Teen's Brains Explain Mood Swings

Aug. 18 -- It's the hope of just about every exasperated parent — to one day understand the adolescent brain. Now some scientists are doing cutting-edge research that may bring that day closer.

In charting the brain's normal development through adolescence, scientists discovered the brain's anatomy apparently keep on evolving far more than ever thought, which may help explain why can teens act the way they do.

Teenager Bryan Wright is one of hundreds of volunteers taking part in the research at the Child Psychiatry Branch of the National Institute of Mental Health in Bethesda, Md.

On summer evenings, Wright, 17, allows government researchers to peer into the very deepest recesses of his brain, just as they've been doing since he was 13.

Using magnetic resonance imaging, or MRI, government researchers can now journey through the brain, from top to bottom, left to right, back to front, and most important, from year to year.

"Recent advances in imaging technology, even over the last 18 months to two years, allow us to really zero in on specific brain parts," said Dr. Jay Giedd, who directs the project as chief of brain imaging at the research center.

Giedd, like most of his colleagues, had thought that since the brain has reached 90 percent of its full size by the age of 6, that it was virtually fully developed. Not so.

"What's new is that the brain's anatomy in the teen years is changing far more dynamically than we would ever have guessed," said Giedd.

In other words, the "makeup" of the brain, the individual elements of the brain, continue to evolve and become more efficient throughout the teenage years, even into a person's 20s.

New Findings Explain Mood Swings

Giedd's images show a thickening in gray matter on the outer part of the brain peaks at age 11 in girls and at age 12 in boys. Then, during the teen years, the brain trims back excess cells and connections so what's left is more efficient.

The cells and connections used the most survive and flourish, and those not used will whither and die, said Giedd.