A study by researchers at the University of Colorado has found that a small amount of physical exercise could protect the elderly from long-term memory loss. Sudden onset of memory loss has been linked to infection, illness or injury in old age.

"Our research shows that a small amount of physical exercise by late middle-aged rats profoundly protects against exaggerated inflammation in the brain and long-lasting memory impairments that follow a serious bacterial infection," said Barrientos of the psychology and neuroscience department. The results of the study were published in The Journal of Neuroscience.

In the study researchers found rats infected with E.coli bacteria experienced detrimental effects on the hippocampus area of the brain, which plays an important role in processing information from short-term memory, long-term memory and spatial navigation. Previous research has also found that microglia, immune cells of the brain, become more reactive with age.

The older rats in the study once infected showed microglia releasing higher and prolonged concentration of inflammatory cytokines which not only stimulate production of enzymes that degrade the brain matrix but also inhibit brain cell repair.

Research showed that aging rats that ran just over half a kilometer each week were protected against infection-induced memory loss. "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," said Barrientos.

These finding are considered important because people advanced in age are more vulnerable to memory impairments following immune challenges such as bacterial infections or surgery.

"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 said. “The next step of this research is to examine the role that stresses hormones may play in sensitizing microglia, and whether physical exercise slows these hormones in older rats."