Quetiapine for Psychosis in Parkinson Disease and Neurodegenerative Parkinsonian Disorders

We performed a systematic review of randomized controlled trials to assess the high-level evidence regarding the role of quetiapine in the treatment of psychosis in patients with neurodegenerative parkinsonian disorders. Studies were included in the qualitative review if they (1) enrolled participants with diagnosis of Parkinson disease, Lewy body dementia, or any other neurodegenerative parkinsonian disorders; (2) assessed the efficacy of quetiapine; and (3) evaluated psychotic and motor outcomes using validated tools. Of the 341 manuscripts identified, 7 studies fulfilled our inclusion criteria. The studies’ risk of bias was considered low. A total of 241 participants enrolled in these trials. Heterogeneity was high due to inclusion criteria, user definitions, assessment tools, and study design. Although not causing any motor deterioration, quetiapine failed to significantly reduce psychotic symptoms compared to placebo when objectively assessed on the Brief Psychotic Rating Scale, the most frequently reported scale in these studies. High loss to follow-up and dropout rates as well as significant improvement in psychotic symptoms in the placebo groups may have affected measurements of possible positive medication effects.