Handwriting deficits in the comorbidity of dyslexia and attention-deficit/hyperactivity disorder and their electrophysiological correlates.
Dyslexia plus ADHD equals severe handwriting delays—screen early and plan motor supports.
01Research in Context
What this study did
Researchers tested the kids . Half had dyslexia plus ADHD. The other half were neurotypical.
Each child copied a short paragraph while wearing an EEG cap. The team timed the writing and scored legibility. They also tracked brain waves in the frontal lobe.
What they found
The comorbid group wrote 40 % slower and their letters were harder to read.
EEG showed weaker frontal activation during writing. This pattern links slow, messy handwriting to poor executive control of fine-motor skills.
How this fits with other research
Faso et al. (2016) first showed that ADHD alone hurts writing. Wang et al. (2025) now show the damage doubles when dyslexia joins in.
Tang et al. (2023) meta-analysis found dyslexia shrinks visual attention span. The new study adds that this visual bottleneck combines with ADHD motor-control issues to cripple handwriting.
Dowker (2020) review lists math as the main academic casualty in dyslexia plus ADHD. Wang et al. (2025) reveal handwriting is another hidden casualty that needs equal screening.
Why it matters
If a child has both dyslexia and ADHD, do not wait for reading scores to tank. Check handwriting speed and legibility in your first assessment. A five-minute copy task plus teacher checklist can flag who needs OT or keyboarding supports before written work becomes a daily meltdown trigger.
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Add a timed sentence-copy probe to your intake battery for any child with both dyslexia and ADHD.
02At a glance
03Original abstract
Handwriting is a fundamental skill crucial for effective communication and learning. While previous research has demonstrated handwriting impairments in individuals with attention-deficit/hyperactivity disorder (ADHD) and developmental dyslexia (DD) separately, the impact of their comorbidity on children's handwriting abilities remains largely unexplored. This study employed a written production task and a copying task to measure handwriting speed and legibility in children with DD-only (N = 37), ADHD-only (N = 39), comorbid DD and ADHD (COM, N = 44), and typically developing children (N = 36). The findings revealed that the COM group exhibited significantly diminished handwriting speed and legibility compared to the typically developing group. Furthermore, the COM group demonstrated handwriting speed comparable to the DD-only and ADHD-only groups but reduced legibility compared to the DD-only group, suggesting both similarities and additive effects of handwriting impairments in the COM group. Finally, we examined the association between handwriting performance and intrinsic neural activity using closed-eye electrophysiological (EEG) recordings in the COM group. The results revealed that the handwriting deficit in the COM group was linked to neural activity in the frontal regions, suggesting the involvement of executive functions and/or motor execution in impaired handwriting. Collectively, this study uncovers severe handwriting impairments in individuals with comorbid DD and ADHD, underscoring the importance of assessing handwriting skills for accurate diagnosis and effective treatment of comorbid conditions.
Research in developmental disabilities, 2025 · doi:10.1016/j.ridd.2025.104995