Definition of Developmental reading disorder:

Developmental reading disorder, also called dyslexia, is a reading disability resulting from the inability to process graphic symbols.

Causes, incidence, and risk factors:

Developmental reading disorder (DRD) is not caused by vision problems, but rather by problems with the brain's ability to recognize and process symbols. Children with DRD may have trouble rhyming and separating the sounds in spoken words. These abilities appear to be critical in the process of learning to read.

A child's initial reading skills are based on word recognition, which involves being able to separate out the sounds in words and match them with letters and groups of letters. More developed reading skills require the linking of words into a coherent sentence. Because DRD children have difficulty connecting the sounds of language to the letters of words, they may have difficulty understanding sentences.

Most children with DRD have normal intelligence, and many have above-average intelligence. The disorder is a specific information processing problem that is not connected with the ability to think or to understand complex ideas.

DRD may appear in combination with developmental writing disorder and developmental arithmetic disorder. All of these involve using symbols to convey information. These conditions may appear alone or in any combination.

Other causes of learning disability and, in particular, reading disability, must be ruled out before a diagnosis of DRD can be made. Cultural and educational shortfalls, emotional problems, mental retardation, and diseases of the brain (for example AIDS) can all cause learning disabilities.