Why this gets confused
Learning differences look similar from the outside. A child who is not finishing work, not turning in assignments and not performing to their apparent ability presents the same way whether the cause is dyslexia, attention, language or something else entirely.
The cost of getting it wrong is time. A student given attention supports for a decoding problem will still not be able to read. A student given reading intervention for an attention problem will sit through instruction they cannot hold on to. Both will be described as not responding, and both will lose a year or more.
The differences are clear once you know what question each one answers.
Side by side
| Difference | Core difficulty | Most visible in |
|---|---|---|
| Dyslexia | Connecting sounds to letters, decoding and spelling words | Reading accuracy, reading speed, spelling |
| Dysgraphia | The physical and organizational act of writing | Handwriting, letter formation, getting ideas onto paper |
| Dyscalculia | Number sense and mathematical reasoning | Quantity, math facts, place value, time and money |
| ADHD | Attention, working memory and executive function | Sustaining focus, starting tasks, following through |
| Language disorder | Understanding and using spoken language itself | Vocabulary, sentence structure, following directions |
| Speech sound disorder | Producing speech sounds accurately | Intelligibility of speech, not of reading |
Dysgraphia
Dysgraphia affects writing: forming letters, spacing them, keeping them on a line, and organizing thought into written text at anything like the speed of thinking. Handwriting is often laborious and hard to read, and written output is far shorter and simpler than the same student’s speech.
It overlaps heavily with dyslexia, because both involve written language and both produce poor spelling. The distinction is that a student with dysgraphia alone can usually read normally. If reading is fine and writing is the wall, dysgraphia is the better question to ask.
Dyscalculia
Dyscalculia is a difficulty with number sense: understanding quantity, estimating, recalling math facts, holding place value, and reasoning about time and money. It is roughly as common as dyslexia and dramatically less often identified.
The two co-occur often enough that a student with identified dyslexia who is also struggling in math should not be assumed to be struggling only because of the reading in word problems. That is a real effect, but it is not the only possible explanation, and it is easy to check.
ADHD
ADHD affects attention, working memory, task initiation and follow through. It is the difference most often confused with dyslexia, because a child who cannot decode will look inattentive during reading and a child with ADHD will lose the thread of a passage they can technically read.
The useful test is context. A student with ADHD is generally inattentive across settings and subjects, including ones they find easy. A student with dyslexia will focus perfectly well on a task that does not require reading, and will appear to lose attention specifically when text is involved.
Estimates vary, but a substantial share of students with dyslexia also meet criteria for ADHD, commonly reported at around thirty percent. This is not either or. When both are present both need addressing, and treating only one is the most common reason a student appears not to respond to intervention.
Developmental language disorder
Developmental language disorder affects spoken language itself: vocabulary, grammar, following multi-step directions, and expressing complex ideas. It is common and under-recognized, and it frequently coexists with dyslexia.
The distinction that matters is the listening comprehension check. A student with dyslexia understands material perfectly when it is read to them. A student with a language disorder does not, because the difficulty is with the language, not with getting to it off the page. Any thorough evaluation will test this directly.
When there is more than one
Overlap is the norm rather than the exception. It is entirely common for a student to have dyslexia and ADHD, or dyslexia and dysgraphia, or all three. A good evaluation identifies each one rather than stopping at the first plausible explanation.
- Insist on a full picture. If an evaluation identifies dyslexia and stops, ask directly whether attention, language and math were assessed.
- Address each difference on its own terms. Reading intervention does not treat attention. Attention support does not teach decoding.
- Re-check the assumption if progress stalls. A student receiving genuinely good structured literacy who is not progressing usually has something else going on that has not been named.
- Watch for anxiety. Years of unexplained failure produce it reliably, and it can look like any of the differences above.
Testing and diagnosis explains what a comprehensive evaluation covers and how to tell whether the one you were offered is comprehensive.
Where this information comes from
This page draws on the organizations below alongside the clinical experience of the therapists who teach at Key School. Where the sources disagree, or where a policy is still changing, we say so in the text instead of picking an answer for you.
- Fact sheets on dyslexia and co-occurring conditions International Dyslexia Association
- Individuals with Disabilities Education Act, eligibility categories U.S. Department of Education
- Learning Disabilities: Condition Information Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health
- Learning and thinking differences explained Understood.org
