Trends in concept and nosology of autism spectrum disorder: A review.

Autism Spectrum Disorder is a neurodevelopmental disorder characterized by persistent deficits in social communication, social interaction and restricted, repetitive patterns of behavior, interests or activities. The concept of autism has changed since its inception, from childhood schizophrenia to neuro-variation. These changes in concept have been accompanied by changes in the diagnostic threshold through which the 'case' of autism is identified. The occurrence of multiple changes in its diagnostic criteria over last 80 odd years opens up the possibility of challenges being posed to the existence of the disorder as it is today, with a possibility of newer conceptualization of autism coming up in the future. The potential consequences of the changes in its nosology and concept, such as those on the management and on prevalence estimation are some of the essential issues which need attention. In the current paper, we evaluate the evolution of the concept and nosology of autism with an overview of the accompanying impact of these changes.