The relationship between sleep duration and cortical sulcal width in midlife and older adults

Abstract

AbstractBackgroundEmerging evidence suggests that poor sleep is associated with worse cognitive and structural brain health, and an increased risk of developing dementia (Bubu et al., 2016; Fjell et al., 2022; Tai et al., 2022). The present study investigated the influence of sleep duration on the cognition‐brain relationship in older adults using sulcal width (SW), a reliable measure of changes in the ageing brain (Bertoux et al., 2019). The influence of napping, depression likelihood, and genetic risk for dementia (APOE ε4 status) was also explored.MethodParticipants were 137 cognitively normal adults, aged 46‐72 from the Prospective Imaging Study of Ageing (PISA). Demographic information, sleep duration, and depressive symptoms were collected via online questionnaires. Cognition was assessed using the Cambridge Brain Systems battery. APOE genotype was determined from blood‐extracted DNA. Imaging data was acquired using a 3T Siemens PRISMA scanner. SW was extracted using the Morphologist pipeline (Borne et al., 2020).Canonical Partial Least Squares (PLS) were used to obtain latent variables of cognition and SW. ANCOVAs measured the effect of sleep duration categories (7‐7.5 hours versus {<7 or ≥8 hours}) on the cognitive and SW components, with sex and age as covariates. Status of depression likelihood was added as a covariate of interest. The effect of napping, and APOE ɛ4 allele on these same components were measured by ANCOVAs, with sex and age as covariates.ResultWe observed a significant effect of sleep duration on SW (F(1, 133) = 4.17, p = 0.043, Fig. 1). This effect remained significant (F(1,132) = 4.89, p = 0.029) after including depression likelihood as a covariate, which was also significant in the model (F(1,132) = 4.62, p = 0.034). A significant interaction between APOE ε4 status and age (p = 0.050) on SW was also observed.ConclusionResults add weight to studies suggesting that not too much or too little sleep is needed to maintain brain health in later life (Li et al., 2022; Liang et al., 2019). Depression, a risk factor for dementia (Livingston et al., 2020), was also associated with poorer brain health. Results suggest that at approximately 60 years of age, the influence of a positive APOE ε4 status is associated with increasing age‐related brain atrophy.