a person reading a bookDyslexia is caused by more than just one part of the brain, reports new research from the Yale University School of Medicine. The study contributes to the existing body of research about dyslexia—one of the most commonly diagnosed learning disabilities in the United States—by showing that dyslexia is characterized by disrupted connections in multiple brain networks, rather than just one brain region. Understanding dyslexia may help clinicians and educators improve reading interventions for young people with the disorder.

The researchers conducted brain scans to assess the brain’s connectivity. They used functional magnetic resonance imaging (fMRI) to scan multiple brain regions of 75 children and 104 adults. Some of the participants had dyslexia, but others were typical readers. The research team analyzed activity between brain regions and compared the scans of the dyslexic and non-dyslexic participants.

Children and adults with dyslexia exhibited decreased connectivity between brain regions, particularly between regions related to vision and to word formation. The researchers noted that young adults with dyslexia had high levels of activity in brain regions associated with phonology—the part of language that deals with sounds. This suggests that people with dyslexia may transition from “sounding out” words to automatically recognizing words’ visual form later than is typical.

“As far as we know, this is one of the first studies of dyslexia to examine differences in functional connectivity across the whole brain … Compared to typical readers, dyslexic readers had weaker connections between areas that process visual information and areas that control attention, suggesting that individuals with dyslexia are less able to focus on printed words,” explained lead author Emily Finn, PhD student at Yale University School of Medicine.

This research is published in the journal Biological Psychiatry.

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