Dyslexia: Signs, Causes, Types, and Key Statistics

Author: Disabled World (DW)
Updated/Revised Date: 30 Jul 2026

Table of Contents:
Synopsis - Definition - About This Section - FAQs - Publications - Subtopics

Synopsis

An overview of dyslexia, a language-based learning disability, covering its signs, causes, types, related conditions, and diagnosis in children and adults.

At a Glance

• 1 - In 2015 the U.S. Senate voted unanimously to formally define dyslexia as an unexpected difficulty in reading despite the intelligence to read far better.
• 2 - The three recognized types are developmental, trauma, and primary dyslexia, each with different origins in brain development or injury.
• 3 - Dyslexia commonly overlaps with other conditions, including ADHD, which occurs in 12 to 24 percent of individuals with dyslexia, dysgraphia, and auditory processing disorder.
• 4 - Research found that 35 percent of adults with dyslexia reported childhood physical abuse compared with 7 percent of those without, highlighting the value of screening.

Topic Definition

Dyslexia

Dyslexia, sometimes called developmental reading disorder or alexia, is a language-based learning disability marked by difficulty learning to read, spell, and process written and spoken language despite having normal or above-average intelligence. It stems from challenges with the underlying building blocks of reading, such as phonological awareness, decoding sounds into words, processing speed, orthographic coding, and rapid naming, rather than from a lack of effort or ability. People with dyslexia may reverse letters and numbers, read slowly and inaccurately, struggle with spelling and directions, and think in pictures instead of words, yet they often show real strengths in creativity, problem solving, and big-picture thinking. Widely recognized internationally as a cognitive disorder, dyslexia tends to run in families and is estimated to affect up to one in ten people, making it the most common cause of reading difficulty among schoolchildren.

Overview

Dyslexia, also known as Alexia or developmental reading disorder, is characterized by difficulty with learning to read and with differing comprehension of language despite normal or above-average intelligence. This includes difficulty with phonological awareness, phonological decoding, processing speed, orthographic coding, auditory short-term memory, language skills and verbal comprehension, or rapid naming. Internationally, dyslexia is designated as a cognitive disorder, related to reading and speech. The National Institute of Neurological Disorders and Stroke definition describes it as "difficulty with spelling, phonological processing (the manipulation of sounds), or rapid visual-verbal responding."

Several learning disabilities often occur with dyslexia, but it is unclear whether these learning disabilities share underlying neurological causes with dyslexia. These disabilities include:

• Attention deficit disorder: A significant degree of comorbidity has been reported between ADHD and dyslexia or reading disorders; it occurs in 12 to 24% of all individuals with dyslexia.
• Dysgraphia: A disorder which expresses itself primarily through writing or typing, although in some cases it may also affect eye to hand coordination, direction, or sequence oriented processes such as tying knots or carrying out a repetitive task.
• Auditory Processing Disorder: A condition that affects the ability to process auditory information. Auditory processing disorder is a listening disability. It can lead to problems with auditory memory and auditory sequencing.
• Developmental Coordination Disorder: A neurological condition characterized by a marked difficulty in carrying out routine tasks involving balance, fine-motor control, kinesthetic coordination, difficulty in the use of speech sounds, problems with short-term memory and organization are typical of dyspraxics.

In 2015, the U.S. Senate voted unanimously to define dyslexia as "an unexpected difficulty in reading for an individual who has the intelligence to be a much better reader; and due to a difficulty in getting to the individual sounds of spoken language, which impacts the ability of an individual to speak, read, spell, and often learn a language." This definition expands on and brings forward the definition adopted by the International Dyslexia Association (IDA) which also refers to the unexpected nature of dyslexia. According to the IDA, up to 20 percent of the population may show symptoms of dyslexia.

A person with dyslexia disorder experiences difficulty reading, writing, with letters, words, and numbers, as well as reversing letters and words. It is estimated that 10 to 15% of children have Dyslexia. Children with Dyslexia are confused with letters and numbers, and often learn to think in pictures and images instead.

Types of Dyslexia

• Development dyslexia: Caused during the early stages of fetus development and is hormonal in nature. This Dyslexia decreases as a child grows up and is mostly found in boys rather than girls.
• Trauma dyslexia: Occurs if the part of the brain that commands reading and writing abilities is injured.
• Primary Dyslexia: Does not change with age and is a malfunction on the left side of the brain.

Causes of dyslexia are typically hereditary in nature and are not caused by any emotional trauma.

Children with Dyslexia face problems at school, and this negative experience at school often causes behavior problems. The child gets frustrated due to lack of achievement and hence they abstain from going to school. Dyslexic people may have some exceptional strengths. He/She may learn computers before others of similar age, and may be brighter in sports, and possess great creative abilities. Having Dyslexia doesn't mean that the person is dumb or mentally disturbed, they may be average or above average in intelligence.

Learning disabilities affect about 5 percent of all school-age children in public schools in the United States. The majority of schoolchildren who receive special education services have deficits in reading, and dyslexia is the most common cause.

Signs of Dyslexia

• Delayed Speech.
• Terrible with spelling.
• Slow choppy inaccurate reading.
• Late establishing a dominant hand.
• Extreme difficulty learning cursive writing.
• Dysgraphia (inability to perform the act of writing).
• Trouble memorizing their address, phone number, or the alphabet.

