmhealth.org/patient+and+visitor+guide/hipaa.  Note that once your information has been 
shared with others as described under Question 9.2, it may no longer be protected by the privacy regulations 
of the federal Health Insurance Portability and Accountability Act of 1996 (HIPAA).  
9.4 When does my permission to use my PHI expire?
Your permission expires at the end of the study, unless you cancel it sooner. You may cancel your permission 
at any time by writing to the researchers listed in Section 10 "Contact Information" (below).  If you withdraw 
your permission, you may no longer be eligible to participate in this study.
9.5 Will I be contacted for other studies?
No, unless you indicate by initialing below that you may be contacted by other researchers at the University of 
Michigan for studies for which you may eligible. If you agree to be contacted for other studies we will keep 
your name and contact information in a separate password-protected database.
I agree to be contacted about other research studies for which I may qualify. If I cancel my permission for this 
study I will not be contacted for other studies.
YES / NO (circle one) 
Initials: _________
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 13 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
10. CONTACT INFORMATION
10.1 Who can I contact about this study?
Please contact the researchers listed below to:

Obtain more information about the study

Ask a question about the study procedures or treatments

Talk about study-related costs to you or your health plan 

Report an illness, injury, or other problem (you may also need to tell your regular doctors)

Leave the study before it is finished

Express a concern about the study
Principal Investigator:  Roger L. Albin, MD
Mailing Address:  5023 BSRB, 109 Zina Pitcher Place, Ann Arbor, MI, 48109-2200
Telephone:  734-764-1347
Study Coordinator: Teresa Scerbak
Mailing Address: NCAC, 2901 Hubbard Drive, Suite 2722, Ann Arbor, MI 48109-2435
Telephone:  734-936-9115
You may also express a question or concern about a study by contacting the Institutional Review Board 
listed below:
University of Michigan Medical School Institutional Review Board (IRBMED)
2800 Plymouth Road
Building 520, Room 3214
Ann Arbor, MI 48109-2800
Telephone: 734-763-4768  (For International Studies, include the appropriate calling codes.)
Fax: 734-763-1234
e-mail: irbmed@umich.edu 
If you are concerned about a possible violation of your privacy or concerned about a study you may contact 
the University of Michigan Health System Compliance Help Line at 1-866-990-0111.
When you call or write about a concern, please provide as much information as possible, including the name of 
the researcher, the IRBMED number (at the top of this form), and details about the problem.  This will help 
University officials to look into your concern.  When reporting a concern, you do not have to give your name 
unless you want to.
11.  RECORD OF INFORMATION PROVIDED
11.1 What documents will be given to me?
Your signature in the next section means that you have received copies of all of the following documents:

This "Consent to be Part of a Research Study" document.  (Note: In addition to the copy you receive, 
copies of this document will be stored in a separate confidential research file 
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 14 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
12.  SIGNATURES
Sig-A
Consent to Participate in the Research Study
I understand the information printed on this form.  I have discussed this study, its risks and potential benefits, 
and my other choices with ______________________.  My questions so far have been answered.  I understand 
that if I have more questions or concerns about the study or my participation as a research subject, I may 
contact one of the people listed in Section 10 (above).  I understand that I will receive a copy of this form at the 
time I sign it and later upon request.  I understand that if my ability to consent or assent for myself changes, 
either I or my legal representative may be asked to re-consent prior to my continued participation in this study.
Print Legal Name: ___________________________________________________________________
Signature: _________________________________________________________________________
Date of Signature (mm/dd/yy): ________________________
Sig-D
Consent/Assent to Collect for Unspecified Future Research
This project involves the option to allow the study team to keep your identifiable data for use in future research.  
I understand that it is my choice whether or not to allow future use of my specimens.  I understand that if my 
ability to consent or assent for myself changes, either I or my legal representative may be asked to re-consent 
prior to my continued participation in this study.
_____ Yes, I agree to let the study team keep my identifiable data for future research.
_____ No, I do not agree to let the study team keep my identifiable data for future research.
Print Legal Name: ___________________________________________________________________
Signature: _________________________________________________________________________
Date of Signature (mm/dd/yy): ______________________________
 
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024


Page 15 of 15
Consent Subtitle: ________________________
Consent Version: Dec 2023
Sig-G
Principal Investigator or Designee
I have provided this participant and/or his/her legally authorized representative(s) with information about this 
study that I believe to be accurate and complete.  The participant and/or his/her legally authorized 
representative(s) indicated that he or she understands the nature of the study, including risks and benefits of 
participating.
Printed Legal Name: __________________________________________________________________
Title: ______________________________________________________________________________
Signature: _________________________________________________________________________
Date of Signature (mm/dd/yy): ________________________
Study ID: HUM00166765   IRB: IRBMED   Date Approved: 12/13/2023   Expiration Date: 12/6/2024