The Real Cause of Dyslexia: Brain Scans Show the Story

A common myth about dyslexia is that it’s caused by weak visual processing.

One reason this myth is so stubborn is because it sounds reasonable. After all, we use vision to read, so if reading is hard, there must be a problem with the brain’s visual system, right?

Wrong.

Scientists have known for years that the real cause of dyslexia lies in the brain’s auditory system. Kids and adults with dyslexia who confuse letters like b’s and d’s don’t do it because they see the letters as the same, but because they hear them as the same.

It’s the reason interventions like one-on-one brain training that strengthen auditory processing are seven times more effective than tutoring at improving reading skills. (A Chicago School District study showed that, on average, one year’s worth of tutoring produces a three-month net gain in reading skills, while the average result of LearningRx one-on-one brain training is a three-year net gain in reading skills in just six months!).

Now groundbreaking research provides greater understanding into the link between dyslexia and the brain.

The study, conducted by researchers at The Center for the Study of Learning at Georgetown University Medical Center, used fMRI technology to compare the brains of children with and without dyslexia. What they discovered is that while children with dyslexia do show differences in the part of the brain responsible for visual processing, those differences are the result of dyslexia, not the cause.

The cause-and-effect intricacies of dyslexia could be seen when children in the study were given an intervention that strengthened auditory processing and phonemics. When auditory processing was improved, reading not only improved, but the part of the brain responsible for visual processing also showed increased activity. Researchers say this sequence of events suggests that visual processing is improved by better reading, and not the other way around.

The study confirms that “early identification and treatment of dyslexia should not revolve around these deficits in visual processing,” says Olumide Olulade, Ph.D., the study’s lead author and post-doctoral fellow at GUMC.