Assessing ASD Symptoms and Comorbid Psychopathology in Adults with ASD: Who Should You Ask?

Background: ASD symptoms and psychiatric comorbidities in adults with ASD are notoriously difficult to assess. Recently, self- and other-report versions of the Social Responsiveness Scale, Second Edition (SRS 2) have been normed on adults. In regards to psychopathology, there are several well-established measures to assess psychiatric symptoms in typically developing adults. To the authors’ knowledge, the few assessment tools specifically designed to assess for comorbid psychiatric symptoms in individuals with ASD are still in their infancy. However, little is known about the agreement between self- and other-reports of these symptoms in adults with ASD on available assessment tools.  

Objectives:  To explore agreement between self- and caregiver-report of ASD symptoms and comorbid psychopathology. 

Methods:  Twenty-one adults diagnosed with ASD ages 18- to 35-years-old (M = 22.57, SD = 4.03) enrolled in a 16-week social skills intervention. 91% were male and 95% were Caucasian. Prior to beginning the intervention, ASD diagnosis was confirmed via the Checklist for Autism Spectrum Disorders (CASD; M = 22.67, SD = 3.17) and verbal IQ was estimated using the Kaufman Brief Intelligence Scale, Second Edition (KBIT 2; M = 93.40, SD = 18.84). Exclusionary criteria included verbal IQ below 70. Additionally, the participants and a primary caregiver completed the Adult Self-Report (ASR) or Adult Behavior Checklist (ABCL), as well as the SRS 2. 

Results:  Intraclass (ICCs) and Pearson correlations between raters for ASD symptoms on the SRS 2 were significant only for the Social Cognition (ICC & r = .54, p < .01) and Social Motivation (ICC & r = .51, p < .01) subscales. Inter-rater differences were examined using paired-samples t-tests. There were significant differences between self- and caregiver-report on all subscales of the SRS 2. Effect sizes for these differences ranged from medium to large (Cohen’s d range = .42 to .72). There were no significant differences between self- and caregiver-report on any of the subscales on the Adult Self-Report/Adult Behavior Checklist. When intraclass (ICCs) and Pearson correlations between raters for these subscales were examined the all subscales were significant correlated except for the Withdrawn Problems, Thought Problems, Rule-breaking Problems, and Avoidant Problems subscales. The Aggression and Externalizing subscales had the highest correlations suggesting that these variables are observed more consistently between young adults with ASD and their caregivers as compared to the other subscales. 

Conclusions:  The SRS 2 demonstrated poor inter-rater reliability between reporters. Caregivers of young adults with ASD consistently rated their children higher on the SRS 2 than individuals rated their own behavior. This suggests that importance of acquiring other-reports of ASD symptoms when assessing young adults’ symptoms of ASD. The ABCL and ASR demonstrated high inter-rater reliability between reporters. These results suggest that these broadband measures of psychopathology are valuable tools for researchers and/or clinicians to screen for the presence of symptoms of internalizing and externalizing disorders in adults with ASD. The high inter-rater reliability provides more confidence for the utility of these instrument when obtaining a self-report rating.