Hearing about the benefits of exercise can get old. Sure, physical activity is good for the bones, brain and heart – and may even help ward off cancer. But it's tough to stay motivated if you're too busy, hate gyms or have a bum knee.
If you're in that boat, this could be the jolt that gets you lacing up those sneakers: Daily movement, starting in midlife, is the best defence against age-related memory loss, according to a landmark Australian study.
After following 387 women for two decades, researchers at the University of Melbourne found that participants who did some form of movement every day were less likely to suffer memory loss in their 60s and 70s, compared to their sedentary peers.
Those who stayed sharp were not necessarily gym rats, let alone marathon runners, said neurologist Cassandra Szoeke, director of the Women's Healthy Ageing Project, a long-term population-based study. Her paper, in the American Journal of Geriatric Psychiatry, suggests a little goes a long way.
"It turned out that just any type of physical activity on a daily basis was important for cognition 20 years later," Szoeke said. "These are people who walk around the block every day – they don't jog."
Previous studies of how exercise slows the progression of cognitive decline have involved patients in their 60s and 70s.
"But dementia, we now know, takes two to three decades to develop," she pointed out.
Szoeke and her team set out to find risk factors for dementia that could be changed. Participants were between the ages of 45 and 55 when the study began in 1992. The researchers tested their cognitive abilities at the outset to get a baseline measure. They noted lifestyle factors including physical activity, diet, education level, employment, marital status, number of children and smoking. At points throughout the study, they measured participants' cholesterol and hormone levels, height, weight, body mass index (BMI) and blood pressure.
In the study, regular physical activity had the most protective effect on short-term memory. By how much? Szoeke couldn't say; that data is part of a followup paper still in the works. But aerobic exercise – the kind that makes you breathe heavily – proved less important than frequency of movement. "People who were moving once a week had worse memory than those who were moving daily," she said. "We found a linear relationship."
About 20 per cent of women in the study said they did some form of exercise – even as simple as going for a walk – every day. (The researchers did not track the number of minutes.) Other than staying active, women with less memory loss over time were also more likely to have normal blood pressure and normal levels of high-density lipoprotein, or "good cholesterol." Low-density lipoprotein, or "bad cholesterol," was not a factor in memory loss. Nor was weight or BMI.
While exercise has an effect on these physiological measures, the researchers accounted for that in their analysis, Szoeke said. "The study supports a hypothesis that physical activity has a direct relationship with cognition, over and above any influence on weight and cholesterol."
The takeaway, Szoeke said, "is to move more, and move often." She urges people to find forms of daily activity they can stick with over the long haul. "For the guy who has arthritis and knee pain, that might be swimming."
To stay healthy as you age, she added, "you don't start at 70."