Catherine Lord and Rebecca M. Jones
Background: The nosology of autism spectrum disorders (ASD) is at a critical point in history as theﬁeld seeks to better deﬁne dimensions of social-communication deﬁcits and restricted/repetitivebehaviors on an individual level for both clinical and neurobiological purposes. These differentdimensions also suggest an increasing need for quantitative measures that accurately map their dif-ferences, independent of developmental factors such as age, language level and IQ. Method: Psycho-metric measures, clinical observation as well as genetic, neurobiological and physiological researchfrom toddlers, children and adults with ASD are reviewed. Results: The question of how to conceptu-alize ASDs along dimensions versus categories is discussed within the nosology of autism and theproposed changes to the DSM-5 and ICD-11. Differences across development are incorporated into thenew classiﬁcation frameworks. Conclusions: It is crucial to balance the needs of clinical practice inASD diagnostic systems, with neurobiologically based theories that address the associations betweensocial-communication and restricted/repetitive dimensions in individuals. Clarifying terminology,improving description of the core features of ASD and other dimensions that interact with them andproviding more valid and reliable ways to quantify them, both for research and clinical purposes, willmove forward both practice and science.
Keywords: Autism spectrum disorders, dimensions, classi-ﬁcation, diagnosis, DSM-IV, DSM-5, development.