Scientists have revealed the main causes of dyslexia – and how it can cause parts of the brain to shrink.
The learning difficulties that often cause patients to misspell and misread words are known to run in families.
But scientists in the Netherlands have now identified the exact DNA mutations that could be responsible for the problem – as well as the specific impact on the structure of the brain.
Dyslexia is partly influenced by genes and can be inherited, explains study author and neurogenetics researcher Sourena Soheili-Nezhad.
“Yet dyslexia is a complex trait, which cannot be explained by changes in a single brain region or gene,” he added.
‘By studying exactly which genes influence which brain networks, we can understand how cognitive functions develop differently in this learning problem.’
In the studypublished in the journal Science Advances, researchers used data from more than a million people collected by 23andMe, a company that sells at-home DNA testing kits.
This data revealed the genetic variants that increase the likelihood of someone having dyslexia – which affects around one in ten Britons.
According to the NHS, an estimated one in ten people in Britain have some degree of dyslexia.
Researchers then used information from the UK Biobank – a collection of health data from 30,000 people, including medical imaging and DNA mutations – to look for similarities in the brain scans of people with the previously identified genetic variant.
Researchers found that people with the telltale genetic traits had lower brain volume in brain areas involved in movement coordination and processing of speech sounds.
They also found above-average brain volume in the part of the brain responsible for vision.
A reduced amount of white matter, deeper tissue in the brain that contains nerve fibers, has also been linked to dyslexia.
“Although our study used data from adults, some of the changes are likely related to altered brain development during early life stages, for example in fetus or during childhood, which then remains stable throughout life,” says Genomics researcher Clyde Francks. , who also worked on the study.
‘Other changes may reflect the brain’s responses to decades of altered behavior in people with a higher genetic predisposition to dyslexia.
‘For example, avoiding reading for years in personal and professional life can impact the brain’s visual system.’
However, the study authors say that future research should focus on data from children, rather than adults, to track developmental brain changes linked to causing dyslexia.
“Understanding the brain basis of dyslexia could also potentially help achieve earlier diagnosis and educational intervention in the future, with more targeted strategies that fit the profiles of individual children,” Soheili-Nezhad added.
Intelligence is not affected by dyslexia, but people with learning difficulties may struggle at school unless they receive extra support.
Dyslexia is difficult to diagnose at an early stage because some symptoms, such as frequent spelling or pronunciation errors, occur normally when children learn to read and write.
Most children with learning difficulties are not noticed until primary school, but some people with the condition are missed well into adulthood.
The NHS suggests that parents who are concerned about their child’s reading and writing should first talk to their teacher and then consider seeking advice from a GP.
It adds that adults can arrange an assessment with the British Dyslexia Association.