Mechanisms of Airway Protection Dysfunction in Parkinson's Disease
Conditions: Parkinson Disease
Sponsor: University of Florida

Title: Mechanisms of airway protec5on dysfunc5on in Parkinson’s disease 
 
NCT #: NCT03321019 
 
Version date:  
5/22/2020

1. Title:  
Mechanisms of airway protection dysfunction in Parkinson's disease 
2. Investigators:  
Karen Hegland, PhD, CCC-SLP 
Michael Okun, MD 
 
 
 
Yuhan Mou, MA, CF-SLP 
 
 
 
Michaela Mir, M.A., CCC-SLP 
 
 
 
May Smith-Sherry, M.A., CCC-SLP 
 
 
 
Bryn Taylor, M.A., CF-SLP 
 
 
 
Alyssa Terry, M.S., CCC-SLP 
3. Abstract: 
Aspiration pneumonia (APn) occurs at a disproportionately high rate in patients with Parkinson’s 
disease (PD) versus healthy age-matched older adults. This study aims to determine the underlying 
causative factors that contribute to airway protection deficits in PD in order to reduce the incidence 
of aspiration-related illness in these patients. Previous studies suggest that PD patients present with 
deficits in airway somatosensation and sensory processing and filtering. However, it remains 
unknown whether these changes are related to observable motor deficits of swallowing or cough in 
people with PD. As such, this study aims to 1) better understand the relationships between blunted 
airway somatosensation, reflex cough sensitivity and effectiveness, and swallowing function in 
people with PD, 2) determine whether measures of discriminative and affective processing of 
general airway sensation is/are associated with deficits in reflex cough and swallowing function, as 
well as 3) determine whether over-filtering of airway stimuli is associated with swallowing or 
cough deficits.  
4. Background: 
 
Airway somatosensation in people with PD 
PD is a progressive neurologic condition that is associated with deficits in both swallowing and 
cough function, as well as high rates of aspiration pneumonia (APn) (1, 2). Yamanda and 
colleagues have shown that people with a history of APn demonstrated significantly reduced 
sensitivity to airway irritants, quantified as a blunted urge-to-cough (UtC) (3). The UtC is a 
respiratory sensation that precedes a cough bout (4, 5). The UtC is blunted in people with PD as 
compared with age-matched controls, and even further blunted in people with PD and 
concomitant dysphagia (6, 7). Our preliminary data strongly suggest that general airway 
somatosensation is also blunted in people with PD with and without concomitant dysphagia. 
We hypothesize that blunted airway somatosensation contributes to the development of 
swallowing and cough deficits in people with PD. The objective of this aim is to determine the 
relationships between blunted airway somatosensation, reflex cough sensitivity and 
effectiveness, and swallowing function in people with PD. Based on our preliminary studies, we 
predict that blunted airway somatosensation will appear earlier (years 0 – 5 post-diagnosis) in the 
disease process than either cough or swallowing dysfunction, and that by 6-10 years post-

diagnosis, blunted respiratory somatosensation will correlate with reduced reflexive cough 
sensitivity and effectiveness, and decline in swallow function and safety (Figure 1). We will 
determine airway somatosensitivity using resistive inspiratory loads (8). We will perform 
fluoroscopic studies to evaluate swallowing function, and reflex cough testing using capsaicin to 
determine sensitivity and effectiveness. We will perform these tests in people across a range of 
disease durations. The rationale is that by determining the general respiratory sensitivity, reflex 
cough sensitivity to an airway irritant (capsaicin), as well as swallowing and cough effectiveness, 
we will be able to identify whether the onset of swallowing and/or cough deficits occur after 
reduced respiratory somatosensation. These data will provide support to our hypothesis that 
reduced respiratory somatosensation underlies observable motor deficits in swallowing and 
cough function, as well as reduced reflex cough sensitivity. This will significantly advance our 
understanding of the perceptual sensory components of airway protective deficits in PD, and 
provide much needed information regarding why airway protection deficits develop. 
Such outcomes are critically important to advancing the management of patients with PD and 
other neurodegenerative diseases. 
 
