Atypical sensory traits and changes in white matter microstructures connected to the amygdala and hippocampus of the autistic brain

Aim Autism spectrum disorder (ASD) is characterized by atypical sensory traits. Understanding whether these traits of individuals with ASD are associated with white matter fiber tracts connected to these subcortical structures may be important; however, this relationship remains unexplored. Therefore, we examined associations between sensory traits and abnormalities in white matter fiber tracts in individuals with ASD. Methods Overall, 40 adults with ASD and 83 typically developing (TD) adults were included, and all participants were aged over 18 years. The participants completed the Adolescent/Adult Sensory Profile (AASP), a self-reported questionnaire, and underwent diffusion tensor imaging. We computed four diffusion tensor metrics (fractional anisotropy [FA], mean diffusivity, axonal diffusivity, and radial diffusivity [RD]) for the bilateral amygdala-connected white matter (AWM) and hippocampus-connected white matter (HWM). Results The ASD group exhibited lower FA and higher RD in both the AWM and HWM than the TD group. Significant group differences were observed in correlations between sensation seeking and right white matter microstructures: for the FA of the AWM, the ASD group exhibited a significant positive correlation, whereas the TD group tended toward a negative correlation, and for the FA of the HWM, the ASD group tended toward a positive correlation, whereas the TD group exhibited a significant negative correlation. Conclusion The abnormal sensory traits in ASD pathogenesis may result from demyelination or axonal damage in the AWM and HWM, indicating that the right hemispheric dominance of ASD is present in the white matter structures associated with abnormal sensory processing.