Alterations in the inferior longitudinal fasciculus in autism and associations with visual processing: a diffusion-weighted MRI study.
Bart Boets, Lien Van Eylen, Kevin Sitek and 5 others
PMID 29449909WHAT IT FOUND
Adolescents with autism showed reduced structural connectivity in the right inferior longitudinal fasciculus, a brain tract linking visual and temporal regions.
This connectivity difference was associated with slower visual search when targets were hard to distinguish from distractors, but not with social communication scores.
Key findings
01Individuals with ASD showed significantly reduced fractional anisotropy (FA) in the right inferior longitudinal fasciculus compared to controls, an effect that persisted across multiple analysis methods and survived correction for multiple comparisons.
02Adolescents with ASD were slower to detect targets in a visual search task, particularly when the target and distractors were highly similar, though this difference did not survive strict correction for multiple comparisons.
03Lower FA in the right inferior longitudinal fasciculus was associated with slower visual search performance and a more fragmented processing style, but no significant associations were found with social communication symptoms.
STILL TO COME
How it was doneWhat they found
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What it does not show
The sample size was small (17 per group), limiting power to detect subtle differences or confirm the absence of effects in other tracts. The study included only males with IQs above 80, so findings may not generalize to females or individuals with intellectual disability. The visual search group difference did not survive strict correction for multiple comparisons. The study is cross-sectional and cannot determine if these brain differences cause the behavioral symptoms or are a consequence of them.
Declared interests
The authors declared no competing interests. The work was supported by various research foundations including the Fonds Wetenschappelijk Onderzoek and the KU Leuven Research Council.
The easy way to misread this
Do not interpret the reduced connectivity in the right ILF as a diagnostic marker or a direct cause of social communication difficulties. The study found no significant association between this brain difference and social symptoms, and the behavioral effects were limited to specific visual search tasks in a small sample of high-functioning males.