Autism regression, defined by the loss of previously acquired social, communicative, and language skills, affects approximately 25%-30% of children on the autism spectrum, most commonly emerging between 12 months and 30 months of age. Once debated as a potential artifact of parental recall or observation bias, contemporary evidence—including home-video analyses and prospective sibling studies—establishes regression as a biologically grounded neurodevelopmental deviation rather than a psychogenic