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Author Spotlight: Unveiling the Connection Between Sleep Disorders and Cognitive Symptoms in Depression
Published on: April 26, 2024
Sleep regularity is associated with cognitive function and shows an inverted U-shaped relationship with serum
Yue Cao1, Jaehee Lee1, Jaehoon Seol2
1Graduate School of Comprehensive Human Sciences, Doctoral Program in Physical Education, Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8574, Japan.
Objectives:
Day-to-day sleep patterns have been hypothesized to influence cognitive health and Alzheimer's disease. However, it remains unclear whether sleep irregularity is associated with cognitive function and its key marker, brain-derived neurotrophic factor (BDNF), especially in individuals with subjective concerns about cognition and sleep but who are otherwise relatively healthy.
Methods:
A total of 458 participants (aged 65.0 ± 11.1 years, 51.1 % female) participated in the Tsukuba Happiness Life Study between 2023 and 2024 in Japan. Day-to-day sleep patterns were measured using the Sleep Regularity Index (SRI) via 24/7 actigraphy. Cognitive function was evaluated using a comprehensive assessment battery. Serum BDNF was measured in a subgroup of 232 participants. Multivariate regression analysis was used for the main analysis.
Results:
Overall, the SRI ranged from 10.86 to 85.59; after adjusting for demographic factors and total sleep time, participants with higher SRI (range, 65.35-85.59) exhibited higher global cognitive function (B = 0.13, 95 % CI = 0.02, 0.24) than the lower SRI group (range, 10.86-54.08). Notably, a nonlinear relationship (inverted U-shaped) was observed between SRI and serum BDNF levels, whereas balanced SRI (around 60) and the middle SRI group exhibited significantly higher serum BDNF levels (B = 0.17, 95 % CI = 0.04, 0.30) than the lower SRI group.
Conclusions:
Higher SRI serves as an important factor for cognitive function. Maintaining a balanced SRI, which is neither too rigid nor highly irregular, might benefit Alzheimer's disease progression.
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