Overview
- A Neurology study tracked 2,183 dementia-free adults around age 79 with chest-worn monitors for about 12 days and followed them for roughly three years.
- Participants with the weakest rest-activity rhythms had nearly 2.5 times the risk of developing dementia compared with those with the strongest rhythms.
- Each standard-deviation decrease in relative amplitude, a key measure of circadian strength, was associated with a 54% increase in dementia risk.
- People whose daily activity peaked at 2:15 p.m. or later had a 45% higher risk than those whose activity peaked earlier in the afternoon.
- Researchers emphasize the study shows association rather than causation and note limitations such as missing data on sleep disorders, urging trials to test circadian-targeted interventions.