Social anxiety symptoms in autism spectrum disorder and social anxiety disorder: Considering the reliability of self-report instruments in adult cohorts.

Adults with autism spectrum disorder (ASD) are at elevated risk for social anxiety disorder (SAD). Limited information exists on the reliability of social anxiety instruments with these adults and their performance when compared to individuals with SAD without ASD. This study examines psychometric properties of self-report social anxiety instruments in autistic adults without intellectual disability, compared to adults with SAD. Additionally, we compared instrument scores between a subgroup of autistic adults with a dual diagnosis of SAD (ASD + SAD) and adults with SAD only. Adults diagnosed with SAD (N = 316) or ASD (N = 102) were recruited from the Brain and Mind Centre in New South Wales, Australia. Sixty autistic participants also received a diagnosis of SAD (ASD + SAD). Participants completed the Liebowitz Social Anxiety Scale-self-report, the Social Interaction Anxiety Scale, the Social Phobia Scale, and the Brief Fear of Negative Evaluation Scale. All instruments showed excellent internal consistency in autistic adults. The instruments showed evidence of convergent validity, and the strength of relationships between measures were equivalent between ASD and SAD groups. For all instruments, performance of these instruments in autistic adults with a SAD diagnosis was very similar to performance in adults diagnosed with SAD but without ASD. Findings support the use of these instruments for identifying social anxiety symptoms in autistic adults without intellectual disability and have utility for mental health clinical services. LAY SUMMARY: Autistic adults often experience social anxiety. We examined the use of four social anxiety questionnaires in autistic adults, compared to adults with SAD. We found similar results between autistic adults and adults with SAD, suggesting that these questionnaires can be useful for measuring social anxiety symptoms in autistic adults. These findings have implications for clinical services, as they show that these instruments are reliable when used with autistic adults.