Developmental Reading Disorder

A condition in which reading ability is significantly below the norm in relation to chronological age and overall intellectual potential.

Also referred to as reading disability, reading difficulty, and dyslexia, developmental reading disorder is the most commonly diagnosed learning disability in the United States. Estimates of its prevalence vary widely, ranging from 4% of children—the figure given by the American Psychiatric Association's Diagnostic and Statistical Manual—to 20%, the figure given by a 1995 study directed by Sally E. Shaywitz of Yale University. According to the latter figure, some 10 million children in the United States have some form of reading disability.

Reading disabilities are diagnosed up to five times more frequently in boys than girls, although some sources claim that this figure is misleading because boys are more likely to be screened for learning disabilities due to their higher incidence of disruptive behavior, which draws the attention of educators and other professionals. Most reading disabilities were formerly grouped together under the term dyslexia, which has largely fallen out of favor with educators and psychologists because of confusion over widespread and inconsistent use of the term in both broad and narrower contexts. Developmental reading disorder is distinct from alexia, which is the term for reading difficulties caused by brain damage from injury or disease. However, neurological studies of alexia have helped researchers better understand reading disabilities.

Types of and causes of reading disorders

Reading disabilities have been classified as either dyseidetic, dysphonetic, or mixed. Children with the dyseidetic type are able to sound out individual letters phonetically but have trouble identifying patterns of letters when they are grouped together. By comparison, dysphonic readers have difficulty relating letters to sounds, so their spelling is totally chaotic. Children with mixed reading disabilities have both the dyseidetic and dysphonic types of reading disorder.

A variety of causes have been advanced for developmental reading disorder. Researchers favoring a biological explanation have cited heredity, minimal brain dysfunction, delays in neurological development, and failure of the right and left hemispheres to function properly together.

Developmental reading disorder is often identified in the first grade, when reading instruction begins. Children with reading disabilities lag behind their peers in reading progress and have serious spelling problems. They also tend to have trouble writing (many have poor handwriting), have an unusually small vocabulary, and favor activities that do not require verbal skills. Also, like children with other learning disabilities, those with developmental reading disorder often earn poor grades and dislike school, reading, and homework. Even at the preschool stage, there are certain problems, such as trouble sounding out words and difficulty understanding words or concepts, which may foreshadow a reading disability.

The outcome of treatment for reading disabilities varies, depending on the quality of the remedial reading program, the severity of the disorder, and the motivation and intelligence of the child. Given the proper remedial help, some children with reading disabilities have been able to successfully complete high school, college, and even graduate school, while others have been forced to limit their vocational choices to fields that do not demand strong literacy skills. Factors that have been found to contribute to the success of treatment include early intervention (elementary rather than secondary school); an IQ over 90; instruction by qualified reading specialists; and a total of over 50 hours of instruction.