Overview

• Two Université de Montréal–led studies identify complementary MRI predictors that distinguish future Parkinson’s disease from dementia with Lewy bodies in people with isolated REM sleep behavior disorder.
• Lower left-hemisphere DTI-ALPS glymphatic index was associated with a 2.4-fold higher likelihood of later Parkinson’s, with no similar link to Lewy body dementia.
• The companion study found that elevated free water in the basal nucleus of Meynert predicted an eightfold greater risk of future dementia with Lewy bodies.
• The Neurology paper analyzed 428 participants across five countries with about six years of follow-up, and the Alzheimer’s & Dementia paper included 438 participants with a median 8.4-year follow-up.
• Researchers say the markers could enable personalized screening, targeted surveillance, and better trial recruitment, though replication and standardization are needed before routine clinical use.