Dyslexia is a specific reading disability due to a defect in the brain's processing of graphic symbols.
It is a learning disability that alters the way the brain processes written material and is typically characterized by difficulties in word recognition, spelling and decoding. People with dyslexia have problems with reading comprehension.
The National Center for Learning Disabilities1 says that dyslexia is a neurological and often genetic condition, and not the result of poor teaching, instruction or upbringing. Dyslexia is not linked to intelligence.
Contents of this article:
What is dyslexia?
The problem in dyslexia is a linguistic one, not a visual one. Dyslexia in no way stems from any lack of intelligence. People with severe dyslexia can be brilliant.
Dyslexia commonly causes difficulties in word recognition, spelling and decoding.
The effects of dyslexia, in fact, vary from person to person. The only shared trait among people with dyslexia is that they read at levels significantly lower than typical for people of their age. Dyslexia is different from delayed reading development, which may reflect mental disability or cultural deprivation.
According to the University of Michigan Health System, dyslexia is the most common learning disability.2 Eighty percent of students with learning disabilities have dyslexia.
The International Dyslexia Association3 estimates that 15% to 20% of the American population have some of the symptoms of dyslexia, including slow or inaccurate reading, poor spelling, poor writing, or mixing up similar words.
The British National Health Service,4 estimates that 4-8% of all schoolchildren in England have some degree of dyslexia.
It is estimated that boys are one-and-a-half to three times more likely to develop dyslexia than girls.
The Dyslexia Association5 in Australia states: "A dyslexic individual can be successful because of their abilities not in spite of. A dyslexic may struggle to succeed because of their negative experiences in the learning environment not because of dyslexia."
Dyslexia affects people of all ethnic backgrounds, although a person's native language can play an important role. A language where there is a clear connection between how a word is written and how it sounds, and consistent rules grammatical rules, such as in Italian and Spanish, can be more straightforward for a person with mild to moderate dyslexia to cope with.
However, languages such as English, where there is often no clear connection between the written form and sound, as in words such as "cough" and "dough," can be more challenging for a person with dyslexia.
Dyslexia explained - video
The TED video below explains the difficulty in processing language that exists in people with dyslexia.
Symptoms of dyslexia
A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.
The Dyslexia Research Trust6 includes these as the most common signs and symptoms associated with dyslexia:
A child with dyslexia may have more difficulty than usual in reading, spelling and concentrating.
- Learning to read - the child, despite having normal intelligence and receiving proper teaching and parental support, has difficulty learning to read
- Milestones reached later - the child learns to crawl, walk, talk, throw or catch things, ride a bicycle later than the majority of other kids
- Speech - apart from being slow to learn to speak, the child commonly mispronounces words, finds rhyming extremely challenging, and does not appear to distinguish between different word sounds
- Slow at learning sets of data - at school the child takes much longer than the other children to learn the letters of the alphabet and how they are pronounced. There may also be problems remembering the days of the week, months of the year, colors, and some arithmetic tables
- Coordination - the child may seem clumsier than his or her peers. Catching a ball may be difficult
- Left and right - the child commonly gets "left" and "right" mixed up
- Reversal - numbers and letters may be reversed without realizing
- Spelling - may not follow a pattern of progression seen in other children. The child may learn how to spell a word today, and completely forget the next day. One word may be spelt in a variety of ways on the same page
- Phonology problems - phonology refers to the speech sounds in a language. If a word has more than two syllables, phonology processing becomes much more difficult. For example, with the word "unfortunately" a person with dyslexia may be able to process the sounds "un" and "ly," but not the ones in between
- Concentration span - children with dyslexia commonly find it hard to concentrate for long, compared to other children. Many adults with dyslexia say this is because after a few minutes of non-stop struggling, the child is mentally exhausted. A higher number of children with dyslexia also have ADHD (attention-deficit hyperactivity disorder), compared to the rest of the population
- Sequencing ideas - when a person with dyslexia expresses a sequence of ideas, they may seem illogical for people without the condition
- Autoimmune conditions - people with dyslexia are more likely to develop immunological problems, such as hay fever, asthma, eczema, and other allergies.
On the next page, we look at the possible causes of dyslexia and how dyslexia can be diagnosed. On the final page we discuss treatments for dyslexia, including interventions to help children and adults improve their reading and writing skills. We also list famous people who are known or thought to have dyslexia.