Youth with conduct disorder (CD) have extensive brain structure differences, new research showed.
In findings that illuminate the differences in areas of the brain critical for emotional processing and decision making, investigators found lower cortical surface area and reduced volume in the limbic and striatal regions of the brain, as well as lower thalamus volume, in youth with CD.
"We know very little about this disorder even though it can carry a high burden for families and societies," colead author Yidian Gao, PhD, of the University of Birmingham in Birmingham, United Kingdom, said in a press release.
"The sample included in our study is 10-20 times larger than previous studies and contains data on children from North America, Europe, and Asia. It provides the most compelling evidence to date that CD is associated with widespread structural brain differences," he added.
The findings were published online on July 16 in The Lancet Psychiatry.
An Understudied Disorder
In the largest study of its kind, researchers at the Universities of Bath and Birmingham in the United Kingdom collaborated with research teams across Europe, North America, and Asia, as part of the Enhancing NeuroImaging Genetics through Meta-Analysis–Antisocial Behavior Working Group to learn more about one of the "least researched psychiatric disorders," they wrote.
Investigators used MRI to examine the brain structure of 1185 children with a clinical diagnosis of CD and 1253 typically developing children from 17-21 across 15 international study cohorts.
After adjusting for total intracranial volume investigators found that youth with CD (29% women, mean age, 13.7 years) had lower total surface area and lower regional surface area in 26 of the 34 cortical regions, spanning all four lobes of the brain compared with their typically developing counterparts (35.6% women, mean age, 13.5 years).
Youth with CD also showed greater cortical thickness in the caudal anterior cingulate cortex (P = .0001) and lower cortical thickness in the banks of the superior temporal sulcus vs those without CD (P = .0010).
In addition, the CD group also had lower volume in the thalamus (P = .0009), amygdala (P = .0014), hippocampus (P = .0031), and nucleus accumbens (P = .0052).
Most findings remained significant after adjusting for intelligence quotient, psychiatric comorbidities, and psychotropic medication use. Of note, group difference in cortical thickness, 22 of 27 differences in surface area. In addition, three of four subcortical differences remained robust after adjusting for co-occurring attention-deficit hyperactivity disorder (ADHD), the most frequent comorbidity.
When investigators divided individuals with CD into two subgroups — those with high vs low levels of callous-unemotional traits — they found limited overall differences. However, those with high callous-unemotional traits had lower surface area in the superior temporal and superior frontal gyri vs those with low callous-unemotional traits and the typically developing group.
Investigators also found that individuals with childhood-onset CD had greater cortical thickness in the caudal anterior cingulate cortex compared with those with adolescent-onset CD.
Study limitations include comparison of different cohorts with differing protocols that could affect the validity of the findings. In addition, subgroup samples were small and had lower statistical power.
"Our finding of robust brain alterations in conduct disorder — similar to those in more widely recognized and widely treated disorders such as ADHD — emphasize the need for a greater focus on conduct disorder in research, treatment, and public policy," the authors noted.
Study funding and disclosure information is noted in the original article.