Evidence-Based Review of Pharmacotherapy Used for Parkinson's Disease Psychosis

To summarize and evaluate the existing literature regarding medications to treat Parkinson's disease (PD) psychosis.

MEDLINE (1946 to March 2017), EMBASE (1980 to March 2017), CINAHL (1982 to March 2017), and PsychInfo (1887 to March 2017) were searched using the following terms: Parkinson disease, Parkinson's disease, psychotic disorders, psychosis, delusions, and hallucinations.

The search was limited to randomized controlled trials (RCTs) reporting human outcomes. Data extracted included the following: study design, population, setting, intervention, control, outcomes related to psychosis and safety, and potential biases assessed using Cochrane Collaboration's Risk of Bias Assessment Tool.

After assessment, 16 of 235 studies were included; 11 articles reported comparisons between active drug and placebo, whereas 5 compared clozapine and an active comparator. Placebo-controlled trials demonstrated benefit for clozapine (n = 2) and pimavanserin (n = 2), with no firm benefits observed for quetiapine (n = 4) or olanzapine (n = 3). Comparative studies demonstrated improved efficacy in symptom scores when clozapine or comparator agent (n = 2, quetiapine; n = 1, olanzapine; n = 1, risperidone; and n = 1, ziprasidone) was assessed alone. However, no comparator data suggest that one agent is better than another, and none are yet available for pimavanserin. Overall risk of bias across all studies was moderate to high.

Despite lack of rigor in study designs, published data to date suggest that clozapine and pimavanserin should be considered drugs of choice to treat PD psychosis.