The New Definition of Dyslexia: What It Means for the Students We Work With

I’ve been doing a lot of reading lately about the new 2025 definition of dyslexia and what it means for the way we understand dyslexia in clinical practice.

In 2025, the International Dyslexia Association released an updated definition of dyslexia:

“Dyslexia is a specific learning disability characterized by difficulties in word reading and/or spelling that involve accuracy, speed, or both and vary depending on the orthography. These difficulties occur along a continuum of severity and persist even with instruction that is effective for the individual’s peers. The causes of dyslexia are complex and involve combinations of genetic, neurobiological, and environmental influences that interact over the course of development. Multiple underlying factors, including difficulties with phonological and morphological processing, have been linked to dyslexia. Secondary consequences include reading comprehension difficulties and reduced reading and writing experience that can impede growth in language and knowledge. Dyslexia is associated with increased risk for adverse mental health outcomes and reduced educational attainment and employment opportunities.”

International Dyslexia Association, 2025

There’s quite a lot packed into the new definition, so I thought it might be useful to break it down and talk about what I think are some of the most important parts for those of us working with dyslexic students.

What I particularly like about the new definition is that it reflects something we see all the time as speech pathologists:

Dyslexia doesn’t look the same in every student.

One student may have significant difficulty decoding unfamiliar words but relatively good reading comprehension. Another may read accurately, but painfully slowly. Another might appear to be coping reasonably well with reading but continue to have significant difficulty with spelling. And then there are students who have difficulties across reading, spelling and oral language.

So why do these students look so different if they all have dyslexia? I think the new definition gives us a much better framework for understanding this.

What are some of the key changes?

At its core, the new definition describes dyslexia as a difficulty with word reading and/or spelling, involving accuracy, speed or both. It also recognises that dyslexia occurs along a continuum. Some students experience relatively mild difficulties, while for others the impact is significant and persistent. The definition also acknowledges that these difficulties can persist even when a student has received instruction that is effective for their peers.

This is useful when we’re looking at a student’s history. A student may have had access to good-quality literacy instruction and made progress, but their learning may have been much slower, required considerably more repetition, or their difficulties may have persisted compared with their peers. How a student has responded to instruction over time gives us another piece of information when we’re trying to understand their literacy profile.

One of the biggest changes in the definition is in how we think about why dyslexia occurs. The definition describes dyslexia as resulting from a combination of genetic, neurobiological and environmental influences that interact throughout development.

Clinically, I think this gives us a much more useful way of understanding the students we work with.

There isn’t one dyslexia profile

For many years, dyslexia has been very closely associated with phonological processing difficulties. And phonological processing is still extremely important.

Many students with dyslexia have difficulty developing, storing or accessing precise phonological representations of words. We may see difficulties with phonemic awareness, learning sound-letter relationships, decoding unfamiliar words or developing accurate spelling representations.

But these difficulties are common in dyslexia, not universal.

A student doesn’t need to demonstrate a particular phonological weakness to have dyslexia. Finding a phonological processing weakness also doesn’t, by itself, explain everything about a student’s reading and spelling difficulties.

This is where looking at the student’s whole literacy profile becomes much more helpful.

What about RAN?

Rapid automatised naming, or RAN, is another area that comes up frequently when we’re working with students with dyslexia. A student may know their letter-sound correspondences and be able to decode words accurately, but reading remains slow and effortful. They may need far longer than expected for familiar words to become automatic.

RAN can help us understand some of these students.

Difficulties with rapid retrieval are associated with dyslexia and particularly with reading fluency and automaticity. But, like phonological processing, RAN isn’t a single explanation for dyslexia. A weak RAN score can also occur alongside other difficulties, including language and attention difficulties.

So instead of thinking:

“Poor RAN = dyslexia”

I find it more useful to ask:

“How might this difficulty with rapid retrieval be contributing to the reading profile I’m seeing?”

Oral language belongs in the picture too

As speech pathologists, oral language is an important part of how we understand a student’s overall literacy profile. Difficulties with vocabulary, morphology, syntax and broader language development can occur alongside dyslexia and may also contribute to the development and impact of literacy difficulties.

At the same time, strong oral language skills can be a real strength for some students with dyslexia. A student may have significant difficulty reading words accurately or fluently, but have strong vocabulary, reasoning and understanding of complex ideas. These skills can support their comprehension and help them compensate for some of their reading difficulties.

