LONDON (Reuters Life!) - Brain scans of aggressive, antisocial teenage boys with the condition known as conduct disorder have found differences in the size and structure of parts of the brain that may be linked to their behavior.
A study by British scientists showed the differences were there regardless of the age at which the patients developed the disorder -- a finding which challenges the view that adolescents who develop conduct disorder are merely imitating badly behaved peers and do not have differences in their brains.
Conduct disorder (CD) is a psychiatric condition characterized by higher than normal levels of aggressive and antisocial behavior. It is more common in boys than girls, can develop in childhood or in adolescence, and experts say it affects around five out of every 100 teenagers. Children and adolescents with CD are at greater risk of developing further mental and physical health problems when they are adults.
In the study, neuroscientists at the University of Cambridge and the Medical Research Council's Cognition and Brain Sciences Unit used magnetic resonance imaging to measure the size of particular regions in the brains of 63 teenage boys with conduct disorder compared with 27 teenage boys who showed no symptoms of behavioral disorder.
Their findings, published in the American Journal of Psychiatry, showed that the amygdala and insula -- regions of the brain that contribute to emotion perception, empathy and recognizing when other people are in distress -- were strikingly smaller in teenagers with antisocial behavior.
The changes were present both in those with childhood-onset CD and in adolescence-onset CD, and the greater the severity of the behavior problems, the greater the reduction in the volume of the insula, the scientists said.
"Changes in gray matter volume in these areas of the brain could explain why teenagers with conduct disorder have difficulties in recognizing emotions in others," said Graeme Fairchild, who led the research and is now based at Southampton University.
He said more studies were needed to investigate whether these changes in brain structure are a cause or a consequence of conduct disorder.
SOURCE: bit.ly/f7E7IF American Journal of Psychiatry, online March 31, 2011.