Previous studies have shown 
that multiple airway protective 
behaviors are impacted in people 
with PD, most notably, 
functional decline to the 
mechanisms of swallowing and 
cough. The consequence of 
concurrent swallowing and 
cough dysfunction is 
uncompensated airway 
compromise (silent aspiration), 
indicative of significant sensory 
deficits whereby a reflexive 
cough response is not produced 
in response to aspirate material 
in the larynx or airway. People 
with PD exhibit deficits in multiple sensory modalities, including proprioception, 
mechanosensation and olfaction (9, 10, 11). There is a breadth of information regarding 
somatosensory deficits associated with decline in motor functions such as posture and gait, and 
much of the literature supports the hypothesis that there is a sensory origin to PD motor 
symptoms (12). Specific sensory deficits within the upper airway include significantly higher 
laryngeal somatosensory detection thresholds compared to healthy controls (13), and blunted 
perception of the urge-to-cough (UtC) to cough-inducing airway irritants (1, 6, 14, 15). These 
sensory abnormalities occur in conjunction with decreased swallowing safety and cough 
effectiveness (1, 6, 13). Despite this evidence that changes in upper airway sensation accompany 
motor deficits, the evaluation and management of airway protection in PD and other neurologic 
diseases continues to focus solely on observable motor deficits of swallowing. 
 
Changes to brainstem areas involved in swallowing and cough generation are affected at the 
earliest points in PD (16). While severe dysphagia is typically not seen until later stages of the 

disease, there are subtle changes that may occur to the pressures generated in the oropharynx 
during swallowing even in the early and mid-stages (Hoehn &Yahr (H&Y) 1 – 3) (17). Hammer 
and colleagues (2013) studied 18 patients with PD (mean disease duration: 6 years), and found a 
moderate correlation (r = 0.40, p = 0.02) between laryngeal somatosensory thresholds and 
disease severity. Interestingly, their results did not show deficits of swallowing safety in the PD 
group even though the PD group had significantly higher laryngeal somatosensory thresholds 
compared with age matched controls. These researchers suggested that “sensory abnormalities 
may precede penetration and aspiration deficits in the clinical progression of PD” (Hammer et 
al., 2013; page 4) (13), which is a hypothesis that is also supported by our preliminary studies. 
 
Preliminary Studies: 
General respiratory 
sensation is blunted in PD, 
independent of disease 
severity or swallowing safety: 
In order to understand 
whether people with PD 
experience blunted 
respiratory somatosensation 
we conducted a preliminary 
study to examine the 
perception and magnitude 
estimated of inspiratory loads 
of various intensities. Our study compared 14 patients with PD to 13 age and sex matched 
healthy adults (HCs). The results show that people 
with PD exhibit blunted magnitude estimation of 
inspiratory resistive loads as compared with the 
control group regardless of whether they exhibit 
measureable decline in swallowing safety, or of 
disease severity (Figure 2 panels A and B). These 
data indicate general respiratory sensation is blunted 
even when dysphagia is not present, and in the early 
stages of the disease, thus lending preliminary 
support to the hypothesis that blunted respiratory 
somatosensation precedes the onset of swallowing 
deficits in PD. 
 
Reflex cough sensitivity is blunted in later PD 
compared to earlier PD and age-matched controls: 
In an ongoing study we are measuring sensitivity to 
the airway irritant capsaicin by examining the 
perceived UtC. To date, participants include 76 men 
and women with PD, ranging from 1 to 23 years 
post-diagnosis and 51 age-matched control participants. Our interim analysis show that 
participants within 10 years of diagnosis (Figure 3, PD 1-4 and PD 5-9 groups) do not exhibit a 
significant difference in the UtC sensitivity as compared to the control group, however the PD 
10+ group does exhibit a significantly blunted UtC sensitivity compared to controls (Figure 3). 

 
Airway sensory processing in people with PD 
Central neural processing of sensory stimuli is critical for generating appropriate motor plans, 
and this sensorimotor relationship is disrupted in PD, resulting in many of the hallmark motor 
symptoms (9-11). Sensory processing involves both discriminative and affective processing 
components, and each is critical for generating an appropriate motor response. Discriminative 
processing refers to the ability to detect and gauge the intensity or magnitude of a stimulus, 
whereas affective processing refers to determination of stimulus characteristics, such as 
pleasantness or unpleasantness (4, 18). As well, sensory stimuli may be gated, or filtered, out 
from connecting to the sensory cortex, and this process is normal and expected for many 
somatosensory modalities to prevent an over abundance of redundant sensory stimuli (19, 20). 
Our preliminary data suggest that there are changes in both discriminative and affective 
processing and filtering of airwaysensation in people with PD as compared to an age- and sex-
matched control group (21), however to date it is unknown whether these deficits are related to 
observable motor deficits of swallowing or cough. The objective of this aim is to determine 
whether measures of discriminative and affective processing of general airway sensation is/are 
associated with deficits in reflex cough and swallowing function. Further we aim to determine 
whether over-filtering of airway stimuli is associated with swallowing or cough deficits. Based 
on preliminary data we expect that people with PD will exhibit reduced discriminative 
processing components of airway stimuli. With disease progression, measures of affective 
processing components will decline and this will directly correlate with diminished reflex cough 
sensitivity and swallowing function. In order to achieve this objective, we will measure 
swallowing and cough function, reflex cough sensitivity, and the event-related sensory evoked 
potential (SEP) to an airway stimulus. We will compare the latency and amplitude of the SEP 
waveform component peaks to swallowing safety and physiology, and cough effectiveness and 
sensitivity, in people with PD across a range of disease durations. The rationale is that by 
determining the relationship between discriminative and affective processing of airway sensation 
and airway protective behaviors (swallowing and cough) we will better understand what type of 
sensory deficits are impacting airway protective function. 
 
