Altered frontal aslant tracts as a heritable neural basis of social communication deficits in autism spectrum disorder: A sibling study using tract-based automatic analysis.
A weaker frontal aslant tract on MRI tracks social-communication deficits in boys with autism and their unaffected brothers, pointing to inherited brain wiring.
01Research in Context
What this study did
Lo et al. (2019) scanned boys with autism, their unaffected brothers, and typically developing kids. They used MRI to measure the health of a white-matter cable called the frontal aslant tract.
The team also gave each child social-communication tests. They wanted to see if tract health lined up with real-life social skills.
What they found
Tract health slid down a ladder: best in typical kids, middling in brothers, worst in autistic boys. Lower tract scores tracked with weaker social-communication scores even in the unaffected siblings.
The pattern hints the brain difference is inherited, not just a side effect of having autism.
How this fits with other research
Heald et al. (2020) looked at adults with autism and found white-matter damage in different tracts, but those changes did not link to behavior. Together the studies show age and tract choice matter: FAT seems tied to social skills in youth, while other tracts may not explain adult cognition.
Greene et al. (2019) also point to frontal problems in autism. They showed teens with autism recruit medial frontal areas oddly during word tasks. Yu-Chun’s team adds a structural reason — a weak frontal aslant tract — that could feed both social and language quirks.
Berenguer et al. (2018) found poor real-life theory-of-mind and pragmatics drive social problems in autism. Yu-Chun gives a neural footnote: the same social deficits may stem in part from a heritable wiring glitch in the frontal lobe.
Why it matters
If you test social skills in a boy with autism, remember the brain story may run in the family. When an unaffected sibling shows subtle social slips, the same frontal tract could be the culprit. You can’t fix white matter with ABA, but knowing the biological load helps you set realistic social goals and explain variability to parents.
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02At a glance
03Original abstract
Investigating social behaviors and brain structural alterations in unaffected siblings of individuals with autism spectrum disorder (ASD) may help identify intermediate phenotypes of social communication deficits in ASD. This study hypothesized that such intermediate phenotypes could be identified in white matter tracts of the social communication model that exhibited reduced tract integrity and associations with social communication deficits. Boys with ASD (N = 30), unaffected male siblings (N = 27), and typically developing (TD) boys (N = 30) underwent clinical evaluation and MRI scanning. Group differences in generalized fractional anisotropy (GFA) values, a white matter integrity index derived from diffusion MRI data, and the relationships of GFA with the Social Responsiveness Scale (SRS) scores and the Child Behavior Checklist (CBCL/4-18) scores were investigated. Significant differences were found in the GFA values of the frontal aslant tract (FAT) among the three groups, with the decreasing order of GFA from TD to siblings to ASD. The GFA values of the FAT were associated with the social communication scores (on the SRS) in the sibling group, and those of the superior longitudinal fasciculus III were associated with the social problems scores (on the CBCL/4-18) in the boys with ASD. Due to the altered tract integrity and association with social communication deficits in the unaffected siblings of individuals with ASD, the FAT might be a heritable neural basis for social communication deficits of ASD. Autism Res 2019, 12: 225-238 © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Autism spectrum disorder (ASD) is a group of highly heritable disorders with social communication deficits as one of the core symptoms. This study aimed to identify a neural trait of social communication deficits in individuals with ASD. We investigated brain structural alterations and their associations with social communication scores in unaffected siblings of individuals with ASD. The siblings' frontal aslant tract was found to be impaired, and this tract showed a significant association with the social communication scores. Our findings support that the frontal aslant tract might be a potential neural trait of social communication deficits in ASD.
Autism research : official journal of the International Society for Autism Research, 2019 · doi:10.1002/aur.2044