In a community-based sample of 183 Framingham Heart Study participants with Parkinson's disease, annual dementia incidence was 5.0% and mortality 10.5%, with older age at PD diagnosis predicting higher risk while sex and education showed no association.

Although not mechanistic or therapeutic, the study informs prognosis and patient stratification for clinical trials by identifying older age at PD onset as a key predictor of dementia risk in community settings.

Limited information exists on incident dementia in individuals with Parkinson's disease (PD) in US community-based samples. We examined cognitive statuses and PD diagnoses of 183 individuals in the Framingham Heart Study (FHS) to establish incident dementia, mortality rates, associations with sex, age at PD onset, and education level. Annual incidence rates of dementia (5.0%, 95% CI [3.7%-6.4%]) and mortality (10.5%, 95% CI [8.7%-12.3%]), did not differ by sex or education level. Increased age at PD diagnosis was a significant risk factor for incident dementia and mortality. Sex may not be a significant risk factor for community-based PD dementia.