Impact of Physical Activity on Cognitive Decline, Dementia, and Its Subtypes: Meta-Analysis of Prospective Studies

Abstract

The association of physical activity with dementia and its subtypes has remained controversial in the literature and has continued to be a subject of debate among researchers. A systematic review and meta-analysis of longitudinal studies on the relationship between physical activity and the risk of cognitive decline, all-cause dementia, Alzheimer's disease, and vascular dementia among nondemented subjects are considered. A comprehensive literature search in all available databases was conducted up until April 2016. Well-defined inclusion and exclusion criteria were developed with focus on prospective studies ≥ 12 months. The overall sample from all studies is 117410 with the highest follow-up of 28 years. The analyses are performed with both Bayesian parametric and nonparametric models. Our analysis reveals a protective effect for high physical activity on all-cause dementia, odds ratio of 0.79, 95% CI (0.69, 0.88), a higher and better protective effect for Alzheimer's disease, odds ratio of 0.62, 95% CI (0.49, 0.75), cognitive decline odds ratio of 0.67, 95% CI (0.55, 0.78), and a nonprotective effect for vascular dementia of 0.92, 95% CI (0.62, 1.30). Our findings suggest that physical activity is more protective against Alzheimer's disease than it is for all-cause dementia, vascular dementia, and cognitive decline.

Figure 1

PRISMA flowchart for search strategies.

Figure 2

Posterior box plots describing the 95% credible intervals for each study's specific odds ratio (OR) estimate where (a) represents high and (b) represents moderate against no/low physical activity for dementia.

Figure 3

Posterior box plots describing the 95% credible intervals for each study's specific odds ratio (OR) estimate where (a) represents high and (b) represents moderate against no/low physical activity for Alzheimer's disease.

Figure 4

Posterior box plots describing the 95% credible intervals for each study specific odds ratio (OR) estimate for high against no/low physical activity for vascular dementia.

Figure 5

Posterior box plots describing the 95% credible intervals for each study's specific odds ratio (OR) estimate where (a) represents high and (b) represents moderate against no/low physical activity for cognitive decline.