Psychosis in Parkinson's disease: therapeutic options

This publication offers a review of the pharmacological interventions studied for Parkinson's disease psychosis. Before initiating drug therapy for psychosis, possible contribution of antiparkinsonian medications to psychosis must be minimized by reducing their dose and completely switching them to levodopa if indicated. As a group, second- generation antipsychotics have been studied the most for Parkinson's disease psychosis. Evidence of efficacy for psychosis and safety for motor side effects is strongest for clozapine but routine use of clozapine is limited by its potential to cause agranulocytosis and the stringent monitoring requirements. Based on several open-label studies, quetiapine appeared to be a reasonable alternative, but recent double-blind studies create uncertainty about its efficacy. Olanzapine and aripiprazole have limited efficacy and are associated with worsening of motor symptoms. Literature is limited and lacks clarity about the utility of risperidone and ziprasidone in this scenario. Recently, encouraging literature has emerged on the use of donepezil and rivastigmine in patients with Parkinson's disease dementia and psychosis. There is a considerable need to further study the existing drugs and explore other pharmacotherapies in Parkinson's disease psychosis. Future research should ensure sound methodological quality and control for confounding variables to provide results that could be used reliably in clinical practice.