Bad behaviour disorder that 5% of children could have ‘can be spotted in brain scan’

A mental health disorder that has been associated with behaviours in children such as fighting, bullying and rule-breaking could be spotted in brain scans, a new study suggests.

Scientists have found distinct structural differences in the brains of children who have conduct disorder (CD), an under-recognised condition also associated with lying, stealing, skipping school and a lack of remorse. Around 5% of children aged between five and 16 are thought to have conduct disorder in the UK.

Scientists said that while it is still unclear what causes these differences, they suspect childhood adversities such as maltreatment may play a role.

The findings are based on brain scans of nearly 2,500 children in what the team said was the largest study of its kind.

Lead author Dr Yidian Gao, from the School of Psychology and Centre for Human Brain Health at the University of Birmingham, said their research “provides the most compelling evidence to date that CD is associated with widespread structural brain differences”.

Dr Marlene Staginnus, joint lead author from the Department of Psychology at the University of Bath, said: “Although we don’t yet know how the differences that we have identified could be used to improve treatment for children with CD, it is clear that children who have this disorder cannot simply be labelled ‘naughty’.”

According to the Royal College of Psychiatrists, it is much more than ordinary childish mischief or adolescent rebelliousness, with long-lasting and extreme aggressive behaviours.

Although associated with a high burden for families and societies, conduct disorder is one of the least researched psychiatric disorders, scientists said.

To find out more, an international team led by the University of Birmingham analysed the brain scans of 1,185 children diagnosed with conduct disorder and 1,253 without the condition.

Results showed the surface area of the brain’s outer layer, the cortex, was “significantly reduced” in children with conduct disorder, the researchers said.

The areas deep within the brain, associated with functions such as emotion regulation, language and reasoning, were also lower in volume, they added.

The researchers said they did not find any significant differences between girls and boys with conduct disorder, although boys are more likely to be diagnosed.

Some of the brain differences associated with conduct disorder were similar to those previously found in children with ADHD (attention deficit hyperactivity disorder), the team said, but there were also other features distinct to conduct disorder traits, such as lack of empathy or guilt.

Dr Staginnus said: “Given that CD is such a significant contributor to our global mental health burden, we really need to see investment in research at similar levels to that of ADHD and autism.”

Dr Stephane De Brito, from the Centre for Human Brain Health at the University of Birmingham, said: “There is a lot of work examining potential risk factors for CD, but it is still unclear what are the causes of those brain structural differences in young people with CD.

“We suspect that early adversities, for example, experiences of childhood maltreatment might play an important role.

“And by understanding how CD links to later issues, including criminality in adulthood, but also anxiety and depression, we start to see how important it is to understand and help young people with CD and their families.”