Physical activity attenuates the risk for dementia associated with aging in older adults with mild cognitive impairment. Findings from a population-based cohort study.

From 2016 to 2040 the number of people with dementia in the United Kingdom is expected to increase by 57%, while 70% percent of it is due to a higher life expectancy. Thus, we analyzed the overall and age-stratified effect of physical activity on risk of dementia in participants with mild cognitive impairment (MCI) of the English Longitudinal Study of Ageing (ELSA). Participants of the ELSA, aged over 50 with MCI, were followed-up nine times between 2002 and 2019. Physical activity was assessed using a self-reported, validated questionnaire and participants were classified as inactive, low, or moderate-to-high active. Medical diagnosis of dementia was self-reported or determined using the Informant Questionnaire on Cognitive Decline in the Elderly. Data from 521 participants with MCI were analyzed (56% women; mean [SD] age, 68.7 [10.6]). Over 17-year follow-up, 20.5 (95%CI: 17.3 to 24.2)% were diagnosed with dementia. The risk of incident dementia was reduced in participants engaging in low (HR: 0.34; 95%CI: 0.22 to 0.54) or moderate-to-high (HR: 0.16; 95%CI: 0.08 to 0.33) levels of physical activity. Risk of dementia in adults aged 80 or more engaging in low or moderate-to-high levels of physical activity was not different from inactive adults aged between 50 and 69 years. Results were sustained after competing risk regression model and sensitivity analyses to reduce the impact of reverse causality. Physical activity appears to minimize the risk associated with aging in older adults with MCI.