Abnormalities in the connectivity of white matter in teens with conduct disorder may play a role in the presence and severity of antisocial behavior in these youth, indicates a new study in PLOS ONE. Compared to healthy peers, adolescents with conduct disorder had measurably different cellular connectivity—increased fractional anisotropy— in 7 different regions of the brain as measured using the MRI-based technique diffusion tensor imaging (DTI).
“The increased fractional anisotropy we report contrasts with findings from studies of antisocial adults, possibly resulting from abnormal/precocious white matter development in conduct disorder during childhood, which plateaus later in development,” wrote Sagari Sarkar of King’s College London in the U.K. and her colleagues. “This hypothesis is consistent with similar patterns of white matter maturation observed in other specific neurodevelopmental disorders.”
The researchers used MRI to obtain measures from 27 males with conduct disorder between 12 and 19 years old—all with a history of severe aggressive or violent behavior— and from 21 typical, healthy control boys of the same ages. The participants and their parents also filled out the Antisocial Process Screening Device (APSD) and Strengths and Difficulties Questionnaire (SDQ).
The participants in both groups were recruited within the same geographical areas in London with no significant differences in ethnicity, history of alcohol or cannabis use, or hyperactivity levels, and none of the participants were taking medication or had any other psychiatric diagnoses except ADHD in the control group and ADHD and/or conduct disorder in the experimental group.
The findings revealed significantly greater fractional anisotropy in 7 brain regions of the boys with conduct disorder: in the left cerebellar white matter, in the right superior longitudinal fasciculus, and bilaterally in the inferior and superior cerebellar peduncles, corticopontocerebellar tract, posterior limb of internal capsule and corticospinal tract. The behavioral analysis indicates these regions may contribute to the formation of emotional and behavioral features of conduct disorder, the authors noted.
“Although the precise significance of fractional anisotropy is not agreed on, it is regarded as a measure of inter- and intra-axonal properties, including the organization within and between fibers, axonal diameter, and myelination,” the authors wrote.
No controls showed increased fractional anisotropy, but fractional anisotropy correlated positively with APSD and SDQ scores across all the participants. No similar correlation occurred within either group: this could be because the between-group differences drove the correlation or because the sample size of each group was too small to see correlations, they concluded.
Sarkar S, Dell’Acqua F, Walsh SF, et al. A whole-brain investigation of white matter microstructure in adolescents with conduct disorder. PLoS ONE. 2016;11:e0155475.