June 25, 2009

Brain scans support dyslexia subtypes

Scottish medical scientists say they have discovered specific structural differences in the brains of people with distinct subtypes of dyslexia.

The University of Edinburgh researchers say their findings are among the first to directly link brain structure with dyslexia subtype and symptom severity.

Led by Cyril Pernet, the researchers compared magnetic resonance imaging scans of the brains of 38 people who had dyslexia with a typical brain constructed from the scans of 39 normal readers. The scientists found distinct neurological differences associated with specific language difficulties within the group of those with dyslexia. The differences were found in the brain's right hemisphere.

The scientists said it's increasingly accepted that dyslexia might not be a single disorder, but a group of related neurological pathologies.

These results provide evidence for the existence of various subtypes of dyslexia characterized by different brain phenotypes, Pernet said. In addition, behavioral analyses suggest that these brain phenotypes relate to different deficits of automatization of language-based processes "¦

The study appears in the journal BMC Neuroscience.