Although both swallowing and cough clearly have motor components, they are typically not 
considered to be classic motor features of PD, which traditionally includes akinesia, rigidity, 
and/or tremor of upper and lower extremities. While precise etiology of swallowing and cough 
deficits in PD remains unknown, a recent study by the Arizona Parkinson’s Disease Consortium 
showed inclusion of alphasynuclein protein in the sensory nerve terminals of the upper airway in 
10 PD patients, post-mortem, and that there was a significant association between the amount of 
this protein and the presence of dysphagia (22). 
Schindlbeck et al., investigated somatosensory 
symptoms in de novo PD patients, and found that 
although somatosensory symptoms were present 
in 67% of study participants, there was not 
neurographic evidence of peripheral nerve 
damage, strongly indicating that in the early 
phase of the disease sensory changes are likely 
not due to peripheral sensory neuropathy (23). 
 

The neural mechanisms mediating swallowing and cough include a brainstem-mediated pathway 
as well as a supramedullary pathway (24). Studies have identified activity in multiple cortical 
areas during swallowing, voluntary cough and reflex cough to capsaicin (e.g., (19, 20, 25). This 
suggests that in cases where the intensity of a stimulus is insufficient to trigger the brainstem-
mediated responses, the accurate perception of respiratory sensations is critically important for 
the generation of airway protective behaviors. When people with PD experience aspiration, it is 
typically small amounts of aspirate material that enter the larynx (Figure 6), and the strength of 
this stimulus is not necessarily adequate to trigger the brainstem-mediated reflex cough response. 
Therefore, the supra-medullary sensory processing of the airway stimulus is requisite to 
producing a cough response to eject the aspirate material. Experimentally, cough-inducing 
stimuli, such as low concentrations of capsaicin, can be used to study the cough response to 
varying intensities of the stimulus (i.e., those strong stimuli that would presumably activate the 
brainstem-mediated pathway) and those weak stimuli that likely depend on supra-medullary 
sensory process to modulate the cough response. 
 
The sensory evoked potential 
(SEP) is a neural correlate of 
sensory perception that can be 
elicited across multiple sensory 
modalities, for example audition 
(26) somatosensation (27). For 
the airway, the SEP can be 
produced by a mechanical 
stimulus such as an inspiratory 
occlusion (28, 29) , which is 
similar to applying the 
inspiratory loads in terms of 
serving as a general respiratory 
stimulus. The resulting waveform consists of multiple component peaks (Figure 7) that reflect 
both discriminative and affective sensory processing (30, 31). Specifically, the early peak ‘P1’ is 
related to discriminative processing, the ‘N1’ is related to both discriminative and affective 
processing, and the later P2, and N2 peaks are related to higher order cognitive processing (32). 
This technique can also be used to examine sensory filtering, or gating, which is defined as the 
brain’s ability to filter redundant sensory information (28, 32).  
 
Preliminary 
studies:  
Reduced 
discriminative and affective processing of airway mechanical stimuli in PD: We have recently 
reported the results of our study investigating the processing of an air-puff stimulus to the 
posterior pharyngeal wall in people with PD. Participants were 13 people with PD, and 7 age- 
and sex-matched healthy older adults (controls). In both the PD and control participants we were 
able to successfully record SEP component peaks (Figure 7). People with PD exhibit changes to 

both P1 (discriminative) and N2 (affective) peaks as compared to healthy older adults (Table 4). 
Specifically, people with PD over-filter the P1 and N2 peaks, indicating that there is sensory 
information that is prohibited from reaching the level of conscious perception and processing. A 
limitation of this study was that the apparatus for delivering the air puff stimulus was 
uncomfortable for most participants, and this may have increased attention to the stimulus, which 
is known to modulate the N1, P2 and N2 peaks (33). Nonetheless, this preliminary study lends 
support our hypothesis that discriminative and affective processing and stimulus filtering are 
affected in PD, however it remains unknown whether/how attention affected these results, or 
whether they relate to changes in the airway protective functions of cough and/or swallowing. 
 
