The underlying symptom structure of autism spectrum disorders: A factor analytic approach using the developmental, dimensional and diagnostic interview

• CFA of previously proposed models did not fit our data adequately.
• EFA pointed towards a 5-factor model, partially confirming DSM-5 dimensions.
• Items did not segregate as expected by their allocation in diagnostic algorithm subdomains.

Several studies have focused on the underlying symptom structure of Autism Spectrum Disorders (ASD), but results have been equivocal. We performed a confirmatory factor analysis on data of the Developmental, Dimensional and Diagnostic Interview of 275 participants with ASD between 3 and 23 years of age, aimed at strengthening the empirical evidence of previously published factor structure solutions using the same instrument. As none of these hypothesised models fitted our data, an exploratory factor analysis was undertaken. Results pointed towards a five factor model. A ‘Restricted and Repetitive Behaviour and Interest’ factor could be separated from ‘Shaking and Nodding’, ‘Emotional Reciprocity’ and two other factors that both represented deficits in social interaction and communication. Although not completely confirming, our results are generally in favour of the present DSM-5 criteria. By showing that the items did not fully segregate according to theoretically postulated subdomains, we offer a possible explanation for the heterogeneity in proposed factor structures for ASD.