Scientists have long known that as the brain matures though adolescence, it loses gray matter -- the collection of brain cells and their connections that are linked with intelligence. Now, after mapping the brains of 13 healthy children every two years with magnetic resonance imaging (MRI), researchers from the National Institute of Mental Health and the University of California, Los Angeles, have pinpointed the gray matter's disappearing act.

The losses generally begin at the top and back of the brain, regions associated with functions such as senses and basic motor control, then spread forward to the parts linked to higher-level functions. By age 20, the maturation is largely complete.

Does that mean your cognitive powers peak before 20? Only from your teenager's point of view. Adults get the benefit of continued development of white matter -- the tissue that connects brain cells with one other -- well into middle age. White matter is also believed to play a role in cognitive function.

These findings could help explain some diseases, like childhood-onset schizophrenia, that show a similar pattern of gray matter loss.

-- Brian Reid

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Last updated: 11/27/2003 - 10:22 AM