Brain-based language problems such as dyslexia and dysgraphia fall under the general heading of "specific learning disability," but a new study from the University of Washington shows that they are distinct disorders that require different types of instruction.

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About 36 percent of the students receiving special education services in the United States have normal intelligence, but struggle with reading, writing, speaking and doing math.

Dyslexia is one of the most common of those disabilities and involves problems with reading and spelling words.

Dysgraphia is a lesser known disorder that impairs handwriting, and also is characterized by poor spelling, but may not affect reading ability.

Federal special education law lumps them under one category, but new research from the University of Washington makes the case that they are distinct disorders that require different types of instruction.

The researchers scanned the brains of 40 children in grades 4-9 who were diagnosed as having dyslexia, dysgraphia or were typically developing readers and writers.

The study’s lead author, Todd Richards, a UW radiologist, and his colleagues recorded the kids’ brain activity as they performed different tasks such as filling in a missing letter in a word or planning a composition about space travel they would write later outside the scanner.

The researchers found differences in how efficiently messages traveled between nerve cells in their brains.

Typically developing kids used fewer, more direct highways, indicating more efficient processing.

(Donna Grethen / Op Art)
(Donna Grethen / Op Art)

The kids with dyslexia and dysgraphia showed different patterns — they had fewer direct highways with more detours through side streets and alleys. In other words, their brains had to work a lot harder.

What’s more, the patterns for dyslexia and dysgraphia also looked different from each other, indicating they are neurologically distinct disabilities.

That’s why it’s important that kids receive a proper diagnosis, then specialized instruction tailored to it, said Virginia Berninger, an educational psychologist who worked with Richards on this study and others and heads the UW Interdisciplinary Learning Disabilities Center.

“So many of these kids never get the kind of instruction they need,” Berninger said, “and we just keep showing over and over again that if you find out what’s wrong and you teach that skill, voilà, they can learn.”

For the full study, see the latest issue of the journal NeuroImage: Clinical.