Toward a functional classification for autism in adulthood.

Autism spectrum disorder (ASD) is a heterogeneous condition that affects development and functioning from infancy through adulthood. Efforts to parse the heterogeneity of the autism spectrum through subgroups such as Asperger's and Profound Autism have been controversial, and have consistently struggled with issues of reliability, validity, and interpretability. Nonetheless, methods for successfully identifying clinically meaningful subgroups within autism are needed to ensure that research, interventions, and services address the range of needs experienced by autistic individuals. The purpose of this study was to generate and test whether a simple set of questions, organized in a flowchart, could be used in clinical practice and research to differentiate meaningful subgroups based on individuals' level of functioning. Once generated, subgroups could also be compared to the recently proposed administrative category of Profound Autism and to groupings based on standardized adaptive measures. Ninety-seven adults with autism or related neurodevelopmental disorders participating in a longstanding longitudinal study, or their caregivers if they could not answer for themselves, completed phone interviews when the participants were ~30 years old. Information from these phone interviews was used to generate vignettes summarizing characteristics and aspects of the daily lives of each participant (e.g., language level, vocational activities, and social relationships). Three expert clinicians then used these vignettes to classify each participant based on their level of support needs. Meaningfully distinct subgroups within the sample were identified which could be reliably distinguished from one another. Implications of such categorizations and future directions are discussed.