Lack of funding and did not complete enrollment.

This study evaluates the effect of transcranial direct current stimulation (tDCS) on non-motor symptoms of Parkinson's disease, including depression and cognitive symptoms. Participants are randomized to receive active or sham tDCS for 30 minutes over 10 treatment sessions.

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;