Aerobic exercise may shield aging brain

NEW YORK (Reuters Health) - Keeping the heart fit with aerobic exercise may also boost older adults’ brainpower, a research review suggests.

In an analysis of pooled data from previous clinical trials, researchers in the Netherlands found that when healthy adults older than 55 improved their fitness through aerobic exercise, there was also often an improvement in memory, attention or other mental abilities.

The findings appear in the Cochrane Library, a publication of the Cochrane Collaboration, an international organization that evaluates medical research.

Aerobic exercise is any activity, such as brisk walking, that gets the heart rate up and improves endurance, over time. This type of exercise has proven benefits for the heart.

At the same time, research has linked regular exercise to better cognitive function in older adults -- but it has not been clear whether this is related specifically to aerobic exercise and gains in cardiovascular fitness.

To investigate, Dr. Maaike Angevaren and colleagues at the University of Applied Sciences in Utrecht reviewed 11 clinical trials conducted in the U.S., France and Sweden that involved a total of 670 adults older than 55.

Some studies tested the effects of aerobic exercise against no exercise only; others also included comparison activities, like flexibility or strength training, or social activities.

In eight of these studies, the researchers found, participants who engaged in aerobic exercise showed an average improvement in their fitness levels. That improvement coincided with gains in certain measures of mental acuity.

Still, it’s not clear that the improved physical fitness bestowed the benefit, according to Angevaren and her colleagues. When the researchers excluded non-exercisers from the analysis, there was no consistent evidence that aerobic exercise was more beneficial than other forms of exercise.

“It needs to be established whether the same effects can be achieved with any type of physical exercise,” Angevaren said in a statement.

However, she also pointed to reasons why aerobic exercise, or improved cardiovascular fitness in particular, would benefit the brain.

“Improvements in cognition as a result of improvements in cardiovascular fitness are being explained by improvements in cerebral blood flow, leading to increased brain metabolism which, in turn, stimulates the production of neurotransmitters and formation of new synapses,” Angevaren explained.

Neurotransmitters are chemicals that carry messages between nerve cells, and synapses are the connections through which this communication takes place.

Improved cardiovascular fitness may also protect the brain by lowering the risks of heart disease and stroke, Angevaren said. Cardiovascular disease is known to contribute to problems with mental function.

SOURCE: Cochrane Database of Systematic Reviews, online April 16, 2008.