The Finnish Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study had previously found that leisure-time physical activity in midlife was related to lower dementia risk 20 years later. In a recent update to this study, researchers looked at the impact of leisure-time physical activity on dementia risk from mid- to late life, and at how body mass index (BMI), sex, and genetics impact dementia risk. The researchers not only looked at levels of physical activity but also at the impact of physical activity levels increasing or decreasing.
The participants’ average age at the start of the study was 51. There was data on physical activity and dementia available for 1,411 individuals in the larger CAIDE study. Physical activity was assessed by asking participants how often a week they engaged in leisure activity that causes breathlessness that lasts at least 20 to 30 minutes. Individuals categorized as having high physical activity did leisure exercise between daily and three times a week. Intermediate was considered between once a week and 203 times a month, and low was between a few times a year and never. In terms of cognitive function, dementia in general and Alzheimer’s Disease more specifically were both tested for. As for genetics, participants were screened for the APOE gene, which has some variations that are associated with greater risk of Alzheimer’s. The researchers also looked into the potential impact of age, sex, years of education, marital status, physically demanding occupations, midlife BMI, and cardiorespiratory or musculoskeletal disease.
At the 28-year checkup point (when the average age of participants was 79), 17 percent of CAIDE participants had developed dementia. Participants with dementia were more likely to be older, have higher BMI, lower education, female, smokers, and widowed or separated. A decrease in physical activity from baseline to follow-up was also associated with a greater risk of dementia. Physical activity at work and cardiovascular or musculoskeletal disease were not statistically associated with a change in risk for dementia.
In terms of physical activity, older participants, men, individuals with physically demanding jobs, and lower BMI reported lower leisure-time physical activity. Those individuals with high levels of physical activity in midlife were most likely to retain their level of physical activity in late life. Of those individuals who were unable to perform physical activity in midlife due to injury or illness, 71 percent increased their leisure-time physical activity at follow-up.
As for the association between midlife leisure-time physical activity and dementia, the group with low physical activity had a 40 percent relative risk of developing dementia. This association remained at the same level even when education, midlife BMI, marital status, smoking, occupation physical activity level, and musculoskeletal or cardiorespiratory conditions were factored in. The genetic risk associated with the APOE gene did not change this result. Similar results were also obtained when the analysis looked specifically at Alzheimer’s cases instead of all dementias. The positive impact of physical activity appeared to be greatest among men, overweight individuals, and individuals who did not carry the APOE gene associated with higher Alzheimer’s risk.
As for the impact of changes in leisure-time physical activity, those who maintained high levels of physical activity or who increased their physical activity levels had lower dementia risk than individuals who continued to have low physical activity at both time points. There were no differences in dementia risk for those who had low or moderate physical activity at both time points, or for those whose physical activity had decreased at follow-up.
Based on this data, the researchers suggest that “the window of opportunity for physical activity interventions to prevent dementia may extend from midlife to older ages.” They also note that additional information is needed about the type, intensity, and duration of physical activity that are most effective for combating late-life cognitive decline.
Tolppanen A-M, Solomon A, Kulmala J, et al. Leisure-time physical activity from mid- to late life, body mass index, and risk of dementia. Alzheimer’s & Dementia. (2014). DOI: 10.1016/j.jalz.2014.01.008