People who stay just as active after age 70 as they did before are less likely to experience age-related declines in mental functioning, new study findings suggest.

Previous studies have stressed the importance of keeping the body active in old age in order to keep the mind active, as well. The current research suggests that it's not just being active, but staying active, that can make a difference, the authors note.

"The results of this study suggest that stimulating elderly to be physically active with at least a medium-low intensity or becoming even more physically active (in duration or intensity) could be important for keeping their brains fit," write the researchers, led by Dr. B.M. van Gelder of the National Institute for Public Health and the Environment in the Netherlands.

In the journal Neurology, van Gelder and colleagues write that physical activity protects the brain by keeping the heart and blood vessels healthy, which boosts blood flow to the brain and reduces the risk of stroke.

In addition, some studies suggest that exercise may even help the mind by stimulating the creation of new brain cells.

Given that physical activity tends to change with age, the researchers investigated whether these changes can influence mental function in a study of 295 men aged 70 to 90 from Italy, Finland and the Netherlands.

The participants were asked about the intensity and duration of exercise, including activities such as walking, biking, hobbies, gardening, odd jobs and playing sports. The researchers followed the men for 10 years, noting who increased or decreased their amount of physical activity.

The researchers checked participants' mental functioning using a standardized test that examines memory, calculation, language abilities, and other aspects of brain acuity.

At the outset of the study, Italian men were the most active, typically spending their time on gardening. In Finland, the most popular activity was walking; for Dutch men, it was bicycling.

On average, Dutch and Italian men decreased the amount of time they spent exercising over the 10-year period, and all men exercised with less intensity over time.

However, men who decreased their amount of physical activity by at least 1 hour each day experienced the largest decline in mental functioning -- nearly three times greater than that seen in men who spent the same amount of time exercising as before.

And the more men reduced the amount of time they spent exercising, the larger was their mental decline over the 10-year period.

SOURCE: Neurology, December 28, 2004.