Summary: A large-scale genetic study shows that DNA differences linked to dyslexia are associated with measurable variations in brain regions that support motor coordination, vision, and language processing.
Researchers combined genetic data from over one million people with brain imaging from tens of thousands of adults to compute polygenic scores for dyslexia and examine how these scores relate to brain anatomy. Higher genetic predisposition to dyslexia correlated with reduced volume in areas tied to speech processing and motor control, and with increased volume in parts of the visual cortex. Changes were also seen in the internal capsule, a deep white matter pathway that connects brain regions.
These results reinforce the view of dyslexia as a multifaceted neurodevelopmental condition and point to biological pathways that may help identify at-risk individuals earlier and guide more individualized educational support.
Key Facts:
- Brain Links: Genetic predisposition to dyslexia is associated with structural differences in regions that process vision, coordinate movement, and support speech and language.
- Shared Influences: The internal capsule shows genetic overlap between dyslexia and related traits such as intelligence, educational attainment, and ADHD.
- Developmental Patterns: Some brain differences likely originate in early development, while others may reflect lifelong behavioral adaptations to reading challenges.
Source: Max Planck Institute for Psycholinguistics
Background: Dyslexia affects reading and spelling and is common among school-age children. Genetic factors contribute substantially to risk, but how these genetic influences map onto brain structure across the general population has been unclear.
A team led by researchers at the Max Planck Institute for Psycholinguistics analyzed genetic variants associated with dyslexia identified from genome-wide data collected by a large consumer genetics cohort. They then applied those findings to compute individual polygenic scores for dyslexia in more than 30,000 adults with brain MRI scans available through a major population study.
Although the imaging dataset did not include formal dyslexia diagnoses for most participants, individuals varied in their genetic risk for the trait. By correlating these polygenic scores with regional brain measures, the team could identify brain structures that are influenced by the genetic liability for dyslexia in the wider population.
Findings in brain anatomy
Higher polygenic scores for dyslexia were linked to smaller volumes in cortical areas involved in motor planning and the processing of speech sounds, suggesting impaired or altered development of networks that support phonological decoding and the motor components of speech and reading. Conversely, dyslexia-related genetic variation was associated with larger volumes in parts of the visual cortex, a pattern that may reflect compensatory or developmental differences in visual processing.
The study also highlighted consistent microstructural differences in the internal capsule, a major white matter tract that connects subcortical and cortical regions. Importantly, this area showed overlapping genetic associations with dyslexia, educational attainment, fluid intelligence, and attention-deficit/hyperactivity disorder (ADHD), indicating shared biological pathways among these correlated traits.
Interpreting development and experience
The authors note that some of the observed brain differences likely arise early in development—potentially during prenatal growth or infancy—and persist into adulthood. Other alterations may reflect adaptations or consequences of lifelong behavioral patterns tied to reading difficulty. For example, limited exposure to reading across many years could influence the structure and function of visual processing circuits.
What this means for diagnosis and intervention
Recognizing specific brain networks influenced by dyslexia-related genetics opens avenues for earlier identification and more targeted interventions. Mapping how particular genetic profiles affect brain development and function could help tailor educational strategies to individual cognitive strengths and weaknesses, improving outcomes for children with reading difficulties.
Future directions
To separate causes from consequences, the researchers plan to repeat similar analyses in cohorts of children and adolescents. Studying younger brains will help determine which structural differences precede the emergence of reading problems and which develop later in response to behavior and experience.
“Dyslexia is influenced by many genes and involves multiple brain systems,” says first author Sourena Soheili-Nezhad. “By connecting genetic risk to brain networks, we gain clearer insight into how cognitive functions diverge in people with higher liability for dyslexia.”
About this genetics and dyslexia research news
Author: Anniek Corporaal
Source: Max Planck Institute for Psycholinguistics
Contact: Anniek Corporaal, Max Planck Institute
Image credit: Neuroscience News
Original Research: Open access. Title: “Distinct impact modes of polygenic disposition to dyslexia in the adult brain” by Sourena Soheili-Nezhad et al. (DRYAD)
Abstract
Distinct impact modes of polygenic disposition to dyslexia in the adult brain
Dyslexia is a common, partially heritable condition that affects reading ability. In a study of up to 35,231 adults, researchers examined how genetic predisposition to dyslexia relates to brain structure. Individual genetic variants that increase dyslexia risk exhibited distinct patterns of association across brain regions.
Independent component analysis revealed multiple brain networks with unique genomic profiles tied to dyslexia susceptibility. Networks implicated include circuits for motor coordination, vision, and language processing.
Polygenic scores for traits genetically correlated with dyslexia—spanning cognitive, behavioral, and reading-related measures—showed partial overlap with the dyslexia profile in their brain-wide associations. Across these traits, microstructural variation of the internal capsule emerged as a consistent feature, while reduced motor cortex volume appeared more specifically associated with dyslexia’s genetic disposition.
These findings identify genetic and neurobiological signatures that may contribute to dyslexia and to its relationship with other cognitive and educational traits in the population.