Depression in Parkinson’s Disease

Depression is the most common psychiatric complication affecting persons with Parkinson’s disease (PD). Depressive symptoms may affect as many as half of all PD patients at some point in their illness, and, in many cases, depressive symptoms actually predate motor signs and symptoms. Aggressive surveillance for and treatment of depression is critical, since untreated depression produces a great deal of human suffering, and depression is usually treatable. In PD patients, depression may have even more impact on functional status than in other patients with depression. However, there is still uncertainty about many aspects of depression in PD despite an increasing amount of research devoted to this topic. In particular, issues revolving around differentiating depression from PD symptoms, the role of cognitive impairment from PD on mood symptoms, and unique treatment concerns in this population can be challenging for the clinician. This chapter provides an update on what is known about depression in PD, including its epidemiology, clinical features, neuropsychological features, and treatment, focusing on major themes of research in this field.