The MRI scans showed, for example, that the orbitofrontal cortex (shown in blue) and medial temporal cortex (red) were more similar in terms of thickness in youths with conduct disorder than in controls.
Image credit: Nicola Toschi
So concludes a study by an international team published in the Journal of Child Psychology and Psychiatry.
First author Graeme Fairchild, associate professor in abnormal psychology at the University of Southampton in the United Kingdom, and colleagues used magnetic resonance imaging (MRI) to examine the brain structure of teenage and young adult men diagnosed with conduct disorder.
Conduct disorder is a cluster of persistent behavioral problems displayed in childhood and adolescence, such as aggressive and destructive behavior, stealing, and lying. In older children, it can also include staying out all night and use of weapons.
The researchers note that evidence already exists that the brains of people with serious behavior problems are different, but this tends to be simplistic and focused in limited regions, such as the amygdala - the brain's emotion center.
However, conduct disorder is a complex behavioral disorder, and one might expect the brain differences to be more complex and affect more than one brain region, they suggest.
Therefore, in their investigation, the team looked for brain regions with similar or different thicknesses as this might indicate coordinated or non-coordinated development between regions.
For the study, the researchers carried out MRI brain scans on 58 male teenagers and young adults diagnosed with conduct disorder. They also included 25 peers without such a diagnosis, as typically developing, "healthy" controls. The participants were all aged 16-21.
'Most of the brain is involved'
The researchers found that participants with childhood onset conduct disorder - sometimes referred to as "early starters" - had a strikingly higher number of cases where brain regions had the same thickness as controls.
In contrast, the participants with adolescent-onset conduct disorder - sometimes termed "late starters" - had a lower number of cases where brain regions had the same thickness compared with controls.
The researchers confirmed the findings with a separate, independent sample of 37 participants with conduct disorder and 32 healthy controls. All participants in this second sample were male, aged 13-18.
Prof. Fairchild says the differences between the youths with both forms of conduct disorder and their healthy peers "show that most of the brain is involved, but particularly the frontal and temporal regions of the brain."
He argues that the findings are "compelling evidence" that conduct disorder is a "real psychiatric disorder," and not just an exaggerated form of teenage rebellion as some experts have suggested.
The study also indicates there are important differences in the brains of people who develop conduct disorder early in childhood and those who develop it later during their teens.
However, while the findings highlight the key role the brain plays in the development of conduct disorder, they do not explain how the changes come about. For example, to what extent are they influenced by people's genes, and to what extent are they affected by the environment they are raised in?
While the study does not answer these questions, the researchers believe the findings could help to measure the effect of interventions. Using a brain map of conduct disorder it might be possible, for example, to see if interventions such as psychological therapy can reverse some of the changes noted in the study.
"More research is now needed to investigate how to use these results to help these young people clinically and to examine the factors leading to this abnormal pattern of brain development, such as exposure to early adversity."
Prof. Graeme Fairchild