The Independent Associations of Physical Activity and Sleep with Cognitive Function in Older Adults

Article type: Research Article

Authors: Falck, Ryan S.^a | Best, John R.^a | Davis, Jennifer C.^a | Liu-Ambrose, Teresa^{a; b; *}

Affiliations: [a] University of British Columbia, Faculty of Medicine, Aging, Mobility and Cognitive Neuroscience Laboratory, Djavad Mowafaghian Centre for Brain Health, Vancouver, BC, Canada | [b] Centre for Hip Health and Mobility, Vancouver Coastal Health Research Institute and University of British Columbia, Vancouver, BC, Canada

Correspondence: [*] Correspondence to: Teresa Liu-Ambrose, PhD, PT, University of British Columbia, Faculty of Medicine, Aging, Mobility and Cognitive Neuroscience Laboratory, Djavad Mowafaghian Centre for Brain Health & Centre for Hip Health and Mobility, 212-2177 Wesbrook Mall, Vancouver, BC V6T 1Z3, Canada. Tel.: +1 604 875 4111/Ext. 69059; E-mail: teresa.ambrose@ubc.ca.

Abstract: Background:Current evidence suggests physical activity (PA) and sleep are important for cognitive health; however, few studies examining the role of PA and sleep for cognitive health have measured these behaviors objectively. Objective:We cross-sectionally examined whether 1) higher PA is associated with better cognitive performance independently of sleep quality; 2) higher sleep quality is associated with better cognitive performance independently of PA; and 3) whether higher PA is associated with better sleep quality. Methods:We measured PA, subjective sleep quality using the Pittsburgh Sleep Quality Index (PSQI), and objective sleep quality (i.e., fragmentation, efficiency, duration, and latency) using the MotionWatch8© in community-dwelling adults (N = 137; aged 55+). Cognitive function was indexed using the Alzheimer’s Disease Assessment Scale-Plus. Correlation analyses were performed to determine relationships between PA, sleep quality, and cognitive function. We then used latent variable modelling to examine the relationships of PA with cognitive function independently of sleep quality, sleep quality with cognitive function independently of PA, and PA with sleep quality. Results:We found greater PA was associated with better cognitive performance independently of 1) PSQI (β= –0.03; p < 0.01); 2) sleep fragmentation (β= –0.02; p < 0.01); 3) sleep duration (β= –0.02; p < 0.01); and 4) sleep latency (β= –0.02; p < 0.01). In addition, better sleep efficiency was associated with better cognitive performance independently of PA (β= –0.01; p = 0.04). We did not find any associations between PA and sleep quality. Conclusions:PA is associated with better cognitive performance independently of sleep quality, and sleep efficiency is associated with better cognitive performance independently of PA. However, PA is not associated with sleep quality and thus PA and sleep quality may be related to cognitive performance through independent mechanisms.

Keywords: Cognitive function, older adults, physical activity, sleep

DOI: 10.3233/JAD-170936

Journal: Journal of Alzheimer's Disease, vol. 63, no. 4, pp. 1469-1484, 2018