Can a Parkinson's drug boost brain function in depressed seniors?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Age ≥ 60 years 2. Diagnostic and Statistical Manual-5 (DSM5) diagnosis of Major Depressive Disorder, Persistent Depressive Disorder, or Depression Not Otherwise Specified (NOS) 3. MADRS score ≥ 15 4. Decreased processing speed (0.5 SD below age-adjusted norms on the WAIS-IV Coding task or Trail Making Test, Part A) or decreased motor speed (gait speed/average walking speed on 15' course ≤ 1m/s, or 0.5 SD below age-, gender- and education-adjusted norms on the grooved pegboard test) 5. Capable of providing informed consent and adhering to study procedures Exclusion Criteria: 1. Diagnosis of substance abuse or dependence (excluding Tobacco Use Disorder) in the past 12 months 2. Other psychiatric disorders including a history of psychosis, psychotic disorder, mania, or bipolar disorder. Other comorbid psychiatric disorders are allowable if the depressive disorder diagnosis is considered to be the primary problem 3. Primary neurological disorder, including dementia, stroke, Parkinson's disease, epilepsy, etc 4. SBT \> 10 5. MADRS suicide item \> 4 or other indication of acute suicidality 6. History of inpatient psychiatric hospitalization in the last year; 7. History of suicidal ideation in the last 6 months, operationalized as a 'yes' response to item 4 or 5 in the "Suicidal Ideation" section of the Columbia-Suicide Severity Rating Scale (CSSRS) 8. Any suicidal behavior in the last year (operationalized as a 'yes' response to any item in the "Suicidal Behavior" section of the CSSRS, including actual interrupted, aborted, or preparatory acts) 9. Current or recent (within the past 2 weeks) treatment with antipsychotics or mood stabilizers, or use of antidepressants where washout is not advisable 10. History of hypersensitivity, allergy, or intolerance to Carbidopa/levodopa 11. Any physical or intellectual disability adversely affecting ability to complete assessments 12. Unstable medical illness 13. Mobility limiting osteoarthritis of any lower extremity joints, symptomatic lumbar spine disease, or history of joint replacement / spine surgery that limits mobility 14. Diagnosis of HIV 15. History of significant radioactivity exposure (nuclear medicine studies or occupational exposure).