Exercising to Remember

For those looking for another reason to get out and exercise, a CU-Boulder study reveals that just a little physical exercise can help protect us from long-term memory loss in old age.

In the study, CU research associate Ruth Barrientos and her colleagues in the psychology and neuroscience department showed aging rats that ran just over half a kilometer each week were protected against infection-induced memory loss.

“Strikingly, this small amount of running was sufficient to confer robust benefits for those that ran over those that did not run,” Barrientos says. “This is an important finding because people of an advanced age are more vulnerable to memory impairments following immune challenges, such as bacterial infections or surgery.”

The news is especially significant because the nation’s baby boomers are aging and the risk of diminished memory function in this population is of great concern, says Barrientos, who emphasizes the importance of developing effective noninvasive therapies.

Past research has shown that exercise in humans protects against dementia and declines in cognitive function associated with aging. Researchers also have shown that dementia is often preceded by bacterial infections, such as pneumonia or other immune challenges.

“To the best of our knowledge, this is the first study to show that voluntary exercise in rats reduces aging-induced susceptibility to the cognitive impairments that follow a bacterial infection and the processes thought to underlie these impairments,” Barrientos says.

In the study, researchers found rats infected with E. coli bacteria experienced detrimental effects on the hippocampus, an area of the brain that mediates learning and memory.

When the older rats in the study encountered a bacterial infection, the immune cells of the brain, called microglia, released inflammatory molecules called cytokines in an exaggerated and prolonged manner. This supports earlier research that has shown these immune cells become more reactive with age.

“In the current study we found that small amounts of voluntary exercise prevented the priming of microglia, the exaggerated inflammation in the brain and the decrease of growth factors,” Barrientos says.

What’s next? She plans to examine the role stress hormones may play in sensitizing microglia and whether physical exercise slows these hormones in older rats.