Parkinson's disease is a disabling neurodegenerative disorder that affects 7-10 million people worldwide. Psychiatric symptoms are a significant non-motor feature of this disease and have been found to have significant impact on health related quality of life. Psychiatrists should have an awareness of nuances in diagnosis and management of psychiatric illness in this unique patient population. The pathophysiology of Parkinson's disease is complex, with neurodegeneration affecting dopaminergic, serotonergic, noradrenergic and cholinergic systems. As such, more than 50% of patients will develop symptoms of depression and/or anxiety. Medications used to treat Parkinson's disease, such as levodopa or dopamine agonists can produce manic and even psychotic symptoms. Patients can also develop an addiction to these medications and begin abusing them. This can result in mania, impulse control disorders and psychosis.

Pharmacology and management of patients with Parkinson's disease is complex due to interplay between treatments needed for their disease and the resulting psychiatric comorbidities. The role of an interdisciplinary team, composed of experts in neurology, psychiatry and even neurosurgery, is cruicial to success in treating these patients. This team becomes significantly more important when patients are evaluated for Deep Brain Stimulation (DBS). Psychiatrists should be aware of specific comorbidities, such as untreated severe depression or psychosis, which may make patients a poor candidate for this procedure. Psychiatrists should also be familiar with how to manage psychiatric complications following DBS along with the interdisciplinary team.