VOA常速英语:Physical Activity in Teen Years Helps Prevent Mental Decline

A new study finds regular physical activity as a teenager may prevent cognitive impairment - a decline in mental abilities - decades later.

Previous studies found that people who were physically active in later life were more likely to avoid mental decline as they aged.

This new study asked more than 9,000 American women over age 65 about their level of physical activity as teenagers, and at ages 30, 50, and late in life.

"And what we found was that people who were physically active on a regular basis had lower risk of cognitive impairments in late life," said Laura Middleton, the Canadian researcher who led the study. "But it seemed that teenage physical activity was particularly important in terms of the prevention of cognitive impairments."

The women in the study who said they were physically active just once a week showed less cognitive impairment as measured by a standard test, but the link was strongest among those who were active decades earlier, as teenagers.

Middleton points to a couple of long-lasting effects that physical activity can have on still-growing teenage bodies. One is that exercise could help strengthen the blood vessels in the head, which nourish the brain.

"Physical activity is also known to affect the repair mechanisms in the brain. So people who are more physically active, who exercise, can actually improve the repair mechanisms in the brain," she says.

Interestingly, there was not a strong correlation between the amount of physical activity and the extent of cognitive impairment.

The study involved women only, and speaking via Skype, Middleton said other studies that have looked at the relationship between exercise and cognitive decline found the link stronger in women. She added there is still a message in her research for men.

"Most studies have still found that physical activity is beneficial for men. And there's no reason to suggest that the finding that teenage physical activity is most important of the four ages shouldn't apply to men."

Dr. Laura Middleton reports her research in the Journal of the American Geriatrics Society.