Dyslexia has long suffered from inconsistent definitions, leading to significant disparities in diagnosis and support. A team of researchers from top universities has proposed a new definition to unify understanding and improve support for those with dyslexia.
By gathering insights from 58 international experts, the new definition highlights dyslexia as a set of processing difficulties affecting literacy skills, influenced by genetic and environmental factors, and often co-occurring with other developmental disorders. A follow-up study emphasizes the need for a structured four-step assessment process to ensure early and effective intervention.
A Call for a New Dyslexia Definition
A new definition of dyslexia is needed to better describe the condition and ensure those affected receive the right support, according to new research.
Over the years, dyslexia has been defined in various ways, creating confusion and inconsistencies in diagnosis and access to support. As a result, whether a child gets the help they need can depend on where they live, leaving many without proper resources.
To address this issue, researchers argue that dyslexia should be redefined and a standardized definition adopted across the UK.
The research was conducted by the University of Birmingham, the SpLD Assessment Standards Committee (SASC), Kings College London, and the University of Oxford. It was published today (February 25th) in the Journal of Child Psychology and Psychiatry.
The Last Major Update: The Rose Review
Julia Carroll, Professor of Psychology in Education at the University of Birmingham who led the study, said: “There has not been a new attempt to define dyslexia since the Rose Review in 2009. The review provided a definition and argued for specialist teachers to help identify and support dyslexia. Despite the Rose definition significantly influencing practice, it has gathered criticism over the last 15 years and has not been universally accepted.
“In addition to this, there is no clear universal pathway for the assessment of children with dyslexia in England, Wales and Northern Island, and the process for identifying learning needs and interventions can vary massively from place to place. Adopting a universal definition for dyslexia is the first step to improving support for children experiencing the challenges of dyslexia.”
Building a New Definition with Experts
The researchers brought together 58 international experts in dyslexia, including academics, specialist teachers, educational psychologists, and individuals with dyslexia, to vote on whether they agreed with several key statements about dyslexia. The statements covered six key sections: the definition of dyslexia, intellectual abilities and dyslexia, the etiology of dyslexia, co-occurrence with other disorders, the changing impact of dyslexia over a lifespan, and common misconceptions.
Key Elements of the New Dyslexia Definition
42 statements received a consensus of more than 80% and were accepted by the group. They were then used to create the new definition of dyslexia:
- Dyslexia is a set of processing difficulties that affect the acquisition of reading and spelling.
- In dyslexia, some or all aspects of literacy attainment are weak in relation to age, standard teaching and instruction, and level of other attainments.
- Across languages and age groups, difficulties in reading fluency and spelling are a key marker of dyslexia.
- Dyslexic difficulties exist on a continuum and can be experienced to various degrees of severity.
- The nature and developmental trajectory of dyslexia depends on multiple genetic and environmental influences.
- Dyslexia can affect the acquisition of other skills, such as mathematics, reading comprehension or learning another language.
- The most commonly observed cognitive impairment in dyslexia is a difficulty in phonological processing (i.e. in phonological awareness, phonological processing speed or phonological memory). However, phonological difficulties do not fully explain the variability that is observed.
- Working memory, processing speed and orthographic skills can contribute to the impact of dyslexia.
- Dyslexia frequently co-occurs with one or more other developmental difficulties, including developmental language disorder, dyscalculia, ADHD, and developmental coordination disorder.
A Broader and More Inclusive Perspective
Professor Carroll continued: “A definition of a learning disorder such as dyslexia, should allow researchers and practitioners to consistently establish what should, or should not be considered ‘dyslexia’, what the boundaries to diagnosis should include, and what elements are important in assessment. Our new definition retains the idea of difficulties with reading and spelling relative to age, ability, or educational expectations. However, it is less focused on English speakers and children. In line with evidence, we highlight that phonological processing has a causal link to dyslexia, but that other factors also play an important role in explaining variability in presentation. We also note the high rates of co-occurrence between dyslexia and other developmental difficulties.”
Improving Dyslexia Assessments
In a second study from the same group, published in the Dyslexia Journal, the researchers examined ways to improve dyslexia assessments which start with the new definition. The process agreed upon by the expert panel fell into four main steps once a child has presented with difficulties in reading, spelling, or writing fluency that affect daily functioning:
- Stage 1: Consider, rule out, and respond to other factors that might be the primary reason for reading, spelling, or writing difficulties.
- Stage 2: Gather further information and, where necessary, intervene with additional support fast and early. Be aware of warning signs and likely indicators that suggest the possibility of persistent difficulties.
- Stage 3: Observe, record, and evaluate response to intervention.
- Stage 4: Where the response to intervention is stalling or failing, refer for a comprehensive assessment by a specialist teacher assessor or psychologist with appropriate training.
The study argues that, along with the standard definition, there should be a national statutory pathway to dyslexia assessment following this process.
The Urgency for Change
Professor Carroll concluded: “Dyslexia is a complex learning disorder that can look different from person to person. It can have lasting impacts on education and then on working life if not identified and addressed properly. By not having a universal process to identify and support people with dyslexia, we are letting down so many of our children and young people. If the government is serious about improving SEND provision in schools, then updating and standardizing the definition and assessment for dyslexia should be a priority.”
Reference: “Toward a consensus on dyslexia: findings from a Delphi study” by Julia M. Carroll, Caroline Holden, Philip Kirby, Paul A. Thompson, Margaret J. Snowling and , 25 February 2025, Journal of Child Psychology and Psychiatry.
DOI: 10.1111/jcpp.14123
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