All age-related neurodegenerative conditions appear in conjunction with rising levels of chronic inflammation. The immune system runs awry with age, and while the immune cells of the central nervous system are significantly different in type and character from those of the rest of the body, inflammation is still a major consequence of age-related immune failure. In turn, that inflammation accelerates other ongoing degenerative processes. Calorie restriction is the most reliable and well-studied way of modestly slowing aging, and here researchers demonstrate that it is more effective than exercise when it comes to postponing the rise of inflammation in the brain.
Practicing both calorie restriction and regular exercise is a great idea, but only because these options are free. Calorie restriction results in sizable health benefits in humans, and even though it doesn't extend human life spans by anywhere near the same proportion as is observed in mice, it is still something for nothing. But should be we supportive of research efforts that expend billions and decades on attempts to recreate slices of the calorie restriction response? Probably not, when that is a poor alternative to building rejuvenation therapies after the SENS model of damage repair. Why spend large amounts of time and funding on trying to slightly slow aging rather than trying to halt and reverse aging? Both are equally plausible goals at the present time. Why pick the worse option?
Microglia are brain cells that help maintain the integrity and normal functioning of brain tissue. Dysfunction of these cells, as may occur in disease, is linked to neurodevelopmental disorders and neurodegenerative conditions. Aging is also associated with inflammation driven by microglia in specific regions of the brain, but it is unclear whether diet or lifestyle can influence this process.
Researchers investigated the impact of high- and low-fat diets on inflammation and microglial markers in a specific brain region - the hypothalamus - of 6-month-old mice. They further looked at the effect of low- or high-fat diets on the microglia of 2-year-old mice, which were also given a lifelong exercise regime (voluntary running wheel) or lifelong restricted diets (a 40% reduction in calories). "Aging-induced inflammatory activation of microglia could only be prevented when mice were fed a low-fat diet in combination with limited caloric intake. A low-fat diet per se was not sufficient to prevent these changes."
The researchers also found that exercise was significantly less effective than caloric restriction at preventing these changes, although work by others has shown that exercise is associated with reducing the risk of other diseases. There is still much more work needed to understand the meaning of these findings. In the study, mice were only given one type of diet throughout their lives. It remains unclear how changing between diets would alter these results - for example whether switching to a low-fat diet could undo the negative consequences of a high-fat, unrestricted diet. Further studies are also needed to determine how these changes correspond to the cognitive performance of the mice.