(PhysOrg.com) -- Girls may be 'protected' from displaying antisocial behaviour until their teenage years, research suggests. The findings indicate that the brains of people with conduct disorder may operate differently and that antisocial behaviour may not simply be a result of bad choices.
Previous studies have shown that boys who develop conduct disorder (characterised by increased aggressive and antisocial behaviour) in childhood have difficulties recognising anger and disgust in others, but those who develop the disorder in adolescence do not.
In the new study, researchers from the University of Cambridge found that girls with severe antisocial behaviour also experience similar problems recognising emotions. But the girls studied - whose problems began when they were teenagers - more closely resembled boys whose antisocial behaviour began in childhood.
"This suggests that there are interesting differences in antisocial behaviour between girls and boys, with girls being protected from showing antisocial behaviour until their teenage years for reasons we don't yet understand," said Dr Graeme Fairchild, who led the research.
The researchers compared 25 girls aged 14-18 years with high levels of antisocial and/or violent behaviour with 30 others displaying no such behaviour disorder.
They measured the girls' ability to recognise six primary facial expressions: anger, disgust, sadness, fear, surprise and happiness. The results showed that the girls with antisocial behaviour made a large number of errors when asked to recognise anger and disgust, but had no problems recognising the other facial expressions.
"Our findings suggest that antisocial behaviour or violence may not simply reflect bad choices but that, at some level, the brains of individuals with antisocial behaviour may work differently," said Dr Fairchild.
He said this might make it harder for them to read emotions in others - particularly in realising that someone is angry with them - and to learn from punishment.
The team will now look to study conduct disorder further using brain scans.
Around 5 per cent of school-age children meet the criteria for conduct disorder, which is linked to a range of factors including physical abuse in childhood and attention deficit hyperactivity disorder. Conduct disorder is approximately three to four times more common in boys than girls.