University of Denver: Discovery may cut risk for dyslexia
As is the case with many toddlers, Michael Thieme’s early spoken language was quirky. He called his older brother William “Illiam,” for example. “He couldn’t get his W’s out,” his mother, Annette Thieme, said. Unlike most, Michael had speech problems that persisted into kindergarten, putting him at risk for the reading difficulty known as dyslexia. Michael’s parents didn’t stop at speech therapy. They also enrolled both sons in a five-year study at the University of Denver to uncover why early speech and language problems so often lead to dyslexia. The study, which just ended, showed a genetic link between early speech problems and later dyslexia. Both problems showed up in the same genetic regions, said DU psychologist Bruce Pennington.
He presented results Wednesday at the International Dyslexia Association’s annual meeting in Denver. The discovery could lead to earlier intervention for kids at risk of reading disorders, to a better understanding of the brain structures underlying speech, language and reading, and, eventually, to drugs that help correct problems, Pennington said. “Not too long ago, people said complex disorders were all in your mind, or in your experience,” he said. “Now we’re finding they’re like a lot of medical diseases – heart disease, diabetes. Genes change anatomy and affect disease.” Annette Thieme suspects it was her genes that affected her son’s early speech. “I’m sure it came from me,” Thieme said, as her sons, now 9 and 11, demonstrated the gamelike tests researchers challenged them with during the past several years. Pulling on headsets to listen to recorded directions, Michael and William quickly became engrossed in a task involving remembering odd new names given to tiny plastic animals. A giraffe became “said,” for example, William explained. In kindergarten, Annette Thieme struggled with speech, she said, in much the same way Michael did. Both mother and son outgrew their speech and language problems, and neither has dyslexia, a reading disorder in which people have difficulty recognizing or deciphering printed words. But about one in three toddlers who have speech and language problems do develop dyslexia, Pennington’s team found. Researchers and educators want to learn how to pick out those vulnerable children early, to get them extra help, he said. Pennington and other researchers cautioned that there are no true “reading genes.” Reading is a cultural invention only a few thousand years old, too young for evolution to have shaped genes to control it, said Robert Dougherty, a Stanford University biologist. Instead, reading relies on brain structures developed for other purposes, from visual to communicative, he said. So perhaps it’s not surprising that Pennington and other scientists are finding not one gene but many associated with speech, language and reading problems. Shelley Smith, a geneticist at University of Nebraska Medical Center, ran tests on the families Pennington studied. She found that early speech problems corresponded to regions of at least three chromosomes – 1, 6 and 15, all also involved in dyslexia. Psychologists, geneticists and anatomists are finally unveiling the connections among genes, brains and language that lead to strong or poor readers, she said. “This is such an exciting time,” she said. “It’s finally all coming together.”