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by Beth Howard
Updated August 16, 2023
Exercise is one of the most powerful ways to support your brain health. People who are physically active tend to fare better in terms of cognition and memory.
Among more than 501,000 people ages 40 to 69 followed for at least 10 years, those who did activities such as swimming, cycling or playing strenuous sports had a 35 percent lower risk of dementia compared with those who maintained low levels of activity. This study, reported in 2022 in Neurology, is one of many showing the benefits of physical activity.
“Exercise makes our brains work better, improves our thinking, memory and learning and induces brain growth as opposed to erosion,” says neuropsychiatrist John J. Ratey, an associate clinical professor of psychiatry at Harvard Medical School.
The hippocampus, a region of the brain involved in memory formation, typically begins to shrink as people age, eventually leading to memory loss. But working out can stop and even reverse these negative processes, triggering the growth of new cells and plumping up this vital brain region. Among 120 older adults assigned to either a brisk walking group or a stretching “control” group, those who took brisk walks increased the size of the hippocampus by 2 percent in a year's time. That’s equivalent to rolling back the clock one or two years, the researchers suggested in 2011 in the journal PNAS.
One way exercise prompts these changes is by releasing a substance called brain-derived neurotrophic factor, or BDNF. “I call it Miracle-Gro for the brain,” Ratey says. “It’s truly a brain fertilizer. It helps grow the brain and makes it tougher and more resilient to stress and aging.” Physical activity has also been shown to increase the levels of other growth factors in the brain, including vascular endothelial-derived growth factor (VEGF) and insulin-like growth factor one (IGF-1), which aid the growth of nerve cells in the hippocampus, researchers reported in 2023 in Ageing Research Reviews.
Regular physical activity safeguards the aging brain in other important ways, including improving mood and lowering stress. Stress hormones erode the connections between the nerve cells in the brain, and chronic depression causes some brain regions to shrink, Ratey says. However, exercise fuels the production of “feel-good” neurochemicals such as serotonin and dopamine. They counteract the negative consequences of stress hormones and depressive moods, thus helping to maintain brain health. "Exercise is like taking an antidepressant," he says.
Regular workouts increase blood flow to the brain, which responds by making more capillaries. The result: More nutrients and oxygen reach and nourish different brain regions. Exercise also takes aim at inflammatory conditions like hypertension and diabetes that damage the brain and cardiovascular system.
Both aerobic and other types of exercise, such as resistance or strength training, can positively affect the brain. Even some active forms of housework are associated with reduced risk of dementia. The good news: You don't need to run marathons or heft heavy dumbbells to see a benefit.