The Therapeutic Effect of Transcranial Direct Current Stimulation on Depression in Parkinson's Disease

Inclusion Criteria: 1. In the opinion of the investigator, the participant is capable of understanding and complying with protocol requirements. 2. The participant or, when applicable, the participant's legally acceptable representative signs and dates a written, informed consent form and any required privacy authorization prior to the initiation of any study procedures. 3. Suffers from Parkinson's disease fulfill the Parkinson's Disease Society Brain Bank clinical criteria with insidious 2 or more PD symptoms (bradykinesia, tremor, or rigidity). 4. Suffers from "DSM-IV major depressive disorder, single episode" or "DSM-IV major depressive disorder, recurrent" according to Diagnostic \& Statistical Manual of Mental Disorders, 4th Edition - Text Revision (DSM-IV-TR) criteria. 5. Reported duration of the current episode is ≥4 weeks and has not been treated with antidepressants. 6. Has a Montgomery-Åsberg Depression Rating Scale (MADRS) total score ≥20 at the screening (baseline) visit. 7. Is a man or woman aged 18 to 75 years, inclusive. Exclusion criteria: 1. Subjects known to have allergies to sertraline and pimozide. 2. Subjects showed any signs of substantial risk of suicide during the trial. 3. Subjects ever received electroconvulsive treatment. 4. Subjects co-morbid with other major mental disorders or with substance/alcohol dependence or abuse in the past 6 months per DSM-IV criteria. 5. Nursing women, pregnant women or patients suspected pregnant. 6. History or presence of clinically significant hepatic, cardiovascular or renal disease, or other serious medical disease that might compromise the study. 7. History of seizure disorder or need to taking medications that increase the risk of seizure. 8. History or presence of dementia and any previous history of brain tumor, brain arteriovenous malformation, encephalitis or meningitis. 9. Subjects ever received or plan to receive brain surgery during the trial. 10. Subjects with pacemaker or are contraindicated for MRI.