Longitudinal Stability and Change of Self-Reported Anxiety in Youth with ASD

Background: Heterogeneity is a feature of Autism Spectrum Disorders (ASD). Co-occurring disorders such as anxiety further contribute to this variability (Gillott, Furniss, & Walter, 2001). However, concerns with ASD-specific challenges (e.g. language and cognitive skills) raise questions about the reliability of self-report of internalizing disorders such as anxiety as a tool for research with this population (Grondhuis & Aman, 2012). To address these questions, the stability and change of self-reported anxiety symptoms were examined in children with ASD compared to children with Attention Deficit Hyperactivity Disorder (ADHD) or typical development (TD) across a 15-month period of growth.   

Objectives:  1) To examine diagnostic group differences across multiple dimensions of anxiety symptoms. 2) To compare diagnostic groups on test-retest self-report reliability. 3) To examine group differences in change of anxiety symptoms over time.  

Methods:  One hundred twenty-five 8- to 16-year-old children with ASD, ADHD or TD provided two sets of self-report on March’s Multidimensional Anxiety Scale for Children (MASC; 1997, 2013) approximately 15 months apart. ASD was confirmed using the ADOS-2 and ADHD symptoms were confirmed with the Conners Parent Report scale. The mean ages of the ASD, ADHD, and TD groups were 11.4, 12.2, and 11.5 years, respectively. The mean IQs of the groups were 101, 100, and 115, respectively, and IQ was a covariate in analyses where appropriate.

Results:  The groups differed on the MASC Total Anxiety and Physical Symptoms scales at both time points (TP, Table 1). The groups differed on the Anxiety Disorder index and Separation Anxiety at TP2. Post hoc analyses revealed the ASD group was higher on Total Anxiety than the TD group and higher on the Physical Symptoms than both the ADHD and TD groups at TP1. Post hoc analyses also revealed that the ASD group was higher on Total Anxiety and Physical Symptoms than both comparison groups at TP2. They were also higher on Separation Anxiety and the Anxiety Disorder Index than the ADHD group at TP2 (Table 1).

There was evidence of stability across the 15-month interval for self-report of Total Anxiety, Physical Symptoms, and Separation Anxiety in all groups (Table 2). Social Anxiety and the Anxiety Disorder index displayed evidence of stability in the ASD and TD groups.

Report of Physical Symptoms increased across time significantly for all groups (Table 1), but this increase was greatest for the TD group; F(2,115)=3.42, p=0.04. Total Anxiety also increased for the ASD and TD groups. The anxiety disorder index increased only for the ASD group; F(1, 56) = 8.12, p =. 006.

Conclusions: The results support the hypothesis that self-report in this subgroup of children with ASD provides meaningful information about trait-like individual differences in anxiety, and that school-aged children with ASD appeared to be at greater risk for significant increases in clinical levels of symptoms of an anxiety disorder than did children in the comparison groups. These observations bolster the need for more research on proactive monitoring and treatment of anxiety disorders in children with ASD.