Overview
- More than 2,000 dementia-free adults in the ARIC cohort (average age 79) wore chest ECG/accelerometer patches for about 12 days and were tracked for a median of three years.
- Participants with the weakest circadian rhythm strength had nearly 2.5 times the risk of developing dementia after adjustments for age, vascular factors, education, and APOE ε4 status.
- Individuals whose daily activity peaked at or after about 2:15 p.m. faced a 45% higher dementia risk than those with earlier peaks.
- In the strongest rhythm group, 31 of 728 participants developed dementia compared with 106 of 727 in the weakest group, underscoring the gradient in risk.
- Researchers emphasize the observational design, limited sleep-disorder data, and the need for replication plus trials of chronotherapy such as light-based or structured routine interventions.