Early Signs of Dyslexia: Can Language Development Tell Us Something Before a Child Learns to Read?
When parents think about dyslexia, they often think about a child struggling to read, spell, or sound out words.
But reading development begins long before a child picks up their first book.
The language skills children develop during the toddler and preschool years create an important foundation for later reading and writing. In fact, research suggests that subtle differences in early vocabulary development may be associated with later dyslexia and reading difficulties.
So, can we identify dyslexia in a toddler based on their vocabulary?
No—and that is not what the research suggests.
But early language development may give us another piece of the puzzle when we are trying to understand a child's risk for later literacy difficulties.
Dyslexia Is More Than a Reading Problem
Dyslexia is often associated with difficulties in phonological processing—the ability to recognize, remember, and manipulate the sounds in spoken language.
These skills are essential when children begin learning how sounds connect to letters.
However, researchers have increasingly examined dyslexia as more than a single underlying deficit. Children with dyslexia can have different combinations of strengths and weaknesses across their language and literacy systems.
Research has also demonstrated an important relationship between dyslexia and Developmental Language Disorder (DLD), although they are distinct diagnoses. maassen-et-al-2022-early-produc…
This is one reason I believe we need to look beyond a child's reading level when evaluating literacy.
Reading does not exist in isolation.
Vocabulary, grammar, phonological awareness, decoding, spelling, morphology, comprehension, and written language all interact as a child learns to read and write.
What Does a Toddler's Vocabulary Have to Do With Dyslexia?
A 2022 study published in the Journal of Speech, Language, and Hearing Research followed 262 children as part of the Dutch Dyslexia Program.
Of those children, 169 had a familial risk for dyslexia and 93 did not.
Researchers examined the children's productive vocabulary—the words children actually said—at:
17 months | 23 months | 29 months | 35 months
Then, years later, the researchers assessed reading in second and third grade. Among the children with a family history of dyslexia, 60 eventually received a diagnosis of dyslexia. maassen-et-al-2022-early-produc…
This gave researchers a unique opportunity.
Instead of simply comparing toddlers with and without a family history of dyslexia, they could look back and ask:
Did the children who eventually developed dyslexia show differences in their language development years before they learned to read?
The answer was yes—but with some important qualifications.
Researchers Looked at More Than How Many Words Children Said
One of the most interesting parts of this study is that researchers didn't just count vocabulary words.
They also examined what kinds of words the children were using.
They looked at categories including:
Nouns — words that name people, places, objects, and things
Predicates — including verbs and adjectives
Closed-class words — grammatical words such as pronouns, prepositions, articles, helping verbs, question words, and connecting words
These grammatical categories give us information about how a child's language system is developing—not simply how many words they know. maassen-et-al-2022-early-produc…
And that distinction turned out to be important.
What Did the Study Find?
Children who eventually developed dyslexia tended to have smaller expressive vocabularies earlier in development.
At 23 months, the children who later developed dyslexia had significantly smaller total vocabularies and fewer words across several major word categories compared with the other groups.
Differences were still present at 29 months.
But by 35 months, overall vocabulary differences between the groups had essentially disappeared.
There was one interesting exception: differences in closed-class words persisted. Children who later developed dyslexia continued to show lower numbers of these grammatical words than the control group. maassen-et-al-2022-early-produc…
In other words, looking only at how many words a child knew did not tell the entire story.
Does This Mean a Late-Talking Toddler Has Dyslexia?
Absolutely not.
This is probably the most important point for parents to understand.
The researchers found that early vocabulary development was a significant but weak predictor of later reading fluency and dyslexia.
The correlations between several vocabulary measures at 23 months and later word and pseudoword reading fluency were weak.
That means we cannot look at a 2-year-old with a small vocabulary and conclude:
"This child is going to have dyslexia."
Many children with delayed vocabulary development will not develop dyslexia, and dyslexia cannot be identified from vocabulary size alone.
Instead, early vocabulary development may be considered one potential risk indicator among many.
What If Dyslexia Runs in My Family?
Family history matters, but having a parent or relative with dyslexia does not mean a child will automatically develop dyslexia.
This study demonstrated that distinction particularly well.
