Investigating language skills as a mediator between IQ and anxiety in autistic youth

Background Anxiety is a common condition noted to cause significant impairment in some autistic youth. Previous research has found that autistic youth tend to exhibit higher levels of traditional anxiety symptoms with higher IQ scores and higher language abilities. In this study of the relationship between anxiety, intelligence, and language skills in autistic youth, it was hypothesized that a mediational relationship would be observed in which IQ exerts its influence over anxiety through language skills. Method Participants consisted of 293 autistic youth between the ages of 7 and 18. Anxiety was assessed with the Revised Children’s Anxiety and Depression Scale, language with the Oral and Written Language Scales Version II, and IQ (performance, verbal, and full-scale) was measured with the Wechsler Abbreviated Scale of Intelligence Version II. A simple mediation model was used with IQ as the predictor variable, language as the mediator variable, and anxiety as the outcome variable. This analysis was conducted three times so that performance, verbal, and full-scale IQ could be examined as separate predictors. Results The results of this study confirmed our hypothesis with a full mediation effect for each IQ scale, although verbal IQ was too strongly correlated with language scores for it to be considered a separate construct from our language measure. Conclusions This model should inform further autism research in that the influence of IQ and language over anxiety should not be viewed as independent factors but as a set of constructs that exert a shared influence.