Running and other exercise is as beneficial for the brain as for the body. People who keep fit tend to have larger brains, better memories and clearer thinking, scientists have discovered. Conversely, unfit people have smaller brains and reduced cognitive skills.
The new findings add to growing evidence that exercise can protect the human brain against ageing, staving off the damage that builds up with age and even prompting it to replace dying cells — potentially reducing the risk of degenerative diseases such as Alzheimer’s.
Some of the latest findings are contained in NeuroImage, a scientific journal that has devoted its latest issue to research papers describing the phenomenon.
In one, scientists at Kentucky University put 30 adults aged 59-69 on a treadmill to measure their heart and lung capacity, and used an MRI scanner to assess the blood flow to their brains.
They found people who were less fit had smaller brains while those who were active had larger brains — a seemingly simple result but one with huge implications for health policy.
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They wrote: “We observed a positive relationship between cardio-respiratory fitness and cerebral blood flow. We found that better myocardial function was associated with greater cerebral blood flow to . . . the cingulate cortex and precuneus.” Conversely, they wrote: “Low measures of resting cardiac function are associated with smaller brain volumes, delayed recall and poorer cognitive performance.”
The results, they added, showed that: “Maintaining fitness through regular activity and exercise is instrumental in preserving brain health late in life [whereas] declines in cardiac function are associated with cognitive impairment.”
In a separate study, scientists in Germany saw similar improvements in the hippocampus — a brain area vital for memory — of 21 adults aged 60-77 as they went through a three-month fitness programme. They were accompanied by improvements in memory. “The changes in fitness, hippocampal perfusion [blood flow] and volume were positively related to changes in recognition memory and early recall for complex spatial objects,” they wrote in the journal Molecular Psychiatry.
Just why exercise protects brain cells is hard to discern in humans but research in mice gives a clue. Scientists at the National Institute on Aging, in Baltimore, compared mice that had been exercised regularly on a wheel with others that were sedentary. They found that in the fit mice, cells in the hippocampus were actively reproducing but those of their flabby colleagues were in decline.
Henriette van Praag, a co-author on the paper, in NeuroImage, said: “For most people, physical health and brain health once seemed to have little connection. This has been changed by discoveries in rodents that wheel-running increases production of new neurons in the hippocampus.”
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The findings come as the Global Council on Brain Health, a scientific collaboration of British and American experts on ageing, is finalising its first report.
“Moderate-intensity aerobic activity such as brisk walking, cycling or running can produce changes in brain structure and function,” said Linda Clare, professor of clinical psychology of ageing and dementia at Exeter University and a council member. “These changes increase cognitive reserve, making the brain more resilient to neuropathology.”
Professor James Goodwin, chief scientist at Age UK, which helped convene the group, said it was clear that active lifestyles reduced the risk of cognitive decline seen in ageing but too little was known about the underlying mechanisms.
One possibility is that fit people have stronger circulations, giving the brain a better supply of blood and nutrients.
“ Brain deterioration is seen as inevitable and unpreventable. But that is wrong — your lifestyle is intimately linked to the health of your brain,” Goodwin said.