ADHD and Dyslexia: The Common Overlap

ADHD and dyslexia are two separate conditions that co-occur far more often than chance would predict. They are not the same condition; the underlying cognitive difficulties are different. But they share genetic risk factors, they share some surface features, and they need to be considered together when either one is being assessed. This article covers the overlap, the practical implications, and how UK assessment and support work when both are present.

What dyslexia is

Dyslexia is a specific learning difficulty that affects reading and spelling. The British Dyslexia Association defines it as a difficulty primarily affecting accurate and fluent word reading and spelling, with phonological awareness, verbal memory and processing speed often weaker than would be expected from the person's other cognitive abilities ^[5]. Dyslexia is identified through specialist educational psychology assessment, not through medical diagnosis in the way ADHD is.

Dyslexia is not a reflection of general intelligence. Many adults with dyslexia have strong reasoning, vocabulary, conceptual and creative abilities. The difficulty is specifically with the mechanics of decoding and producing written language.

How often the two co-occur

Across the literature, somewhere between 25 and 40 percent of children diagnosed with ADHD also meet criteria for dyslexia or another specific learning difficulty ^{[3, 4]}. The reverse is also true: around 15 to 40 percent of children with dyslexia also meet criteria for ADHD. The figures vary by sample and method but the overlap is consistent across studies and is much higher than the rates in the general population.

The genetic studies show shared risk factors. Twin and family studies have identified overlap in the heritable components of ADHD and dyslexia, with some genes implicated in both. This is part of why the two co-occur at much higher rates than would be expected if they were independent.

Why they often get confused

ADHD and dyslexia produce some similar-looking surface features that lead to under-recognition of one when the other is being investigated:

• Reading difficulty in a child with ADHD might be assumed to be primarily attentional. The child loses their place, skips lines, or stops mid-paragraph; this could be ADHD-driven distractibility or it could be dyslexia-related decoding difficulty.
• Disengagement from written work in a child with dyslexia might look like ADHD. A child who avoids writing tasks because the mechanics are exhausting can be misread as inattentive or unmotivated.
• Reading slowly in a child with dyslexia can be read as ADHD-related working memory difficulty.
• Self-correction difficulties in writing can stem from either condition; the underlying mechanism is different.

The clinical resolution requires both conditions to be considered. Children whose ADHD assessment shows persistent reading or writing difficulty disproportionate to their other cognitive abilities should also be assessed for dyslexia. Children whose dyslexia assessment shows persistent attention and self-regulation difficulty across multiple settings should also be assessed for ADHD.

How the two conditions are different

The underlying cognitive picture is distinct ^{[3, 4]}:

ADHD

A neurodevelopmental condition affecting executive function: attention, working memory, impulse control, emotional regulation. ADHD is diagnosed clinically using DSM-5-TR or ICD-11 criteria, focused on developmental history, current symptoms and functional impact across multiple settings ^[1]. Treatment includes specialist medical management, including medication where indicated under NICE NG87 ^[2].

Dyslexia

A specific learning difficulty affecting the cognitive mechanisms of reading and spelling. Phonological processing (the ability to manipulate the sound structure of language) is the core deficit. Dyslexia is identified by a specialist educational psychology or specialist teacher assessment, not by medical diagnosis. Support is educational: structured literacy programmes, assistive technology, examination access arrangements, and adjustments to writing-heavy academic and workplace demands.

Both are lifelong; neither resolves in adulthood, though both can be substantially supported with the right interventions.

How treatment and support work when both are present

When ADHD and dyslexia are both present, the support package usually combines elements of both ^{[2, 5]}:

ADHD medical management

Where indicated, standard ADHD treatment under NICE NG87 with stimulants or non-stimulants. Medication often improves the attentional and working memory contributors to reading, although it does not address the underlying phonological difficulty.

Specialist literacy support

Structured literacy programmes (synthetic phonics, Orton-Gillingham-based approaches, or similar) delivered by specialist teachers or tutors. Assistive technology including text-to-speech, speech-to-text, and reading rulers.

School and workplace adjustments

EHCPs for children where appropriate, reasonable adjustments under the Equality Act 2010 for adults at work and in higher education. Examination access arrangements (extra time, scribe, reader, separate room).

Joined-up assessment where possible

A combined assessment that addresses both conditions in one report is more useful than two separate documents that do not reference each other. NeuroFX provides private adult ADHD assessment and paediatric ADHD assessment for children aged 6 and upwards; dyslexia assessment is typically delivered by educational psychologists or specialist assessors and is a separate process. The two assessments often inform each other.

When the late-diagnosis pattern fits

Many adults with co-occurring ADHD and dyslexia were diagnosed with one or neither in childhood. The pattern that brings them to assessment in adulthood is usually a combination of:

• Lifelong difficulty with reading or writing that has been worked around but not resolved
• ADHD-type difficulties (attention, task initiation, emotional regulation) that have intensified with the demands of adult life
• A child or partner being diagnosed first
• Reaching a point in work or family life where the workarounds have stopped working

The order of assessment depends on the picture. Where ADHD-type difficulties dominate, ADHD assessment first is often most useful, with dyslexia assessment to follow. Where reading and writing difficulty are the primary concerns, specialist dyslexia assessment first may be more useful. The two complement each other rather than competing.

What this means in practice

• ADHD and dyslexia co-occur in around 25 to 40 percent of children with ADHD and around 15 to 40 percent of children with dyslexia. The genetic risk factors overlap.
• The two are distinct conditions: ADHD is an executive function condition; dyslexia is a specific learning difficulty affecting reading and spelling mechanics.
• ADHD assessment is medical; dyslexia assessment is typically delivered by educational psychologists or specialist assessors.
• When both are present, the support package combines ADHD medical management with specialist literacy support and educational or workplace adjustments.
• Where one is being assessed, the other should be considered, particularly where surface features could be explained by either.

When to speak to a professional

Speak to your GP if you suspect ADHD in yourself or your child. Speak to the school SENCo, or to an educational psychologist or specialist dyslexia assessor, where dyslexia is suspected. The British Dyslexia Association website has information on finding a specialist assessor. Seek urgent help via 111, 999 or A&E for any acute mental health crisis.

Sources

1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR). Washington, DC: American Psychiatric Association Publishing; 2022.
2. NICE. Attention deficit hyperactivity disorder: diagnosis and management. NG87. National Institute for Health and Care Excellence. https://www.nice.org.uk/guidance/ng87
3. Willcutt EG, Pennington BF. Comorbidity of reading disability and attention-deficit/hyperactivity disorder: differences by gender and subtype. Journal of Learning Disabilities. 2000;33(2):179-191.
4. Germano E, Gagliano A, Curatolo P. Comorbidity of ADHD and dyslexia. Developmental Neuropsychology. 2010;35(5):475-493.
5. British Dyslexia Association. Definitions and key facts. https://www.bdadyslexia.org.uk/