Is Dyslexia a Learning Difficulty?
Yes, dyslexia is definitively classified as a specific learning disorder characterized by difficulties in reading, writing, and spelling despite at least average intelligence. 1, 2, 3
Classification and Definition
Dyslexia is formally recognized as a neurodevelopmental disorder under DSM-5 classification, representing the most common type of learning disability with a prevalence of approximately 5%. 2, 4
The core diagnostic features include:
- Difficulty with decoding (reading aloud) and spelling that is persistent and heritable, occurring across the IQ range 2, 3
- Receptive language-based deficits characterized by problems with fluent word recognition, rapid automatic naming, and reading comprehension 3
- Phonological processing impairment that makes it difficult to use the alphabetic code to decode written words 3, 5
Critical Distinction from Intellectual Disability
Dyslexia must be differentiated from intellectual disability (ID/IDD), as these are separate diagnostic entities. 6 While ID/IDD involves impairments in general mental abilities affecting adaptive reasoning across conceptual, social, and practical domains, dyslexia is a specific learning disorder that occurs in individuals with at least average intelligence. 6, 2
The American Academy of Child and Adolescent Psychiatry guidelines explicitly state that ID/IDD must be differentiated from specific learning disorders like dyslexia. 6
Clinical Characteristics
Key features that distinguish dyslexia as a learning difficulty:
- Persistence: A child failing to read adequately in 1st grade has high probability of reading poorly in 4th grade and high school 5
- Strong heritability: Occurs in up to 70% of identical twins and 50% of individuals with an affected parent or sibling 5
- Independence from general intelligence: Can occur in individuals with average or above-average IQ scores 2, 5
- Lifelong condition: Represents an early-onset, heritable, life-long neurodevelopmental disorder 2
Associated Complications
40% to 60% of children with dyslexia develop psychological manifestations including anxiety, depression, and attention deficit, which require concurrent management. 4 A disproportionate share of incarcerated individuals have dyslexia, with behavioral manifestations often leading to life choices resulting in unemployment, drug misuse, and incarceration. 1
Diagnostic Approach
The diagnostic assessment requires:
- Battery of standardized reading and spelling tests 4
- Evaluation of psychological state 4
- Information from parents and teachers 4
- Use of multiaxial classification system 4
Important caveat: The historical "discrepancy definition" (requiring gap between IQ and reading ability) has fallen from favor, as poor decoding skills require the same interventions regardless of IQ level. 2
Treatment Implications
Dyslexia is treatable through specific instructional interventions that must be directed at the language-based etiology, not visual or perceptual training. 3, 5 Effective programs include explicit instruction in phonological awareness, decoding, fluency training, vocabulary, and comprehension, delivered intensively (100 minutes daily for 8 weeks) in small groups. 5
There is no valid scientific evidence supporting vision therapy, muscle exercises, behavioral/perceptual vision therapy, prisms, or colored lenses as treatments for dyslexia. 3 Children with dyslexia have the same visual function and ocular health as children without learning disabilities. 3