Dementia May Occur Less Often, Develop Slower in Parkinson Disease Patients

In a study published online in *Neurology*, researchers suggest that dementia in patients with Parkinson's disease (PD) may occur less frequently or take longer to develop than previously thought. Julia Gallagher and colleagues from the University of Pennsylvania examined the long-term risk of dementia among participants in two groups: the Parkinson’s Progression Markers Initiative (PPMI) multisite international study and a long-standing PD research cohort at the University of Pennsylvania (Penn). The study followed 417 PD patients from the PPMI cohort and 389 from the Penn cohort. The findings revealed that in the PPMI cohort, the estimated probability of developing dementia after 10 years of disease duration was 9%, 15%, and 12% based on different assessment tools, such as site investigator diagnosis, the Montreal Cognitive Assessment, and the Movement Disorder Society-Unified Parkinson’s Disease Rating Scale, respectively. In the Penn cohort, 47% of participants were eventually diagnosed with dementia. The median time to dementia onset in this group was 15 years, with estimated probabilities of 27%, 50%, and 74% at 10, 15, and 20 years of disease duration, respectively. “These findings offer updated and more optimistic estimates of the long-term dementia risk in PD, indicating a potentially longer period to intervene and prevent or delay cognitive decline,” the authors noted. Some authors disclosed financial connections to the biopharmaceutical industry; the PPMI is partially funded by biopharmaceutical companies.