BACKGROUND:

Hallucinations and delusions are frequent in patients with Parkinson disease (PD) and may have severe clinical consequences for those patients and their caregivers. However, the prevalence and clinical features of these symptoms have not been studied in a representative sample.

OBJECTIVE:

To study the prevalence and clinical correlates of psychosis in a population-based sample of patients with PD.

METHOD:

Total ascertainment of patients with PD in a defined geographical area in Norway was attempted through a detailed community study. Clinical evaluation consisted of a neurologic examination and assessments of depression and cognition. Psychosis was assessed with the thought disorder subscale of the Unified Parkinson's Disease Rating Scale.

RESULTS:

A total of 245 patients with PD were identified, 235 (95.9%) of whom participated in this study. Twenty-three patients (9.8%) had hallucinations with insight retained, and another 14 patients (6.0%) had more severe hallucinations or delusions. Psychotic symptoms were associated with age, stage and diagnostic subgroup of PD, severity of depression, and cognitive impairment. Type, duration, and dose of antiparkinson drug therapy did not differ between those patients with PD who had or did not have psychosis. In a polychotomous logistic regression analysis, severity of depression, cognitive impairment, and impairment of activities of daily living were the only significant concomitants of psychosis.

CONCLUSIONS:

Hallucinations and delusions are common in patients with PD. More advanced and widespread brain changes seem to increase the risk for developing psychosis in patients with PD receiving levodopa therapy.