The study will examine 30 patients between ages 50-80, newly diagnosed with early-stage Parkinson's Disease. Patients will be randomized to receive either Citalopram or Carbidopa-levodopa. The investigators' primary outcome measure will be change in quality of life over a prospective period of 6 months. Secondary outcome measures will include change in mood state and motor symptoms, as well as comparison of improvement between two treatments.

Primary investigators would also like to collect quantitative electroencephalogram (qEEG) recordings, which is a reading of brain activity as an additional interest of this study. Primary investigators will assess the qEEG recordings for electrophysiological findings before and after interventions.

Inclusion Criteria:

• Patients aged 50-80 years of age presenting with diagnoses of early stage Parkinson's Disease (UPDRS part III score <20) without a previous treatment trial of either antidepressants or levodopa and able to provide consent.
• Screened positive with depressive symptoms suggestive of an underlying mild to moderate major depressive episode on the PHQ-9 (scores 10-20).

Exclusion Criteria:

• Currently taking an antidepressant (SSRI, SNRI, TCA, MAOi), antipsychotic, or dopaminergic Parkinson medication, or in the last 8 months.
• Tremor with a UPDRS-part III score of 3 or more.
• Currently participating in another clinical trial, which might directly influence findings of this study.
• Inability to provide informed consent.
• Dementia as defined by Montreal Cognitive Assessment (MoCA) score of <24 and/or clinical evidence of dementia.
• A lifetime diagnosis of another mental disorder including bipolar I or II disorder, schizophrenia, schizoaffective disorder, schizophreniform disorder, delusional disorder, moderate and severe alcohol use disorder as per chart review or patient self-report.
• High risk of suicide (e.g. active suicidal ideation and/or current/recent intent or plan) as per self-report or relevant item on the PHQ-9.
• Non-correctable clinically significant sensory impairment.
• Unstable medical illnesses including delirium, uncontrolled diabetes mellitus, hypertension, and hyperlipidemia or cerebrovascular or cardiovascular risk factors that are not under medical management, including QTc>480 on Electrocardiogram.