Children who don’t listen, or rebellious teenagers, sometimes draw blood from their fingernails. We usually turn a blind eye, knowing that this is part of development. But in 3 percent of cases, antisocial behavior spirals out of control. These children and teens suffer from antisocial behavior disorder, also known as conduct disorder (CD). They display long-term aggressive behaviors such as fighting at school, shoplifting, and sometimes violence toward their parents, which results in bruises.
Although antisocial behavior differs from child to child, all children experience limitations on multiple fronts, including problems at home, at school, and in dealing with others. CD is therefore one of the most challenging psychological disorders in children. However, research into the neurological basis of CD has long lagged behind that of disorders such as ADHD and autism.
magnetic resonance imaging scans
Now a recent study offers more clarity. MRI scans show that the brain structure of children with antisocial behavior disorder average differs from that of children without a diagnosis. The publication appeared this week in the scientific journal. Lancet Psychiatry.
The MRI data come from fifteen international studies, all part of the Enigma consortium, a global partnership that exchanges knowledge and results on brain structures in disorders such as ADHD, autism and CD.
The study compares scans of 1,185 participants with CD and 1,253 participants without a diagnosis, all between the ages of 7 and 21. “This is a huge group, almost impossible to capture in a single study,” says Lucres Nauta-Jansen, professor and researcher at the Department of Child and Adolescent Psychiatry at the UMC in Amsterdam. Although he was not directly involved in this research, he was involved in one of the 15 studies.
Smaller parts of the brain.
Brain scans revealed that specific parts of the brain are smaller in participants with conduct disorders. Especially in areas important for emotion regulation, decision-making and empathy. “Smaller studies have already shown this,” says Nauta-Jansen. “But it is fantastic that this has now been confirmed with much more data.”
It is striking that of the 32 brain areas examined in the participants with CD, 26 turned out to be smaller. These areas were widely spread throughout the brain, which surprised the researchers. “This suggests that the shrinking of brain areas may differ from person to person. This may reflect the diversity within the group with this behavioural disorder,” explains Nauta-Jansen. “For example, some children develop the disorder early, while others only do so in adolescence. In addition, some exhibit cold and unemotional traits, while others do not.”
Boys and girls
The huge data set also allowed the team to take into account intelligence, age, gender and ADHD. None of these factors seemed to influence the results. “This is the first study to compare such a large group of boys and girls with CD. The fact that there do not appear to be any significant differences in the underlying brain structures between these two groups is at odds with the long-held idea of a gender difference,” Nauta-Jansen says.
The researchers also found little difference in brain structure between participants who develop behavioural problems at an early age and those who only do so during puberty. “We always assumed that the group that developed the disorder at an early age would show more brain abnormalities than the later group. But that doesn’t seem to be the case either,” Nauta-Jansen says.
The link between brain structure and behavioural problems in CD is now clear. “However, the question of cause and effect remains,” says Nauta-Jansen. “To find out, we need to examine children more frequently and for longer during their development to see when and why these brain changes occur.”
‘A child with CD is not naughty’
Commenting on the study, Marlene Staginnus, co-lead author of the study, emphasises that children with CD cannot simply be labelled as “naughty”. “Unfortunately, we don’t yet know how the differences we have identified can be used to improve the treatment of children with CD,” says Staginnus, a researcher at the University of Bath, UK. “But given that CD contributes so significantly to mental health problems, there is a real need to invest in research at a level similar to that for ADHD and autism.”
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