Psychiatric Complications in Parkinson Disease

Although Parkinson disease (PD) is primarily considered a movement disorder, the high prevalence of psychiatric complications suggests that it is more accurately conceptualized as a neuropsychiatric disease. Affective disorders, cognitive impairment, and psychosis are particularly common in PD and are associated with excess disability, worse quality of life, poorer outcomes, and caregiver distress. Yet, in spite of this and their frequent occurrence, there is incomplete understanding of the epidemiology, phenomenology, risk factors, neuropathophysiology, and optimal treatment strategies for these disorders. Psychiatric complications are typically comorbid, and there is great intra- and inter-individual variability in presentation. The hallmark neuropathophysiological changes that occur in PD plus the association between exposure to dopaminergic medications and certain psychiatric disorders suggest a neurobiological basis for most psychiatric symptoms, although psychological factors are probably involved in the development of affective disorders. Although antidepressants, antipsychotics, and cognition-enhancing agents are commonly prescribed in PD, controlled studies demonstrating efficacy and tolerability of these drugs are virtually nonexistent. Because of the high prevalence and complexity of psychiatric complications in PD, geriatric psychiatrists are in a position to offer valuable consultation and clinical care to this population. This article provides an overview of the epidemiology, pathophysiology, clinical presentation, and management of the most common psychiatric complications in PD.