5. Specific Aims: 
 
The specific aims for this project are: 
 
Aim 1: To determine the relationships between blunted airway somatosensation, reflex cough 
sensitivity and effectiveness, and swallowing function in people with PD. 
 
Hypothesis 1: We predict that blunted airway somatosensation will appear earlier (years 0 – 5 
post-diagnosis) in the disease process than either cough or swallowing dysfunction, and that by 
6-10 years post-diagnosis, blunted respiratory somatosensation will correlate with reduced 
reflexive cough sensitivity and effectiveness, and decline in swallow function and safety. 
 
Specific aim 2: To determine whether measures of discriminative and affective processing of 
general airway sensation is/are associated with deficits in reflex cough and swallowing function 
in people with PD. 
 
Hypothesis 2: People with PD will exhibit reduced discriminative processing components of 
airway stimuli. With disease progression, measures of affective processing components will 
decline and this will directly correlate with diminished reflex cough sensitivity and swallowing 
function. 
 
Specific aim 3: To determine whether over-filtering of airway stimuli is associated with 
swallowing or cough deficits in people with PD. 
 
Hypothesis 3: Over-filtering of airway stimuli will be associated with deficits in reflex cough and 
swallowing function in people with PD. 
 
Aim 4: Determine the relationships between observable motor aspects of swallowing, cough, and 
cough sensitivity over a 3-year time period in people with PD. 
 
Hypothesis 4: Swallowing safety and physiology in people with PD will exhibit significant 
differences over 3 time points, spaced 10 – 18 months apart. For people within 9 years of PD 
diagnosis, reduced reflex cough sensitivity will not be a sensitive and/or specific indicator of 
swallowing dysfunction. However, for those with a greater disease duration (10+ years), reflex 
cough sensitivity will be a sensitive and specific biomarker of swallowing dysfunction. 
 
 

6. Research Plan: 
 
Protocol 1 (Aims 1-3) 
This prospective experimental study will include male and female adults with PD, as well as a 
control group consisting of healthy adults. We aim to recruit 30 participants in each group. We 
will recruit PD participants from the patient population at UF Fixel Institute for Neurological 
Diseases. Healthy control participants will be recruited from the community population, 
including spouses and caregivers of PD participants, as well as HealthStreet. All participants will 
provide written consent before enrollment into the study, which will be approved by Institutional 
Review Board (IRB) at the University of Florida.  
 
Inclusion criteria:  
1.) Between the ages of 45 and 85 years  
2.) Diagnosis of PD, Hoehn and Yahr stages I – IV, by a fellowship trained neurologist arriving 
at the diagnosis of PD by applying strict UK brain bank criteria (PD participants only) 
 
Exclusion criteria: 
1. Neurological disorders other than PD (i.e., stroke, multiple sclerosis, etc.) 
2. Difficulty complying due to neuropsychological dysfunction (i.e., severe depression) 
3. Allergy to capsaicin or hot peppers 
4. History of cancer in the head, neck, or lungs (not including skin cancer on the head/neck that 
did not require major surgical resection significantly altering anatomy or radiation to head/neck 
tissue). 
5. History of smoking in the past 5 years 
6. Any neurological disorder including PD (Healthy control group only) 
 
Experimental design and procedures: This prospective experimental study will be completed in 
one or two study visit(s) taking between 1 and 3 hours each. Testing will be conducted in a quiet 
clinical research space. Verbal and written informed consent will be obtained by qualified 
members of the investigative team. Following informed consent, all participants will complete a 
health history questionnaire to assess inclusion/exclusion criteria (Appendix 1).  As well, the 
consenting investigator will review the electronic medical record to ensure inclusion/exclusion 
criteria are met.  
 
The experimental protocol will consist of 1.) Review of electronic medical record to determine 
participant disease status 2.) Baseline pulmonary function measures 3.) Baseline depression and 
apathy scales, 4.) Inspiratory resistive load presentation 5.) Reflex cough assessment 6.) 
fluoroscopic swallow study 7.) Measures of event-related sensory evoked potential (SEP) to an 
airway stimulus.  
 
