A new study from the University of Washington shows that not all reading disabilities are the same and that tests and brain imaging can identify different kinds of specific learning disabilities.
These findings highlight the need to change how children with learning disabilities are diagnosed and treated, says lead author Virginia Berninger, a professor of educational psychology at the UW College of Education.
The paper "Differential diagnosis of dysgraphia, dyslexia, and OWL LD: behavioral and neuroimaging evidence," recently was published in the journal Reading and Writing and co-authored by Todd Richards, professor of radiology, and Robert Abbott, professor of education.
Their study shows that three different kinds of specific learning disabilities (dysgraphia, dyslexia, or oral and written language learning disability) can be defined on the basis of tests that identify their underlying defining characteristics. These underlying characteristics can be diagnosed through tests of children's ability to process and produce different-sized units of language.
Individuals with dysgraphia have trouble with individual letters, both writing the letters legibly and automatically. Meanwhile, individuals with dyslexia have trouble reading and spelling entire words. Individuals with oral and written language learning disability (OWL LD) have trouble with using series of ordered words to understand through listening and reading and to express ideas through talking and writing.
In their study, UW researchers asked children in grades 4 through 9 diagnosed with different specific learning disabilities (SLDs) to do a common task like choosing a correctly spelled word during brain scanning. In reviewing those brain scans, researchers found the number and pattern of connections differ for students with dysgraphia, dyslexia and OWL LD.
"Both students with dyslexia and with OWL LD may have trouble with reading," Berninger said. "But those with dyslexia struggle in learning to decode unknown words and those with OWL LD in reading comprehension."
Compared to children in the control group, Berninger also said children with SLDs showed much greater activation of a structure in the emotional brain. That suggests those children are experiencing social emotional distress over their persisting learning difficulties.
The brain findings add to other recent findings by researchers at the UW Learning Disabilities Center that show white matter and gray matter brain differences between dysgraphia and dyslexia. Brain differences are also found between control group children without specific learning disabilities and those with dysgraphia, dyslexia and OWL LD.
Berninger said the finding is significant because children are currently qualified for services under an umbrella category of SLDs, yet the criteria for doing so vary from state to state and are not based on scientifically supported diagnosis of different kinds of SLDs.
"The reason these problems are persisting beyond third grade for many children is because they aren't being addressed properly," Berninger said. "We have shown that all three are treatable, but we need to tailor the treatment to the specific learning disability."
As many as one in five children may struggle with one or more of the SLDs that UW researchers studied, Berninger said, and differential diagnosis is critical to providing appropriate instruction. For example, other research by the Learning Disabilities Center has shown that computers can assist teachers in providing differentiated instruction for the various SLDs.
The center is now transitioning to move two decades of research into educational practice, Berninger said. Efforts are under way to rethink pre-service and in-service professional development for educators at all levels, from teachers to principals to district-level administrators.
"We need to implement assessment-intervention links across K-to-5 to prevent specific learning disabilities and optimize achievement of all students, including those living in poverty and those whose first language is not English," Berninger said.
In addition, changes to federal and state policy are needed to better identify, diagnose and treat SLDs.
"There's a lot of suffering out there that we can end if we address these learning disabilities earlier on," Berninger said. "We have evidence from our other research studies that specific learning disabilities are preventable if identified and individually tailored instruction is provided throughout early and middle childhood in general education."
Virginia Berninger, Professor of Educational Psychology
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