Old Brains Don't Work
That Badly After All,
Especially Trained Ones
March 3, 2006; Page B1

Maybe I'm guilty of wishful thinking, but more and more research seems to be pointing to a rare bit of good news about aging: Old brains have gotten a bum rap.

Yes, some of the downbeat findings have stood the test of time. Older brains do process information more slowly, probably starting in middle age. As a result, they take a bit longer to make decisions or judgments, and to assimilate complex information.

Older brains are less nimble, too, taking longer to switch from one task to another. Since in "multitasking" you are actually switching among tasks -- from driving to chatting to checking the tailgater -- in split-second jumps, loss of agility means old brains don't handle simultaneous tasks as well.

But as scientists reassess old results, even findings that have achieved iconic status are being questioned. For one thing, neurons don't abandon ship. "It used to be thought that normal cognitive decline occurred because of loss of neurons throughout the brain," says Marilyn Albert of Johns Hopkins School of Medicine. But new techniques show that most regions hold on to their neurons (and even 70-year-olds produce new neurons), with little to no loss in the hippocampus, where memories form, or the frontal cortex, site of such executive functions as planning and judgment.

One problem with studies comparing old and young brains is that old brains are different not only because they have been around longer. The lives their owners lead are different. The elderly tend to have fewer new experiences, be less physically active and socially engaged, and live in less complex environments. All of these impair the production of new neurons and the maintenance of neural circuitry.

"The trouble with retirement is, there are not a lot of social or intellectual demands," says research psychologist Denise Park of the University of Illinois at Urbana-Champaign. "Life becomes routinized," a recipe for cognitive decline. Some of the decline attributed to aging may therefore reflect not aging per se but factors much more within people's control.

Such as? Consider a recent study of short-term memory. Scientists had two groups of volunteers, one 19 years old to 30 and the other 60 to 77, look at pictures of faces and of the outdoors. Soon after, the volunteers saw more pictures and decided if they had seen them before.

The younger brains, as a group, had better recall. More telling, their activity differed. Shown a face, there was higher activity in the "face-seeing" area and little in the "place" area. Shown a scene, the pattern of high and low activity switched. Most of the older brains, though, showed activity in both regions when trying to recall either a face or a scene, suggesting difficulty repressing distractions.

"It suggests they were not filtering out irrelevant information," says neurologist Adam Gazzaley of the University of California, San Francisco, who led the 2005 study, published in Nature Neuroscience.

But one-third of the older volunteers did just as well as the younger adults and, intriguingly, showed the same pattern of focused brain activity. Apparently, trouble inhibiting irrelevant information and blocking distractions, which impairs short-term memory and reasoning, is not as inevitable as had been thought.

What makes these older brains look young? One possibility is training. Attention and focus are top-down functions, in that the prefrontal cortex orders regions that see or hear to pay attention to important stuff and ignore the rest. Top-down activity seems to be among the most trainable mental functions.

A basic change the brain undergoes with age may also be reversible with training. Older brains often use both the left and right half of a region for something young brains do with only one side. Sometimes that improves performance. Older adults who activate both the left and right prefrontal regions, which are involved in memory, have pretty good short-term memory, says Illinois' Kirk Erickson. The reason may be that two-sided activation of the prefrontal regions compensates for deficits in the hippocampus. In contrast, on tasks such as judgment, decision-making, concentration and multitasking, two-sided activation seems to impair performance, as if the brain is too scattered.

Yet in a study published online last month in Neurobiology of Aging, Dr. Erickson and Illinois' Arthur Kramer found that old brains can be trained to act like young ones.

The scientists had volunteers watch a computer screen and press a button when certain targets appeared. That required focus and decision-making. At first, the brains of older adults (age 55 to 80) had the characteristic two-sided activation and made more mistakes than young brains. But after five hours of practicing and receiving feedback, the older brains got better -- and showed one-sided activity, like the young.

"This suggests that the brains of older adults remain relatively flexible, able to alter brain circuits in response to training," says Dr. Erickson.

Yes, brains age. But their ability to remake themselves and respond to training is undeniable.