Scientists trace adolescent rage to the shape of teenage brains

Published on Monday 25 February 2008 21:21

ADOLESCENT anger and angst can be traced to the individual shape of the teenage brain, a study has shown.

Significant associations were seen between the size of brain structures linked to emotion and clashes between a group of youngsters and their parents.

One brain area, the amygdala, was found to be enlarged in teenagers prone to having prolonged and aggressive arguments.

A lack of balance in the size of two other regions in the brain cortex was linked to aggression and "dysphoria" – anxious and "whining" behaviour – but only in boys.

The Australian scientists filmed one-on-one issue discussions or "problem solving interactions" between 137 adolescents aged 11 to 14 and their parents. Topics were deliberately chosen to be provocative.

Scores were allocated to the behaviour exhibited by each youngster according to a standard scale used by psychologists which included traits such as anger, contempt, belligerence, anxiety, or being "happy" or "caring".

Each adolescent then had his or her brain structure mapped by a magnetic resonance imaging scanner.

The scans focused on the "limbic system" – the part of the brain that deals with emotion. Specifically, the scientists measured the size of the amygdala, anterior cingulate cortex (ACC) and orbitofrontal cortex, as well as the relative size of the brain regions.

Increased amygdala volume was associated with a longer duration of aggressive behaviour in both boys and girls. A similar effect resulted from having a smaller left than right ACC, but only in boys.