Physical Activity and Dementia: Is Timing Everything?

 

Now your competent? doctor needs to get you recovered enough to do this exercise and hopefully prevent dementia/Alzheimers. From age 56 to 68 I probably walked on average 10,000 steps a day. Absolutely nothing about that was from my doctor or therapists, spasticity prevents me walking normally, so I'm destroying my left knee.

My midlife exercise capability(50-56) was almost reduced to nothing because my incompetent? doctor had nothing to get me 100% recovered.

3 years post stroke at a physical I had a resting heart rate of 54 at age 53, level of an athlete. My doctor asked what exercises I was doing, 'I've done no exercises for the past 3 years'. So now after 19 years of little exercise I'm no longer that athlete.

Nothing here is useful in any sense to create protocols that will be repeatable and guarantee prevention of dementia.

Physical Activity and Dementia: Is Timing Everything?

This transcript has been edited for clarity. 

Hello. I’m Dr JoAnn Manson, professor of medicine at Harvard Medical School and Brigham and Women’s Hospital. In several studies, regular physical activity has been linked to lower risk for cognitive decline and dementia. But a key question is whether physical activity during certain adult life stages is most associated with dementia risk.

This important question was addressed in a recent study published in JAMA Network Open. The main findings of the study were that higher physical activity levels were particularly important in midlife and later life, and that higher fourth and fifth quintiles of activity(What specifically does this mean?) were associated with a 40% lower dementia risk during follow-up, when compared with the lowest levels of physical activity. Physical activity in early life was not clearly associated with dementia risk. 

The authors looked at prospective data from more than 4000 participants in the Framingham Heart Study Offspring cohort. All participants were dementia-free at baseline and had physical activity assessed at three life stages: early adulthood (26-44 years), midlife (45-64 years), and late life (65-88 years). During follow-up, 567 participants developed all-cause dementia.

Higher levels of moderate or heavy activity(EXACT definition needed!) in midlife or later life were linked with lower dementia risk. Physical activity in midlife was only associated with lower dementia risk among participants without an APOE4 Alzheimer's risk gene. Late-life activity, however, was associated with reduced dementia risk among both APOE4 carriers and noncarriers, suggesting late-life physical activity may offset some APOE4-related changes. 

There are multiple potential mechanisms underlying the reduced dementia risk associated with physical activity. Exercise reduces inflammation, helps to maintain favorable body composition, increases cerebral blood flow, and favorably affects neuroplasticity and levels of brain-derived neurotropic factor expression; the latter have previously been shown in rodent studies.

Although identifying specific life stages when physical activity appears most beneficial for preventing or delaying the onset of dementia may help inform guidelines and strategies for prevention, it's important to keep in mind that many studies, including the Bogalusa Heart Study, suggest that physical activity early in life is also critically important for coronary heart disease, stroke, and other chronic disease risk reduction. Therefore, beginning healthy lifestyle habits early in life is probably the best strategy of all in terms of cardiometabolic and general health. It seems that the policy that it's never too early and never too late to become physically active would be best.