The independent and joint association of accelerometer-measured physical activity and sedentary time with dementia: a cohort study in the UK Biobank

Abstract

Background: Research on the association of physical activity and sedentary time with dementia is accumulating, though elusive, and the interaction effects of the two remain unclear. We analysed the joint associations of accelerometer-measured physical activity and sedentary time with risk of incident dementia (all-cause dementia, Alzheimer's disease and vascular dementia).

Methods: A total of 90,320 individuals from the UK Biobank were included. Accelerometer-measured total volume of physical activity (TPA) and sedentary time were measured at baseline and dichotomised by median (low TPA [< 27 milli-gravity (milli-g)], high TPA [≥ 27 milli-g]; low sedentary time [< 10.7 h/day], high sedentary time [≥ 10.7 h/day]). Cox proportional hazards models were used to evaluate the joint associations with incident dementia on both additive and multiplicative scales.

Results: During a median follow-up of 6.9 years, 501 cases of all-cause dementia were identified. Higher TPA was associated with a lower risk of all-cause dementia, Alzheimer's disease and vascular dementia; the multivariate adjusted hazard ratios (HRs) (95% CI) per 10 milli-g increase were 0.63 (0.55-0.71), 0.74 (0.60-0.90) and 0.69 (0.51-0.93), respectively. Sedentary time was only found to be linked to all-cause dementia, and the HR for high sedentary time was 1.03 (1.01-1.06) compared with that for low sedentary time. No additive and multiplicative relationship of TPA and sedentary time to incident dementia was found (all P values > 0.05).

Conclusion: Higher TPA level was related to a lower risk of incident dementia irrespective of sedentary time, which highlighted the implication of promoting physical activity participation to counteract the potential detrimental effect of sedentary time on dementia.

Keywords: Accelerometer; Dementia prevention; Physical activity; Sedentary time.

Fig. 1

Flowchart of participant selection

Fig. 2

Restricted cubic splines for dose–response associations between TPA and sedentary time with incident dementia. a TPA and all-cause dementia; b TPA and Alzheimer’s disease; c TPA and vascular dementia; d Sedentary time and all-cause dementia; e Sedentary time and Alzheimer’s disease; f Sedentary time and vascular dementia. The 95% CIs of the adjusted hazard ratios are represented by the shaded area. Multivariable models were adjusted for age at baseline, sex, ethnicity, education and Townsend deprivation index, smoking status, alcohol intake frequency, body mass index, baseline cardiovascular disease, hypertension, diabetes, cancer and depression

Fig. 3

Adjusted risk of incident dementia according to TPA (milli-g) and sedentary time (h/day) profile. Cox proportional hazards models were adjusted for age at baseline, sex, ethnicity, education and Townsend deprivation index, smoking status, alcohol intake frequency, body mass index (BMI), history of cardiovascular disease (CVD), hypertension, diabetes, cancer and depression. Abbreviations: TPA, total volume of physical activity; milli-g

Fig. 4

Stratified analysis for the association between TPA and sedentary time with all-cause dementia risk. Subgroup analyses were conducted for high TPA and low sedentary time compared with low TPA and high sedentary time. Models were adjusted for age at baseline, sex, ethnicity, education, Townsend deprivation index, smoking status, alcohol intake frequency, body mass index, history of cardiovascular disease, hypertension, diabetes, cancer and depression. Abbreviations: TPA, total volume of physical activity, milli-g; BMI, body mass index; CVD, cardiovascular disease

Fig. 5

Stratified analysis for the association between TPA and sedentary time with vascular dementia risk. Subgroup analyses were conducted for high TPA and low sedentary time compared with low TPA and high sedentary time. Models were adjusted for age at baseline, sex, ethnicity, education, Townsend deprivation index, smoking status, alcohol intake frequency, body mass index, history of cardiovascular disease, hypertension, diabetes, cancer and depression. Abbreviations: TPA, total volume of physical activity, milli-g; BMI, body mass index; CVD, cardiovascular disease

Fig. 6

Stratified analysis for the association between TPA and sedentary time with Alzheimer’s disease risk. Subgroup analyses were conducted for high TPA and low sedentary time compared with low TPA and high sedentary time. Models were adjusted for age at baseline, sex, ethnicity, education, Townsend deprivation index, smoking status, alcohol intake frequency, body mass index, history of cardiovascular disease, hypertension, diabetes, cancer and depression. Abbreviations: TPA, total volume of physical activity, milli-g; BMI, body mass index; CVD, cardiovascular disease