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Chasing time : the specific impacts and dynamic relationships of physical activity, sedentary behaviour, and sleep on older adults' cognitive health

University of British Columbia

Effective lifestyle and behavioural strategies which maintain the cognitive health of older adults with Mild Cognitive Impairment (MCI) – a transition stage between healthy cognition and dementia – are greatly needed. There are three time-use activity behaviours which all humans engage in daily: physical activity (PA), sedentary behaviour (SB), and sleep. Each time-use activity behaviour is linked to cognitive health, although the magnitude of these relationships are still uncertain. There is also preliminary evidence that these time-use activity behaviours share a complex and dynamic relationship with each other and cognitive health. Thus, the aim of this dissertation was two-fold: 1) to advance the current knowledge about the dynamic relationships between time-use activity behaviours and cognitive health; and 2) to characterize potential time-use activity behaviour intervention strategies for promoting cognitive health. Using a systematic review of observational studies, I showed SB is associated with poorer cognitive function. I next conducted three cross-sectional studies which found 1) the relationships of PA and SB with cognitive function differ by MCI status; 2) PA is associated with better cognitive function independent of any sleep index, while only sleep efficiency is associated with cognitive performance independent of PA; and 3) PA is associated with greater brain cortical thickness independent of SB, but SB is not associated with cortical thickness independent of PA. I then conducted a secondary analysis of a randomized controlled trial (RCT), where I found that while the intervention significantly increased older adult PA, it did not improve cognitive function. My final thesis study was a proof-of-concept RCT to examine the effects of multimodal chronotherapy to promote better sleep among older adults with MCI and poor sleep; I found the intervention improved subjective sleep, but did not improve objective sleep or cognitive function. The results of my thesis contribute to a better understanding of how time-use activity behaviours impact older adult cognitive health, and helps to refine the public health message for best promoting healthy cognitive aging through lifestyle.

Text

2020-04-09

Attribution 4.0 International

http://hdl.handle.net/2429/73958

Rehabilitation Sciences

University of British Columbia

UBCV

http://creativecommons.org/licenses/by/4.0/