Dementia Risk Intertwined With Exercise at Two Life Stages

 Did your competent? doctor get you recovered enough to do this exercise and possibly prevent dementia? Oh no; You DON'T have a functioning stroke doctor, do you?

Dementia Risk Intertwined With Exercise at Two Life Stages

Key Takeaways

• Higher physical activity in midlife was associated with a 40% lower dementia risk over 26 years.
• Late-life physical activity also was linked with less dementia risk.
• Exercise and activity can increase cerebral blood flow, reduce inflammation, and boost neuroplasticity.

Physical activity in both midlife and late-life was linked to substantially less dementia risk, a long-term analysis of a large cohort showed.

Compared with the lowest quintile of midlife physical activity, the top two quintiles were associated with 40% lower all-cause dementia risk over 26 years (HR 0.60 for quintile 4, 95% CI 0.41-0.89; HR 0.59 for quintile 5, 95% CI 0.40-0.88), reported Phillip Hwang, PhD, MPH, of Boston University, and colleagues.

Likewise, the top two quintiles of late-life physical activity were linked with 36% to 45% less dementia risk over 15 years (HR 0.64 for quintile 4, 95% CI 0.42-1.00; HR 0.55 for quintile 5, 95% CI 0.35-0.87), Hwang and co-authors wrote in JAMA Network Open.

The findings suggest that higher midlife and late-life physical activity are both associated with similar reductions in all-cause dementia and Alzheimer's dementia risk, Hwang and colleagues observed from their cohort study. In contrast, physical activity in early adulthood was not associated with all-cause dementia or Alzheimer's dementia, the researchers said.

"Being more physically active in middle-to-later life may help to reduce the risk of developing dementia," Hwang told MedPage Today.

"Identifying specific times or age periods when physical activity may be most beneficial for preventing or delaying the onset of dementia can better inform recommendations and strategies for prevention, as well as potential physical activity-related interventions across the life course," he added.

Exercise may be an important modifiable lifestyle factor for dementia risk, Hwang and colleagues noted. A report from the Lancet Commission on dementia prevention indicated that a lack of physical activity was associated with cognitive loss.

Further evidence comes from a U.K. Biobank analysis suggesting that high levels of cardiorespiratory fitness may partly offset genetic risk for Alzheimer's disease and dementia. Also, in the Harvard Aging Brain Study, moderate levels of activity were associated with longer periods without cognitive impairment in people with elevated brain amyloid levels.

Mechanisms for the physical activity-cognition relationship have been suggested to include exercise increasing cerebral blood flow, reducing inflammation, and boosting neuroplasticity. It's also been known to increase brain-derived neurotrophic factor expression in rodents.

To identify when being active had the strongest relationship with incident dementia, Hwang and colleagues evaluated prospective data from 4,354 people in the Framingham Heart Study Offspring cohort.

Participants were dementia-free at baseline and had physical activity assessed at baseline, early adulthood, midlife, and late life. Activity was self-reported using a physical activity index that determined a composite score weighted by hours sleeping and in sedentary, slight, moderate, or heavy activities.

The early adult group had 1,526 participants who were 26-44 years old. The midlife group had 1,943 people ages 45-64, and the late-life group had 885 participants ages 65-88. Overall, about 53% of participants were women. Participants in each ascending age group were followed for an average of 37.2, 25.9, and 14.5 years, respectively.(When I was 53 - 3 years post stroke - I had a resting heart rate of 54, cardiovascular fitness of an athlete, and that was doing no real exercise since my stroke at age 50.)

Over the study period, 567 people developed all-cause dementia, including 62 early adult (4%), 273 midlife (14%), and 232 late-life participants (26%).

Higher levels of moderate or heavy activity in midlife -- but not in early adulthood or late life -- were linked with lower dementia risk. Slight physical activity was not correlated with dementia.

In midlife, higher activity was associated with lower dementia risk only in people without an APOE4 Alzheimer's risk gene. Late-life activity, however, was associated with reduced dementia risk among both APOE4 carriers and noncarriers.

Activity may partly offset some APOE4-related changes, "which could be a potential reason why findings were observed in middle and late life for noncarriers but only in late life among carriers," the researchers wrote.

Among the study's limitations, physical activity was self-reported and may have been misclassified, Hwang and colleagues acknowledged. Mortality rates were higher among people with lower activity levels and older ages; this may have influenced results.

Reverse causation may be a concern in the late-life group, the researchers noted. "However, this concern is attenuated by the long follow-up time (mean 14.5 years) and exclusion of prevalent dementia cases at baseline," they noted.