Exploring Mechanisms for Neuropsychiatric Symptoms of Parkinson Disease Using Transcranial Direct Current Stimulation

Inclusion Criteria:

- Abel to provide written informed consent is obtained in the English language

- Age 18 to 95 years old

- Movement Disorder Society Clinical Diagnostic Criteria for probable idiopathic
Parkinson disease

- Report disabling depressive or neuropsychiatric symptoms prior to study entry

- Capacity to understand the nature of the study;

Exclusion Criteria:

- Known structural brain disease such as a neoplasm, abscess etc.

- Pre-existing skull / scalp defects that would impede standardized electrode placement

- Current electronic or metal implants

- Diagnosis of Bipolar Disorder, Post-Traumatic Stress Disorder, a Psychotic Disorder or
any other non-unipolar depressive disorder as a principal diagnosis in the 6 months
prior to screening;

- Concurrent treatment with medication which may affect tDCS (benzodiazepines,
anticonvulsants, dextromethorphan and pseudoephedrine)

- Endorse active suicidal ideation at enrollment or during any study visit, or have
attempted suicide in the six months prior to screening;

- History of substance abuse or dependence in the 2 months prior to screening;

- Considered to be at significant risk of committing homicide;

- Unstable medical condition;

- Score less than 22 on the Montreal Cognitive Assessment (MoCA)

- Women of childbearing potential who are pregnant or are considering becoming pregnant
during the length of the study;

- There has been a change in their depression or psychotherapy treatment regimen in the
2 weeks preceding screening;