The Types of Dyslexia

Dyslexia is a learning disability (LD) that affects a person’s ability to read. A person with dyslexia might also have trouble with developing other language skills, such as writing, spelling, and pronouncing words. 

According to the International Dyslexia Association, dyslexia is the most common learning disability and the most common reason for difficulties in reading, writing, and spelling. It's estimated that 5% to 10% of the population has dyslexia, although some estimates are as high as 17%. 

Dyslexia appears in different forms based on causes—developmental (which includes primary and secondary) and acquired—and subcategories related to symptoms. Read on to learn more about the types and subcategories of dyslexia.

Types

Under the umbrella category of dyslexia, researchers have identified different types based on the cause.

Developmental

Developmental dyslexia is present from birth. This type includes primary and secondary dyslexia.

Primary dyslexia is due to inherited genes or a genetic mutation that first occurs in the person themselves. Some estimates suggest that 40% to 60% of children whose parents have dyslexia will also develop this learning disability.

In primary dyslexia, dysfunction is in the left side of the brain—which is involved in reading—and affects a person’s ability to process language. It’s more common among males than females.

Secondary dyslexia is caused by issues with neurological development during the fetal period (in the womb). As with primary dyslexia, the symptoms of secondary dyslexia are present starting in early childhood.

Acquired

Acquired dyslexia, also known as trauma dyslexia or alexia, appears in childhood or adulthood as the result of an injury or illness. This could be brain trauma, stroke (brain injury due to a blocked blood vessel or bleeding in the brain), or dementia (a progressive decline in memory, thinking ability, and behavior).

Subcategories

In addition to the main types of dyslexia based on cause, researchers and educators often refer to subcategories of dyslexia based on how they are experienced: phonological, surface, rapid naming, double deficit, visual, and deep. Each of these subcategories is associated with a specific cluster of dyslexia symptoms.

Phonological

Phonological dyslexia affects a person’s phonemic awareness, which is their ability to break words down into individual sounds. People with this kind of dyslexia can often process and understand whole words, but not the individual sounds that make them up. They have trouble decoding and sounding out words.

Surface

People with surface dyslexia have trouble recognizing familiar words on the page and matching printed words to their sounds. This makes it hard for them to memorize and remember words, even ones they’ve already learned.

Rapid Naming

If someone has trouble naming letters, colors, and numbers quickly, they might have rapid naming deficit dyslexia. This type of dyslexia involves difficulties both with reading pace and language processing.

Double Deficit

People with double deficit dyslexia have issues in two different areas of reading, such as rapid naming and phonological awareness.

Visual

Visual dyslexia is likely caused by issues with the parts of the brain involving visual processing. People with visual dyslexia often have a hard time remembering what they just read. They might also have trouble with spelling, forming letters, and other aspects of writing.

Deep

Deep dyslexia is a form of acquired dyslexia that results from trauma to the brain’s left hemisphere. This type of dyslexia affects someone’s ability to sound out nonsense words. It also involves semantic errors—substituting one word for a related one while reading (think “avenue” for “road” or “feline” for “cat”).

Diagnosis

While symptoms of dyslexia can affect someone at any time, it's usually diagnosed in childhood. There's no single standardized test for dyslexia. Instead, after ruling out other possible causes for reading difficulties (such as hearing or vision problems), your healthcare provider can make a referral to a psychologist for an assessment. 

In addition to prior evaluation reports, school reports, and family history, a psychologist will evaluate you or your child for the following symptoms of dyslexia:

• Poor reading comprehension
• Problems with pronouncing words
• Delayed speech
• Inability to rhyme
• Being unable to tell left from right 
• Letter reversal
• Mirror/“backward” writing
• Writing difficulties
• Confusing letters with each other
• Poor grammar and sentence structure
• Slow reading
• Poor spelling

The assessment will include the results of the evaluation, as well as suggestions for improving reading ability at home and school.

How to Cope

After learning that your child has dyslexia, it’s important to address the problem as early as possible. While people can learn to read at any age, early intervention—ideally in kindergarten or first grade—has the best prognosis.

Here are some of the ways you can help your child learn to read if they have dyslexia.

• Structured Literacy instruction: Structured Literacy instruction is an intensive method for teaching children to decode words. This method uses multisensory learning, phonics instruction, and phonological awareness to help kids learn to read in a systematic way.
• At-home exercises: It’s important for people with dyslexia to practice reading regularly at home. A psychologist or school counselor might recommend specific exercises to help your child learn to read and process language, such as tracing letters with their finger or using flashcards to sound out words. 
• Developing an Individualized Education Plan (IEP): If your child receives a diagnosis of dyslexia, you can work with their school to develop an Individualized Education Plan (IEP) to suit their particular educational needs. Accommodations might include extra tutoring or additional time to complete tests and assignments, among others.
  

Summary

Dyslexia is a learning disability that affects a person's ability to read. Someone with dyslexia may also have trouble spelling, writing, and pronouncing words. The main types of dyslexia based on the cause are developmental and acquired.

Both primary dyslexia and secondary dyslexia are types of developmental dyslexia. Primary dyslexia is caused by inherited genes or a genetic mutation that leads to dysfunction in the left side of the brain. Secondary dyslexia is caused by neurological issues that begin during the prenatal period (in the womb).

Acquired dyslexia occurs after injury or illness, such as stroke, brain trauma, or dementia. Subcategories of dyslexia include phonological, surface, double deficit, visual, deep, and rapid naming deficit.

Symptoms of dyslexia often appear during early childhood. People with dyslexia can learn to read, write, and spell using Structured Literacy instruction and at-home reading exercises. An Individualized Education Plan may be developed for children with dyslexia to improve their performance at school.

A Word From Verywell

If you think your child might have dyslexia, it’s important to seek help as soon as possible. Tell your child’s healthcare provider, school principal, and/or school counselor if you suspect they're having trouble with reading.

With the right combination of structured, intensive reading instruction, at-home practice, and support, people with dyslexia can learn to read, write, and express themselves fluently.