Dec. 5, 2000 -- In this day and age, dyslexia is a common term, but what's really known about it, and do doctors really know how to treat it? A new study may help point the way.
Dyslexics may have difficulty with reading, spelling, understanding language they hear, or expressing themselves clearly through the spoken word or in writing. Dyslexia can hamper a person's success -- both at school and in the workplace. Moreover, about 5-17% of school-age children have the disorder.
Although we read with our eyes, reading problems associated with dyslexia may be more related to difficulty in recognizing or understanding rapidly changing sounds, according to this new research published in the Dec. 5, 2000 issue of the Proceedings of the Natural Academy of Sciences.
Learning how to read involves hearing as well as vision, and is closely linked to spoken speech. This explains why children learning to read -- or poor readers of any age -- move their lips when they read silently.
"Even though reading is primarily a visual activity, we've known for a long time that children and adults with dyslexia have problems processing language that they hear," says Gabrieli. "That impairment gives them a poor framework on which to build reading skills."
While the part of the brain normally involved in this type of hearing task was much less active in dyslexic readers, brain activity and performance on the hearing task improved in two of three dyslexic readers who took part in a rigorous training program.
"Humans are not born knowing how to read -- they need to be trained over a period of many years, far longer than it takes for them to understand spoken speech," researcher John D. Gabrieli, PhD, an associate professor of psychology at Stanford University, tells WebMD.
"Functional MRI makes it possible to define activated brain areas very precisely," Teija Kujala, PhD, a professor of psychology at the University of Helsinki in Finland, tells WebMD. Kujala was not involved in the study.
In this research, the task during the MRI involved listening to rapidly changing sounds, since this resembles the type of sound processing involved in understanding spoken speech. The researchers studied eight adults with dyslexia and ten adults with no history of reading or language problems.
When exposed to rapidly changing, as opposed to slowly changing, sounds, normal readers -- but not dyslexic readers -- had increased activity in a certain part of the brain.
After three of the dyslexic readers took part in an intensive training program designed to improve this type of sound processing, two of them had dramatically increased activity in the same area of the brain, and also did better on tests of understanding spoken speech. The third subject had no improvement in either brain activity or sound processing tests.
"Our work helps identify a part of the brain that may be critical in learning to read effectively, and shows that even adults with dyslexia can be trained to use this part of the brain better," says Gabrieli.
Future research will use functional MRI along with psychological testing to help find different groups of patients with dyslexia, each with a unique pattern of brain activity that might respond to a different type of training.
"If future studies show improved reading performance together with changes in brain activity caused by training, we would be closer to finding relevant ways of [healing] dyslexia," Kujala says.