Clinical phenotype of Parkinson disease dementia

To determine which clinical features best characterize Parkinson disease dementia (PDD), compared with Alzheimer disease (AD) and dementia with Lewy bodies (DLB), and to determine the pathologic basis for PDD.

We examined 103 participants enrolled in a longitudinal study (nondemented control = 10, PD = 42, DLB = 20, AD = 31) who were followed to autopsy using standardized protocols. We characterized the features of PDD using published criteria for AD and DLB as a framework. Statistical analysis was performed using chi(2) and Fisher exact tests, Kaplan-Meier curves, and logistic regression models.

The sample's mean age was 74.0 years (range 53 to 91 years), and individuals were followed for a mean of 3.4 visits (range 1 to 12 visits). During longitudinal follow-up, 83% of subjects with PD developed dementia, defined as a Clinical Dementia Rating score of >or=0.5. Features that distinguished PDD from AD included cognitive fluctuations (p = 0.001), visual (p < 0.001) and auditory (p = 0.006) hallucinations, depression (p = 0.003), and sleep disturbance (p = 0.003). These PDD features were identical to those observed for DLB. The pathologic substrates for PDD included DLB (38%), AD (32%), and nigral LB alone (24%). Clinical predictors of PDD were visual hallucinations (odds ratio [OR] 21.3; 95% CI: 1.5 to 309.6) and male gender (OR 9.6; 95% CI: 1.3 to 71.4).

Parkinson disease dementia (PDD) shares identical clinical features with dementia with Lewy bodies (DLB); both entities can be distinguished from Alzheimer disease. The presence of PDD/DLB features at any time during the course of PD is highly predictive of dementia and the presence of LB at autopsy; in particular, male gender and visual hallucinations in PD predict dementia.