Half of patients with Parkinson's disease and psychosis treated with antipsychotic agents, including drugs that may worsen Parkinson symptoms, study finds

According to background information in the article, many individuals with a diagnosis of PD -- including up to 45,000 of those living in the United States -- eventually develop psychosis. "However," the authors write, "AP use in PD is complicated by is potential to worsen parkinsonism and limited evidence for efficacy." Parkinson's disease is also associated with dementia and complications of that condition, which may be exacerbated by APs; a "black box" warning about those risks was placed on labels of many APs beginning in 2005. The authors note, "Further study of this issue is critical given both the high prevalence of psychosis in this population and that parkinsonian symptoms and frequent comorbid dementia may make this population more likely to experience adverse outcomes, including mortality, with AP treatment."

Daniel Weintraub, M.D., from the University of Pennsylvania, and colleagues compared Veterans Affairs data from fiscal year (FY) 2002 and FY 2008. Specifically, they examined rates and predictors of AP prescribing for 2,597 patients with PD and psychosis, stratified by dementia status (793 with dementia and 1,804 without dementia). These data were compared with data from 6,907 patients with dementia and psychosis but no PD.

Half of the patients with PD and psychosis received an AP prescription, and most of those prescriptions were for atypical APs. Use of APs appeared to be higher among patients who had diagnoses of both PD and dementia than among those without dementia. Between FY 2002 and FY 2008, the overall rate of AP prescribing in patients with PD was unchanged; however, the researchers noticed a decrease in the use of some APs and an increase in the use of others.

The authors also noted that whereas individual drugs' prescribing rates changed during the study period, the overall rate of prescriptions was constant, despite warnings about the use of these agents in patients with dementia. "Approximately one-third of our PD sample had comorbid dementia, and many more likely had mild cognitive impairment (MCI)," write the authors. "This has significant clinical implications in PD given the increased morbidity and mortality associated with typical and atypical AP use in dementia populations." They add that although prescribing habits seemed to shift toward drugs that are often better tolerated by patients with PD, those drugs are not necessarily safer or more effective. Lastly, the authors call for more studies "to further understand what factors contribute to both overall and specific AP use in this population, and longitudinal studies [to] assess the impact of AP treatment on morbidity, mortality, and progression of parkinsonism."