Dyslexia is a common learning difficulty where genetic factors play a significant role. A study published in Science Advances, led by the Max Planck Institute for Psycholinguistics in Nijmegen, identified genetic variants associated with dyslexia and their correlation with brain structure.
Approximately 5% of school-age children experience severe difficulties in reading and spelling, known as dyslexia. The first author, Sourena Soheili-Nezhad, stated, "Dyslexia is partly influenced by genes and is quite strongly heritable. However, it is a complex trait that cannot be explained by changes in a single brain region or a single gene." The research aims to identify specific genes that affect brain networks involved in cognitive functions.
The study analyzed data from over 30,000 adults in the UK Biobank, calculating 'polygenic scores' for dyslexia and linking them to brain scans. Although the database did not specify which individuals had dyslexia, the genetic predisposition varied and showed connections to distinct brain areas.
Notably, a higher genetic risk for dyslexia was associated with lower volume in brain regions responsible for movement coordination and processing speech sounds, while increased volume was observed in the visual cortex. Furthermore, differences were found in the internal capsule, a white matter bundle linked to educational attainment and attention deficit/hyperactivity disorder (ADHD).
Clyde Francks, the senior author, explained, "These results are consistent with dyslexia as a complex trait that can involve a combination of altered cognitive processes." Future studies aim to investigate brain changes in children to determine causative factors of dyslexia.
Understanding the neurological basis of dyslexia may facilitate earlier diagnosis and tailored educational interventions for affected children, according to Soheili-Nezhad.