Does Being Bilingual Impact Executive Functions in Autism Spectrum Disorders?

Background: Executive functions comprise skills essential for daily life. One of these is cognitive flexibility, often measured by set-shifting tasks (Eigsti, 2011). Some studies have shown enhanced executive functioning in bilinguals relative to monolinguals (e.g., Bialystok & Martin, 2004; Bialystok & Viswanathan, 2009), ascribed to the control bilinguals need to exert over the competing activation of their two languages (Bialystok, 2007; Green, 1998). However, this so called “bilingual advantage” has not been found consistently (e.g., Engel de Abreu, 2011; Namazi & Thordardottir, 2010).

Objectives: While many studies have examined the impact of bilingualism on executive functions (EF) in typically-developing children, few have investigated this relationship in a neurodevelopmental disorder with known EF impairments. If a bilingual advantage exists, it might mitigate executive dysfunction in such a case. Individuals with Autism Spectrum Disorders (ASD) demonstrate EF impairments, specifically, children with ASD tend to exhibit perseverative responses on set-shifting tasks (e.g., Ozonoff et al., 2004). Conversely, children with ASD show spared skills in other cognitive domains such as verbal short-term memory (e.g., Boucher et al., 2012; Zinke et al., 2010). We examine the impact of bilingualism on set-shifting abilities in ASD. We hypothesized that bilingual children with ASD would be impaired in set-shifting relative to bilingual typically-developing (TYP) children, but would be less impaired than monolinguals with ASD (biTYP> biASD> monoASD). As a control we hypothesized that short-term memory would not differ between groups.

Methods: Bilingual TYP, bilingual ASD, and monolingual ASD groups were matched on nonverbal IQ, chronological age, gender and socioeconomic status. The target sample includes 20 biTYP, 15 biASD, and 15 monoASD 5- to 9-year-olds. Participants include French, Spanish or English speakers (or speakers of any 2 of these languages). To evaluate set-shifting skills we used a computerized version of the Dimensional Change Card Sort task (DCCS; Zelazo, 2006), where the dependent variable is passing 5 of 6 post-switch trials. In addition, we obtained a parental report of executive function behaviors in daily life via the Behavior Rating Inventory of Executive Functioning (BRIEF; Gioia et al., 1996). Short-term memory was assessed by the number repetition subtest of the Clinical Evaluation of Language Fundamentals (CELF-4; Semel et al., 2003).

Results: Preliminary data is available from 10 biTYP, 6 biASD, and 12 monoASD children. Findings generally pattern in line with our predictions. On the DCCS bilingual children with ASD perform better than their monolingual counterparts, and in fact better than TYP bilinguals (percent of children passing the DCCS post-switch phase: biTYP= 60%; biASD= 83%; monoASD = 50%). Parent ratings on the BRIEF set-shift subscale also follow predictions (lower scores = higher functioning: biTYP M = 45; biASD M = 62; monoASD M = 64). In contrast, short-term memory was not significantly different across groups (number repetition standard score biTYP M = 10.1; biASD M = 9.3; monoASD M= 7.7). 

Conclusions: Data collection is ongoing and will allow us to investigate in a larger sample if the set-shifting difficulty experienced by monolinguals with ASD is significantly reduced in bilinguals with ASD.