Dyslexia appears to be caused by two distinct types of brain problems, a new study has found. The researchers, from Yale, used scanning devices to examine the brains of 43 young adults with known reading disabilities while they performed reading tasks. Another group of 27 good readers were also studied.
All the subjects had been tracked for reading ability since elementary school. One group appeared to have what the researchers called a “predominantly genetic type” of dyslexia. These students had gaps in the neural circuitry that the normal readers used for the basic processing of sound and language, but had learned to enlist other parts of the brain to compensate for the difficulty. They still read slowly but can comprehend what they read.