Neuroimaging Helps Predict Which Dyslexics Will Learn to Read

Their study, the first to identify specific brain processes involved in an individual's ability to overcome reading problems, could lead to new interventions to help dyslexics better learn to read.

"This gives us hope that we can identify which children might get better over time,” said Fumiko Hoeft, MD, PhD, an imaging expert and instructor at Stanford University's Center for Interdisciplinary Brain Sciences Research (Palo Alto, CA, USA). "More study is needed before the technique is clinically useful, but this is a huge step forward.”

Dr. Hoeft is first author of an article that was published online December 20, 2010, in the journal Proceedings of the [US] National Academy of Sciences (PNAS). The senior author is John Gabrieli, PhD, a former Stanford professor now at the Massachusetts Institute of Technology (MIT; Cambridge, MA, USA).

Dyslexia, a learning disability that impairs an individual's ability to read, affects 5% to 17% of children in the United States. Dyslexic children's ability to improve their reading skills varies greatly, with about one-fifth able to benefit from interventions and develop adequate reading skills by adulthood. But up to now, what occurs in this brain to allow for this improvement remained unknown.

Earlier imaging studies have shown greater activation of specific brain regions in children and adults with dyslexia during reading-related tasks; one area in particular, the inferior frontal gyrus, is used more in dyslexics than in typical readers. As the researchers noted in their paper, some experts have hypothesized that greater involvement of this part of the brain during reading is related to long-term gains in reading for dyslexic children.

For this study, Dr. Hoeft and colleagues tried to determine whether neuroimaging could predict reading improvement and how brain-based measures compared with conventional educational measures.

The researchers gathered 25 children with dyslexia and 20 children with typical reading skills - all around age 14 - and assessed their reading with standardized tests. They then used two types of imaging, functional magnetic resonance imaging (fMRI) and diffusion tensor imaging, as the children performed reading tasks. Two-and-a-half years later, they re-evaluated reading performance and asked which brain image or standardized reading measures taken at baseline predicted how much the child's reading skills would improve over time.

What the researchers found was that no behavioral measure, including widely used standardized reading and language tests, reliably predicted reading gains. However, children with dyslexia who at baseline showed greater activation in the right inferior frontal gyrus during a specific task and whose white matter connected to this right frontal region was better organized showed greater reading improvement over the next two-and-a-half years. The researchers also discovered that looking at patterns of activation across the whole brain allowed them to predict very accurately future reading gains in the children with dyslexia. "The reason this is exciting is that until now, there have been no known measures that predicted who will learn to compensate,” stated Dr. Hoeft.

As the researchers noted in their article, "fMRI is typically viewed as a research tool that has little practical implication for an individual with dyslexia.” However, these findings suggest that, after additional study, brain imaging could be used as a prognostic tool to predict reading improvement in dyslexic children.

Another promising implication, according to Dr. Hoeft, involves therapy. The research demonstrates that gains in reading for dyslexic children involve different neural processes and pathways than those for typically developing children. By understanding this, researchers could develop therapies that focus on the appropriate regions of the brain and that are, in turn, more effective at improving a child's reading skills.

Dr. Hoeft stated that this study might also encourage the use of imaging to enhance the understanding (and potentially the treatment) of other disorders. "In general terms, these findings suggest that brain imaging may play a valuable role in neuroprognosis, the use of brain measures to predict future reductions or exacerbations of symptoms in clinical disorders,” she explained.

The authors noted several caveats with their findings. The children were followed for two-and-a-half years; longer-term outcomes are unknown. The study also involved children in their teens; more research, according to the investigators, is needed to determine whether brain-based measures can predict reading progress in younger children. Dr. Hoeft is now working on a study of prereaders, being funded by the US National Institute of Child Health and Human Development (Bethesda, MD, USA).

Related Links:
Stanford University's Center for Interdisciplinary Brain Sciences Research