Significantly increased risk seen for participants at the 5th percentile relative to the median sleep regularity index
By Elana Gotkine HealthDay Reporter
WEDNESDAY, Dec. 13, 2023 (HealthDay News) — There is a U-shaped association for sleep regularity with incident dementia, according to a study published online Dec. 13 in Neurology.
Stephanie R. Yiallourou, Ph.D., from the Turner Institute for Brain and Mental Health in Monash University in Melbourne, Australia, and colleagues examined the relationship between sleep regularity and incident dementia using data from 88,094 U.K. Biobank participants. During seven days of accelerometry, the average sleep regularity index (SRI) was calculated as the probability of being in the same state at any two time points 24 hours apart.
During a median follow-up of 7.2 years, the researchers identified 480 cases of incident dementia. A nonlinear association was seen between the SRI and risk for dementia with hazard ratios following a U-shaped pattern after adjustments for demographic, clinical, and genetic confounders (APOE ε4). Relative to the median SRI, hazard ratios were 1.53 (95 percent confidence interval, 1.24 to 1.89) and 1.16 (95 percent confidence interval, 0.89 to 1.50) for participants with SRI at the 5th and 95th percentiles, respectively. Gray matter and hippocampal volume tended to be lowest at the extremes of SRI in a subset of participants with brain magnetic resonance imaging (15,263 participants).
“The current results identify sleep regularity as a potential novel dementia risk factor,” the authors write. “Future studies are required because, even in individuals with normal sleep durations, improvement of sleep timing schedules may represent a potential target for the primary prevention of dementia.”
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