Gray matter volume alteration is associated with insistence on sameness and cognitive flexibility in autistic youth.
Insistence on sameness in autistic teens links to smaller left supramarginal gyrus and larger cerebellum, yet these shifts do not predict flexibility test errors.
01Research in Context
What this study did
The team scanned autistic teens and typical peers. They asked who hated changes in routine the most.
They measured gray-matter volume in each brain. Then they ran tests of flexible thinking.
What they found
Kids who fight hardest to keep things the same had smaller left supramarginal gyrus. Their cerebellum was bigger.
Yet brain size did not line up with errors on flexibility tasks. The link was only with the trait, not the test score.
How this fits with other research
Storch et al. (2012) said routine MRI looks normal in high-functioning youth. The new study used finer software and still found tiny shifts, so both can be true.
Hatton et al. (2004) saw larger cerebellar volume years ago. Seng et al. (2022) now ties that growth to insistence on sameness, updating the old picture.
Bai et al. (2023) found GM changes in toddlers linked to social issues. The teen study shows a different region tied to rigidity, together mapping how ASD traits track across ages.
Why it matters
You cannot see rigidity on a regular scan, but voxel-based studies give clues about why change is painful for some clients. Use this when you explain to parents: the brain literally handles sameness differently. It also warns us that cognitive-flexibility drills may not shrink the rigidity; we may need environmental supports instead.
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02At a glance
03Original abstract
Restricted and repetitive behaviors (RRBs) are hallmark characteristics of autism spectrum disorder (ASD). Previous studies suggest that insistence on sameness (IS) characterized as higher-order RRBs may be a promising subgrouping variable for ASD. Cognitive inflexibility may underpin IS behaviors. However, the neuroanatomical correlates of IS and associated cognitive functions remain unclear. We analyzed data from 140 autistic youth and 124 typically developing (TD) youth (mean age = 15.8 years). Autistic youth were stratified by median-split based on three current IS items in the autism diagnostic interview-revised into two groups (high, HIS, n = 70, and low, LIS, n = 70). Differences in cognitive flexibility were assessed by the Cambridge neuropsychological test automated battery (CANTAB). T1-weighted brain structural images were analyzed using voxel-based morphometry (VBM) to identify differences in gray matter (GM) volume among the three groups. GM volume of regions showing group differences was then correlated with cognitive flexibility. The HIS group showed decreased GM volumes in the left supramarginal gyrus compared to the LIS group and increased GM volumes in the vermis VIII and left cerebellar lobule VIII compared to TD individuals. We did not find significant correlations between regional GM volumes and extra-dimensional shift errors. IS may be a unique RRB component and a potentially valuable stratifier of ASD. However, the neurocognitive underpinnings require further clarification. LAY SUMMARY: The present study found parietal, temporal and cerebellar gray matter volume alterations in autistic youth with greater insistence on sameness. The findings suggest that insistence on sameness may be a useful feature to parse the heterogeneity of the autism spectrum yet further research investigating the underlying neurocognitive mechanism is warranted.
Autism research : official journal of the International Society for Autism Research, 2022 · doi:10.1002/aur.2732