A report by the Ontario Brain Institute suggests regular physical activity can not only help people with Alzheimer's or other dementias better manage their disease, but it also can significantly delay onset of dementia and even prevent it.
The report is based on a review of almost 900 studies from the last 50 years that examined the relationship between physical activity and Alzheimer's — a disease that affects more than 500,000 Canadians and is predicted to hit a million-plus within a generation.
"This is the strongest evidence to date that physical activity makes a significant difference to the management and the development of Alzheimer's disease," said Dr. Donald Stuss, president and scientific director of the Ontario Brain Institute.
Among the findings from the pooled study data was that people who were the most physically active had a 38 per cent lower risk of developing Alzheimer's than those who were the least physically active.
Dr. Laura Middleton, an assistant professor of kinesiology at the University of Waterloo, said that while preventing Alzheimer's and other dementias would be ideal, even delaying onset of symptoms would reduce the number of overall cases and the related costs to families, society and the economy.
"The good news is because Alzheimer's disease is a disease of later life, just by delaying the onset by two years, we may be able to reduce the prevalence of Alzheimer's disease or dementia by 25 per cent in Canada," Middleton told a media briefing Thursday.
Delaying onset by five years might cut in half the number of people afflicted, she said.
"So if we can do that through strategies such as physical activity, the projection would go from the steep incline to a relatively flat line just by delaying the onset by five years."
Stuss said routine physical activity not only has benefits for managing and preventing the development of dementia, it's also been shown to reduce the risk of other medical conditions, among them breast and colon cancer, cardiovascular disease and depression.
"Physical activity is powerful," he said.
Yet only a small proportion of adults, teens and children are meeting age-based national physical activity guidelines, said Christa Costas-Bradstreet, relations manager for Participaction Canada.
"We at Participaction feel that we have an inactivity crisis in Canada," said Costas-Bradstreet.
"Canadians are heavier, rounder, weaker and less flexible than they were one generation ago," she added, citing the most recent Canadian Health Measures Survey.
That study showed that 85 per cent of adults do not meet activity guidelines, while another found that 93 per cent of children and youth fall below recommended activity levels.
National guidelines from 2011 say adults need 150 minutes per week of moderate to vigorous exercise — so half an hour, five times a week — which can even be done 10 minutes at a time because the effects have been shown to be cumulative.
Costas-Bradstreet said activities could include brisk walking, running, swimming or dancing — whatever a person enjoys most and will do routinely. But it could also mean walking after getting off the bus farther from one's destination, parking the vehicle a distance away and walking or taking a walk at lunch.
The activity should be vigorous enough to make a person breathe harder and break a sweat, but not so taxing that it leaves them gasping.
The guidelines also recommend muscle and bone strengthening two days a week, while adults 65-plus are advised to add activities such as tai chi, yoga or pilates for improving balance to prevent falls.
Middleton said it may pay off most to start being physically active early in life, but as to what is the best type of exercise, researchers aren't yet sure.
Ballroom dancing has been touted as a good activity because learning and remembering the intricate steps works the mind at the same time as the person gets a physical workout.
Middleton said intentional exercise, such as going jogging, is a small portion of a person's daily activities.
"Oh yes, you go to the gym, you run, you walk, you do strength training, but you're also active over the course of the day through your chores, through your activities of daily living, if you go shopping," she said.
So "exercise" could include doing chores, gardening, walking to the store as opposed to driving — "all these little ways of being physically active."
A study by her research group found that people with the highest levels of overall physical activity had a 90 per cent lower risk of developing cognitive impairment over a two- to five-year period compared to those who were the least physically active, Middleton said.
The take-home message is simple: "Live an active life, ideally throughout the day, and start doing it as soon as possible."
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