The Delphi definition of Dyslexia

A new Delphi consensus definition of dyslexia has recently been published, bringing together leading experts to improve understanding, assessment and practice. You can read more through PATOSS and in the published research papers in the Journal of Child Psychology and Psychiatry and the Dyslexia Journal.

The Delphi papers, published in the Journal of Child Psychology and Psychiatry and the Dyslexia Journal can be found here:

·       Carroll, J.M., Holden, C., Kirby, P., Thompson, P.A. and Margaret J. Snowling (2025) ‘Toward a consensus on dyslexia: findings from a Delphi study’, Journal of Child Psychology and Psychiatry. Available at https://acamh.onlinelibrary.wiley.com/doi/10.1111/jcpp.14123 

·       Holden, C., Kirby, P., Margaret J. Snowling, Thompson, P.A. and Carroll, J.M. (2025) ‘Towards a Consensus for Dyslexia Practice: Findings of a Delphi Study on Assessment and Identification’, Dyslexia, 31, e1800. Available at https://onlinelibrary.wiley.com/doi/10.1002/dys.1800 

The Delphi Definition

• 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 (DLD), dyscalculia, ADHD, and developmental coordination disorder (DCD).