Clinical characteristics and treatment of psychosis in Parkinson's disease: A narrative review

Parkinson's disease (PD) is a chronic, progressive, neurodegenerative disorder whose clinical presentation consists of motor and non-motor signs and symptoms. Among the non-motor symptoms, psychosis can occur in the later stages of the disease. Psychosis in PD (PDP) is a common, complex, and significantly disabling disorder associated with poorer quality of life, accelerated cognitive decline, need for hospitalization or institutionalization, and mortality. Hallucinations are a significant symptom of PDP, sporadic at first but more frequent in the later course of the disease, and significantly disrupt daily activities. Appropriate and timely screening of psychotic manifestations is necessary for adequate therapeutic procedures. After the exclusion of comorbid conditions as a possible cause of psychosis, correction of antiparkinsonian therapy may be required, and if necessary, the introduction of antipsychotics. The latest therapeutic recommendations include the use of pimavanserin, if available, otherwise second-generation or atypical antipsychotics. Although PDP has long been recognized as a possible complication in the course of the disease, further clinical studies are needed to fully understand its etiopathogenesis and pathophysiological mechanisms.