Another of the many benefits of exercise: a study "shows that a small amount of physical exercise could profoundly protect the elderly from long-term memory loss that can happen suddenly following infection, illnesses or injury in old age. ... aging rats that ran just over half a kilometer each week were protected against infection-induced memory loss. ... 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. Strikingly, this small amount of running was sufficient to confer robust benefits for those that ran over those that did not run. This is an important finding because those of advanced age are more vulnerable to memory impairments following immune challenges such as bacterial infections or surgery. With baby boomers currently at retirement age, the risk of diminished memory function in this population is of great concern. Thus, effective noninvasive therapies are of substantial clinical value. ... Past research has shown that exercise in humans protects against declines in cognitive function associated with aging and protects against dementia. Researchers also have shown that dementia is often preceded by bacterial infections, such as pneumonia, or other immune challenges. ... Previous research has shown that immune cells of the brain, called microglia, become more reactive with age. When the older rats in the study encountered a bacterial infection, these immune cells released inflammatory molecules called cytokines in an exaggerated and prolonged manner. ... 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."