The relationship between bilingual engagement and cognitive aging in regional minority-majority language contexts: A Lifelines study



The sustained and complex life experience of bilingualism has been previously linked to preserved cognitive functioning in the face of typical or pathological brain aging (Dash et al., 2022; Gallo et al., 2022). This cross-sectional study contributed to this line of work by investigating the association between a continuous measurement of bilingual engagement and cognitive aging in regional minority language contexts, which have received limited attention in the literature despite being quite common. We used an existing sample drawn from the Lifelines Cohort Study (Buurke et al., 2023; Scholtens et al., 2015; Sijtsma et al., 2022) comprising Frisian-Dutch bilinguals (n = 7,336) and Low Saxon-Dutch bilinguals (n = 9,888). All participants lived in the north of The Netherlands and ages ranged between 20 and 80, enabling an adult lifespan perspective. Cognitive functioning was measured using the Cogstate Brief Battery, which consists of four tasks assessing processing speed, attention, working memory, and recognition memory (Fredrickson et al., 2010). A bilingual engagement index was calculated using the proportion of use of and the relative proficiency in Dutch and the regional language (Gullifer & Titone, 2020; Li et al., 2020). We modeled the relationship between age and bilingual engagement as a non-linear interaction using generalized additive mixed modeling, and controlled for gender, educational attainment, and city or village of residence in the analysis. The results demonstrated that performance on all cognitive tasks significantly decreased with age, but we did not identify a robust main effect of bilingual engagement or an interaction between bilingual engagement and age. However, we found that Low Saxon-Dutch bilinguals outperformed Frisian-Dutch bilinguals on the cognitive measures across the age range. Further exploration of this effect showed that residents in Groningen and Drenthe (the Low Saxon language areas) outperformed residents of Fryslân, regardless of using a regional language or not. As such, our results suggest that bilingual engagement does not play a key role in processing speed, attention, working memory, and recognition memory performance across the adult lifespan in Frisian-Dutch and Low Saxon-Dutch bilinguals. If any cognitive effects of bilingual engagement are present, we assume that they are relatively small compared to major effects associated with cognition, such as those of age and educational attainment.
Originele taal-2English
StatusAccepted/In press - 2024

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