FREQUENCY OF DEMENTIA IN PARKINSON DISEASE

Objective: To investigate the frequency of dementia in patients with P arkinson disease (PD). Design: Community-based prevalence study. Setti ng: The study population comprised 220 858 inhabitants from the Rogala nd County, Norway. Participants: Almost 400 participants were examined by a neurologist, and 245 were given the diagnosis of PD and included in the study. Measurements: Mental functioning was rated with the Min i-Mental State Examination; Gottfries, Brane, and Steen scale; and the intellectual subscale of the Unified Parkinson's Disease Rating Scale . Criteria from the Diagnostic and Statistical Manual of Mental Disord ers, Third Edition, Revised, were applied during a semistructured inte rview to determine the diagnosis of dementia. Results: Dementia was fo und in 67 patients (27.7%). Patients with dementia were older at the t ime of the study and at onset of PD and had had PD longer than the pat ients without dementia. Major depression was more common among patient s with dementia (23%) than among patients without dementia (2.3%) (chi (2), P<.001), and patients with dementia were more often institutional ized than those without dementia (62% vs 6%, respectively, chi(2), P<. 001). Atypical neurologic features for idiopathic PD tie, early occurr ence of autonomic failure, symmetrical disease presentation, and only moderate response to a dopamine agonist) were associated with more sev ere dementia of a higher frequency rate and with lower scores on cogni tive rating scales. Conclusion: Approximately one quarter of the patie nts with PD had dementia with the motor manifestations of PD. Dementia was associated with depression, institutionalization, older age at on set of PD, and atypical neurologic features.