Autism has long been described as a lifelong neurodevelopmental disorder/condition. Core behavioural features, typically emerging in infancy or early childhood, have been assumed to persist throughout the lifespan. The research, however, suggests that within the vast heterogeneity of autism , not all individuals follow a single, fixed trajectory. Various reports have documented the presentation of " acquired autism " ( regression ) following a period of typical development.

A Simplification That Simplifies Nothing The 5 th  edition, published in 2013, set out to simplify and modernise the nosology of autism-related disorders, replacing the DSM-IV’s cluster of Pervasive Developmental Disorders (PDDs) — Autistic Disorder, Asperger’s Disorder, Childhood Disintegrative Disorder, Rett’s Disorder [ 1 ] and PDD-Not Otherwise Specified (PDD-NOS) — with a single diagnosis: Autism Spectrum Disorder (ASD). The intent was, in principle, laudable: a spectrum

The question of how stable an autism diagnosis is over time has long been debated. While many families and clinicians view an autism diagnosis as lifelong, research suggests that diagnostic stability—how consistently a diagnosis persists over time—depends heavily on which diagnostic framework is used. Emerging evidence indicates that before the introduction of the broader ASD category in the DSM-5  (APA 2013), autism diagnoses were more stable and predictable. Before DSM-5: D

Autism has undergone a remarkable transformation in recent decades. Once thought of as a rare and narrowly defined childhood condition,...