Antipsychotic use in older adults with Parkinson's disease.

The choice of agents to treat psychotic symptoms in Parkinson's disease is important given the potential for antipsychotics to worsen Parkinsonism. The purpose of this study was to estimate the incidence of psychotic symptoms requiring treatment in individuals with Parkinson's disease after starting dopaminergic medications, and to describe the agents being selected as initial antipsychotic therapy. Using the administrative health care databases of Ontario, Canada, individuals 66 years of age or older with Parkinson's disease who were newly treated with dopaminergic agents were identified. Subsequent prescriptions for antipsychotic medications were then identified. A total of 10,347 older adults were newly started on dopaminergic agents between 1998 and 2003. The Kaplan-Meier estimate for the cumulative probability of requiring an antipsychotic at 7 years was 35%; 499 individuals (4.8%; 5.2/100 person-years) were prescribed an antipsychotic within 1 year of starting dopaminergic therapy. The proportion of initial antipsychotic prescriptions for typical antipsychotics decreased from 56% (42 of 75) in 1998 to 9% (8 of 88) in 2002. Antipsychotic use is common in individuals with Parkinsonism newly treated with dopaminergic medication. Typical antipsychotics are still commonly being chosen as first-line agents for older patients, indicating a need for interventions to improve practice.