The children with a family history of dyslexia who did not later develop dyslexia generally did not differ significantly from the control group in their vocabulary development.
The researchers concluded that poorer vocabulary development appeared to be more closely associated with later reading outcome than with family risk alone. maassen-et-al-2022-early-produc…
For parents, the takeaway isn't to panic about early language differences.
It's to pay attention to patterns.
A family history of dyslexia combined with persistent difficulties in speech, language, phonological awareness, learning letter-sound relationships, decoding, spelling, or reading may provide valuable information about a child's developing literacy system.
Reading Starts With Language
One of my favorite ways to explain literacy to families is this:
Reading is language in written form.
Before children can understand language on a page, they are developing an incredibly complex spoken-language system.
They are learning sounds.
Words.
Word meanings.
Sentence structures.
Grammatical rules.
And eventually, they learn that the marks they see on a page represent that language.
This is also why Speech-Language Pathologists can play an important role in literacy evaluation and intervention.
When a child struggles to read, I don't want to know only that reading is difficult.
I want to know why.
Your Child Is Struggling to Read. Now What?
Parents often reach out to me saying:
"My child can read the words but doesn't understand what they read."
"Spelling is a disaster."
"They guess at words instead of sounding them out."
"We practice the same words over and over, but they don't remember them."
"Their teacher says they're behind in reading."
"Dyslexia runs in our family, and I'm starting to see signs."
These concerns can have very different underlying causes.
A comprehensive literacy evaluation can help identify the specific skills contributing to a child's reading and writing difficulties.
Depending on the child, that may include assessment of phonological awareness, phonological processing, decoding, word recognition, spelling, orthographic knowledge, morphology, vocabulary, oral language, reading fluency, reading comprehension, and written language.
The goal shouldn't simply be to determine whether a child is "good" or "bad" at reading.
The goal is to understand how that individual child processes language and print so intervention can be targeted accordingly.
Dyslexia and Literacy Intervention Should Be Individualized
Once we understand why a child is struggling, intervention can become much more specific.
For children with dyslexia and other language-based literacy difficulties, intervention may target skills such as phonemic awareness, sound-symbol correspondence, decoding, encoding and spelling, syllable patterns, morphology, vocabulary, syntax, fluency, and reading comprehension.
As an Orton-Gillingham–trained Speech-Language Pathologist, I approach literacy intervention through both a structured literacy and speech-language lens.
That is especially important for children whose difficulties don't fit neatly into one box.
A child may have dyslexia.
Another may have underlying language difficulties.
Another may have weaknesses in both language and literacy.
And two children who are both "below grade level in reading" may need very different intervention.
The Bottom Line for Parents
Early language differences do not diagnose dyslexia.
But research like this reminds us that literacy development doesn't suddenly begin in kindergarten.
The foundations for reading are developing much earlier.
If you have concerns about your child's reading, spelling, writing, language development, or possible dyslexia, you don't necessarily need to wait for them to fall further behind before investigating why they are struggling.
Sometimes, reading difficulty is only the most visible part of the picture.
A comprehensive literacy evaluation can help us see the rest.
Looking for Dyslexia or Literacy Support in Monmouth or Ocean County, NJ?
NRC Therapy Services provides individualized literacy evaluations and literacy intervention for children with dyslexia, suspected dyslexia, reading difficulties, spelling difficulties, and language-based learning needs throughout Monmouth and Ocean Counties, New Jersey.
Services integrate my training as a Speech-Language Pathologist and Orton-Gillingham–trained provider, allowing me to evaluate and treat both the spoken and written language skills that contribute to successful reading.
If your child is struggling with reading, spelling, decoding, reading comprehension, or written language, a comprehensive literacy evaluation can help identify their individual pattern of strengths and needs and guide appropriate intervention.
Contact NRC Therapy Services to learn more about comprehensive literacy evaluations, structured literacy intervention, and individualized dyslexia support in Monmouth and Ocean County, NJ.
Article referenced: Maassen, B. A. M., Krikhaar, E., van der Leij, A., & Fikkert, P. (2022). Early Productive Vocabulary Composition as Precursor of Dyslexia. Journal of Speech, Language, and Hearing Research, 65, 760–774.