Relationships Between Executive Functions and Temperament in High-Functioning Youth with an Autism Spectrum Disorder

Background: Executive dysfunction is often cited as a central cognitive deficit in autism spectrum disorders (ASD; Pennington & Ozonoff, 1996). However, some studies of executive function (EF) in ASD have shown intact performance (Bryson, 1983) while others suggest impairments (e.g., Ozonoff, et al., 1991; Pascualvaca et al., 1998). In typically developing (TD) individuals, there is support for relationships between EF and temperament. For example, Gonzalez et al. (2001) found that activity level, impulsivity, and inhibitory control were related to Stroop Task performance. Interestingly, there is also mounting evidence for differences in temperament in ASD. Garon et al. (2008) found that high-risk infants (older sibling with ASD) later diagnosed with an ASD were distinguished from non-ASD infants by lower positive affect, higher negative affect and difficulty controlling attention. Similarly, Konstantareas & Stewart (2006) demonstrated that ‘effortful control' best differentiated children with ASD from their TD peers. Objectives: In this study, our goal was to determine if performance on EF tasks is associated with temperament factors in youth with an ASD. Methods: Eleven high-functioning youths with an ASD and 11 TD participants matched for age (range = 8 – 18) and IQ, completed the Wisconsin Card Sorting Test (WCST) and the Stroop Task. One of three temperament questionnaires was administered: Temperament in Middle Childhood Questionnaire (ages 7 – 10, parent-report; Simonds & Rothbart, 2004); Early Adolescent Temperament Questionnaire (ages 9 – 15, parent-report; Ellis & Rothbart, 2001); or Adult Temperament Questionnaire (ages 16 and up, self-report; Rothbart, Ahadi, & Evans, 2000). We examined relationships between performance on EF tasks and attentional control, inhibitory control, and activation control (i.e., subscales comprising effortful control). Results: The ASD and TD group did not differ on their EF performance (WCST total standardized errors: ASD M = 51.3, control M = 47.2, p > .1; Stroop Interference total: ASD M = 31.7, control M = 34.3, p > .1). Moreover, the ASD group had lower scores than the TD group on the attentional control (t = -2.32, p < .05) and inhibition subscales (t = -2.55, p < .05), indicating less ability to control attention and inhibition. The groups did not differ on the activation control subscale. For the TD group, more overall errors and perseverative responses on the WCST were associated with lower activation control (r = -.77 and -.88, respectively) and lower attentional control (r = -.69 and -.80, respectively). However, Stroop Interference scores were not related to any temperament subscale. For ASD participants, there were no associations between WCST performance and temperament data. However, better performance on the Stroop interference trial was significantly correlated with higher scores on the inhibition subscale (r = .71), indicating that a higher level of behavioural inhibition was associated with stronger cognitive inhibition. Conclusions: These preliminary data suggest that individuals with an ASD may differ from their TD peers with respect to how temperament is related to EF. Understanding relationships between EF and temperament may provide important insights into the variability of EF performance across individuals with an ASD.