New MRI Study Identifies Signature White Matter Connectivity Patterns in People with Autism

In new research examining children with autism spectrum disorder (ASD) and those with concurrent developmental coordination disorder (DCD), researchers have found distinct white matter connectivity patterns that may enable neuroradiologists to distinguish between the two conditions.

In the recently published study in Scientific Reports, researchers employed diffusion magnetic resonance imaging (MRI) correlational tractography to compare quantitative anisotropy as well as radial, mean and axial diffusivity in 22 children with ASD, 16 children with DCD and 22 children with typical development (TD). The study authors subsequently correlated the MRI findings with measurements of motor skills (via the second edition of the Movement Assessment Battery for Children (MABC-2) and the modified Florida Apraxia Battery for children (FAB-M)) and social skills (via the Social Responsiveness Scale, 2nd edition).

The researchers found that children with ASD had significantly reduced quantitative anisotropy and axial diffusivity bilaterally in the fronto-parietal cingulum and significantly reduced quantitative anisotropy in the left parolfactory cingulum in comparison to children with DCD and those with TD. They contended these differences are related to core symptomatology of autism and are not associated with comorbid motor impairment.

“ … In the ASD group, we find that decreased (quantitative anisotropy and axial diffusivity) significantly correlate with greater severity of ASD symptomatology and greater alexithymia severity. These behavioral correlations suggest that autism severity and emotion deficits like alexithymia in ASD may be related to white matter abnormalities of the right frontoparietal and left parolfactory cingulum,” wrote Lisa Aziz-Zadeh, Ph.D., the Director of the University of Southern California (USC) Center for the Neuroscience of Embodied Cognition, and colleagues. “By contrast, the left parolfactory cingulum correlates with both motor and emotional measures as well as autism severity, and thus ASD hypo-diffusivity here may be related to broader symptomatology.”

Researchers also noted increased quantitative anisotropy in the right caudal anterior cingulum u-fiber for children with ASD in comparison to those with DCD or TD. The ASD group also demonstrated higher quantitative anisotropy in the left middle cerebellar peduncle with the study authors emphasizing that these “diffusivity differences are significantly correlated with autism severity,” said Aziz-Zadeh and colleagues.

For people with DCD, the study authors noted significantly higher quantitative anisotropy diffusivity in left cortico-descending projections in comparison to children with ASD or TD. The DCD group also had the lowest white matter diffusivity for corpus callosum forceps major/thalamic radiation in comparison to children with ASD or TD, according to the study. Aziz-Zadeh and colleagues added that increased repetitive movements in the DCD population were significantly associated with this specific finding.

In regard to study limitations, the researchers noted that they focused on high-functioning, right-handed children between the ages of eight and 17. Conceding that white matter develops at different rates in different groups, Aziz-Zadeh and colleagues suggested that age and within-group variability (inclusion of left-handed people, etc.) be assessed as factors in future studies. They added that large sample sizes could help facilitate extrapolation of study findings to broader populations.