Incorporating autism traits into an anxiety and depression model results in improved fit and distinct factor structure for autistic youth

Background: The co-occurrence of anxiety and depression (AD+) in autism may be explained by a transdiagnostic internalizing symptom factor. Evidence regarding anxiety and/or depression symptoms in autism is mixed; some presentations conform to DSM criteria, whereas others reflect distinct, autism trait-relatedpresentation. Method: The present study examined the extent to which autism traits relate to anxiety, depression, and AD+ in autism. Anxiety and depression symptoms were measured in autistic youth (ages 6–18) using a DSM rating scale. First, a confirmatory factor analysis (CFA) of anxiety and depression DSM symptoms was conducted. Next, to account for the relation of autism traits, these traits were included with anxiety and depression symptoms in a follow-up exploratory factor analysis (EFA). In addition, the inclusion of anxiety and depression symptoms, and allowing for their overlap, was consistent with a transdiagnostic conceptualization of these symptoms. Results and conclusions: The CFA showed that the DSM model of depression and anxiety symptoms did not adequately fit the autistic participants. The EFA of anxiety, depression, and autism traits supported a model with three factors: Anxiety and Depression, Social Anxiety, and Autism. A subset of autism traits loaded onto the Anxiety and Depression and Social Anxiety factors. Both the DSM and the EFA model had inadequate fit indices, though the EFA showed better fit over the DSM model. In addition, previous research converges with the obtained EFA factors. Overall, the findings highlight the importance of modeling autism traits along with anxiety and depression when examining internalizing symptom structures in autism.