Aging: Brain Boosts, From the Other Side

By Eric Nagourney, NY Times

 November 19, 2002

Elderly people who draw on both sides of the brain seem to do better at some mental tasks than those who use just one side, a new study in the journal NeuroImage reports

It supports a theory that as the brain ages, it may shift its workload so that some tasks once performed primarily by one side are shared more evenly by both. Older people best able to press both brain sides into service do better on skills tests compared with those less adept at using both sides, the study saysThe lead author, Dr. Roberto Cabeza of the Center for Cognitive Neuroscience at Duke, likened the process to what occurs as people age and their muscles weaken. Instead of picking up a heavy object with one arm, they might use two, Dr. Cabeza noted.

"If you aren't flexible in terms of adjusting the patterns of brain activity," he said, "then you are more likely to show decline."

Evidence that the brain may handle functions like memory differently as it ages is relatively new and not well understood. Some scientists, the researcher said, believe the changes simply reflect the breakdown of the brain. Others believe the brain may be doing just what it should do: compensating for the effects of old age.

The study used PET scans to explore changes in the prefrontal cortex, where higher-level reasoning occurs.

The researchers studied one group of people in their 60's and 70's who scored well on a test of mental skills, another group that scored poorly and a third group of people age 20 to 35.

The subjects were given two tests as their brains were scanned. In one, they were asked to remember words they had been given earlier. In the other, they were asked to recall whether they had heard some of those words or read them.

The older volunteers who did best on the tests showed more activity in the two sides of the brain.