White matter compromise in autism? Differentiating motion confounds from true differences in diffusion tensor imaging.
Seraphina K Solders, Ruth A Carper, Ralph-Axel Müller
PMID 28503904WHAT IT FOUND
Head motion can make scans in children and adolescents with autism look different from controls.
After matching motion, one white matter difference disappeared, but another water movement measure stayed higher in autism. This is a scan-reading issue, not a therapy finding.
Key findings
01When groups were matched for head motion, the significant reduction in fractional anisotropy found in the full sample was no longer significant.
02In the motion-matched tractography analysis, mean diffusivity was significantly higher in ASD, and radial diffusivity was increased in the inferior longitudinal fasciculus.
03After motion matching, fractional anisotropy differences were not significant but had moderate to large effect sizes in five of six clusters, and radial diffusivity effect sizes reached medium size in five of six clusters.
STILL TO COME
How it was doneWhat they found
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What it does not show
Strict quality control and motion matching reduced sample size and power. The autism group was mostly high-functioning children who could stay still, so the findings may not apply to lower-functioning children. The study compared group averages, not individual patients. The robust outlier-rejection algorithm did not reproduce the standard algorithm's motion-matched group effects. Participants who moved more did not differ on age, IQ, or symptom severity, but the sample was limited to high-functioning children.
Declared interests
The authors reported no biomedical financial interests or potential conflicts of interest.
The easy way to misread this
Do not read these group imaging differences as a test that can diagnose autism or guide therapy. The final motion-matched analysis was small, and the sample was mostly high-functioning children who could stay still.