Merck Manual

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Stephen Brian Sulkes

, MD, Golisano Children’s Hospital at Strong, University of Rochester School of Medicine and Dentistry

Reviewed/Revised Feb 2022 | Modified Sep 2022

Dyslexia is a specific reading disorder involving difficulty separating single words from groups of words and parts of words (phonemes) within each word.

  • Affected children may be late in speaking, have articulation problems, or have difficulty blending sounds or identifying sounds in words.

  • Academic and intelligence tests are given.

  • Treatment involves direct instruction in word recognition.

Dyslexia is a particular type of learning disorder Learning Disorders Learning disorders involve an inability to acquire, retain, or broadly use specific skills or information, resulting from deficiencies in attention, memory, or reasoning and affecting academic... read more . No estimates of the number of children affected by dyslexia exist, but about 15% of school children receive adaptations or special instruction for reading difficulties. It is identified in more boys than girls. However, it may simply go unrecognized more often in girls. Dyslexia tends to run in families.

Dyslexia occurs when the brain has difficulty making the connection between sounds and symbols (letters). This difficulty is caused by poorly understood problems with certain connections in the brain. The problems are present from birth and may cause spelling and writing errors and reduced speed and accuracy when reading aloud. Although the letter reversals that often occur in children with dyslexia suggest visual problems, in most cases the problems are related to how sounds are perceived by the brain, that is, how the brain understands and interprets them. People with dyslexia do not have problems understanding spoken language.

Symptoms of Dyslexia

Preschool children with dyslexia may

  • Be late in speaking

  • Have difficulty pronouncing words (speech articulation problems)

  • Have difficulty remembering the names of letters, numbers, and colors

  • Have difficulty with word problems despite normal math computation skills

Children with dyslexia often have difficulty blending sounds, rhyming words, identifying the positions of sounds in words, segmenting words into sounds, and identifying the number of sounds in words. Delays or hesitations in choosing words, making word substitutions, and naming letters and pictures are early indicators of dyslexia. Problems with short-term memory for sounds and for putting sounds in the correct order are common.

Many children with dyslexia confuse letters and words with similar ones. Reversing the letters while writing—for instance, on instead of no, and saw instead of was—or confusing letters—for instance, b instead of d, w instead of m, n instead of h—is common. However, many children without dyslexia reverse letters during early elementary school years.

Diagnosis of Dyslexia

  • Reading evaluation

  • Speech, language, and hearing evaluations

  • Psychologic evaluation

Children who are not progressing in word-learning skills by the middle or end of first grade should be tested for dyslexia and other problems that may affect learning. Testing is usually conducted by school personnel and includes speech, language, and hearing tests, intelligence tests, and tests of academic skills.

Treatment of Dyslexia

  • Educational interventions

The best treatment for word recognition problems is direct instruction that incorporates multisensory approaches. This type of treatment consists of teaching phonics with a variety of cues, usually separately and, when possible, as part of a reading program.

Indirect instruction for word recognition is also helpful. This instruction usually consists of training to improve word pronunciation or reading comprehension. Children are taught how to process sounds by blending sounds to form words, by separating words into segments, and by identifying the positions of sounds in words.

Component-skills instruction for word recognition is also helpful. It consists of training to blend sounds to form words, to segment words into word parts, and to identify the positions of sounds in words.

The federal Individuals with Disabilities Education Act (IDEA) requires public schools to provide free and appropriate education to children and adolescents with dyslexia or other learning disorders. Education must be provided in the least restrictive, most inclusive setting possible—that is, a setting where the children have every opportunity to interact with nondisabled peers and have equal access to community resources. The Americans with Disability Act and Section 504 of the Rehabilitation Act also provide for accommodations in schools and other public settings.

As children with dyslexia get older, compensatory strategies may be helpful. These strategies can include use of audio books, computer screen readers (available on most computers), digital recorders, and other technologic adaptations.

Indirect treatments, other than those for word recognition, may be used but are not recommended. Indirect treatments can include using tinted lenses that allow words and letters to be read more easily, eye movement exercises, or visual perceptual training. Drugs such as piracetam have also been tried. The benefits of most indirect treatments have not been proved and may provide unrealistic expectations and delay the teaching that is needed.

More Information

The following are English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

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