Reading disorder Health Article

Definition

Reading disorder is a learning disorder that involves significant impairment of reading accuracy, speed, or comprehension to the extent that the impairment interferes with academic achievement or activities of daily life. People with reading disorder perform reading tasks well below the level one would expect on the basis of their general intelligence, educational opportunities, and physical health. Reading disorder is most commonly called dyslexia. Dyslexia, however, usually includes deficits in spelling and writing as well as reading.

Description

Reading disorder is a learning disorder characterized by a significant disparity between an individual's general intelligence and his or her reading skills. Learning disorders, formerly called academic skills disorders, are disorders that account for difficulty learning and poor academic performance when low performance cannot be attributed to mental retardation, low intelligence, lack of learning opportunities, or such specific physical problems as vision or hearing deficits. Common learning disabilities include reading disorder (often called dyslexia), mathematics disorder, disorder of written expression, and some language processing disorders.

Reading disorder can cause severe problems in reading, and consequently in academic work, even in people with normal intelligence, educational opportunities, motivation to learn to read, and emotional self-control. Reading disorder is different from slowness in learning or mental retardation. In reading disorder, there is a significant gap between the expected level of performance and actual achievement. Difficulties in reading can occur on many levels, and reading disorder may have several causes that manifest in different ways. Common problems in people with reading disorder include:

• slow reading speed
• poor comprehension when reading material either aloud or silently
• omission of words while reading
• reversal of words or letters while reading
• difficulty decoding syllables or single words and associating them with specific sounds (phonics)
• limited sight word vocabulary

Causes

Reading disorder was first recognized in the late nineteenth century, when it was called pure word blindness, then developmental alexia. Starting in the 1960s, educators commonly referred to reading disorder as dyslexia, from the Greek word dys, meaning poor or inadequate, and the word lexismeaning words or language. Despite the long history of reading disorder, its cause is not known.

Learning to read is a complex task. It requires coordination of the eye muscles to follow a line of print, spatial orientation to interpret letters and words, visual memory to retain the meaning of letters and sight words, sequencing ability, a grasp of sentence structure and grammar, and the ability to categorize and analyze. In addition, the brainmust integrate visual cues with memory and associate them with specific sounds. The sounds must then be associated with specific meanings. For comprehension, the meanings must be retained while a sentence or passage is read. Reading disorder occurs when any of these processes are disrupted. For that reason, the roots of reading disorder have proved difficult to isolate, and may be different in different individuals.

Despite the complexity of reading disorder, researchers have found that the condition is at least partially inherited. In 1999, the Centre for Reading Research in Norway studied a large family with reading problems. By evaluating the reading and writing abilities of about 80 family members across four generations, the researchers were able to pinpoint mutations in specific genes that are associated with reading and writing deficits.

It appears that reading disorder may also have causes other than genetic inheritance, as about half the people with this learning disability do not come from families with a history of the problem. Many theories suggest that functional problems in specific areas of the brain underlie reading disorder. Given the complicated demands on the human nervous system involved in reading, it is entirely possible that there are several different problems in brain function related to difficulty in learning to read. What is known is that 90% of children diagnosed with reading disorder have other language deficits. Still other research suggests a possible link with a subtle visual problem that affects the speed with which affected people can read.

Symptoms

Common characteristics of children with reading disorder include:

• difficulty identifying single words
• problems understanding the sounds in words, sound order, or rhymes
• problems with spelling
• transposing letters in words
• omitting or substituting words
• poor reading comprehension
• slow reading speed (oral or silent)

In addition to these symptoms, children with reading disorder often have other delays or learning problems. These include:

• delays in spoken language
• confusion with directions, or right/left-handedness
• confusion with opposites (up/down, early/late)
• mathematics disorder
• disorder of written expression