The Effects of Dopamine on Reward Processing

Study Overview
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Brief Summary
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The purpose of this study is to evaluate the effects of a single low dose of the D2/D3 antagonist amisulpride on reward processing. More generally, this study will test the role of dopamine (a naturally occurring brain chemical) in depression. Hypotheses: Administration of a single low dose of the D2/D3 antagonist amisulpride will (1) improve performance in a behavioral task assessing learning from feedback and (2) boost activation in reward-related brain regions.

Detailed Description
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Through an integration of a functional magnetic resonance imaging (fMRI) approach coupled with a pharmacological challenge, the goal of the current study will be to investigate the role of dopamine in MDD. Participants in this research will include 36 MDD subjects and 36 demographically matched healthy participants recruited from the community by Dr. Pizzagalli's laboratory at McLean Hospital's Center for Depression, Anxiety and Stress Research. This study will include two sessions: The first session will involve a diagnostic interview, and a series of questionnaires and assessments. The second session will take place at the McLean Hospital's Neuroimaging Center, and include the administration of a low-dose of amisulpride (50 mg capsule) or placebo, followed by an fMRI brain scan and administration of two behavioral tasks.

Official Title
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The Effects of Dopamine on Reward Processing

Conditions
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Major Depressive Disorder (MDD)

Intervention / Treatment
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* Drug: amisulpride
* Drug: placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Inclusion Criteria for subjects with Major Depressive Disorder (MDD): Diagnostic and Statistical Manual of Mental Disorders (DSM IV) diagnostic criteria for MDD, diagnosed with the use of the Structured Clinical Interview for DSM Disorders (SCID); Written informed consent; Both genders and all ethnic origins, age between 18 and 45; A baseline score > 16 on the Hamilton Rating Scale for Depression (HRSD) 17-item version; Right-handed. Absence of any psychotropic medications for at least 2 weeks: 6 weeks for fluoxetine, 6 months for neuroleptics, 2 weeks for benzodiazepines, 2 weeks for any other antidepressants. Inclusion Criteria for Control Subjects: Absence of medical, neurological, and psychiatric illness (including alcohol and substance abuse), as assessed by subject history and a structured clinical interview (SCID-I/NP); Written informed consent; Both genders and all ethnic origins, age between 18 and 45; Right-handed; Absence of any medications for at least 3 weeks; Absence of pregnancy. Exclusion Criteria: Exclusion Criteria for All Subjects: Subjects with suicidal ideation where outpatient treatment is determined unsafe by the study clinician. These patients will be immediately referred to appropriate clinical treatment; Pregnant women or women of childbearing potential who are not using a medically accepted means of contraception (defined as oral contraceptive pill or implant, condom, diaphragm, spermicide, intrauterine device, s/p tubal ligation, or partner with vasectomy); Serious or unstable medical illness, including cardiovascular, hepatic, renal, respiratory, endocrine, neurological or hematologic disease; Lifetime history of seizure disorder; Lifetime history or current diagnosis of any of the following DSM-IV psychiatric illnesses: organic mental disorder, schizophrenia, schizoaffective disorder, delusional disorder, psychotic disorders not otherwise specified, bipolar disorder, patients with mood congruent or mood incongruent psychotic features, substance dependence, substance abuse within the last 12 months (with the exception of alcohol abuse within the last 12 months, which is permissible for MDD subjects); eating disorders, post-traumatic stress disorder (lifetime PTSD is exclusionary for control subjects, PTSD within the last 24 months is exclusionary for MDD subjects); simple phobia, social anxiety disorder and generalized anxiety disorders will be allowed only if secondary to MDD; More than five instances of lifetime cocaine or stimulant use (e.g., amphetamine, cocaine, methamphetamine); Use of dopaminergic drugs (including methylphenidate) within the last 6 months; Lifetime history or current diagnosis of dementia, or a score of < 26 on the Mini Mental Status Examination at the screening visit; Lifetime history of adverse drug reactions or allergy to the study drug (amisulpride); Patients with mood congruent or mood incongruent psychotic features; Current use of other psychotropic drugs; Clinical or laboratory evidence of hypothyroidism; Patients with a lifetime history of electroconvulsive therapy (ECT); Patients with renal insufficiency; Failure to meet standard MRI safety requirements Electrolytes, blood urea nitrogen, creatinine: outside the normal range (also ruling out renal insufficiency); Liver function tests above 1.5 times the upper normal; Corrected QT interval (QTc) interval in EKG above 450 ms or EKG indicative of arrhythmia or cardiac conduction abnormalities; Diabetes with poor glucose control; Cardiac disease, bradycardia less than 55 bpm, hypokalemia, congenital prolongation of QT interval or on-going treatment with a medication likely to induce one of these conditions. Currently in cognitive-behavioral therapy

