Health and Disease

Dyslexia: The Reading Disability

Today, dyslexia is the most common learning disability in the United States, affecting 2-15% of the population. The disability substantially interferes in school and work settings, impairing the education of young children.

By Michelle Li

Published 1:57 PM EST, Fri May 7, 2021


Dyslexia is a learning disability that is characterized by difficulty in reading, writing, spelling, and other language skills. It was first discovered in 1887 when German physician Rudolf Berlin published a case study on a young boy who had normal intelligence but faced difficulties in reading and writing (Nelson). A few years later in 1896, the first English-language case study of dyslexia was published by the British doctor W. Pringle Morgan. Similarly to the 1887 case study, Morgan also detailed a 14 year-old boy who had normal intellectual capabilities but had not learned to read. Before the term “dyslexia” was put into widespread use, the condition was referred to by Morgan and others as “word-blindness”. It is still retained the key characteristic of difficulty reading (Nelson). 

It is believed to have a hereditary component and is most commonly identified in the early years through symptoms related to hardships in reading or other language skills. Following a diagnosis, options to treat dyslexia through special education also exist.


Dyslexia is believed to be a hereditary condition, as 40% of boys and 20% of girls with a dyslexic parent also develop the disorder. Four genes have been found to be connected to dyslexia, but no specific cause has been identified for the disorder (Nelson). Some studies involving positron emission tomography or functional magnetic resonance imaging have shown that there is lower activity in the left inferior parietal cortex, left inferior frontal gyrus, the left inferior parietal lobule, and the left middle temporal gyrus of the brain in dyslexic children when they are given reading or word tasks to complete, highlighting the connection between dyslexia and certain areas of the brain (Nelson). 

Symptoms and Diagnoses

The symptoms of dyslexia appear through the affected reading, writing, listening, and speaking abilities of individuals. Some symptoms include slow reading speed, difficulty reading and spelling words, omission of words while reading, poor reading comprehension, reversal of words or letters, confusion between similar letters, delayed speech, and transferrence of information across modes—such as reading out loud or writing thoughts or speech (Nelson; Frey). 

When these symptoms create problems in school or work settings, individuals are referred to testing for dyslexia. As instruction on reading begins in kindergarten or first grade in the U.S., it is rare for dyslexia to be diagnosed before the age of five or six (Frey). Children are generally diagnosed with dyslexia when they demonstrate that their reading level is greater than two levels below the expected average for their age or education (Nelson). Other visual, hearing, speech, intelligence, and word or letter recognition tests are also conducted to rule out disorders that could impair vision or hearing and measure a child’s capabilities; they are also evaluated psychologically to rule out depression or anxiety as a cause for the learning impairment (Nelson, Frey). Generally, reading problems must substantially interfere with school or daily life, as outlined by the APA’s diagnostic criteria for dyslexia (Frey).


Appropriate and early intervention through special education has been proven effective in treating dyslexia. Under the Individuals with Disabilities Education Act, children with dyslexia are entitled to individualized education plans (IEP) that address the learning disability (Nelson; Frey). The IEP defines specific problems and the associated learning objectives. This is usually done through a cross-disciplinary approach. The three core principles of the successful approach developed by Samuel Torrey Orton in the 1920s have a sound/symbol based component, where words are broken down into letters and associated sounds; a multisensory component, where visual, auditory, and kinesthetic connections are strengthened; and a highly structure component, which involves working up from letters to words to sentences with repetitive practice (Nelson). There are also a number of techniques that reading specialists may test out to see which are most effective. Generally, dyslexia can be treated with appropriate intervention; the earlier the diagnosis and intervention, the greater the likelihood of improved reading abilities and less interference in education.


As the most common learning disability in the United States, dyslexia interferes in the education and lives of many individuals each year. While a clear cause has not been identified, a hereditary component and low activity in certain areas of the brain have been linked to the condition. Symptoms are related to impairments in reading, writing, spelling, and speech; evaluations of these impairments are used to diagnose dyslexia. Early treatment through specialized education plans have been proven successful in improving reading and related abilities, providing hope for dyslexic individuals.

Michelle Li, Youth Medical Journal 2021


Frey, Rebecca J., and Jack Lasky. “Developmental Reading Disorder.” The Gale Encyclopedia of Children’s Health: Infancy through Adolescence, edited by Jacqueline L. Longe, 4th ed., vol. 2, Gale, 2021, pp. 846-50. Gale Health and Wellness, Accessed 19 Apr. 2021.

Nelson, Katy, and Jack Lasky. “Dyslexia.” The Gale Encyclopedia of Children’s Health: Infancy through Adolescence, edited by Jacqueline L. Longe, 4th ed., vol. 2, Gale, 2021, pp. 901-04. Gale Health and Wellness, Accessed 19 Apr. 2021.


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