Participant disease status:  
A qualified member of the investigative team will review the electronic medical record and 
record the following information for each PD participant: disease severity (Unified Parkinson’s 
Disease Rating Scale, Hoehn & Yahr score), medications, levodopa equivalent dose, and surgical 
status (specifically presence, target site, and laterality of deep brain stimulator(s)). 
 

Baseline pulmonary function measures:  
We will analyze pulmonary function in all participants. The forced expired volume in the first 
second (FEV1) of a forced vital capacity (FVC) maneuver will be measured for each participant 
using a digital spirometer (Spirovision 3+m, Futuremed; or Koko spirometry, nspire health). 
Maximum inspiratory and expiratory pressure (PiMax; PEMax) will be measured with a 
manometer (MicroRPM, Micromedical Inc.). We will use standard procedures, as put forth by 
the American Thoracic Society, for measuring FVC, FEV1, the ratio of FEV1/FVC, and PiMax/ 
PEMax. 
 
Baseline depression and apathy:  
Participants will complete 2 validated scales, the Beck Depression Index-II (BDI-II) and 
Starkstein Apathy Scale (AS) to determine baseline depression and apathy scores. 
 
Inspiratory resistive load presentation:  
Participants will rate perceived difficulty of breathing in response to various resistive loads 
applied to single inspirations during tidal breathing in order to assess general respiratory 
somatosensation. The participant will be seated in a chair, separated from the investigator and 
experimental apparatus.  The participant will be instructed to “relax and breathe” through a 
facemask connected to a non-rebreathing valve (Hans Rudolph, 2700 series) in line with a 
differential pressure transducer. The inspiratory port of the valve will be connected to the 
resistive loading manifold.  The manifold consists of 5 differential resistors ranging from 2.5 – 
40 cmH2O/lps of resistive pressure, separated by stoppered ports, as well as a no load condition. 
The load is applied by removing the stop for an entire inspiratory breath, and then replacing the 
port to continue resting tidal breathing. The pressure transducer will provide measures of mouth 
pressure and airflow, which will be digitized (PowerLab, ADInstruments) and recorded to a desk 
top computer using LabChart software (ADInstruments). Following each loaded breath, the 
participant will provide an estimate of the perceived difficulty of breathing using a modified 
Borg scale. 
 
Participants will be familiarized with the loads in a practice session prior to initiating the 
experimental protocol. The resistive loads will be applied in a randomized block design, with 
each loaded breath separated by at least three unloaded breaths. Two blocks will be completed 
with each load presented between 3 and 5 times within each block. Therefore, there will be a 
total of between 15 and 25 loaded breaths (3-5 loads x 5 presentations) per block.  Following the 
loaded breath, and one random non-loaded control breath, the participant will be asked to 
estimate the perceived difficulty of breathing on the Borg scale. 
 
Reflex Cough Assessment Procedures: 
Participants will be outfitted with a facemask covering the nose and mouth. The facemask will be 
coupled to a pneumotachograph, differential pressure transducer, and have a side port with a one-
way inspiratory valve for nebulizer connection. The nebulizer will be connected to a dosimeter 
that delivers aerosolized solution during inspiration with a delivery duration of 2 seconds. The 
cough airflow signal will be digitized (Power Lab Data Acquisition System) and recorded 
(LabChart 7; ADInstruments, Inc.) to a laptop computer. 
 
Participants will be seated for an initial 30 seconds of quiet breathing in order to acclimate to the 
facemask. Participants will then complete a capsaicin challenge with three randomized blocks of 

0, 50, 100, 200, and 500 μM capsaicin dissolved in a vehicle solution. Participants will be given 
the instruction “cough if you need to” prior to capsaicin delivery. The solution will be 
administered automatically upon detection of an inspired breath and there will be a minimum of 
one minute between each trial. Participants will be provided water to drink between trials. 
Following each capsaicin trial, participants will rate their urge-to-cough on a modified Borg 
Rating Scale measured 0-10, where 0 is no urge, and 10 is maximal urge. Our research group has 
extensive experience utilizing this methodology to induce cough (e.g., (1, 34-36)). We also hold 
an FDA IND # 76866 for the use of capsaicin in the study of cough reflex sensitivity and motor 
pattern. 
 
