JOIN USA study by British scientists showed the differences were 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 is a psychiatric condition characterised by higher than normal levels of aggressive and antisocial behaviour. 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 behavioural disorder.
Their findings, published in the American Journal of Psychiatry on Friday, showed that the amygdala and insula—regions of the brain that contribute to emotion perception, empathy and recognising when other people are in distress—were strikingly smaller in teenagers with antisocial behaviour.
The changes were present both in those with childhood-onset CD and adolescence-onset CD, and the greater the severity of the behaviour problems, the greater the reduction in the volume of the insula, the scientists said.
“Changes in grey matter volume in these areas of the brain could explain why teenagers with conduct disorder have difficulties in recognising emotions in others,” said Graeme Fairchild, who led the research and is now based at the Britain’s 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.