Poor Reading: A Deep Dive
The link between dyslexia and dysgraphia
How the causes of dyslexia relate to dysgraphia symptoms?
Developmental dysgraphia is a disorder of written expression – especially impairing handwriting and spelling. Dyslexia and dysgraphia often co-occur and share underlying causes. Here we explain how the causes outlined above can lead to dysgraphia symptoms (difficulty in writing) in addition to dyslexia:
Phonological deficits
Spelling and writing errors: The same phonological processing weakness that causes reading trouble also affects spelling (which is part of writing). If a child cannot accurately discern or remember the sounds in a word, they will struggle to spell that word correctly on paper. Thus, a dyslexic individual’s spelling attempts may be phonetically inaccurate or have missing letters. Over time, poor spelling can discourage writing or make written expression very effortful (they pause frequently to think of spellings). In this way, the phonological deficit manifests as a dysgraphia symptom of persistent spelling mistakes and slow writing.
Orthographic memory and working memory deficits
Handwriting and spelling difficulty: Dysgraphia has been linked to problems with orthographic coding in working memory, meaning difficulty holding and reproducing written forms of words. A child with weak orthographic working memory may forget what a letter looks like midway through writing it, or lose track of the sequence of letters in a word they are trying to spell. This leads to inconsistent or jumbled writing. Research shows that children with dysgraphia often have trouble storing and retrieving written words from memory. In practice, this appears as exceedingly slow writing, frequent erasures, unfinished words, or mixing up letter order – classic dysgraphia symptoms caused by a memory bottleneck. (Notably, many children with dyslexia also have impaired orthographic coding, contributing to both their spelling issues and reading of irregular words.)
Visual processing deficits
Illegible handwriting and letter reversals: If a dyslexic individual has a visual processing weakness – for instance, poor visual discrimination or a magnocellular deficit affecting visual guidance of movement – they may also struggle with handwriting. Writing letters requires being able to visually recall the letter shape and notice if it’s formed correctly. A deficit in visual perception can cause letter formation errors, inconsistencies in size/spacing, or writing letters backward (mirror writing), which are dysgraphia symptoms. For example, a visual magnocellular impairment might make it harder to stabilize eye position during writing, yielding wavering lines or irregularly sized letters. Likewise, poor visual memory might mean a child doesn’t recognize that their written ‘b’ is oriented incorrectly versus ‘d’. In short, the visual processing cause of dyslexia (trouble processing text visually) translates to messy, poorly formed, or reversed letters in writing – a dysgraphia hallmark.
Motor/sequencing difficulties
Slow, labored handwriting: Some children with dysgraphia (with or without dyslexia) have difficulty with the fine motor planning required for fluent handwriting. Research indicates they may struggle to plan sequential finger movements without visual guidance. This could be linked to subtle cerebellar or motor learning differences (which in dyslexia have been posited by the cerebellar deficit theory). If a cause of dyslexia in a child includes a more general procedural learning or motor timing issue, this will heavily impact handwriting – resulting in slow, effortful penmanship and fatigue. The child might write extremely slowly, press too hard or too lightly, and have an awkward pencil grip. While such motor coordination issues are not present in all dyslexics, when they are, they clearly produce dysgraphia symptoms in parallel to reading difficulties.
Attention and executive dysfunction
Disorganized writing: The attention regulation problems that sometimes accompany dyslexia (e.g. ADHD) can directly affect writing. Inattentiveness or poor executive control can lead to poorly planned writing, with ideas jumbled or many omissions/corrections – appearing as dysgraphic written expression. Also, if working memory is limited, a student might forget their thought mid-writing, resulting in incomplete sentences or loss of train of thought (another dysgraphia-like outcome). Researchers note that when dyslexia and dysgraphia co-occur, assessing attention and working memory is important for intervention planning, since those shared deficits drive both reading and writing problems.
Summary
In summary, the same cognitive deficits that cause dyslexia often underlie dysgraphia. Phonological and memory deficits impair spelling; visual and motor deficits impair handwriting. It is therefore common to see dyslexia and dysgraphia in the same individual, and treatment should address both reading and writing. One study found that children with dysgraphia fell into two profiles – one group with primarily auditory (phonological) deficits and another with visual-processing deficits (magnocellular) – paralleling the profiles seen in dyslexia. This highlights that intervening on those root causes (auditory-language skills vs. visual-spatial skills) can improve both reading and writing outcomes.
Next up: The visual side of dyslexia
How Visual Skills Shape Legible Writing and Organized Ideas on Paper
Dyslexia isn’t just a language issue—it often involves visual processing too. Discover how visual challenges affect reading, and why they matter more than you think.