Voluntary cough procedure: 
Voluntary cough will be assessed using the same equipment used for reflex cough testing, 
without the nebulizer attached to the side port (side port is capped off). The participant will be 
asked to produce a sequential voluntary cough three times into the facemask attached to the 
pneumotachograph, and to maintain a comfortable seated position for all cough testing.  Each 
cough trial will be separated by approximately 1 minute of quiet breathing. Participants will be 
given the following instructions for cough production: “When you are ready, cough as if 
something has gone down the wrong pipe.” 
 
Cough outcome variable: The concentration of capsaicin that elicits the 2-cough 
response (C2) will be recorded and serve as our measure of cough reflex sensitivity. 
Additionally, airflow measurements will be derived from the reflex and voluntary cough 
waveforms. Measurements will include compression phase duration (CPD), peak expiratory flow 
rate (PEFR), and peak expiratory flow rise time (PEFRT) and cough volume acceleration (CVA= 
PEFR / PEFRT). 
 
Urge-to-cough (UtC):  Following each capsaicin trial participants will rate their urge-to-
cough (UtC) on a modified Borg rating scale, where 0 is no UtC, and 10 is maximal UtC. The 
UtC provides information regarding participants’ perceived magnitude of the stimulus.   
 
Fluoroscopic swallow study:  
Swallowing function and physiology will be assessed using high-resolution digital fluoroscopy at 
a pulse rate of 30 frames per second, digitally stored for retrieval and offline analysis. 
Participants will be seated in the lateral viewing plane. Three trials each of the following 
swallowing tasks will be performed: Thin hold of 10 – 20mL liquid barium administered via cup, 
5-10mL of pudding-thick barium administered via spoon, and 3-oz thin liquid sequential 
swallow administered by cup. Should aspiration be observed on the thin liquid swallows, we will 
omit the third trial and administer the pudding. Should aspiration occur with the pudding bolus, 
we will omit the remaining boluses (bail-out criteria). This protocol was selected because it 
mirrors our clinical protocol, and thus it would be possible to reduce participant burden and 
radiation exposure by replacing a clinical study with a research study, or vice-versa. 
 
Our primary swallowing outcome measure will be score on the penetration-aspiration scale 
(PAS) measured from the videofluoroscopic evaluations of swallowing. Our secondary 
swallowing outcome measures will provide metrics of swallow physiology including swallow 
reaction time (SRT; H1 to B1), duration of laryngeal vestibule closure (dLVC; LVC to LVO), 

duration to laryngeal vestibule closure (LVC) from hyoid burst (H1) (dtLVC_H1), duration to 
LVC from bolus head in pharynx (B1) (dtLVC_B1) and pharyngeal transit time (PTT; B1 to B2). 
 
SEP Procedures:  
Participants will be asked to refrain from strenuous physical activity, large meals and caffeine for 
at least four hours prior to participating. The participant will be seated in a private, 
sound/electrical shielded experimental room, with his or her back, neck and head comfortably 
supported. The participant will be monitored with a video camera. The electroencephalogram 
(EEG) will be collected using a 64-channel Electrical Geodesics Inc. (EGI; Eugene, Oregon, 
USA) net and amplifier system (amplification 20 K, nominal bandpass 0.10–100 Hz). Netstation 
software will be used for continuous recording of EEG data. 
 
The 64-channel EGI electrode net will be placed on the head of the participant. Each participant 
will be instructed to breathe normally through a mouthpiece connected to a non-rebreathing 
valve. The inspiratory port will be connected to an airflow sensing pneumotachograph and 
inspiratory occlusion valve that obstructs the inspiratory airflow. Airflow, mouth and occlusion 
valve pressures will be sensed with differential pressure transducers and signal conditioners. 
Paired, identical inspiratory occlusions will be presented by silently inflating the occlusion valve 
approximately 50ms after the onset of inspiration, and will last for 150 ms. Each occlusion pair 
will be separated by a 500 ms interstimulus interval. The occluded breaths will be separated by at 
least 2 unoccluded breaths. The total time required for the presentation of the occlusions will be 
700ms after the onset of inspiration, which is within the normal 1.5 second inspiratory duration. 
Up to 100 occlusion pairs will be delivered in each experimental trial. The latency from stimulus 
delivery and amplitude for the P1, N1, P2 and N2 peaks will be recorded from both the first (S1) 
and second (S2) occlusion. 
 
Attend/ignore conditions: In order to understand and account for the effect of attention to 
the stimulus on the latency, amplitude, and gating of the airway SEP peaks, we will perform the 
SEP procedure under 2 conditions: attend and ignore. For the attend condition, participants will 
be instructed to pay attention to their breathing and press a button one time whenever they feel 
an obstructed breath. In the ignore trial, the subject will not be given any instructions to pay 
attention to their breathing, and will be asked to watch a series of neutral affective pictures 
(IAPS; (58)) and ignore their breathing. 
 
