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Why It Pays Brain Dividends to Stay Fit in Middle Age

Research shows that staying fit in middle age may reduce dementia risk later.

Monkey Business Images/Shutterstock
Source: Monkey Business Images/Shutterstock

A high level of physical fitness in middle age may significantly decrease a woman’s risk of developing dementia by up to 90 percent compared to a moderate or low level of fitness, suggests a new study.

This was a small study with a few limitations (which we’ll discuss in a moment), but the findings are noteworthy as reinforcement of what we’re learning from multiple studies: Physical fitness is generally linked to improved brain health, even to the degree of providing some protection against the debilitating effects of dementia.

The study spanned more than four decades, beginning in 1968 with a bike exercise test measuring peak cardiovascular activity. Of the 191 women who took the test, 40 achieved the status of “highly fit,” 92 met criteria for moderate fitness, and 59 fell into the low fitness category (the test was stopped on a few occasions for low-fitness participants who developed chest pain or high blood pressure). The average age of the participants was 50.

The women were tested for dementia six times over the span of 44 years, starting in 1974 and concluding in 2009. During that time, 23 percent of the group developed dementia (44 women total), with a percentage breakout that looked like this:

High-fitness participants: 5 percent

Moderate-fitness participants: 25 percent

Low-fitness participants: 32 percent

Unable to finish test: 45 percent

The dementia risk difference between the high-fitness and moderate-fitness groups was 88 percent. In addition, among the high-fitness women who did develop dementia, the onset of the disease was an average of 9.5 years later than onset for women in the moderate-fitness group.

All of which is notable even for a small study, albeit one with the advantage of evaluating dementia risk over time. The study also took into account socioeconomic, lifestyle, and medical factors that may have influenced the results.

“[The results] indicate that negative cardiovascular processes may be happening in midlife that could increase the risk of dementia much later in life," said lead study author Helena Hörder, Ph.D.

Now for the study's limitations. First, the participants’ fitness levels were tested only once, so anything that may have gone wrong for them that day (didn’t sleep well the night before, not feeling well, etc.) counted against them. Likewise, an especially positive test result that single day may not have adequately indicated a true fitness level. At least a handful of fitness tests over time, perhaps a week or two, would have been more reliable. Also, all of the women in this study were from Sweden, so factors ranging from genetics to lifestyle must be considered in the results.

But as we’re seeing from other studies on this topic, these results aren’t alone. They line up well with an emerging theme: Staying physically fit strongly correlates with improved brain health.

"These findings are exciting, because it's possible that improving people's cardiovascular fitness in middle age could delay or even prevent them from developing dementia," Hörder said.

A comparable study that also tracks cardiovascular disease, along with dementia risk, would contribute much to the discussion, because then we’d have more evidence that what’s good for the heart in terms of fitness is also good for the brain.

The latest study was published in the journal Neurology.

© David DiSalvo