Running, walking fast or cycling at 45 would not only help you stay in shape. A new analysis of the famous cohort
Framingham Heart Study shows that a high level ofphysical activity after age 45 is strongly associated with a lower risk of memory problems decades later. A major issue, as more than 55 million people live with dementia worldwide and this number continues to rise.
Available treatments for Alzheimer’s disease only provide a modest slowdown in cognitive decline, are expensive and can cause undesirable effects, recall the authors of the Lancet 2024 Commission. This commission estimates that by acting on 14 modifiable risk factors, including a sedentary lifestyle in middle age, up to 45% of cases of Alzheimer’s disease could be avoided. dementia. And according to a new study, the key moment would be around the
quarantine.
Physical activity in midlife: what the Framingham study shows
The study, published in the journal JAMA Network Openanalyzed data from 4,354 adults from the Framingham cohort followed over the long term. The researchers separated the participants into three age groups: 26–44 years (early adulthood), 45–64 years (midlife), and 65–88 years (late life), all without a dementia diagnosis at baseline.physical activity was assessed by an index which cumulates the hours spent sleeping, sitting or practicing light, moderate or intense activities.
Over follow-up, 567 people developed dementia: 4% in the young adult group, 14% in the middle-aged participants and 26% in the oldest. After accounting for age, sex, BMI or hypertension, only high levels ofphysical activity between 45 and 88 years remained linked to lower risk. The most active people aged 45 to 64 had about 41% lower risk of dementia compared to the most sedentary, and those most active after 65 had about 45% lower risk, with comparable results for Alzheimer’s disease. “While it is commonly assumed that being more physically active earlier in life would provide greater benefits, these results indicate that being physically active after age 65 may be just as important as being physically active after age 45“, Phillip H. Hwang told Medical News Today.
Why 45% less risk in midlife makes a difference
For a reader, these figures remain abstract. Simplifying, if 10 out of 100 very sedentary people developed dementia, we would expect to see only about 6 of those in thephysical activity highest between 45 and 64 years. This statistical gain does not guarantee individual protection, but it greatly changes the probability on a population scale.
The authors also looked at exercise intensity. In middle age, it is mainly moderate or intense activities, among the levels ofphysical activity the highest, which were linked to lower risk, while light activity was not. The APOE ε4 gene, the main genetic factor for Alzheimer’s, modified these associations, with exercise appearing especially protective in people who were not carriers.
What type of exercise from the age of 40, concretely?
The index used in the study does not allow these results to be directly converted into precise minutes of effort. The World Health Organization’s recommendations remain a benchmark: 150 to 300 minutes of moderate-intensity activity per week, or 75 to 150 minutes of vigorous activity, for adults.
The study has several strengths, including long-term follow-up of participants, in-depth analysis of dementia cases, and detailed information on associated variables. However, some aspects may restrict the general extrapolation of the results: the majority of participants are of European origin, the number of cases of dementia in young adults is limited, physical activity is self-reported at a single time point, and it is not possible to assess past activity, which may lead to misclassification or bias.
Nevertheless, the study highlights the importance of physical activity in preventing dementia, particularly during critical periods, i.e. after age 45. She therefore advocates maintaining physical activity throughout life, to prevent Alzheimer’s disease, but also cardiovascular diseases, cancers, etc.