Fitness Increases Brain Size

Everyone knows that aerobic exercise is a great way to lose weight, but new evidence suggests it can also be used to improve memory function and maintain brain health as we age. In a ground-breaking study by Australia's National Institute of Complementary Medicine at Western Sydney University and the Division of Psychology and Mental Health at the University of Manchester in the UK, researchers examined the positive effects of aerobic exercise on the hippocampus and the implications this has for the health of our ageing brains.

Brain health decreases as we get older, with the average brain shrinking by roughly 5 percent per decade after the age of 40. While we like to think we can make up this shortfall with the benefits of experience and wisdom, most of us would love to keep our brains intact for as long as possible. As it turns out, participating in regular aerobic exercise such as cycling, walking, and running is one of the best ways to improve brain function, with regular exercise found to significantly increase the relative size of the left region of the hippocampus in humans as they age.

While research has consistently shown that physical exercise increases the size of the hippocampus in mice, up until now, consistent results for human trials have been hard to come by. In the study, scientists conducted 14 clinical trials which examined the brain scans of 737 people, including a mix of healthy adults, people with mild cognitive impairment such as Alzheimer's, and people with a clinical diagnosis of mental illness including depression and schizophrenia. Participants in the study were aged between 24 and 76 years, with brain scans taken before and after aerobic exercise programs or in control conditions.

According to Joseph Firth, NICM post-doctoral research fellow and lead author of the study, this research provides some of the most definitive evidence to date on the benefits of exercise for brain health: "When you exercise you produce a chemical called brain-derived neurotrophic factor (BDNF), which may help to prevent age-related decline by reducing the deterioration of the brain... Our data showed that, rather than actually increasing the size of the hippocampus per se, the main 'brain benefits' are due to aerobic exercise slowing down the deterioration in brain size. In other words, exercise can be seen as a maintenance program for the brain."

The findings of this study have a number of important implications, including the possibility of developing exercise programs specifically for improving brain volume. According to the study, "focusing on fitness improvement appears to be one method for designing exercise interventions to confer neurobiological benefits." Previous research has already linked cardio fitness programs with improvements in cognitive performance, along with broader benefits for metabolic risk, physical capacities, and mental health outcomes. With physical fitness now also associated with increased brain size in the hippocampus, prescribing aerobic exercise could become a practical "intervention for promoting healthy aging, in order to maintain both physical and neurological functioning into old age."


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