Brain Gain

Smug teens may think they have, on average, more brain cells than adults have. But now, brain researchers in Arkansas have given a nod to the middle-aged. One kind of brain tissue actually increases in adults.

A new study in the Archives of General Psychiatry helps confirm recent research suggesting the adult brain is more malleable than neuroscientists thought. Some researchers believe the adult brain adds small numbers of cells continuously. But others are cautious about the possibility of forming new brain cells with good reason--they might disrupt firmly established neural pathways.

To see whether brains actually gain tissue over time, George Bartzokis, M.D., of the Veterans Administration hospital in Little Rock, examined the brains of 70 men, ages 19 to 76, with magnetic resonance imaging. The images showed the areas of gray matter, outer sections associated with functions such as vision and reasoning, and white matter, the layer of nerve-rich cells that connect different brain regions. Bartzokis found that the gray matter steadily declined with age, confirming the old model of the brain. But he discovered that the connecting white matter actually grew until his subjects reached their late forties. This means adult brains work faster than adolescent ones.

"The idea that once we reach the magical age of 18 we are adults is wrong," says Bartzokis. "There are only two phases: Development and degeneration"