More than one in seven cases of Alzheimer's in Ontario could have been prevented through exercise, according to a report released today summarizing 50 years of research.
"This is the strongest evidence to date that physical activity makes a significant difference to the management and development of Alzheimer's disease," Ontario Brain Institute scientific director Dr. Donald Stuss said at a news conference at Toronto's MaRS Centre.
The Ontario Brain Institute's report looked at nearly 900 studies to better understand the link between physical activity and dementia. It found that one in seven cases of Alzheimer's could be prevented if everyone who reported being inactive in Ontario became active enough to burn roughly 1,600 calories a week.
Last year, nearly 99,000 people in the province were living with Alzheimer's disease. That means more than 15,000 of these cases were potentially preventable.
The report - compiled by York University health researchers Chris Ardern and
Michael Rotondi - also determined that in older adults without Alzheimer’s disease, those who were very physically active were almost 40 per cent less likely to develop Alzheimer’s disease as those who were inactive.
While it's not clear what constitutes enough physical activity to ward off dementia, University of Waterloo kinesiology professor Laura Middleton said most studies look at aerobic exercise such as brisk walking, jogging, swimming and cycling.
"It does seem that this exercise can improve cognitive function," said Middleton, whose research focuses on exercise and dementia. "Newer studies suggest also that strength training may be at least as beneficial as aerobic activity."
Recent federal guidelines recommend adults exercise at least 150 minutes a week, divided into as few as 10 minutes of sustained activity.
But as Middleton pointed out, people can be physically active without consciously exercising. Simple choices such as taking the stairs instead of the elevator or getting off the bus several stops early can help.
Research suggests physical activity helps with cognition because it increases the size of certain regions of the brain, including the hippocampus, which is associated with memory. Animals studies show exercise is linked to the creation of new neurons and new blood vessels in the brain.
The Alzheimer Society has for years encouraged people with dementia to be physically active, said David Harvey, Chief Public Policy and Program Initiatives Officer at the Alzheimer Society of Ontario.
For example, the Alzheimer Society of British Columbia's Minds in Motion project involves fitness instructors at 22 community centres leading programs designed for those with dementia and their caregivers.
"We are calling for a renewed investment in physical activity," said Harvey. "It's never too late. We should never write off an individual as being too old to learn new forms of activity and too old to turn around their health condition."
Read the full report here.