Frequency, Timing of Dementia in Parkinson’s: New Data

TOPLINE:

Dementia in Parkinson’s disease (PD) may occur less frequently or develop over a longer period than previously thought, an analysis of two studies suggests. Increasing age at diagnosis, male sex, and lower education level are significant predictors of dementia development.

METHODOLOGY:

• Long-term dementia risk in patients with PD was assessed from the Parkinson’s Progression Markers Initiative (PPMI) and a National Institutes of Health-funded study at the University of Pennsylvania (Penn), Philadelphia.
• Analysis included 417 participants from the PPMI cohort (mean age, 61.6 years; 65% men) and 389 participants from the Penn cohort (mean age, 69.3 years; 67% men).
• Participants underwent annual or biennial cognitive assessments, including Montreal Cognitive Assessment (MoCA) and Movement Disorder Society — Unified Parkinson’s Disease Rating Scale Part 1 (MDS-UPDRS).
• The primary outcome was the time to dementia diagnosis from PD onset.
• The subanalyses of the Penn cohort were stratified by sex, age at PD disease diagnosis, and years of formal education.

TAKEAWAY:

• In the PPMI cohort, 7% of participants were diagnosed with dementia by the site investigator by year 10 and 8.5% over the entire follow-up. When using alternative dementia definitions (MoCA < 21 or MDS-UPDRS cognitive score ≥ 3), the percentages were slightly higher, at 9.8% and 7.4%, respectively, at 10 years and 11.8% and 11.3%, respectively, over follow-up.
• In the Penn cohort, estimated probability of dementia was 26.5% by year 10, 49.66% by year 15, and 74.39% by year 20, with a median time from PD diagnosis to dementia of 15.2 years.
• The median time from PD diagnosis to dementia varied significantly by age, sex, and education: Median time was 19.4 years for ages < 56 years vs 14.6 years for ages 56-70 years vs 9.2 years for > 70 years (P < .001); 19.4 years in women vs 13.3 years in men (P = .004); and 15.2 years for those with ≥ 13 years of education vs 11.6 years for those with < 13 years (P = .006).
• The probability of a dementia diagnosis was higher in older patients, men, and in those with education < 13 years at all timepoints.

IN PRACTICE:

“The Penn numbers are closer, although still lower at each timepoint, than what had been reported in previous comparable studies, while the PPMI numbers are significantly lower for the first 10 years of disease duration,” the authors wrote. “These results provide updated, and more hopeful, estimates of long-term dementia risk in PD, suggesting a longer window to intervene to prevent or delay cognitive decline.”

SOURCE:

The study was led by Julia Gallagher, BS, Penn. It was published online on August 7 in Neurology.

LIMITATIONS:

The PPMI study had missing data in the outlying years, partly due to the COVID-19 pandemic. The study relied on site investigators to diagnose dementia without mandating the consideration of cognitive test results. The extended time between the diagnosis of PD and enrollment in the Penn cohort may lead to an overestimation of the time to diagnosis of dementia. Both cohorts were highly educated and predominantly White, which may limit the generalizability of the findings.

DISCLOSURES:

The PPMI was supported by the Michael J. Fox Foundation for Parkinson’s Research and other funding partners. Penn data were obtained as a part of a National Institute on Aging grant. Some authors reported receiving research support, consulting fees, or honoraria. Additional funding information and full disclosures are available in the original article.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.