Seniors, all those crosswords and Sudoku puzzles you’ve been doing to keep mentally fit? Put down your pencils and think again, because doctors now advise that physical exercise is the best way to keep your brain from shrinking over the years.

Three different studies released in recent weeks have suggested that exercise is an important key to cognitive and intelligence scores.

Alan Gow, from the University of Edinburgh, studied 638 Scottish citizens born in 1936, who had been followed in a long-term survey on the aging process for the Centre for Cognitive Ageing and Cognitive Epidemiology

Brain shrinkage is linked to problems with memory and thinking in the elderly, and is noted in some forms of dementia.

Gow’s research, published last week in Neurology, showed that program participants who performed more physical exercise each week showed fewer signs of damage in their brains’ white matter, where messages are transmitted. And neuroimaging tests demonstrated that the more active participants’ brains had more grey matter, where thoughts and actions are formed.

Gow’s studies also looked at more sedentary activities such as housework, reading and puzzles, but found exercise was the key factor in boosting the brain.

“It would be physical activity that would seem to have the edge in terms of having a protective effect,” Gow said.

Researchers at McMaster University are also convinced physical activity has a powerful anti-aging effect on the mind.

Dr. Mark Tarnopolsky, professor of pediatrics and medicine at McMaster University in Ontario, has also been studying the effects of exercise on aging from a neuromuscular and neurometabolic perspective.

“We have shown exercise improves the growth of new nerves in the brain,” he told CTV News. “Even things like vision improve after a fairly short time.”

They think exercise may be sending more blood to the brain, and flooding it with nutrients and oxygen. That could protect cells against age-related damage.

And Tarnopolsky’s studies show the benefits appear to kick in at any age, so it’s never too late to get going on a fitness plan.

“Even 65 and older, there are definitely improvements in (brain) function,” Tarnopolsky said.

With a report by CTV’s medical specialist Avis Favaro and producer Elizabeth St. Philip