Hyperlexia

Hyperlexia is a neurodevelopmental reading profile marked by unusually early and strong word-decoding skills that contrast with weaknesses in reading comprehension, listening comprehension, and pragmatic language. It is not a standalone diagnosis in DSM-5-TR or ICD-11 and is most often associated with autism spectrum disorder, though it can also co-occur with language or learning disorders. This monograph offers a comprehensive overview of hyperlexia, from its historical recognition to current theories and classifications. It critically reviews five theoretical accounts and proposes a five-level symptomatic framework distinguishing primary, correlated, secondary, artifactual, and idiopathic features. Drawing on empirical research, including a 2009 psycho-educational study from Singapore, it illustrates the diverse cognitive and linguistic profiles of hyperlexic individuals and the diagnostic challenges posed by their uneven development. The work also synthesizes existing typological models and examines their implications for assessment, differential diagnosis, and educational intervention, with the goal of improving understanding, early identification, and targeted support.