Dyslexia is a condition that makes it hard to learn to read and learn. It happens when there is a problem with the way the brain processes graphic symbols.

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.

Although it is a neurological condition, dyslexia is not linked to intelligence. The effects of dyslexia vary from person to person. The only shared trait among people with dyslexia is that they read at levels lower than typical for people of their age.

Fast facts on dyslexia

  • People with dyslexia often have difficulty learning to read and write.
  • Dyslexia is not related to intelligence.
  • Early diagnosis, guidance, and support can help reduce the impact of dyslexia.
  • People with dyslexia are more likely to develop immunological problems.

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Dyslexia commonly causes difficulties in word recognition, spelling, and decoding.

In a person with dyslexia, the brain processes written material differently. This makes it hard to recognize, spell, and decode words.

People with dyslexia have problems understanding what they read. Dyslexia is a neurological and often genetic condition, and not the result of poor teaching, instruction, or upbringing.

Between 5 and 15 percent of people in the United States have dyslexia.

If a parent, guardian, or teacher suspects a child may have dyslexia, they should ask the child's school about a professional evaluation. Early diagnosis is more likely to lead to effective intervention.

Test results may also open the door to more support for the child.

They may become eligible for special education services, support programs, and services in colleges and universities.

Diagnostic tests often cover the following areas:

  • background information
  • intelligence
  • oral language skills
  • word recognition
  • decoding, or the ability to read new words by using letter-sound knowledge
  • phonological processing
  • automaticity and fluency skills
  • reading comprehension
  • vocabulary knowledge
  • family history and early development

During the assessment process, the examiner needs to be able to rule out other conditions or problems that may show similar symptoms. Examples include vision problems, hearing impairment, lack of instruction, and social and economic factors.

Dyslexia is different from delayed reading development, which may reflect mental disability or cultural deprivation.

The most common signs and symptoms associated with dyslexia can be displayed at any age, but they normally present in childhood.

Childhood symptoms of dyslexia include:

Difficulty in learning to read

Many children with dyslexia have normal intelligence and receive proper teaching and parental support, but they have difficulty learning to read.

Milestones reached later

Children with dyslexia may learn to crawl, walk, talk, and ride a bicycle later than the majority of others.

Delayed speech development

A child with dyslexia may take longer to learn to speak, and they may mispronounce words, find rhyming challenging, and appear not to distinguish between different word sounds.

Slow at learning sets of data

At school, children with dyslexia may take longer to learn the letters of the alphabet and how they are pronounced. There may be problems remembering the days of the week, months of the year, colors, and some arithmetic tables.

Coordination

The child may seem clumsier than their peers. Catching a ball may be difficult. Poorer eye-hand coordination may be a symptom of other similar neurological conditions, including dyspraxia.

Left and right

The child may confuse "left" and "right."

Reversal

They may reverse numbers and letters without realizing.

Spelling

Some children with dyslexia might not follow a pattern of progression seen in other children. They may learn how to spell a word and completely forget the next day.

Speech problems

If a word has more than two syllables, phonological processing becomes much more challenging. 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. 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 attention deficit hyperactivity disorder (ADHD), compared with the rest of the population.

Sequencing ideas

When a person with dyslexia expresses a sequence of ideas, they may seem illogical or unconnected.

Autoimmune conditions

People with dyslexia are more likely to develop immunological problems, such as hay fever, asthma, eczema, and other allergies.

Compensatory strategies can help people cope with dyslexia in daily life. Early diagnosis and support can lead to long-term improvements.

Interventions may include:

  • Psychological testing: This helps teachers develop a better-targeted program for the child. Techniques usually involve tapping into the child's senses, including touch, vision, and hearing.
  • Guidance and support: Counseling can help minimize any negative impact on self-esteem.
  • On-going evaluation: Adults with dyslexia may benefit from evaluation to continue developing their coping strategies and identify areas where more support is needed.

The Brain Foundation in Australia notes:

"Although the outlook for people with dyslexia depends on the severity of their disorder, the majority live normal, productive lives."

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A child with dyslexia may have more difficulty than usual in reading, spelling, and concentrating.

Specialist doctors and researchers are not precisely sure what causes dyslexia.

Some evidence points to the possibility that the condition is genetic, as it often runs in families.

Two key factors appear to be:

  • Genetic causes: A team at the Yale School of Medicine found that defects in a gene, known as DCDC2, were associated with problems in reading performance.
  • Acquired dyslexia: A small minority of people with dyslexia acquire the condition after they are born, usually due to a brain injury, stroke, or some other type of trauma.

According to the University of Michigan Health System, dyslexia is the most common learning disability. 80 percent of students with learning disabilities have dyslexia.

The International Dyslexia Association estimates that 15 to 20 percent of the American population has some of the symptoms of dyslexia, including slow or inaccurate reading, poor spelling, poor writing, or mixing up similar words.

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 grammatical rules, such as Italian and Spanish, can be easier for a person with mild to moderate dyslexia.

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.

The symptoms of dyslexia change with age. This table will show how the condition presents at different stages of life.

Stage of developmentDyslexia symptoms
Before school
  • delayed speech development and vocabulary learning
  • difficulties forming words, such as making the sound in some words backward or mixing up words that sound similar
  • problems retaining information, such as numbers, the alphabet, and colors
School age
  • low reading level for the age group
  • difficulties processing information
  • issues with remembering sequences of objects or information
  • being unable to put an unfamiliar word into sounds
  • taking an abnormally long time with reading and writing tasks
  • avoidance of activities that involve reading
Teenage years and adulthood
  • difficulties reading aloud
  • slow reading and writing that takes a lot of effort
  • spelling issues
  • avoidance of tasks that require reading
  • mispronunciation of words or problems recalling words for a particular object or topic
  • problems with understanding the meaning behind jokes and idioms
  • difficulties learning a foreign language, memorizing, or completing math problems
  • finding it hard to summarize a story

Dyslexia can be broken down into different subtypes, but there is no official list of dyslexia types because they can be classified in different ways.

However, the following categories are sometimes used:

Phonological dyslexia: The person has difficulty breaking down words into smaller units, making it hard to match sounds with their written form. This is also known as dysphonetic dyslexia or auditory dyslexia.

Surface dyslexia: The person cannot recognize a word by sight, making words hard to remember and learn. This is sometimes called dyseidectic dyslexia or visual dyslexia.

Rapid naming deficit: The person cannot quickly name a letter or number when they see it.

Double deficit dyslexia: The person finds it hard to isolate sounds also to name letters and numbers.

Visual dyslexia: The person has an unusual visual experience when looking at words, although this can overlap with surface dyslexia.

Sometimes people refer to "directional dyslexia," meaning it is difficult to tell left from right. This is a common feature of dyslexia, but it is not a type.

If a person has difficulty with math learning, the correct term for this is dyscalculia. It is not dyslexia.