Adam Katz Lecture Series:
Dr. Frank Wood on Dyslexia Neurogenetics

By Liza Young

Dr. Frank Wood, Professor of Neurology and Neuropsychology at Wake Forest University, and author of over 100 peer reviewed articles on learning disabilities, recently spoke at NYU Medical Center as part of the NYU Child Study Center’s Adam Katz Lecture series, discussing “Chromosome to Classroom: Update on Dyslexia Neurogenetics.”

Wood began by stating, “There is a mythology that must be debunked that we can remediate learning disabilities by third grade, after which time the students will be OK.”

Epidemiological studies, Wood elaborated, confirmed that by third grade, scores were raised from the 10th percentile to the 50th on the Woodcock-Johnson test. By eighth grade, however, scores fell to below where they had been in first grade. Wood referred to this phenomenon as the “4th grade slump.” While it’s true that phonemic awareness is the “major underlying skill deficit” in dyslexia, in the long-term a focus on improving decoding skills without raising fluency and vocabulary skills will lead to relapse in student scores after third grade. The issue goes beyond cognitive ramifications as research points to an associated risk of suicidality, depression, and social phobia by adolescence.

With respect to the neurogenetics of reading disability, three genes have been implicated in published research. Damage to chromosome 15 results in expressive and receptive language deficits and significantly affects rapid naming which is the “single strongest predictor for third graders who are already poor readers.” Rapid naming is the reading as quickly as possible of letters, symbols, words, sentence fragments on a page.

The strongest association with dyslexia has been found on chromosome 6, which is closely linked to vocabulary, based on the published research. Both chromosome 6 and 15 are associated with hypo-metabolism, which can be seen through reduced blood flow, in certain areas of the brain.

Wood’s latest endeavor involves research with a population in South Africa; the choice of this region has to do with its being a genetic isolate population composed of descendants of immigrants dating back to the 1600’s who have resisted intermarriage outside their group. Past genetic studies on this population yielding useful information has been done with reference to Huntington’s disease, breast cancer, and hypercholesterolemia.

In this latest study, 1947 4th, 5th and 6th graders were screened on phonemic awareness single word reading, or non-word reading. This was the first large sample, epidemiological study of dyslexia with respect to genetics, and further, done from a multi-genic perspective. The results of the study indicate that there is a strong association between marker genes and symptoms of dyslexia. The expression of dyslexia, however, increases significantly when a mutation occurs on more than one gene; with one mutant gene, the chances of expressed dyslexia are 60-80 percent, but with more than one, the risk goes up to nearly 100 percent.

The most striking finding for Wood was looking at paired double risk cases; those that included a mutation on chromosome 15 compared to those that did not, had fifteen standard score points less in rapid naming.

Looking at the neurological side of dyslexia, area 37 has been routinely implicated with respect to dyslexia, where there is reduced gray matter volume in that location.  The area in the brain correlated with low rapid naming is anterior to area 37, approaching the hippocampus; those with a “Double Deficit” will have reduced thickness in both this area and area 37.

The National Institutes of Health (NIH) only recently approved studies to correlate genetic composition with neuro-imaging in South Africa, an area of study that Wood will continue to comprehensively research.

Wood’s recommendation to teachers and parents is to keep in mind that to improve reading skills for children with dyslexia, the focus must be on fluency training. “Neurons don’t suddenly say, aha, I get it, but one trail after another they change their synaptic threshold,” explained Wood.  It is repetition, throughout the child’s learning career, which will lead to neuronal changes. What Wood has found most beneficial in the classroom is repeated reading—taking a text that is significantly ahead of a child’s reading ability and immersing students in it through repeated reading, talking about the words, using the words in everyday conversation. Wood further stated that starting in first grade children should read as much as possible, including discussion with parents on the reading topics. “If you do this, you overcome what appears to be the most fundamental genetic risk factor in dyslexia; you will have a constitutionally-based fluency as well as a phonology base.”#