While dyslexia is not a mental illness as defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM), it is a neurological condition that affects learning ability in people of normal and even above-average intelligence. Dyslexia is a language-based disability that changes the way the brain normally processes reading material, causing difficulties with word recognition, spelling, and comprehension. More recent studies have also found that dyslexia can affect time-based memory, or prospective memory, which is remembering to do something that was planned for the future.


Signs and symptoms of dyslexia most often appear in childhood but can also occur in adults. Although everyone with dyslexia reads at lower-than-average levels for their age, symptoms vary from one person to another. The most common symptoms are difficulties or delays in learning the alphabet, learning to speak, learning to read, learning to spell, recognizing the order of letters in a word, pronunciation, copying words from another source, and discerning the sound of one word from another. Children with dyslexia may also have problems distinguishing left from right, with activities that involve eye-hand coordination, such as playing tennis. They may also have issues with concentration, focus, and general physical coordination. There is also a link between dyslexia and autoimmune-related conditions such as asthma, allergies and eczema. 


No one knows exactly why some children develop dyslexia, but since the condition often runs in families, researchers believe there may be a genetic component. In fact, genes that may be responsible for a predisposition to dyslexia have been identified. Imaging studies have found that the brains of children with dyslexia develop and work differently than the brains of children who do not have dyslexia, due to alterations in the left hemisphere of the brain. Those with dyslexia have phonological deficits, making it difficult to distinguish the sounds of individual letters and letter patterns in similar words, such as "bat" and "ban" and "bag."

It is also possible for a previously literate adult to acquire dyslexia as a result of a stroke, brain injury, or other traumatic event. Someone with acquired dyslexia, or alexia, loses the ability to read due to damage in the rear part of the left hemisphere of their brain, and often has problems identifying individual letters and numbers.


Dyslexia cannot be cured, but in many cases, it can be managed with compensatory techniques. With children, it is important to recognize symptoms and start taking remedial steps early in life. A formal evaluation uncovers specific deficit areas in reading and writing which vary from child to child. There are also brain-based and environmental differences in children with dyslexia that make it easier for some to learn than others. It is important for individual, specific educational needs to be identified. Children with dyslexia are usually taught by educators who use alternative teaching methods that are modified to meet their individual needs. Family support helps improve the child's self-image and prospects for success. Similar individual evaluations and reading interventions are necessary for adults with acquired dyslexia.


National Institute of Neurological Disorders and Stroke. Dyslexia Information Page. Accessed September 6, 2017.

Smith-Spark JH. A review of prospective memory impairments in developmental dyslexia: Evidence, explanations and future directions. The Clinical Neuropsychologist. Published online August 22, 2017.

International Dyslexia Association website. Accessed September 6, 2017.

Watter K, Copley A, Fitch E. Discourse level reading comprehension interventions following acquired brain injury: A systematic review. Disability and rehabilitation. Published online February 18, 2016.

Starrfelt R. Alexia: what happens when a brain injury makes you forget how to read. The Conversation. University of Copenhagen, Department of Psychology. July 14, 2015.

Last reviewed 03/05/2018