For a student who has weaknesses in both word reading and oral language, the impact can be quite different. They are managing the effort of getting the words off the page while also having less language knowledge to draw on to understand what they are reading.

So even when two students have similar difficulties at the word-reading level, their oral language skills can play an important role in how those difficulties affect comprehension and learning more broadly.

Thinking in terms of risk and resilience

This is probably the part of the newer thinking around dyslexia that I find most helpful. Rather than searching for the underlying deficit, we can think about a student as having a combination of risk factors and protective factors.

For one student, we might see weaknesses in phonological processing and spelling alongside strong vocabulary, reasoning and language comprehension. Another student might have relatively good phonological skills but difficulties with rapid retrieval and automaticity. Another might have weaknesses across phonological processing, oral language and reading fluency.

These different factors accumulate and interact over time.

At the same time, students have strengths and experiences that can support their literacy development. Strong oral language, vocabulary and reasoning can be protective, as can effective instruction and opportunities to develop literacy skills.

This helps us understand not just why students with dyslexia present differently, but why their literacy difficulties can have such different outcomes over time.

Some students have strengths that help them compensate for areas of difficulty. Others have several areas of vulnerability occurring together. The balance of these risk and protective factors can influence the severity and persistence of their literacy difficulties, how they respond to instruction and intervention, and how much their dyslexia affects learning across the school years.

The impact can go beyond reading and spelling

The new definition also recognises that dyslexia can have secondary consequences beyond difficulties at the word-reading and spelling level.

For some students, ongoing difficulty reading words accurately or fluently can make it harder to understand increasingly complex texts. Difficulties with spelling and getting words onto the page can also affect written expression, particularly as the demands of school increase.

The definition also acknowledges the association between dyslexia and poorer psychological wellbeing.

This is something many of us see clinically. Students may have spent years finding reading and spelling much harder than their classmates. We might see avoidance of reading aloud, reluctance to write, anxiety around literacy tasks or reduced confidence in themselves as learners.

The impact will be different for every student, but it reminds us that understanding dyslexia involves looking beyond a set of reading and spelling scores. We also need to understand what those difficulties mean for the student in the classroom and how they are affecting their confidence, participation and learning.

Why does this matter for speech pathologists?

I think it changes the questions we ask. When a student is struggling, we want to understand more than whether they can or cannot complete a particular task.

We want to understand their pattern of strengths and difficulties.

What is happening with their word reading?

Is accuracy the main difficulty, or is fluency and automaticity a bigger issue?

What does their spelling tell us about how they are representing words?

How efficiently are they accessing familiar information?

How strong are their oral language skills?

Are there relative strengths that are helping them compensate?

How have they responded to instruction and intervention over time?

And how are all of these factors interacting for this particular student?

That is where assessment becomes much more useful in helping us understand the student we are working with.

Making sense of the student in front of us

One of the things I enjoy most about working in dyslexia is trying to understand why a student is presenting the way they are. The new definition gives us a framework that fits well with what we see clinically.

Instead of expecting every student with dyslexia to show the same underlying pattern, we can look at the evidence in front of us and ask:

What combination of factors is contributing to this student’s literacy profile?

For me, that is a useful starting point for understanding their difficulties and making decisions about how best to support them.

Want to explore this more deeply?

I’m currently developing a new professional development course for speech pathologists:

Understanding Dyslexia: Beyond the Basics — A deeper look at dyslexia profiles for speech pathologists.

The course will explore the different skills and factors that contribute to reading and spelling profiles, and why students with dyslexia can present so differently.

It’s designed for speech pathologists who already have a foundational understanding of phonological awareness, phonics and structured literacy and want to develop a deeper understanding of the dyslexic students they see in clinical practice.

More information about the course will be coming soon. In the meantime, if you’d like some individual support to better understand dyslexia or work through the profiles of students on your caseload, I also offer one-to-one supervision sessions for speech pathologists. You can book in a time with me here.

Understanding Dyslexia: Beyond the Basics is a new professional development course I’m currently developing for speech pathologists who already work in literacy and want to develop a deeper understanding of dyslexia profiles.

If you’d like to be one of the first to hear when the course is released, join the interest list here.