Exercise Keeps the Brain From Shrinking as We Age

CC BY 2.0. Wikimedia Commons

The average brain shrinks by approximately five percent every decade after the age of 40; but aerobic exercise significantly helps maintain volume, says new study.

It's kind of funny; we're all looking for a silver bullet to boost health and stay sharp, but it's there right in front of us. Exercise! Study after study touts the enormous benefits exercise has to offer, the latest confirming that aerobic exercise can improve memory function and maintain brain health as we age.

Researchers from 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 looked at the effects of aerobic exercise on the hippocampus, an area of the brain that is essential for memory and other brain functions.

As brain health starts its slow decline at around the age of 40, the average brain begins shrinking by around five per cent each decade thereon. Animal studies have shown that exercise actually increases the size of the hippocampus, but until now proof that the same occurs for humans has been inconsistent.

The researchers did a meta-analysis of 14 studies and examined the brain scans of 737 people before and after aerobic exercise programs or in control conditions. The subjects ranged in age from 24 to 76 with an average age of 66 and included both healthy participants as well as those with mild cognitive impairments (like Alzheimer's) and those with a clinical diagnosis of mental illness (like depression and schizophrenia).

The exercise involved included stationary cycling, walking, and running on a treadmill, two to five times a week, for durations ranging from three to 24 months. The new study's authors discovered that while exercise had no effect on total hippocampal volume, it significantly increase the size of the left region of the hippocampus in humans.

"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," says lead author, NICM postdoctoral research fellow, Joseph Firth

Firth says that along with improving regular healthy aging, the results have implications for the prevention of aging-related neurodegenerative disorders such as Alzheimer's and dementia.

The authors conclude that "these results provide meta-analytic evidence for exercise-induced volumetric retention in the left hippocampus. Aerobic exercise interventions may be useful for preventing age-related hippocampal deterioration and maintaining neuronal health." Or to put it another way, if you're looking to keep your brain big and healthy, exercise could be your silver bullet.

See the study here: Effect of aerobic exercise on hippocampal volume in humans: A systematic review and meta-analysis.