Dyslexia

Dyslexia is a brain-based language-learning disability affecting 15%–20% of the population. Reading and spelling skills are below population mean and expected levels based on verbal reasoning. Research has shown a genetic basis for dyslexia with multiple associated genes and often familial history. Differences in brain patterns between normal readers and those with dyslexia have been shown in structural and functional [Page 559]magnetic resonance imaging and studies examining the connectivity of brain regions.

Historically, this learning disability identified in the 1800s was called word blindness. Characterized by poor underlying phonological processing of heard and spoken words and orthographic processing of read and written words, dyslexia interferes with an individual’s ability to convert written words into spoken words (decoding) and spoken words into written words (spelling). Executive functions ...