The literature is full of myths about how to prevent brain aging. One of the most enduring is that exercise can prevent the decline in cognitive function that normally comes with normal aging. An article this week Journal of the American Medical Association – Neurology An experiment is reported that tests the claim that cognitive decline can be prevented by regular exercise or by taking standard heart medications. Over two years, 513 adults exercised approximately three hours per week at moderate to vigorous intensity. Another group of older adults did not exercise but took a standard regimen of statins and blood pressure medication. A third group of older adults did both. Finally, a fourth group did not exercise regularly and did not take medication, essentially matching the experience of older adults in the United States. The study found no significant cognitive benefit from it.
The study was conducted at four locations in the United States. A total of 3290 people were examined, and 513 older adults (aged 60–85 years) without dementia and hypertension, a family history of dementia, and/or self-reported subjective cognitive decline were randomized. 63 percent were women.
The main question was whether combining regular aerobic exercise with drugs commonly used to reduce cardiovascular risk would protect brain health better than either intervention alone. Statins and blood pressure medications work through different mechanisms than exercise. The authors initially hypothesized that the benefits of these two approaches might synergize to reduce the risk of cognitive decline.
The study measured learning and memory abilities using the NIH Toolbox Cognition Battery using preclinical Alzheimer’s cognitive composite and executive function. After the two-year trial ended, the results showed that the group that did regular exercise and/or took standard medication both improved to the same degree as older adults who didn’t exercise or took any medication. The difference between the exercise group and the non-exercise group was not statistically different.
However, as predicted by many other studies, the adults who exercised maintained their cardiorespiratory fitness over two years while the control group’s fitness declined. Adults who took the two drugs showed reductions in systolic blood pressure and LDL cholesterol; However, they showed the same decline in cognitive function as the other three groups.
These results seem to contradict popular myths on the subject that are filled with personal observational studies. Unfortunately, these claims don’t always have real substance. Only randomized trials can demonstrate causation rather than correlation, and these trials, when properly conducted, do not support popular myths. A recent review of the literature found that the apparent benefits of exercise on cognition largely evaporated after correcting for publication bias. The SPRINT MIND trial, which tested low blood pressure in a large population, found no statistically significant improvement in cognitive test scores; However, it reduced the incidence of mild cognitive impairment and dementia when these results were combined.
What makes this study so relevant is that it was designed to determine whether an intervention can improve or preserve cognitive function in people who are still cognitively normal, which is mostly adults at this age. Future studies involving more subjects are needed to determine the role of exercise effects on cognitive tests, the effects of poor diet, and the presence of potential Alzheimer’s risk biomarkers. Current evidence suggests that regular exercise alone, or medication alone, or both together, is not sufficient. If you want to learn about the different effects of exercise on the brain, go here.
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