Dose-response relationship between late-life physical activity and incident dementia: A pooled analysis of 10 cohort studies of memory in an international consortium

Abstract

Introduction: Though consistent evidence suggests that physical activity may delay dementia onset, the duration and amount of activity required remains unclear.

Methods: We harmonized longitudinal data of 11,988 participants from 10 cohorts in eight countries to examine the dose-response relationship between late-life physical activity and incident dementia among older adults.

Results: Using no physical activity as a reference, dementia risk decreased with duration of physical activity up to 3.1 to 6.0 hours/week (hazard ratio [HR] 0.88, 95% confidence interval [CI] 0.67 to 1.15 for 0.1 to 3.0 hours/week; HR 0.68, 95% CI 0.52 to 0.89 for 3.1 to 6.0 hours/week), but plateaued with higher duration. For the amount of physical activity, a similar pattern of dose-response curve was observed, with an inflection point of 9.1 to 18.0 metabolic equivalent value (MET)-hours/week (HR 0.92, 95% CI 0.70 to 1.22 for 0.1 to 9.0 MET-hours/week; HR 0.70, 95% CI 0.53 to 0.93 for 9.1 to 18.0 MET-hours/week).

Discussion: This cross-national analysis suggests that performing 3.1 to 6.0 hours of physical activity and expending 9.1 to 18.0/MET-hours of energy per week may reduce dementia risk.

Keywords: cohort; dementia; dose-response; physical activity; pooled analysis; population-based.

Figure 1.. Location of each cohort.

SALSA=Sacramento Area Latino Study on Aging, USA. MYHAT=Monongahela–Youghiogheny Healthy Aging Team, USA. EAS=Einstein Aging Study, USA. BHAS=Bambuí Health and Aging Study, Brazil. ISA=Ibadan Study of Aging, Nigeria. HELIAD=Hellenic Longitudinal Investigation of Aging and Diet, Greece. LRGS TUA=The Longitudinal Study on Neuroprotective Model for Healthy Longevity, Malaysia. SLAS2=Singapore Longitudinal Aging Study-2, Singapore. SAS=Shanghai Aging Study, China. MAS=Sydney Memory and Aging Study, Australia.

Figure 2.. Categorization of physical activity based on restricted cubic splines.

(A) Density plot of the frequency distribution of the duration and amount of physical activity. (B) Adjusted hazard ratios of dementia relative to 0 hours/week (or 0 METhours/week) of physical activity. The dotted line represented hazard ratios adjusting for age, sex, years of education, and cohorts (model 1). The solid line and the ribbon represented hazard ratios and 95% confidence intervals further adjusting for APOE ε4, BMI, smoking, hypertension, diabetes, stroke, and depression (model 2). ISA and LRGS TUA were not entered into model 2 because of missing information on confounders.

Figure 3.. Dose-response relationship of the duration and amount of physical activity with incident dementia.

Model 1 adjusted for age, sex, years of education, and cohort. Model 2 further adjusted for APOE ε4, BMI, smoking, hypertension, diabetes, stroke, and depression. ISA and LRGS TUA were not entered into model 2 because of missing information on confounders. HR=hazard ration. CI=confidence interval.

Figure 4.. Dose-response relationship of the duration and amount of physical activity with incident dementia in the sensitivity analysis.

Dementia cases identified less than 2 years from baseline interview were excluded. Model 1 adjusted for age, sex, years of education, and cohort. Model 2 further adjusted for APOE ε4, BMI, smoking, hypertension, diabetes, stroke, and depression. ISA and LRGS TUA were not entered into model 2 because of missing information on confounders. HR=hazard ration. CI=confidence interval.