Dyslexia - Who Is Affected and What Happens over Time

Excerpted from
Overcoming Dyslexia: A New and Complete Science-Based Program for Reading Problems at Any Level
By Sally Shaywitz, M.D.

The year 1987 marked a watershed in our quest to understand and more effectively treat reading disability. On August 17, 1987, the Secretary of Health and Human Services, Dr. Otis R. Owen, sent to Congress the long-awaited report of the Interagency Committee on Learning Disabilities (ICLD). The ICLD, chaired by Dr. Duane Alexander and composed of representatives of the different institutes of the National Institutes of Health (NIH) and of the Department of Education, was mandated by Congress to "review and assess Federal research priorities, activities, and findings regarding learning disabilities" and to make recommendations and establish national priorities to increase the effectiveness of research on learning disabilities.

After a comprehensive investigation, the committee declared in "A Report to the U.S. Congress" that the time was right to begin an intensive, all-out drive to understand learning disabilities at a fundamental level. The report called for the establishment of NT H-supported Centers for the Study of Learning and Attention. The National Institute of Child Health and Human Development (NICHD), a branch of the NTH. issued a formal request for proposals for the establishment of such centers. Following an enthusiastic response from more than one hundred investigators and a rigorous review process, three such centers were chosen: one at the University of Colorado, one at Johns Hopkins University, and one at Yale University, directed by my husband, Bennett Shaywitz, and me. Currently, there are four Ml I-funded centers specifically dedicated to increasing our understanding of learning disabilities. This program of targeted research has produced unparalleled results, particularly in our understanding of reading and reading problems. Because I am most intimately aware of the details of the work at the Yale Center and because our own research strategy and findings provide valuable insights into the state of current research in the field. I will use Yale's studies as a model for discussion.

At first we focused on the basic characteristics of the disorder, designing a research study aimed at answering these questions: Who is dyslexic? How many children are affected? Are boys and girls both affected? What happens to a child with dyslexia over time, and how long does the problem last? When does the problem go away, or is it with someone for her entire life? Many of the answers have emerged from the Connecticut Longitudinal Study, which has been ongoing for almost two decades.

The Connecticut Longitudinal Study

In 1978, when I was asked to care for patients with reading difficulties, it was unclear to me just how a physician takes care of children who are dyslexic. There were many basic questions for which I could find no satisfactory answers: for example: Is dyslexia a common problem or a rare one? Most of the information about dyslexia was based on studies of children who had already been identified-either by their schools or by a clinic-as haying a reading problem. I thought there might be large numbers of children sitting at their desks in classrooms all over the country who were unable to read but never accounted for in studies of dyslexia. To understand the lull scope of the problem we needed to count all children with reading problems and not only those who were already visible and receiving help.

In order to differentiate between children who were experiencing reading problems and those who were learning to read with ease, it was necessary to establish exactly what rate of reading development, what behaviors, and what characteristics are normal for children. That required studying large numbers of children over an extended period- us it turned out, from the time they entered kindergarten and through primary school, middle school, and eventually high school and even beyond.

To begin the study we selected children who were attending kindergarten in twenty-four randomly chosen Connecticut public schools in the 1983-84 school year. Expert statisticians selected a study sample that represented the geographic and demographic diversity of Connecticut. Since we wanted to develop a more nuanced understanding of each child, we gathered information on a range of qualities that included mental ability, academic achievement, behavior at home and in the classroom, and self-perception. We obtained information from parents, teachers, and the children themselves. The criteria for those to be enrolled in the study were purposely left vet} broad; we did not want to influence the results by excluding any particular group of children.

We enrolled 445 children in the study. The composition of the group in terms of gender, ethnicity, and race was representative of the population of children entering public kindergarten in Connecticut that year. The participants have been regularly monitored since then. The boys and girls who began this study are now young men and women. Some are attending college, some are in the military or in civilian jobs, and some are in jail. Consistent with national trends, many have married or become parents. Although they now live in twenty-nine different states and have lived in at least seven foreign countries, the vast majority of the original participants (over 90 percent) continue to be committed to the Connecticut Longitudinal Study. Their experiences provide a panoramic view of the process of learning to read. Each of these young men and women is owed a huge debt of gratitude.

Models of Reading and Reading Disability

One of the first questions the Connecticut study addressed was the relation between good and poor readers: Do they form a continuum, or are they two distinct groups? Our educational policy for the identification of reading-disabled children for the past twenty years has been based on the belief that there exists a gap in nature that allows us to separate dyslexic readers from all other readers. "Classification is the art of carving nature at the joints; it should imply that there is indeed a joint there, that one is not sawing through bone," said Scottish psychiatrist R. E. Kendell. Results of our research suggest, however, that there is no natural joint separating dyslexic and good readers.

Evidence from the Connecticut study, as well as from Britain and New Zealand, provides a picture of an unbroken continuum of reading ability and reading disability, a conceptualization referred to as a dimensional model by researchers. The contrasting categorical model features discontinuity-a natural break in the linkage between good and poor readers. A dimensional model recognizes that there are "no natural joints in nature" to separate one group of readers from another, and that while such cutoff points may be imposed, they are arbitrary.

In truth, the need to refer to disorders, even those that occur along a continuum, by a specific diagnostic label often obscures the fact that many, if not most, disorders in nature occur in gradations and thus conform to a dimensional rather than a categorical model. Hypertension, obesity, and diabetes represent common dimensional disorders. Visual and hearing deficits also occur along a continuum. When blood pressure reaches a certain level, a patient is considered to have hypertension. But individuals just on the other side of the cutoff point, although not labeled as hypertensive, will share many traits in common with those said to have hypertension. For hypertension, as for dyslexia, there is no natural gap that separates affected people from others, and a decision is made based on an artificial cutoff point.