SEP outcome measures: a. SEP peaks: The latency and amplitude of the SEP P1 and N2 
peaks under the attend and ignore conditions are the primary outcome variables. Secondary 
outcome measures include the latency and amplitude of the other component peaks, including N1 
and P2 peaks. b. SEP Gating: The ratio of the amplitude the peaks generated by the first and 
second paired occlusions will be calculated for each peak, within the attend and ignore 
conditions. The primary outcome variable will be the ratio of S2/S1 for the P1 and N2 peaks, and 
the S2/S1 ratio for N1 and P2 peaks will serve as secondary outcome variables. 
 
Statistical Analysis  
Aim 1: A multiple regression analysis will be conducted with the slope magnitude 
estimation as the outcome and disease duration, age, and sex as the independent variables in 
addition to their mutual interaction terms. Model selection technique will be adopted to select the 
optimal parsimonial model deemed for the data. We will also perform subgroup analysis to 

compare the slope magnitude estimation between PD patients with PAS (penetration-aspiration 
scale) no more than 2 and PD patients with PAS greater than 2 by adjusting confounding factors 
of age, gender and BMI, etc. to demonstrate that reduced slope of magnitude estimation is 
present in PD patients regardless of PAS status. We will include other swallow and cough 
outcome variables in this model to determine relationships between dependent variables. 
 
Aims 2 and 3: We will first fit a multiple regression model with P1 and N2 peak 
amplitude and gating ratios as the dependent variable and and condition (1 = attend and 2 = 
ignore) as independent variables by controlling confounding variables including age, gender, 
BMI, etc. In order to determine the relationship between P1 and N2 peaks and swallow and 
cough function, we will fit a second multiple regression model with P1 and N2 (amplitude and 
gating ratio), cough and swallow outcomes as the dependent variables and disease duration as the 
primary independent variable by controlling confounding variables including age, gender, BMI, 
etc. Also, model selection technique will be adopted to select the optimal model. Besides the 
primary outcomes of P1 and N2 peaks, other secondary outcomes such as N1 and P2 amplitudes 
and gating ratios will be analyzed. 
 
Protocol 2 (aim 4) 
 
Participants: This study will include men and women with PD, and we will recruit from those 
participating in protocol 1, in addition to the general PD population at UF Fixel Institute for 
Neurological diseases given protocol 2’s larger required N. For participants who did complete 
protocol 1, the procedures will not be replicated in protocol 2 (therefore these participants would 
only complete the 2nd and 3rd protocol 2 visits). The inclusionary and exclusionary criteria will be 
identical to those of protocol 1, with the exception that this protocol will also include people with 
possible or probable progressive supranuclear palsy (PSP) or multiple systems atrophy (MSA). 
 
Power Analysis: To test the hypothesis that the relationship between swallow and cough motor 
deficits, and reflex cough sensitivity varies as a function of disease duration in PD, we would 
compare the penetration/aspiration scale change from baseline with 10 to 18 months apart for PD 
patients. As shown in our pilot study data, the mean (SD) penetration-aspiration scale change 
from baseline for the first two 10 to 14 months period are 2.08 (1.97) and 2.82 (2.33), 
respectively. Based on it, to reach a 0.85 power by controlling the type I error rate to 0.05 for 
detecting this effect size with two-sided test, we would need 155 PD patients. 
 
Procedures to be included from protocol 1 (See protocol 1 for complete description of these 
procedures) 
 
Pulmonary function, depression and apathy, Reflex and voluntary cough procedures, Swallowing 
evaluation procedures will be completed in a manner identical to that described in the preceding 
paragraphs. 
 
Procedures unique to protocol 2:  
Longitudinal measurement of swallowing and cough function: Measures of swallowing and 
cough will be collected at 3 time points spaced 10 – 18 months apart. 
 

For participants who were also in study protocol 1, those swallowing and cough data will be used 
for the first time-point in order to reduce participant burden. 
 
Longitudinal measures of Participant disease status: Disease severity (unified Parkinson’s 
disease rating scale and Hoehn & Yahr score), medications, levodopa equivalent dose, and 
surgical status (specifically deep brain surgery) will be recorded at each study visit. 
Pharmacologic and/or surgical therapies for PD may have known and unknown influences on 
swallowing and/or cough function (i.e., (43)) and will therefore be recorded for this study. 
 
