Effects of Dual-Language Exposure on Language and Executive Function in Children with ASD and ADHD

Background: Dual-language exposure (DLE) has been linked to advantages in executive functioning (EF), particularly in cognitive flexibility, and reduced single-language vocabulary. However, there has been limited research on the effects of DLE on EF and language skills in clinical populations. Prior research indicates possible detrimental effects of DLE on EF and language skills in adults with ADHD, while DLE has not been shown to significantly impact EF or language skills in children with ASD.

Objectives:To investigate the effects of dual-language exposure on executive functioning and vocabulary in children with ASD and ADHD

Methods: Participants were drawn from a sample of 136 children (ages 8-11 years) from Title I schools, enrolled in a clinical trial of two EF interventions. All children met criteria for ADHD or ASD. Household income differed significantly by language exposure (t(110)=5.51, p<.0001). Using the case control matching application of SPSS 24, a final sample of 64 children (n=32 DLE) was created, matched on household income (within $5000). There were no significant differences in age, gender, diagnosis, or full-scale IQ on the Wechsler Abbreviated Scales of Intelligence-II (WASI-II) (Table 1). Parent education was significantly lower among DLE children (t(60)=3.127, p=.003), and thus was controlled for in all subsequent analyses. Vocabulary and EF were assessed using selected subtests of the WASI-II, the Verbal Fluency subtest of the Delis-Kaplan Executive Function System (D-KEFS), the Behavior Rating Inventory of Executive Functioning (BRIEF), and the Flexibility Interference Scale (FIS), a parent rating scale of daily difficulties due to cognitive rigidity.

Results:Hierarchical regression analyses were used to assess differences in EF and language skills by DLE, after controlling for both parent education and child diagnosis, in separate steps. Parent education significantly predicted language skills (WASI-II Vocabulary, F=12.393, p=.001; D-KEFS Category Fluency F=7.328, p=.009), and child diagnosis was associated with language skills at a level approaching significance; however, after controlling for parent education and diagnosis, DLE had no significant effect on language skills (Table 2). After controlling for parent education and diagnosis, DLE was associated with higher EF, including significantly less parent-reported interference from cognitive rigidity on the FIS (F=7.412, p=.009), as well as fewer difficulties with transitions and tolerating change on the BRIEF: Shift subscale (F=3.495, p=.067) and better flexible problem-solving on the WASI-II: Block Design (F=3.668, p=.060), at a level approaching significance (Table 2). After controlling for multiple comparisons, the effects of DLE on the BRIEF: Shift and WASI-II: Block Design were not significant. DLE was not significantly associated with behavioral regulation skills (BRIEF), metacognitive skills (BRIEF), or verbal switching skills (DKEFS; Table 2).

Conclusions: Although concerns about detrimental effects of DLE on language skills are common, the present study adds to prior findings indicating that DLE does not negatively impact language skills in children with neurodevelopmental disorders. Findings also indicate that DLE may have beneficial effects for EF skills in this population, consistent with findings in typically-developing samples. Overall, this study brings into question “common wisdom” that parents of children with neurodevelopmental disorders should limit their children’s exposure to other languages.