Bilingual engagement and cognition across the adult lifespan: Insights from regional minority language speakers in the north of the Netherlands

This retrospective cohort study examined the relationship between a continuous measurement of bilingual engagement (operationalized as language entropy) and cognitive aging in regional minority language speakers. We drew Frisian–Dutch bilinguals ( n = 7,448) and Low Saxon–Dutch bilinguals ( n = 10,114) from the Lifelines Cohort Study and included participants aged 20–80, enabling an adult lifespan perspective. Cognitive functioning was measured using the Cogstate Brief Battery, which assesses processing speed, attention, working memory and recognition memory. We did not observe a robust relationship between bilingual engagement and cognitive functioning. Our results suggest that bilingual engagement does not play a key role in processing speed, attention, working memory and recognition memory performance in Frisian–Dutch and Low Saxon–Dutch bilinguals. Implications for the bilingual engagement measurement and potential investigations into regional minority language bilingualism and cognition are discussed.