In this piece for Aeon, Bruce McEwen discusses how “good stress,” “tolerable stress,” and “toxic stress” act epigenetically on our brain structure, and how we can change our lifestyles to influence our brain’s capacity to adapt to stress.
“These revelations about adult brain neurogenesis have huge implications not only because of the recognition that stem, or progenitor, cells might be used to treat brain damage, but also because of their meaning for lifestyle. Regular physical activity increases this neurogenesis in old as well as young people, and improves memory and mood and even enlarges the hippocampus, which tends to shrink in depression and diabetes among other conditions. Within six months to a year, regular aerobic activity such as walking an hour a day five out of seven days a week not only makes the hippocampus larger and improves memory but also improves decision-making by improving blood flow and metabolic function in the prefrontal cortex, a brain region essential for self-regulation of emotions and impulses as well as working memory. Indeed, regular physical activity is the most important behaviour that one can do to maintain brain and body health. And, as a further illustration of brain-body communication, the ability of exercise to stimulate neurogenesis requires that at least two hormones be taken up from the body into the brain. One of them, IGF-1, comes from the liver, and the other, cathepsin B, comes from muscle.”