Brainstem white matter microstructure is associated with hyporesponsiveness and overall sensory features in autistic children.
Olivia Surgent, Ali Riaz, Karla K Ausderau and 9 others
PMID 36536467WHAT IT FOUND
In autistic children, higher sensory features linked to lower brainstem water diffusion, while non-autistic children showed the opposite.
This suggests brainstem differences in autism are distinct from typical development. These findings do not yet change clinical interventions.
Key findings
01Elevated total sensory features were associated with decreased free-water-eliminated mean diffusivity in the autistic group and increased mean diffusivity in the non-autistic group.
02Within the autistic group, hyporesponsiveness was negatively associated with mean diffusivity in nine of 11 brainstem tracts and positively associated with fractional anisotropy in the middle cerebellar peduncle.
03Whole-brain analysis showed that 21% of significant interaction voxels were in the brainstem/cerebellar white matter, despite these areas comprising only 7% of the total white matter examined.
STILL TO COME
How it was doneWhat they foundWhat it means for OTsWhat it means for SLPs
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What it does not show
The sample size for autistic participants was smaller than intended due to COVID-19 restrictions, which may have reduced statistical power. Sensory features were measured only via caregiver report, not direct observation, which may miss nuances in how the child experiences sensory input. All participants had to communicate verbally and have an IQ above 60 or 70, so the findings do not apply to non-speaking children or those with intellectual disabilities. The study is cross-sectional, so it cannot determine whether brainstem differences cause sensory features or result from them.
Declared interests
Funding was provided by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institute of Neurological Disorders and Stroke, National Institute of Allergy and Infectious Disease, National Institute of Aging, National Cancer Institute, and The Hartwell Foundation.
The easy way to misread this
Do not interpret the association between lower mean diffusivity and sensory features as evidence that the brainstem is 'more developed' or 'better organized' in autistic children. While lower mean diffusivity is often linked to denser white matter, the authors note this measure is indirect and influenced by multiple biological factors, so this finding does not confirm a specific structural cause.