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Language and Cognition in Bilingual and Monolingual Children Post-Stroke
Nomazulu Dlamini, The Hospital for Sick Children, Toronto, Canada
Robyn Westmacott, The Hospital for Sick Children, Toronto, Canada
Elizabeth Rochon, The Hospital for Sick Children, Toronto, Canada
Monika Molan, The Hospital for Sick Children, Toronto, Canada
Objective:
To evaluate bilingual vs. monolingual exposure on language and cognitive outcomes in children following arterial ischemic stroke (AIS), two studies were conducted: (1) large-scale group analysis using Pediatric Stroke Outcome Measure (PSOM); (2) exploratory case studies using neuropsychological measures. We hypothesized bilingual exposure in children post-stroke would not have negative consequences; however, cognitive and linguistic advantages may be observable for bilinguals with stroke onset outside of the neonatal period, allowing sufficient language exposure pre-post stroke. The bilingual case was expected to show poorer performance in absolute scores, due to a bilingual difference not truly reflective of their abilities. Instead, relative change in scores across timepoints was used as a metric of development.
An institutional registry and chart review were used to gather patient and stroke data, including the PSOM and standardized neuropsychological measures performed at several time points post-stroke in 237 children with AIS (44% bilingual), who met inclusion criteria. Children with presumed stroke, deceased patients, and those without two measurement timepoints were excluded to avoid potential confounds. Patients were stratified based on age at stroke onset, i.e., neonatal (<28 days), first-year (28 days-12 months) and childhood (13 months - 18 years), based on previous work using the PSOM that indicated different trajectories of recovery based on age (Felling et al., 2020). Growth curve modeling of PSOM subscales, predicted by age at stroke groups, language groups, and their interactions were used. In Study 2, exploratory, comparative case studies were conducted with a monolingual-bilingual pair, aged 7 and 8 at stroke onset.
In Study 1, an interaction revealed better post-stroke outcomes on the language production subscale among bilingual children aged 1-12 months at stroke (β= -0.32, t =-2.33, p = 0.02). No differences between language groups were observed on the cognitive/behavioral subscale of the PSOM. Age of stroke onset was an important predictor of PSOM performance: older age showed worse cognitive/behavioral PSOM scores, while neonates had significantly better performance compared to the first-year group for language subscales. In Study 2, the bilingual patient’s performance corroborated findings of Study 1, favoring stronger expressive language on letter fluency and the verbal subtest of the Wechsler Intelligence Scale for Children-4th/5th Editions (WISC-IV/V). Cognitive measures recorded improvements in the bilingual’s processing speed and working memory on the WISC-IV/V but difficulties in the bilingual’s verbal and recognition memory, monitoring and inhibition in the California Verbal Learning Test. Parent-reported executive function (Gioia et al., 2015) scores were moderately elevated in the shift and initiate domains at Time 2.
Overall, no true negative consequences of a bilingual environment were found. Bilingualism may have a facilitatory effect on expressive language development post-stroke. Finer-grain cognitive measures revealed difficulties in the bilingual stroke case that were not evidenced with the PSOM. Further research currently in development will look to evaluate language and cognitive development prospectively in both monolingual and bilingual children, across stroke and healthy control groups.