Comparison of DSM-IV and DSM-5 Factor Structure Models for Toddlers With Autism Spectrum Disorder

Objective: The present study examined the factor structure of autism symptoms in toddlers, to aid understanding of the phenotype during the developmental period that represents the earliest manifestations of autism symptoms. This endeavor is particularly timely, given changes in symptom structure from the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) to the recently released Fifth Edition (DSM-5). Method: Factor structure was examined in a sample of toddlers between 12 and 30 months of age (mean = 20.37 months, SD = 3.32 months) diagnosed with autism spectrum disorder (ASD) and recruited from community settings or referred for evaluation (N = 237). Confirmatory factor analyses were conducted comparing the relative fit of 4 distinct, previously proposed and validated models: DSM-5, DSM-IV, 1-factor, and an alternative 3-factor model proposed by van Lang et al. Results: Findings revealed that the 1-factor model provided the poorest fit, followed by the DSM-IV model and the van Lang et al. model. The DSM-5 model provided the best fit to the data relative to other models and good absolute fit. Indicators for the confirmatory factor analyses, drawn from the Autism Diagnostic Observation Schedule Toddler Module (ADOS-T), loaded strongly onto the DSM-5 Social Communication and Social Interaction factor and more variably onto the DSM-5 Restricted/Repetitive Language and Behavior factor. Conclusions: Results indicate that autism symptoms in toddlers, as measured by the ADOS-T, are separable and best deconstructed into the 2-factor DSM-5 structure, supporting the reorganization of symptoms in the DSM-5. Consistency of the present results in toddlers with previous studies in older children and adults suggests that the structure of autism symptoms may be similar throughout development.