L-DOPA for Depression and Anhedonia

Inclusion Criteria: * a. willing and able to give written informed consent * b. men or women, 25-55 years of age * c. a primary diagnosis of Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), current, as diagnosed by the Structured Clinical Interview for DSM-5 * d. score of \>10 on the Patient Health Questionnaire-9 (PHQ-9) or HAM-D score ≥18 * e. off all antidepressant or other psychotropic therapy (e.g. mood stabilizers, antipsychotics, anxiolytics, and sedative hypnotics) for at least 4 weeks prior to baseline visit (8 weeks for fluoxetine) * f. c-reactive protein (CRP) ≥2 mg/L * g. PHQ-9 anhedonia score ≥2 Exclusion Criteria: * a. history or evidence (clinical or laboratory) of an autoimmune disorder * b. history or evidence (clinical or laboratory) of hepatitis B or C infection or human immunodeficiency virus infection * c. history of any type of cancer requiring treatment with more than minor surgery * d. unstable cardiovascular, endocrinologic, hematologic, hepatic, renal, or neurologic disease (as determined by physical examination, EKG and laboratory testing) * e. history of any (non-mood-related) psychotic disorder; active psychotic symptoms of any type; history or current bipolar disorder; history or current gambling disorder; substance abuse/dependence within 6 months of study entry (as determined by standardized clinician interview) * f. active suicidal plan as determined by a score \>3 on item #3 on the HAM-D * g. an active eating disorder (except for patients with binge eating disorder in whom binging is clearly associated with worsening of mood symptoms) * h. a history of a cognitive disorder or traumatic head injury involving loss of consciousness * i. pregnancy or lactation * j. use of gender affirming hormone therapy * k. chronic use of non-steroidal anti-inflammatory agents (NSAIDS) (excluding 81mg of aspirin), glucocorticoid containing medications or statins * l. use of NSAIDS, glucocorticoids, or statins at any time during the study * m. urine toxicology screen is positive for drugs of abuse, n. any contraindication for MRI scanning * o. intolerance, sensitivity or contraindication to carbidopa-levodopa (including history of narrow-angle glaucoma, melanoma, gastric and/or duodenal ulcers, bleeding disorders, or frequent migraines)