DEVELOPMENTAL DYSLEXIA - A specific reading disorder in single-word decoding, usually due to congenital deficiencies in phonologic processing or phoneme awareness.
Other problems with different forms of written language, such as spelling, reading fluency (rate and accuracy), and reading comprehension are affected concomitantly. Dyslexics do not have difficulty understanding spoken language.
No definition of dyslexia is universally accepted, thus incidence is undetermined. An estimated 15% of public school children receive special education for reading problems, of whom 3 to 5% are probably dyslexic. Dyslexia is not gender-related, although more males than females are identified.
Children with reading problems other than dyslexia may demonstrate word-learning problems. However, their problems usually result from difficulties in understanding both written and spoken language or from low cognitive ability.
Symptoms and Signs - Most dyslexics are not identified until kindergarten or 1st grade, when symbolic learning is encountered. However, dyslexia is evidenced in preschool children as delayed language production, speech articulation problems, and difficulties remembering the names of letters, numbers, and colors, particularly in children with a family history of reading or learning problems. Children with phonologic processing problems often have difficulty blending sounds, rhyming words, identifying the positions of sounds in words, segmenting words into pronounceable components, and reversing the order of sounds in words. Delay or hesitation in choosing words (word-finding problems), in substituting words, or in naming letters and pictures is often an early sign of dyslexia. Short-term (working) auditory memory and auditory sequencing problems are common.
Many dyslexics confuse letters and words with similar configurations or have difficulty visually selecting or identifying letter patterns and clusters (sound-symbol association) in words. Reversals or visual confusions tend to occur frequently during the early elementary school years. However, most reading and writing reversals occur because of retention or retrieval problems that cause dyslexics to forget or confuse the names of letters and words that have similar structures; subsequently, d becomes b, m becomes w, h becomes n, was becomes saw, on becomes no.
Drug therapies have also been proposed and are also unsubstantiated. For instance, the use of antihistamines and motion sickness drugs are recommended by one theorist to stabilize certain brain functions that may impair visuoauditory vestibular functions. Piracetam has also been investigated because of its purported ability to improve certain higher cognitive functions.
Many dyslexics develop functional reading skills with direct instruction, although dyslexia is a lifelong problem and many dyslexics never reach full literacy. Compensatory approaches, such as taped texts, readers, and scribes, are used to assist the dyslexic with higher-order learning. Persons with other reading problems may overcome early weaknesses if the cause is maturational. Still others may have persistent reading problems if they exhibit language impairments or cognitive deficiencies.