Effect of cognitive reserve and amyloid deposition on sleep‐dependent cognition in older adults. (31st December 2021)

• Record Type: Journal Article
• Authors: Ourry, Valentin; Rehel, Stéphane; André, Claire; Gonneaud, Julie; Moulinet, Inès; Kuhn, Elizabeth; Touron, Edelweiss; Landeau, Brigitte; Mézenge, Florence; Paly, Léo; Delarue, Marion; De la Sayette, Vincent; Chetelat, Gaël; Rauchs, Géraldine
• Is Part Of: Alzheimer's & dementia. Volume 17(2021)Supplement 1
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-31
• Subjects: Alzheimer's disease -- Periodicals; Alzheimer Disease -- Periodicals; Dementia -- Periodicals; Démence; Maladie d'Alzheimer; Périodique électronique (Descripteur de forme); Ressource Internet (Descripteur de forme); 616.83
• DOI: 10.1002/alz.051998
• Languages: English
• ISSNs: 1552-5260

Abstract

Abstract: Background: Sleep, especially slow wave sleep (SWS), favors efficient cognitive functioning. This effect may be impaired in aging, but might be modulated by cognitive reserve. Indeed, a study reported that highly educated older adults were able to better tolerate the negative effects of subjective sleep disturbances on verbal fluency scores. Growing evidence also suggests that sleep may favor amyloid clearance. In this context, we investigated the effect of cognitive reserve and amyloid deposition on the links between SWS and cognitive performance in older adults. Methods: Baseline data of 135 cognitively unimpaired older adults (mean age ± SD: 69.3 ± 3.8 y) from the Age‐Well cohort were analysed. Participants underwent a neuropsychological assessment, a polysomnography, and a florbetapir PET scan to measure amyloid deposition. Cognitive reserve was estimated using a socio‐behavioral proxy, the Lifetime of Experiences Questionnaire. We conducted linear regressions between SWS (% of total sleep time) and 1) executive functions and 2) episodic memory composite scores. Standardized residuals were extracted so that higher values reflect a better cognition than expected (i.e., greater cognitive resilience). Then, we performed linear regressions with these residuals as dependent variables and cognitive reserve or amyloid deposition as independent variables. Analyses were repeated with age, sex and the apnea‐hypopnea index as covariates. Results: SWS (%) was positively associated with executive functions (p=0.021) and episodic memory (p=0.017) composite scores (Figure 1). For both cognitive domains, higher residuals were associated with better cognitive reserve and lower amyloid deposition (p<0.05) (Figure 2). All links with cognitive reserve remained significant after controlling for the covariates (p<0.05), while those with amyloid deposition were close to the significance threshold (p=0.085 and p=0.054 for executive functions and episodic memory respectively). Conclusions: Individuals with higher cognitive reserve or, to a lesser extent, lower amyloid deposition, were able to better tolerate the effects of low amounts of SWS on executive and episodic memory performance. Cognitive reserve may help maintaining cognitive performance even when sleep is disrupted (i.e., cognitive resilience to sleep changes), while amyloid deposition would increase the vulnerability to poor sleep quality. These findings are important to understand the factors promoting successful aging.