What Is Dyslexia
Dyslexia is a specific learning disability with neurobiological origins. Two major international diagnostic frameworks define it explicitly: the American Psychiatric Association’s Diagnostic and Statistical Manual (DSM-5) and the World Health Organization’s International Classification of Diseases (ICD-11).
DSM-5 Definition
The DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th ed., American Psychiatric Association, 2013) classifies dyslexia under Specific Learning Disorder (315.00) and provides the following note:
Dyslexia is an alternative term used to refer to a pattern of learning difficulties characterized by problems with accurate or fluent word recognition, poor decoding, and poor spelling abilities.
DSM-5 diagnostic criteria require:
- Reading accuracy or fluency substantially below what is expected for chronological age
- Difficulties persisting for at least 6 months despite targeted intervention
- Academic performance significantly and quantifiably below age, intelligence, and education expectations
- Difficulties beginning in school-age years, though may not fully manifest until academic demands exceed individual capacity
- Not better explained by intellectual disability, sensory impairment, other mental or neurological disorder, insufficient instruction, or socioeconomic adversity
ICD-11 Definition
The ICD-11 (International Classification of Diseases, 11th revision, World Health Organization, 2022) classifies developmental dyslexia under Developmental Learning Disorder, code 6A03.0, and defines it as:
Developmental dyslexia is characterised by difficulties in the accurate and fluent reading of words. The individual’s performance on measures of word reading accuracy or fluency is substantially below what would be expected given the person’s chronological age, general level of intelligence, and level of education. These difficulties typically manifest as problems in reading single words (i.e., decoding) and are due to a core deficit in the phonological component of language.
ICD-11 further specifies:
- Difficulties are not explained by sensory impairment (vision or hearing problems)
- Difficulties are not entirely attributable to intellectual developmental disorder or a neurological condition
- Difficulties do not result from lack of educational opportunity
- Difficulties cause significant impairment in academic, occupational, or everyday functioning