Slower Brain Connections May Be at Root of Dyslexia
Researchers find new insight into reading disorder
By Amy Norton
THURSDAY, Dec. 5, 2013 (HealthDay News) -- Glitches in the connections between certain brain areas may be at the root of the common learning disorder dyslexia, a new study suggests.
It's estimated that up to 15 percent of the U.S. population has dyslexia, which impairs people's ability to read. While it has long been considered a brain-based disorder, scientists have not understood exactly what the issue is.
The new findings, reported in the Dec. 6 issue of Science, suggest the blame lies in faulty connections between the brain's storage space for speech sounds and the brain regions that process language.
The results were surprising, said lead researcher Bart Boets, because his team expected to find a different problem. For more than 40 years, he said, many scientists have thought that dyslexia involves defects in the brain's "phonetic representations" -- which refers to how the basic sounds of your native language are categorized in the brain.
But using sensitive brain imaging techniques, Boets and colleagues found that was not the case in 23 dyslexic adults they studied. The phonetic representations in their brains were just as "intact" as those of 22 adults with normal reading skills.
Instead, it seemed that in people with dyslexia, language-processing areas of the brain had difficulty accessing those phonetic representations.
"A relevant metaphor might be the comparison with a computer network," said Boets, of the Leuven Autism Research Consortium in Belgium. "We show that the information -- the data -- on the server itself is intact, but the connection to access this information is too slow or degraded."
And what does that all mean? It's too soon to tell, said Boets. First of all, he said, this study used one form of brain imaging to study a small group of adult university students.
But dyslexia normally begins in childhood. And it's possible, Boets said, that the "intact" phonetic representations in these adults took longer to develop and might have been apparent [only] when they were children.
Even if children with dyslexia have the same underlying brain issue seen in this study, it's not clear how that could be used in managing kids' reading difficulties.
According to Boets, the "most established" way to help children with dyslexia is through instruction on the smallest sounds of speech (called phonemes) and how each corresponds to letters.
And the good news, Boets said, is that those types of tactics should help strengthen the brain connections that seemed to be impaired in this study.
Still, "it is not inconceivable," he added, that these results could be used to develop more-refined therapies that try to zero in on specific brain connections. He pointed to non-invasive magnetic stimulation of certain brain areas as an example -- though that is only speculation for now.