Severity Scores on the Autism Diagnostic Observation Schedule 2 Relate to Inhibitory Control in Children with Autism Spectrum Disorders

Background:  

Deficits in executive functioning, one’s ability to solve complex problems through managing conflicting information, are present in many individuals on the autism spectrum (Robinson, 2009). Specifically, this ability involves inhibition, set-shifting, decision making, and working memory. Poor executive functioning skills are known to correlate with reduced social abilities, more disruptive and aggressive behavior, poorer academic performances, and less successful outcomes in adulthood (see Diamond, 2013 for review). While executive functioning impairments have been acknowledged in autism spectrum disorder (ASD), few studies have looked at the direct relationship between one’s executive functioning and their severity score on the Autism Diagnostic Observation Schedule 2 (ADOS-2).

Objectives:  

To investigate whether ADOS severity comparison scores correlate with executive function abilities in children diagnosed with ASD.

Methods:  

Participants were 19 children with ASD who ranged in age from 7 to 11 years old (15 males; 4 females), with IQs of 80 or above measured using the WASI-2 (Wechsler, 2011). Additional subjects are in the process of being recruited and tested. All participants received a clinical diagnosis on the autism spectrum, determined by DSM-V criteria (American Psychiatric Association, 2013) after administration of the ADOS-2 (Gotham, Risi, Pickles, & Lord, 2007) and the ADI-R (Rutter, Le Couteur, & Lord, 2003). ADOS-2 Comparison Scores were determined by taking the sum of the social affect and restricted repetitive behaviors raw scores and using the Conversion Table for Module 3. Comparison Scores range from 1 to 10, with increasing scores indicating a more severe diagnosis.  

Executive Functioning was broken down into four separate tasks, each completed using a laptop computer: The Color-Word Stroop task measured inhibitory control (Perlstein, et al 1999), the Change Task assessed set-shifting (De Jong, Coles & Logan, 1995; Geurts et al., 2004), the Delay Discounting Task looked at decision making skills (Lamm et al, 2006; Richards et al., 2009), and the Backward Digit Span Task examined verbal working memory skills (Cohen,1997).

Results:  

These preliminary results showed a strong negative correlation between the ADOS-2 Comparison Score and the Congruent-Incongruent Correct Reaction Time for the Stroop (R= -0.70; p = .001), which specifically measures inhibition of interfering information. None of the other three tasks correlated with ADOS symptom severity. However, analysis is ongoing with the continued enrollment of subjects. 

Conclusions:  

The ability of children on the autism spectrum to inhibit conflicting information, a key feature of executive functioning, is related to the severity of their autism diagnosis determined by the ADOS-2. This is consistent with previous literature that shows that inhibiting conflicting information is specifically impaired relative to other aspects of inhibition (Christ et al., 2007). This finding is important in better understanding the underlying features of autism spectrum disorders, and suggests that the development of interventions that target inhibitory deficits specifically may be helpful in reducing the severity of one’s diagnosis.