Relationship between physical activity and incidence of dementia in people aged 50 and over in Europe.

Objective: The aim of this study was to analyse the relationship between physical activity and the incidence of dementia in a cohort of people aged 50 years or older without dementia from different countries in Europe between the years 2013 and 2015.

Methods: Prospective longitudinal design study (2013-2015) with a sample of 46,141 people without dementia in 2013 who participated in the SHARE project in waves 5 and 6, where 15 European countries participated. We defined dementia as a self-report of Alzheimer's disease, organic brain syndrome, senility, or any other serious memory impairment during follow-up. The frequency of moderate, vigorous and moderate-to-vigorous physical activity in 2013 was obtained from a validated questionnaire. Incidences of dementia by year (between 2013 and 2015) were calculated for each category of physical activity. Poisson regression models with robust variance were fitted for the association between physical activity and dementia.

Results: The incidence of dementia was 7.4 [95%CI = 6.8-7.9] cases per 1000 persons per year. Very frequent moderate physical activity is a protective factor for dementia independently of the frequency of vigorous physical activity and inversely. The risk of dementia was 2.36 [95%CI = 1.77-3.14] higher in people who hardly ever, or never did moderate-to-vigorous physical activity comparing to people engaged in it more than once a week independently of the baseline cognitive level.

Conclusion: Physical activity is associated with the incidence of dementia in people aged 50 and over in both men and women in Europe.