Instead of mind games, moving your body is among the most helpful things you can do. At least 150 minutes of moderate physical activity per week, including strength training, yields not just physical benefits but cognitive ones as well. But to be most effective, you need to do it before cognitive decline starts, according to the WHO.
Some evidence to support this recommendation comes from short-term studies. Several randomised studies of tai chi for older adults found it yielded cognitive benefits. Likewise, randomised studies of aerobic exercise for older adults found short-term improvements in cognitive performance.
A systematic review published this year in PLOS One examined 36 randomised studies of exercise programs that were as short as four weeks and as long as a year. It found cognitive benefits of activities such as bicycling, walking, jogging, swimming and weight training.
Results like these may not be durable over time, but doing experiments on the long-term cognitive effects of physical activity is hard. It's not practical to randomly assign people to decades of different levels of activity, and then test their cognitive function in old age.
That's why long-term studies demonstrate an association, not necessarily causation, between a physically active lifestyle and better cognitive performance later in life. It's possible, for example, that people who are motivated (or have the luxury) to be more active over a long period may also do other things or have other characteristics — perhaps even genetic — that ward off cognitive decline.
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A 2017 review in Brain Science concluded that physical activity reduces the risk of cognitive deficits in old age. One study it pointed to was published in JAMA Psychiatry. It assessed the physical activity and television-viewing habits of 3,247 adults over 2 1/2 decades. When the study began in 1985, participants were 18 to 30 years old; when it concluded, they were at least middle-aged. The study found that persistently watching more than three hours of television per day or failing to regularly engage in at least a moderate level of physical activity is associated with worse executive function and lower processing speed in midlife.
Dementia exacts a huge toll, including on families and caregivers. Globally, it affects 5 per cent to 8 per cent of the population at an estimated annual social cost of more than $800 billion, or about 1.1 per cent of the global economic output. A recent study in Health Services Research found that the additional cost of dementia to Medicare is nearly US$16,000 per person over five years. About 14% of people in the United States older than 71 have some form of dementia. Alzheimer's disease is the leading cause, afflicting 5.7 million people.
Exercise won't reduce these numbers to zero, but it could lower them. But why would exercising the body help the mind? There are several potential pathways.
One, suggested by a nearly 10-year study of almost 500 people older than 79, is that physical activity is a gateway for social and cognitive engagement. The study found that participants who were more physically active also had more social contact that engaged their brains.
Physical activity brings us in closer proximity to others, with whom we then interact socially — think running clubs, adult soccer leagues, basketball pickup games or doubles tennis. And the social part, not just the physical one, may help keep our minds active.
But the physical aspect of exercise may help, too, by reducing the likelihood of vascular dementia — a common form of dementia caused by an inadequate supply of blood to the brain. Physical activity can promote the development of new blood vessels in the brain and increase blood flow to it. This can help rid the brain of harmful metabolic waste and provide new blood flow pathways that can be alternate routes if others become blocked.
Exercise also reduces the risks of developing hypertension or Type 2 diabetes, or can help reduce their severity. Both ailments are associated with dementia. Likewise, exercise can help treat and prevent depression and reduce the prevalence of poor sleep — further risk factors for dementia.
The WHO also found evidence linking a reduced risk of cognitive decline to a healthy diet and moderation in alcohol use. Supplements like vitamin E have not been found to be useful.
"A lot of this boils down to common sense," said Mary Sano, director of research at the James J. Peters VA Medical Center in the Bronx and a professor of psychiatry and director of Alzheimer's disease research at the Mount Sinai School of Medicine. "Keep physically and socially active, eat sensibly, don't smoke and don't drink to excess, and treat your treatable conditions."
This approach yields many physical benefits as well. She also advises to "protect your head, which means wear seatbelts and helmets and use sturdy ladders because falls, which occur frequently as we get older, can be devastating to the brain."
So, whether for your body or your mind, put down the phone and go for a walk.
Written by: Austin Frakt
© 2019 THE NEW YORK TIMES
