Antecedent clinical features associated with dementia in Parkinson's disease.

In a prospective cohort study, we examined clinical features in 250 nondemented patients with idiopathic Parkinson's disease (PD) and then evaluated their association with incident dementia during 5 years of follow-up. Seventy-four of the patients became demented. Odds ratios for incident dementia with PD were increased for the following: being older than 70 years of age (2.7; 1.4 to 5.5), having a PD rating scale score greater than 25 (3.0; 1.5 to 6.2), being depressed (2.7; 1.5 to 6.6), being confused or psychotic on levodopa (3.3; 1.3 to 8.7), or having facial masking as a presenting sign (6.1; 1.4 to 26.9).