Yale researchers have, for the first time, identified two types of reading disability: a primarily inherent type with higher cognitive ability (poor readers who compensate for disability), and a more environmentally influenced type with lower cognitive skills and attendance at more disadvantaged schools (persistently poor readers).
The findings, published in the July 1 issue of Biological Psychiatry, show that compensated poor readers were able to overcome some of the disability, improving their ability to read words accurately and to understand what they read. In contrast, the persistently poor readers continued to experience difficulties; as children these readers had lower cognitive ability and more often attended disadvantaged schools.
"These findings indicate the important role of experience in the proper development of the neural systems for reading and offer hope for teaching our most disadvantaged children how to read," said principal investigator Sally Shaywitz, M.D., professor of pediatrics at Yale University School of Medicine and co-director of the National Institutes of Health Yale Center for the Study of Learning and Attention.
Shaywitz said the study resolves a major question in reading disability: why some children compensate for their reading difficulties, while others continue to struggle to read. Brain activation patterns show a disruption in the neural systems for reading in compensated readers. The researchers were surprised to find that the neural circuitry for reading real words is present in persistently poor readers, but has not been properly activated.
"Reading is the most important work of childhood and yet, as many as one in five children struggle to learn to read, with consequences extending beyond childhood into adult life," said Shaywitz. "The discovery that the neural systems for reading are intact in our most disadvantaged and most persistently poor readers has important educational implications and is of special relevance for teaching children to read."
"Children need to be able to sound out words in order to decode them accurately and then, they need to know the meaning of the word to help them decode and comprehend the printed message," said Shaywitz. "Our results show that providing early interventions aimed at stimulating both the ability to sound out words and to understand word meanings would be beneficial in children at risk for reading difficulties associated with disadvantage."
Shaywitz and her team used functional magnetic resonance imaging (fMRI) to examine brain activation patterns in two groups of young adults who were poor readers as children and have been part of the Connecticut Longitudinal study since 1983 when they were five-year-olds. Compensated poor readers made up one group; persistently poor readers were a second group; and a third group of children who were always good readers served as controls.
The children in the study had their reading assessed yearly throughout their primary and secondary schooling. Poor readers were identified by word reading tests in second grade; by ninth grade, some children had improved in reading accuracy (compensated poor readers) while others continued to be poor readers in ninth grade (persistently poor readers).
The study also examined early environmental factors distinguishing the compensated readers from the persistently poor readers that might account for their different brain imaging patterns and outcomes.
"These findings are exciting because they suggest with early stimulation these already present neural systems for reading could be connected properly and allow children to become good readers," said Shaywitz. "They emphasize the importance of the environment and particularly, of teaching."
Other authors on the study included Bennett Shaywitz, M.D., Robert Fulbright, M.D., Pawel Skudlarski, Einar Mencl, Todd Constable, Ken Pugh, John Holahan; Karen Marchione, Jack Fletcher, Reid Lyon and John Gore.
The study was funded by the National Institute of Child Health and Human Development.
Shaywitz may be reached at 203-785-4641 or 203-641-5115.
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Karen N. Peart
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