Impaired Fine Motor Skills in Developmental Dyslexia: A Bayesian Meta-Analysis of 5 Decades of Research.

PURPOSE: Individuals with developmental dyslexia frequently exhibit impairments that extend beyond reading. Numerous studies examine fine motor skill deficits in dyslexia. The current study used meta-analysis to examine whether individuals with dyslexia show differences in motor skills when compared to age-matched individuals with neurotypical development, while also exploring possible moderators of effects.

METHOD: We report findings of a Bayesian hierarchical meta-analysis evaluating evidence of co-occurring motor skills deficits in dyslexia, using literature spanning 5 decades (1970-2025). Included reports compared dyslexic groups with age-matched neurotypical groups on various handwriting, other graphomotor, manual dexterity, speed fine motor, and motor composite tasks (N dyslexia = 3,113, N comparison = 4,521; Mage = 12.4 years, age range: 6.2-30.8 years).

RESULTS

After removing outliers, the data set comprised estimates from 100 studies (k), with 366 effects (m). The Bayesian hierarchical model yielded a mean estimate of medium magnitude, g = -0.56, 95% credible interval (CrI) [-0.67, -0.47], confirming that impaired motor skills often accompany dyslexia diagnosis. Results held in a subgroup analysis involving dyslexic groups confirmed to have no oral language impairments, g = -0.46, 95% CrI [-0.62, -0.31]. Meta-regression analyses indicated that group differences decreased in magnitude from childhood to adolescence but were present through adulthood. Estimates were slightly larger for Chinese than for English orthography, in keeping with the heightened importance of handwriting for character acquisition.

CONCLUSIONS

Results align with conceptualizations of dyslexia as a multifactorial neurodevelopmental disorder. As such, fine motor tasks may be useful in clinical settings for identifying children at a heightened risk of reading difficulties and may inform efforts to develop more comprehensive interventions.