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: There were two groups of subjects: currently experiencing a major depressive episode, or normal health controls. The groups were matched for age, gender, and race. Within each group, half of the subjects were assigned to receive the study drug (amisulpride) and half to receive a placebo.
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: MDD-amisulpride<br>Subjects experiencing a current episode of major depression who are randomized to receive amisulpride | Drug: amisulpride<br>* single low-dose pharmacological challenge, 50 mg amisulpride<br>* Other names: Solian;|
| Placebo Comparator: MDD-placebo<br>Subjects experiencing a current episode of major depression who are randomized to receive placebo | Drug: placebo<br>* single-dose placebo capsule<br>|
| Active Comparator: HC-amisulpride<br>Subjects having no history of mental disorder (healthy controls, HC) who are randomized to receive amisulpride | Drug: amisulpride<br>* single low-dose pharmacological challenge, 50 mg amisulpride<br>* Other names: Solian;|
| Placebo Comparator: HC-placebo<br>Subjects having no history of mental disorder who are randomized to receive placebo | Drug: placebo<br>* single-dose placebo capsule<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Effect on PST Reward Learning | This statistic shows the effect (beta) that the combination of diagnosis and drug has on the ability to learn from rewards during a Probabilistic Selection Task (PST). A higher effect size indicates greater ability to learn from reward trials. | administered after scan | 
| Effect on PST Penalty Learning | This statistic shows the effect (beta) that the combination of diagnosis and drug has on the ability to learn from penalties during a Probabilistic Selection Task (PST). A higher effect size indicates greater ability to learn from penalty trials. | administered after scan | 
| Effect on Caudate Response to Cues | This statistic shows the effect (beta) that the combination of diagnosis and drug has on caudate activation after presentation of a cue. Positive values indicate an increase in activation relative to baseline. | Scan session | 
| Effect on NAcc Response to Cues | This statistic shows the effect (beta) that the combination of diagnosis and drug has on nucleus accumbens (NAcc) activation after presentation of a cue. Positive values indicate an increase in activation relative to baseline. | Scan session | 
| Putamen Response to Cues | This statistic shows the effect (beta) that the combination of diagnosis and drug has on putamen activation after presentation of a cue. Positive values indicate an increase in activation relative to baseline. | Scan session | 
| Effect on Caudate Response to Reward | This statistic shows the effect (beta) that the combination of diagnosis and drug has on caudate activation after Reward outcomes. Positive values indicate an increase in activation relative to baseline. | During scan session | 
| Effect on NAcc Response to Reward | This statistic shows the effect (beta) that the combination of diagnosis and drug has on nucleus accumbens (NAcc) activation after reward outcomes. Positive values indicate an increase in activation relative to baseline. | During scan session | 
| Effect on Putamen Response to Reward | This statistic shows the effect (beta) that the combination of diagnosis and drug has on putamen activation (beta) after reward outcomes. Positive values indicate an increase in activation relative to baseline. | During scan session | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Effect on Caudate-dACC Connectivity After Reward | This statistic shows the effect (beta) that the combination of diagnosis and drug has on functional connectivity between caudate and dorsal anterior cingulate cortex (dACC) in response to reward outcomes | During scan session | 
| Effect on NAcc-MCC Connectivity After Reward | This statistic shows the effect (beta) that the combination of diagnosis and drug has on functional connectivity between nucleus accumbens (NAcc) and mid-cingulate cortex (MCC) in response to reward outcomes. | During scan session | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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MDD, Major Depressive Disorder, Amisulpride