Do dyslexia and stuttering share a processing deficit?

This study assessed the prevalence of childhood stuttering in adults with dyslexia (AWD) and the prevalence of dyslexia in adults who stutter (AWS). In addition, the linguistic profiles of 50 AWD, 30 AWS and 84 neurotypical adults were measured. We found that 17 out of 50 AWD (34%) reported stuttering during childhood compared to 1% of the neurotypical population. This was moderated by the severity of dyslexia: Adults with mild dyslexia showed a lower prevalence rate (15%) of childhood stuttering than those with severe dyslexia (47%). In addition, we observed that 50% of the AWS (n = 30) fulfilled the diagnostic criteria of dyslexia, even though they had never been diagnosed as dyslexic. Compared to neurotypical adults, phonological working memory, awareness, and retrieval were similarly reduced in AWS and AWD. The findings supports the view that stuttering and dyslexia may share a phonological deficit.