The 24-Hour Movement Behaviour Composition and the Risk of Dementia

Abstract

INTRODUCTION: Sleep, sedentary behaviour (SED), light-intensity physical activity (LPA), and moderate-to-vigorous intensity physical activity (MVPA) are collectively termed ‘movement behaviours’. Time spent in these movement behaviours sums to a constant 24 hours/day. Therefore, sleep, SED, LPA, and MVPA are relative proportions of the day, which together make up a total composition called the ‘movement behaviour composition’. The study objective was to use compositional data analysis, an approach well suited to handle proportions, to examine the relationship between the movement behaviour composition and the risk of dementia. METHODS: 93,781 participants from the UK Biobank with a mean age of 62 years were studied. Daily time spent in sleep, SED, LPA, and MVPA were captured using wrist-worn accelerometers worn 24-hr/day for 7 days. New dementia cases, developed over an average 9.6 years of follow-up, were determined using healthcare records. Cox proportional hazards regression with compositional covariates was used to determine the relationship between the 24-hour movement behaviour composition and its components (sleep, SED, LPA, MVPA) with dementia. Results from these regression models were used to estimate how changing the movement behaviour composition would change the risk of dementia. RESULTS: The movement behaviour composition was significantly associated with dementia risk (p<.001). The proportions of the 24-hour day spent in MVPA and LPA were negatively associated with the risk of dementia, while the proportion of the 24-hour day spent in SED was positively associated in the risk of dementia. Sleep was not significantly associated with dementia risk. Estimates suggested that making changes to the movement behaviour composition would change dementia risk. For instance, the risk of dementia would increase by 2-8% if time spent in MVPA was decreased by 15 min/day and reallocated into sleep, SED, or LPA. Conversely, reallocating an extra 15 min/day into SED by reducing time spent in sleep, LPA, or MVPA would increase dementia risk by 2-8%. CONCLUSION: The daily movement behaviour composition was associated with dementia. Changing the composition would change dementia risk.