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Study questions accuracy of brain changes found in scan of kids with autism

White matter connections in the brain from a MRI.
White matter connections in the brain from a MRI.
By Xavier Gigandet et. al. [CC-BY-2.5 (http://creativecommons.org/licenses/by/2.5)], via Wikimedia Commons

Head movements during scans cause the brain changes seen on the scans of some children with autism spectrum disorder (ASD), according to research released January 29. If children move their heads during specialized brain scans, the results are affected, report researchers from Bangor University in the United Kingdom.

Past studies used a special type of brain scan to check for differences in the brains of children with ASD when compared to children without the disorder. These studies suggested that a cause of some autism symptoms is a problem with the connections between brain parts. The studies used a type of brain scan called diffusion-weighted magnetic resonance imaging (DW-MRI).

The new research shows that head movement can impact the results of DW-MRIs. Dr. Kami Koldewyn, who led this research, explains:

“Movement during scanning causes a drop in contrast in the area being imaged - in a way similar to how movement or camera shake while taking a photo will cause the image to blur. Because the signal we use in DW-MRI is related to image intensity, movement causes a direct change in what we are trying to measure. Even relatively small differences between groups in how much they move during a scan can make big differences in DW-MRI measures. Differences in these measures between groups may have been incorrectly interpreted as less robust connections in white-matter tracts when they may have simply been differences in head movement during scanning.”

Koldewyn and her colleagues scanned 125 children including 52 with autism and 73 without the disorder. When researchers reviewed the scans and factored in head movement, they found only one major difference between the two groups. They observed a difference in the white matter tract called the right inferior longitudinal fasciculus. This tract "connects early visual areas with higher-level visual areas of the brain important for face and object recognition." Problems with this white matter track are associated with face recognition problems in some children with ASD.

Koldewyn points out the need for better quality scans. She said, "to achieve the high quality results needed to understand a complex disorder like ASD, we need to think carefully about how to improve scanning techniques and agree on what analysis methods are sufficiently robust.”

More information about ASD is available from Nationwide Children's Hospital and Massachusetts General Hospital.

An overview of earlier studies about white matter connections and autism is on the website of Molecular Autism.

The study, "Differences in the right inferior longitudinal fasciculus but no general disruption of white matter tracts in children with autism spectrum disorder", is published in the Proceedings of the National Academy of Sciences.

Sources:

New study leads to calls to review past studies of brain differences between people with ASD and the general population

Differences in the right inferior longitudinal fasciculus but no general disruption of white matter tracts in children with autism spectrum disorder