Changes in visual areas of the brain during infancy may precede autism diagnosis

Summary: Children diagnosed with ASD at 24 months had differences in visual processing areas of the brain that were apparent at six months of age, a new study reports.

Source: NIH

According to a study funded by the National Institutes of Health, infants who were diagnosed with autism spectrum disorder (ASD) at 24 months had differences in visual processing areas of the brain that were apparent at 6 months.

The researchers hypothesized that the disruption of visual processing could interfere with how infants see the world around them, altering how they interact and learn from caregivers and their environment.

These early changes could affect later brain development and play a role in ASD symptoms.

The study was led by Jessica Girault, Ph.D., of the University of North Carolina School of Medicine, Chapel Hill, and her colleagues. It appears in the American Journal of Psychiatry.

The study recruited 384 pairs of siblings, the oldest of whom had been diagnosed with ASD. Previous research by the team found that younger siblings were more likely to develop ASD if their older siblings had higher levels of ASD traits.

The researchers performed magnetic resonance imaging scans on the brains of younger siblings at 6, 12 and 24 months of age.

The researchers hypothesized that the disruption of visual processing could interfere with how infants see the world around them, altering how they interact and learn from caregivers and their environment. Image is in public domain

Among the 89 younger siblings who developed ASD, those whose older siblings had severe ASD traits had greater brain volume and surface area, which controls speech, thought, emotions, reading, writing and learning; larger area in the part of the visual cortex important for object recognition; and less mature connections in the splenium, which connects the brain’s left and right visual cortices and plays a role in visual attention.

Funding: NIH funding was provided by the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institute of Mental Health, and National Institute of Neurological Disorders and Stroke.

About this ASD research news

Author: Robert Bock
Source: NIH
Contact: Robert Bock-NIH
Image: Image is in public domain

Original research: Free access.
Infant visual brain development and hereditary genetic responsibility in autismby Girault, JB et al. American Journal of Psychiatry

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Summary

Infant visual brain development and hereditary genetic responsibility in autism

Objective:

Autism spectrum disorder (ASD) runs in families, and younger siblings of ASD probands are more likely to develop ASD themselves. Prospective MRI studies of siblings report that atypical brain development precedes the diagnosis of ASD, although the link between brain maturation and genetic factors is unclear. Since familial recurrence of ASDs is predicted by higher levels of proband ASD traits, the authors investigated associations between proband ASD traits and brain development in younger siblings.

Methods :

In a sample of 384 proposing-sibling pairs (89 concordant pairs for ASDs), the authors examined associations between ASD traits and sibling brain development at 6, 12, and 24 months in major MRI phenotypes: total brain volume, cortical surface, extra-axial cerebrospinal fluid, occipital cortical surface, and splenic white matter microstructure. The results of the primary analyzes led the authors to implement a data-driven approach using functional connectivity MRI at 6 months.

Results:

Higher levels of evidence-based ASD traits were associated with greater total brain volume and area and greater surface area and reduced white matter integrity in visual system components in siblings who developed an ASD. This corresponded to lower functional connectivity between multiple networks and the visual system in all siblings during infancy.

Conclusion :

The results provide evidence that specific phenotypes on early ASD brain MRI reflect quantitative variation in familial ASD traits. Multimodal anatomical and functional convergence on cortical regions, fiber pathways, and functional networks involved in visual processing suggests that hereditary responsibility plays a role in shaping the prodromal development of visual circuits in ASD.

Briana R. Cross