In older individuals, exercise is associated with an increase in the number of large-diameter vessels in the cerebral region of the brain and with an increase in blood flow in the three major cerebral arteries, researchers announced at the annual meeting of the Radiological Society of North America, which is being held here this week.

As the investigators noted, narrowing and loss of small vessels may contribute to cognitive decline. This area of the brain controls functions that include consciousness, memory, initiation of activity, emotional response, language and word associations.

A study of 12 healthy older adults, ages 60 to 80 years, was conducted by Feraz Rahman and colleagues at the University of North Carolina in Chapel Hill. Six subjects exercised over 3 hours a week in aerobic sports on a regular basis for 10 or more years, while the other six had exercised less than 1 hour a week during that period.

"The numbers are small because it is hard to find healthy older adults who can participate ... especially inactive but still healthy older adults," Rahman explained. Age and cognitive ability were similar in the two groups and both groups were relatively healthy, with no significant cardiovascular or psychological conditions, including depression.

Rahman's team used MRI and other methods to visualize cerebral blood vessels and determine cerebral blood flow.

Active subjects had more small blood vessels and greater cerebral blood flow than inactive individuals, Rahman told meeting attendees.

The total number of vessels with a radius of 0.2 to 0.3 millimeters was approximately 150 in the active individuals and approximately 100 in the inactive group.

"We found that as the blood vessel radius went up, the blood flow went up in the active group, while an increase in radius correlated with a decrease in blood flow in the inactive group," Rahman reported.

"We also found that a loss of small vessels is not an issue in active adults, because the average vessel size increases and blood flow is positively correlated with radius. However, in inactive adults, the number of small vessels is an issue."

In their meeting materials, Rahman's group states: "An aerobic exercise program may be a vital part of healthy aging by preventing the narrowing and loss of small cerebral vessels and consequent decrease in cerebral blood flow."

Although the results of cognitive testing at the beginning of the study were similar in the two groups and no significant psychiatric issues or depression were noted, "we are still looking at other factors that might be correlated with activity," Rahman told Reuters Health in an interview after his presentation.

It would also be interesting to conduct a long-term study, Rahman continued. "These are still relative young individuals. It would be interesting to see if there is a difference going forward."

Rahman is currently a medical student at Thomas Jefferson University in Philadelphia, Pennsylvania.