Researchers have identified significant findings on the relationship between white matter microstructure (WMM), traumatic brain injuries (TBIs), and disruptive behaviour disorders (DBDs) in children. The study, involving a large sample of children aged 9–10 years, highlights crucial sex-specific differences in the effects of these conditions on brain development. The findings were published in the journal Frontiers in Neuroscience.

The research focused on a sample drawn from the Adolescent Brain Cognitive Development Study, comprising 673 children with DBDs and 836 typically developing (TD) peers. The study aimed to distinguish the impact of DBDs and TBIs on the WMM of boys and girls separately. This distinction is crucial, as previous studies often overlooked the sex-specific nuances in brain structure changes associated with these conditions.

Dr Guido I. Guberman, a neurosurgery resident at McGill University, said: “There is a large body of evidence showing that TBIs have a substantial impact on white matter microstructure and development. There are also several studies showing that children with disruptive behaviour disorders display alterations in WMM.”

The study’s findings indicate that boys and girls with DBDs exhibit distinct differences in WMM compared to their TD counterparts. Boys with DBDs had changes in the corpus callosum (CC) and corticospinal tract (CST) compared to kids without TBIs. These differences stayed the same even when IQ, age, and pubertal stage were taken into account. In particular, the CC genus in boys had lower absolute diffusivity and higher axonal density than in TD boys. This suggests that boys with DBDs have a unique pattern of WMM changes.

Dr Guberman added: “Our study confirms our previous work that boys with DBDs are at higher risk of sustaining TBIs, and demonstrates that the same is true for girls with DBDs. Our study then demonstrated unique patterns of WMM differences as a function of the presence of DBDs and TBIs.”

In girls, the differences were observed in the inferior fronto-occipital fasciculus (IFOF) and the body of the CC. Girls with DBDs had more axons in the left and right IFOF and fewer axons in the right inferior longitudinal fasciculus (ILF). They also had less absolute diffusivity in the CC body. These findings suggest that DBDs may influence WMM in a sex-specific manner, potentially affecting the neural pathways related to emotional and cognitive processing.

Dr Guberman highlighted the use of advanced imaging techniques: “Using cutting-edge diffusion MRI techniques, we found differences in the WMM of the genu of the corpus callosum and the left corticospinal tract in boys with DBDs compared to TD boys, and in the left and right inferior fronto-occipital fasciculi, the left inferior longitudinal fasciculus, and body of the corpus callosum in girls with DBDs compared to TD girls.”

A notable aspect of the study is its examination of the compounded effects of TBIs on children with DBDs. The results revealed that a higher proportion of children with DBDs had sustained TBIs compared to their TD peers. Specifically, 7.75% of boys and 4.83% of girls with DBDs had experienced TBIs, compared to 2.59% and 2.07% of TD boys and girls, respectively.

Dr Guberman further explained the implications of these findings: “Our study therefore demonstrates that WMM is altered in boys and girls with DBDs, and the presence of TBIs appears to be associated with additional WMM differences.”

Among children with TBIs, those with DBDs showed additional alterations in WMM compared to injured TD children. For boys, significant differences were found in the left CST, robust even after adjusting for various covariates such as CU traits and ADHD. In girls with TBIs, the right uncinate fasciculus (UF) showed higher axonal density in those with DBDs compared to their TD counterparts.

Dr Guberman suggested future directions: “The findings from our study can help inform a number of different interventions. Future studies could assess whether intervention programmes known to decrease the severity of DBDs can also decrease the rates of TBIs. Children could be screened for the presence of DBDs, and personalised injury prevention programmes could be put in place to reduce their risk of TBIs.”

These results show that TBIs may exacerbate the already compromised brain pathways in children with DBDs, particularly those involved in emotional regulation and decision-making. The study’s authors suggest that the combination of DBDs and TBIs might lead to more pronounced developmental challenges, highlighting the importance of addressing both conditions in clinical interventions.

The research provides valuable insights into the neurological underpinnings of DBDs and the additional burden posed by TBIs in affected children. It emphasises the need for sex-specific approaches in both research and treatment, given the distinct patterns of WMM alterations observed in boys and girls. The study also suggests that preventive measures and targeted therapies should consider the increased risk of TBIs in children with DBDs, aiming to mitigate the compounded effects on brain development.

Dr Guberman remarked on the potential for future research: “There are also new and exciting developments in the field of advanced MRI that are improving our capacity to analyse brain structure at the microscopic level. Future projects could expand on the findings of our study to better understand the microstructural impacts of TBIs, DBDs, and the simultaneous presence of both conditions.”