Is physical activity a potential preventive factor for vascular dementia? A systematic review

Background: Physical exercise has several beneficial effects, including reduced risk for Alzheimer's disease. Although several studies of potential risk factors for vascular dementia (VaD) exist, including physical activity, the studies have usually included few participants and there are no meta-analyses addressing this key topic. Methods: The MEDLINE database was searched using the key words 'physical exercise' 'activity' or 'walking' in combination with 'dementia' and 'vascular dementia'. Potentially relevant studies were assessed and summarised by two of the authors, and longitudinal studies with operationalised definition of physical activity providing risk for VaD in both groups were included in the meta-analysis using pooled estimates from a random effects model. Results: A total of 24 longitudinal studies, including 1378 patients with VaD, were included in the review. The majority of individual studies did not report significant associations. Five studies fulfilled criteria for meta-analysis, including 10,108 non-demented control subjects and 374 individuals with VaD. The meta-analysis demonstrated a significant association between physical exercise and a reduced risk of developing VaD: OR 0.62 (95% CI 0.42-0.92). Conclusions: We conclude that there is evidence supporting the hypothesis that physical activity is likely to prevent the development of VaD, and should be highlighted as part of secondary prevention programmes in people at risk for cerebrovascular disease.