A complete psychological evaluation should be done on your child if you suspect the disorder, special education personnel can carry out the evaluation. The evaluation should include: a developmental, medical, behavioral, academic and family history, a measure of general intellectual functioning (IQ testing), testing on oral language, memory, auditory processing, visual processing, visual motor integration, phonemic awareness, phonemic decoding, word recognition, decoding, spelling, reading, reading comprehension, written expression, and handwriting (would be done by an occupational therapist).

Adult Dyslexia

Adults with Dyslexia may hide reading problems, spell poorly, and avoid writing. These adults often have good creative skills, though. Many adults with Dyslexia are unemployed. They have difficulty in finding a proper job due to their inability. This makes them lose their self-confidence.

Some common signs and symptoms of dyslexia:

• Spelling: This is one of the most common signs of dyslexia. Not only will someone have trouble spelling difficult words, but simple words will be challenging as well. Often times, words will be spelled just as they are spoken. For example: "nock" instead of "knock" or "serch" replaces "search".
• Comprehension: Dyslexia isn't limited to spelling and math. People also have trouble with their comprehension skills. For example, they may have difficulty following directions as well as repeating words that are spoken to them. This is specifically important when it comes to reading comprehension.
• Direction: People who are dyslexic will have trouble with their directional awareness. Not only will they confuse "left" and "right" or "up" and "down". But following maps and compasses are a challenge as well.
• Interchanging letters: Many times numbers like "16" will become "61" or a "b" may turn into a "d".
• Math: Adults with dyslexia have trouble understanding basic math, which includes putting numbers in their proper sequence. Many times, people will reverse numbers; it may also be hard for them to count to 100.

Abuse

1/3 of dyslexic adults report being physically abused during childhood. Investigators examined a representative sample of 13,054 adults aged 18 and over in the 2005 Canadian Community Health Survey, including 1,020 respondents who reported that they had been physically abused during their childhood and 77 who reported that they had been diagnosed by a health professional with dyslexia.

Adults who have dyslexia are much more likely to report they were physically abused before they turned 18 than their peers without dyslexia. (University of Toronto and the University of North Carolina School of Medicine in Chapel Hill)

Thirty-five percent of adults with dyslexia report they were physically abused before they turned 18. In contrast, seven percent of those without dyslexia reported that they had experienced childhood physical abuse.

Even after accounting for age, race, sex, and other early adversities such as parental addictions, childhood physical abuse was still associated with a six-fold increase in the odds of dyslexia. (Esme Fuller-Thomson, professor and Sandra Rotman Endowed Chair at University of Toronto's Factor-Inwentash Faculty of Social Work)

It is important that primary health care providers and school-based practitioners working with children with dyslexia screen them for physical abuse. Dyslexia is a treatable learning disability - however, it's essential to act as soon as possible.

Dyslexia Facts and Statistics

• Over 50% of NASA employees are dyslexic.
• It is estimated that 1 in 10 people have dyslexia.
• 20% of school-aged children in the US are dyslexic.
• Dyslexia has nothing to do with not working hard enough.
• Dyslexia occurs in people of all backgrounds and intellectual levels.
• With appropriate teaching methods, dyslexia can learn successfully.
• Over 40 million American Adults are dyslexic - and only 2 million know it.
• Dyslexia in not just about getting letters or numbers mixed up or out of order.
• 80% of people associate dyslexia with some form of retardation - this is not true.
• Dyslexia is not tied to IQ - Einstein was dyslexic and had an estimated IQ of 160.
• Dyslexia runs in families; parents with dyslexia are very likely to have children with dyslexia.
• People with dyslexia may excel at connecting ideas, thinking out of the box, 3D thinking, seeing the big picture.
• Dyslexics may struggle with organizational skills, planning and prioritizing, keeping time, concentrating with background noise.
• Dyslexia is a language-based learning disability or disorder that includes poor word reading, word decoding, oral reading fluency and spelling.
• Many famous people are dyslexic including: Orlando Bloom, Whoopi Goldberg, Stephen Spielberg, Kiera Knightley. Albert Einstein and Patrick Dempsey.
• People with dyslexia often excel, or are gifted, in areas of art, computer science, design, drama, electronics, math, mechanics, music, physics, sales, and sports.

Frequently Asked Questions

Can dyslexia be cured?

Dyslexia is a lifelong condition rather than an illness that can be cured, but with structured, evidence-based teaching and support many people learn to read and manage it successfully.

At what age can dyslexia be diagnosed?

Signs can appear in early childhood, and while some indicators show before school age, a formal diagnosis is often made once a child begins learning to read, though it can be identified at any age.

Is dyslexia the same as a vision problem?

No, dyslexia is a language-based processing difference rather than a problem with the eyes, so glasses or vision therapy alone do not address the underlying reading challenge.

What teaching methods work best for dyslexia?

Structured, multisensory approaches that explicitly teach the links between sounds and letters, such as phonics-based programs, are widely regarded as the most effective for dyslexic learners.

Can adults be diagnosed with dyslexia?

Yes, many adults are diagnosed later in life through assessments of reading, spelling, and processing skills, which can open access to workplace accommodations and support.

Does dyslexia affect intelligence?

Dyslexia is not linked to lower intelligence, and people with dyslexia span the full range of intellectual ability, with many being of average or above-average intelligence.

Are there accommodations available at school or work?

Common accommodations include extra time on tasks, audiobooks, text-to-speech tools, and modified assignments, which help level the playing field without lowering standards.

Curated and edited by Ian C. Langtree, Founder & Editor-in-Chief, Disabled World. This section is maintained by the Disabled World editorial team.

Last updated: 30 Jul 2026