Swallow and cough outcome measures (described in detail in protocol 1): 
1. Slope of UtC sensitivity 
2. Cough sensitivity: Capsaicin concentration that elicits the 2-cough response (C2) 
3. Cough motor (airflow) measures: CPD, PEFR, PEFRT, CVA 
4. Swallowing performance measures: Penetration-aspiration scale scores (PAS) 
5. Swallowing physiology measures: SRT, dtLVC_H1, dtLVC_B1, dLVC, PTT 
 
Statistical analysis: In the statistical analysis, we would fit a linear mixed effects model to take 
into account the repeated measurement by regarding each subject as a cluster. Specifically, in the 
analysis, the repeatedly measured outcome, i.e. change of penetration-aspiration scale scores 
(PAS), C2, cough and swallowing physiology variables from baseline, will be fitted by adjusting 
for fixed effects terms including baseline PAS, age, sex, medications, levodopa equivalent dose, 
surgical status, and disease duration (2=third 10-18 month; 1=second 10-18 month; and 0=first 
10-18 month) and the random effects term due to participants. Restricted resampling model 
selection (Zou et al. 2015) technique will be adopted to conduct the valid statistical inference for 
repeated measurement data and it is also robust to missing data which is particularly useful for 
this study. Expected outcomes: Results of this aim are expected to provide a clinical deliverable 
in the form of sensitive and specific predictor(s) of airway protection dysfunction that are more 
customized for patients with different PD durations. As well, because of the study’s prospective 
longitudinal design, this study will also be the first to examine the natural history of cough 
function in people with PD over the proposed 3-year time period. 
 
Data storage: All participant records will be maintained in HIPPA compliant storage. Paper 
copies of the ICF will be kept in a locked cabinet, in the locked research laboratory of the PI 
(D2-063 or DG-143; K. Hegland).  Paper data collection forms will be kept in a separate, locked 
file cabinet, also in the research laboratory of the PI. Paper forms will not include participant 
names or dates; rather participants will be assigned a unique participant ID number that will be 
kept separate from the name.  Electronic database files containing summary data for individual 
participants and compiled data for all participants will be saved according to participant number 
within a limited access, password protected folder on the PI’s P-drive. 
 
7. Possible Discomforts and Risks 
 
Completion of the Beck Depression Index-II (BDI-II) and Starkstein Apathy Scale (AS) may 
make some participants feel uncomfortable or sad. We will provide participants whose scores fall 
outside the norm with contact information for UF psychiatry and psychology for further 
evaluation and care if desired.  
 

Some participants may find breathing against a resistive load and/or through a mouthpiece to be 
effortful or difficult and may report feeling breathless. We will instruct the participants to “relax 
and breathe” as well as provide breaks to allow them to breath naturally without the mouthpiece 
in place throughout the tasks.  
 
Delivery of capsaicin has been found to be safe, reliable, and reproducible in multiple research 
studies involving both healthy and disordered populations. Although risks associated with 
capsaicin are low, participants may report a ‘tingling’ or ‘hot’ sensation that passes quickly with 
the swallowing of water. Thus, water will be available throughout study procedures. 
 
Completion of a fluoroscopic swallow study involves patient exposure to radiation. However, we 
will minimize the amount of radiation exposure according to standard clinical practice: 
thoroughly explaining the protocol to the patient prior to the study and engaging the fluoroscopy 
only when the patient is completing each swallowing task. In addition, our protocol allows for 
the substitution of a clinical fluoroscopic swallow study with a research study, or vice-versa, to 
reduce unnecessary participant burden and radiation exposure. 
 
For the SEP procedure, the EEG net that will be placed on the patient’s head will be soaked in an 
electrolyte solution prior to placement. As such, the patient’s head and hair may become damp. 
We will place clean dry towels around the patient’s shoulders to keep any excess moisture from 
seeping into their clothes and provide additional towels to dry off their hair following completion 
of the procedure.   
 
8. Possible Benefits 
 
For most participants, there are no direct benefits for participating in this study. However, 
completion of a fluoroscopic swallow study, if one has not yet been completed as a part of 
his/her normal clinical care, may identify signs and symptoms of dysphagia and/or aspiration, 
with subsequent referral for appropriate management.  
 
9. Conflict of Interest 
 
There are no real or potential conflicts associated with this project for any members of the 
investigative team. 
 
 
 
 
 
 
 
 
 

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