DSM Criteria that Best Differentiate Intellectual Disability from Autism Spectrum Disorder

Clinical characteristics of autism spectrum disorder (ASD) and intellectual disability (ID) overlap, creating potential for diagnostic confusion. Diagnostic and statistical manual of mental disorders (DSM) criteria that best differentiate children with ID and some ASD features from those with comorbid ID and ASD were identified. Records-based surveillance of ASD among 8-year-old children across 14 US populations ascertained 2816 children with ID, with or without ASD. Area under the curve (AUC) was conducted to determine discriminatory power of DSM criteria. AUC analyses indicated that restricted interests or repetitive behaviors best differentiated between the two groups. A subset of 6 criteria focused on social interactions and stereotyped behaviors was most effective at differentiating the two groups (AUC of 0.923), while communication-related criteria were least discriminatory. Matching children with appropriate treatments requires differentiation between ID and ASD. Shifting to DSM-5 may improve differentiation with decreased emphasis on language-related behaviors.