August 20, 2015

Exercise for My Aging Brain: Less Is Not More but It Might Be Good Enough

No doubt I'll never find a study that claims less exercise is better than more. However, a new study suggests that a small amount of exercise may improve our ability to think as we age... and that more exercise may not necessarily be better.

We all know that working out is good for us. But precisely how much exercise do we need to gain various health benefits? Is the same dose of exercise that promotes heart health equally good for brain health?

For the new study, scientists at the University of Kansas Alzheimer's Disease Center tried to determine just how much exercise we need to improve our thinking skills.

The team recruited 101 sedentary, healthy adults with no symptoms of dementia or cognitive impairment. Those subjects were all 65+, the age when people typically begin to show worrisome declines in memory and cognition.

Baseline for Aerobic and Cognitive Fitness
The subjects then completed a series of tests to measure aerobic capacity and skills pertaining to memory and thinking.

The volunteers were randomly assigned among four groups, who
  • Walked briskly for 75 minutes weekly.
  • Walked briskly for 150 minutes weekly (the current recommended standard).
  • Walked briskly for 225 minutes weekly.
  • Simply continued their normal lives.
Under supervision at their local YMCA, the exercisers worked out on treadmills or elliptical machines. After 26 weeks, they completed the same aerobic and cognition tests they'd taken earlier.

No Brainer: Clear Correlation between Exercise and Physical Fitness
Physical differences became quickly apparent. All exercisers improved their fitness, and subjects who exercised most gained the most endurance capacity. Control group members showed no change.

According to Dr. Jeffrey Burns, co-director of the University of Kansas Alzheimer’s Disease Center and the study’s senior author: "There was a very clear dose-response relationship" between walking and fitness.

The relationship between exercise and cognition was murkier.

Most exercisers showed improved thinking skills in two cognition categories that normally decline with age:
  • Ability to control attention
  • Ability to create mental maps of physical spaces.
Interestingly, these improvements were generally consistent among all exercisers, regardless of weekly treadmill time. The clear correlation between exercise time and improvements that the scientists found in aerobic results did not apply in cognition results.

According to Dr. Burns, "a small dose of exercise" may be sufficient to improve many aspects of thinking and more sweat may not produce noticeably more cognitive benefit. He added that the aerobic fitness that comes with exercise brings other health benefits.

Still Murky: Relation between Exercise and Cognition
Questions remain about exercise and cognition. Burns said, "We need to be able to say, this much exercise will provide these benefits." He suspects that clearer guidelines might inspire more people to exercise.

Toward that end, Burns and his team are working on a study to determine -- if they can -- how much of what type of exercise might help delay the onset of dementia.

In the meantime, Burns thinks his recent findings carry a useful take away: Briskly walking 20-25 minutes several times a week -- a dose of exercise most of us can handle -- may help keep our brains sharp.

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