Physical activity and dementia : Long-term follow-up study of adult twins

Abstract

Introduction. Physical activity is associated with a decreased occurrence of dementia. In twins, we investigated the effect of persistent physical activity in adulthood on mortality due to dementia. Materials and methods. Physical activity was queried in 1975 and 1981 from the members of the older Finnish Twin Cohort (n = 2 1,791), who were aged 24-60 years at the end of 1981. The subjects were divided into three categories according to the persistence of their vigorous physical activity. Dementia deaths were followed up to the end of 2011. Results. During the 29-year follow-up, 353 subjects died of dementia. In individual-based analyses the age-and sex-adjusted hazard ratio (HR) was 0.65 (95% CI 0.43-0.98) for subjects partaking in vigorous physical activities in both 1975 and 1981 compared to those who were inactive in both years. No significant change was observed after adjusting for potential confounding factors. The corresponding HR for within-pair comparisons of the less active twin versus the more active co-twin was 0.48 (95% CI 0.17-1.32). The results for analyses of the volume of physical activity were inconclusive. Conclusions. Persistent vigorous leisure-time physical activity protects from dementia, and the effect appears to remain after taking into account childhood environment.