What is dyslexia?

In February 2025 a new consensus definition of dyslexia was published in the UK. The Dyslexia Delphi Study (Carroll etal. 2025) redefined dyslexia, moving us froward from the definition provided by Jim Rose in 2009. This more up to date definition is the one assessors are now using to diagnose children in the UK.

Dyslexia is a specific learning difficulty that affects how a person learns to read, write, and spell. It is present from birth, often runs in families, and is linked to differences in how the brain processes language — particularly the sounds within words.

At the heart of dyslexia are differences in phonological processing. This includes noticing and working with sounds in words, remembering those sounds, and being able to quickly name letters or symbols. Most people with dyslexia experience difficulty in more than one of these areas.

These sound-based differences don’t explain everything a child with dyslexia might struggle with. Many also find memory, processing speed, or recognising written word patterns more challenging. These differences can make learning to read feel slower and harder than expected.

As a result, children with dyslexia often have ongoing and unexpected difficulties with reading, spelling, and writing — even when they receive good teaching and extra support. Across languages and at all ages, slow or effortful reading and spelling are key signs of dyslexia.

Dyslexia often occurs alongside other developmental differences. It commonly overlapping with language differences and attentional difficulties. Dyslexia does not have a single cause. It develops through a combination of genetic and environmental factors. A family history of dyslexia or literacy difficulties — especially in close relatives — increases the likelihood.

Dyslexia describes how a child learns — not how capable they are. When their learning differences are understood and supported, many children with dyslexia grow into creative, resilient, and resourceful thinkers, with strengths that reach far beyond the page.

References

Carroll, J. M., Holden, C., Kirby, P., Thompson, P. A., Snowling, M. J., & Dyslexia Delphi Panel (2025). Toward a consensus on dyslexia: findings from a Delphi study. Journal of Child Psychology and Psychiatry, 0(0). 1-12. https://acamh.onlinelibrary.wiley.com/doi/10.1111/jcpp.14123

Rose, J. (2009) Identifying and teaching children and young people with dyslexia and literacy difficulties. Nottingham Dcsf Publications.