Estimates state that dyslexia affects between 5-10% percent of the population. Some speculate it may affect up to 20% of the population. However, as symptoms range from mild to severe and many individuals are never diagnosed, it’s difficult to obtain an exact number. But, dyslexia is one of the most common language-based learning difficulties and learning disabilities, affecting 70-80% of those who struggle with reading.
Dyslexia is a spectrum. The impact that dyslexia has is different for each individual, highly dependent on its severity and the effectiveness of instruction or remediation (this is where the Orton-Gillingham Approach comes in).