A new study finds that aerobic exercise slows down decreasing brain size in older age, helping to maintain cognitive function.

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Aerobic exercise serves as a 'maintenance program for the brain', researchers say.

Aerobic exercise is a type of workout that increases the heartbeat and stimulates it to pump more oxygen through the body, yet it doesn't immediately produce shortness of breath. Some examples of aerobic exercise include running, cycling, and swimming.

Among the many health benefits that aerobics brings, some notable ones are weight loss, boosting cardiovascular health, reducing anxiety, and regulating moods.

A recent study covered by Medical News Today emphasized how low-intensity exercise can prevent depression.

And now, researchers from the National Institute of Complementary Medicine (NICM) at Western Sydney University in Australia — in collaboration with colleagues from the Division of Psychology and Mental Health at the University of Manchester in the United Kingdom — are looking at the possible benefits that aerobic exercise might hold for the brain.

Naturally, brain size decreases by around 5 percent every 10 years after age 40. This effect of brain aging is also sometimes tied with cognitive decline.

Lead author Joseph Firth, an NICM postdoctoral research fellow, says that when we exercise, our brains produce a chemical that could help to prevent cognitive decline.

"When you exercise you produce a chemical called brain-derived neurotrophic factor [...] which may help to prevent age-related decline by reducing the deterioration of the brain," he explains.

The researchers' findings were recently published in the journal NeuroImage.

Aerobics boosts size of left hippocampus

Existing studies using the animal model have suggested that physical exercise has the potential to greatly benefit the brain by stimulating the growth of nervous tissue and slowing down or preventing cognitive decline.

The same had been hypothesized in the case of humans, but the evidence so far has been fairly limited.

In the new study, the scientists reviewed 14 different clinical trials with a pooled data source of 737 brain scans taken before and after involvement in aerobic exercise programs, as well as during a control setting.

All the participants were between 24 and 76 years old — aged 66, on average — and they included cognitively healthy adults alongside individuals with mild cognitive impairment, depression, and schizophrenia.

Firth and colleagues were interested in investigating how aerobic exercise might impact the brain. Some workout programs that the participants were involved in included walking, stationary cycling, and treadmill exercise.

The programs lasted between 3 and 24 months, and they consisted of two to five exercise sessions per week.

It was found that aerobic exercise did not impact the overall volume of the hippocampus — that is, a region of the brain that plays a key role in the formation and consolidation of memory — but it did increase the size of the left part of this brain region.

Research has indicated that the left side of the hippocampus, specifically, is involved in memory function and verbal learning.

Firth explains that what this suggests is that aerobic exercise can decelerate age-related cognitive decline promoted by the decrease in size of the left hippocampus.

"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."

Joseph Firth

These results, Firth suggests, may have important implications in terms of preventing the onset of neurodegenerative disorders such as Alzheimer's disease. Still, additional research is needed in order to explore the possibilities offered by this avenue.

"[T]he link between cardiorespiratory fitness with both structural and performance increases," the researchers conclude, "indicates this as a suitable target for aerobic training programs to improve brain health."