Core idea

Spring is here, and with the warmer weather, many people’s thoughts turn to exercise. By now, just about everyone knows that study after study has shown that exercise reduces the risk of cardiovascular problems and overall mortality risk, as well as promoting psychological well-being. But what about dementia? Does exercise also protect us against Alzheimer’s disease and related disorders? This seems logical, given that exercise has so many other benefits. But research has been inconclusive. This creatively designed study by Andel and colleagues addressed some problems in previous research to shed new light on whether physical exercise in midlife helps prevent dementia 30 years later.

What they say

One problem with some earlier studies is that they have looked at physical exercise too close to the start of dementia; their follow-up periods are 4-7 years. This means that someone could have stopped exercising because he or she had early dementia symptoms, rather than the lack of exercise raising the risk of dementia. Andel and colleagues used data that asked people about their level of exercise when they were around 50 and did a follow up after 30 years – which pretty much insures that people’s exercise at the earlier time wasn’t affected by dementia. Another problem has to do with heredity. People may be genetically disposed both to get dementia and to have lower exercise patterns. A neat feature of this research is that it included a study of twins, comparing late-life twin pairs where one twin got dementia and the other one did not.

In the original assessment in 1967 – 1970, participants were asked how much exercise they had between the ages of 25 – 50: hardly any, light exercise, regular exercise, or hard physical training. They also controlled for various factors, including gender, age, education, smoking, and body mass index, among others. Light and regular exercise were associated with lower risk of dementia compared with “hardly any exercise.” The most benefit came from regular exercise. Interestingly, there was an even stronger protective effect of exercise for people who were overweight.

What it means

The authors note limitations to the study, especially that the measure of exercise was based on the respondents’ own reports (and are a summary of a long period of time). But the findings do suggest that in addition to helping us lose weight and feel good, exercise in midlife may be a very promising way to reduce our risk of getting dementia later on.

Reference

Andel, R., Crowe, M., Pedersen, N.L., Fratiglioni, L., Johansson, B., & Gatz, M.  (2008).  Physical Exercise at Nudkufe and Rish of Dementia Three Decades Later:  A Population-Based Study of Swedish Twins.  Journal of Gerontology:  Medica Sciences. 63A:1, 62-66.