Associations between Physical Activity in Old Age and Dementia-Related Mortality: A Population-Based Cohort Study

BACKGROUND: Findings from the literature vary in relation to whether physical activity brings about less cognitive decline in old age. The present study investigated self-reported levels of physical activity in old age and its association with the risk of dementia-related mortality. METHODS: We included data from 31,086 subjects, between 65 and 80 years old, from the CONOR (Cohort of Norway) database. Cox regression analysis was used to estimate the risk of association. RESULTS: Taking part in 'light' (not causing perspiration or panting) activities of <3 h per week was associated with a decreased risk of dementia-related mortality, with a hazard ratio (HR) of 0.74 and a 95% confidence interval (CI) of 0.62-0.88, and of >3 h per week, with an HR of 0.61 and a 95% CI of 0.51-0.73. When taking part in 'hard' (causing perspiration or panting) activities, a similar risk (HR = 0.56; 95% CI 0.43-0.72) was observed for >3 h per week. Interestingly, the highest reduction in risk was seen for 'hard' activities of <3 h per week (HR = 0.50; 95% CI 0.41-0.61). CONCLUSION: Physical activity during leisure time in old age was associated with a lower risk of dementia-related mortality when compared to inactive individuals.