Psychiatric aspects of Parkinson's disease

Parkinson's disease (PD) is essentially characterized by the motor symptoms in the form of resting tremor, rigidity and bradykinesia. However, over the years it has been recognized that motor symptoms are just the “tip of the iceberg” of clinical manifestations of PD. Besides motor symptoms, PD characterized by many non-motor symptoms, which include cognitive decline, psychiatric disturbances (depression, psychosis and impulse control), sleep difficulties, autonomic failures (gastrointestinal, cardiovascular, urinary, thermoregulation) and pain syndrome. This review evaluates the various aspects of psychiatric disorders including cognitive decline and sleep disturbances in patients with PD. The prevalence rate of various psychiatric disorders is high in patients with PD. In terms of risk factors, various demographic, clinical and treatment-related variables have been shown to be associated with higher risk of development of psychiatric morbidity. Evidence also suggests that the presence of psychiatric morbidity is associated with poorer outcome. Randomized controlled trials, evaluating the various pharmacological and non-pharmacological treatments for management of psychiatric morbidity in patients with PD are meager. Available evidence suggests that tricyclic antidepressants like desipramine and nortriptyline are efficacious for management of depression. Among the antipsychotics, clozapine is considered to be the best choice for management of psychosis in patients with PD. Among the various cognitive enhancers, evidence suggest efficacy of rivastigmine in management of dementia in patients with PD. To conclude, this review suggests that psychiatric morbidity is highly prevalent in patients with PD. Hence, a multidisciplinary approach must be followed to improve the overall outcome of PD. Further studies are required to evaluate the efficacy of various other measures for management of psychiatric morbidity in patients with PD.