Study Links Disrupted Circadian Rhythms to Increased Dementia Risk

Wendy Wang, PhD, MPH, from the Peter O’Donnell Jr. School of Public Health at UT Southwestern Medical Center in Dallas, Texas, notes that changes in circadian rhythms often occur with aging, which may contribute to the risk of neurodegenerative diseases like dementia.

Rather than relying on self-reported data, this study utilized accelerometer data from chest-based ambulatory ECG patches worn continuously for about 12 days. This enabled researchers to measure the strength, regularity, and timing of circadian rhythms in everyday life. One key metric was “relative amplitude,” reflecting the difference between active and inactive periods over a 24-hour cycle. Participants in the weakest rhythm category faced nearly 2.5 times the risk of developing dementia compared to those with the strongest rhythms, even after factoring in age, cardiovascular risk factors, education, and genetic predispositions like APOE ε4 status. Additionally, each standard-deviation decrease in rhythm strength corresponded to a 54% increase in dementia risk.

The timing of daily activity also played a critical role. Individuals whose activity peaked later in the day, after 2:15 p.m., had a 45% higher risk of dementia compared to those whose peak activity occurred earlier. This later timing, referred to as a later “acrophase,” could signify a discrepancy between the body's internal clock and environmental factors such as daylight, with previous studies linking such misalignment to inflammation and metabolic disruptions.

Notably, the study included a racially diverse group of participants, enhancing its applicability compared to earlier research often limited to more homogeneous populations.

While this study does not establish a causal relationship between circadian disruption and dementia, it underscores the importance of circadian rhythms as a potentially modifiable risk factor. Wearable devices effectively capturing circadian patterns could pave the way for personalized dementia risk assessments alongside genetic, vascular, and cognitive evaluations.

The findings further suggest that interventions like light therapy, structured sleep schedules, and time-restricted eating should be explored for their potential to help maintain cognitive health, particularly in individuals exhibiting early signs of circadian disruption. By demonstrating the correlation between everyday activity rhythms, as measured by wearable technology, and future dementia risk, this research advances the understanding of circadian biology within clinical settings.