P2‐296: BILINGUALISM, EXECUTIVE CONTROL, AND COGNITIVE RESERVE: IMPLICATIONS FOR PREVENTION OF ALZHEIMER'S DISEASE

Recent evidence for a bilingual advantage in non-linguistic executive control tasks involving inhibition and management of response conflict has led to the suggestion that being bilingual contributes to increased cognitive reserve, hence preventing or delaying the onset of Alzheimer's disease (AD). Further investigation may shed more light on the relevance of bilingualism for AD prevention. We assessed the performance of older (≥ 60 years) bilingual Welsh/English speakers (n = 50) and monolingual English speakers (n = 49) living in North Wales, UK, on a range of executive control tasks covering the domains of mental generativity and speed, working memory, set-shifting and switching, and inhibition and management of response conflict. There were no differences between monolingual and bilingual groups in key demographic variables or in health and functional status, but monolinguals performed better on tests assessing English language ability. Across the 40 executive function indices assessed, bilinguals performed better on 9, mostly with small effect sizes, while monolinguals performed better on 31, with a mix of mainly small and medium effect sizes. Univariate analyses suggested a monolingual advantage in mental generativity and speed, working memory, and set-shifting and switching, which was greatly reduced in the domain of inhibition and management of response conflict. Only three differences were significant after correction for multiple comparisons, with monolinguals performing significantly better on spatial span forwards, elevator counting with reversal and design fluency switching tasks. Multivariate analysis confirmed the monolingual advantage in working memory and in set-shifting and switching. Variations in degree of daily use of the two languages in the bilingual group had no significant effect on performance. The two groups did not differ on a measure of cognitive reserve. Being bilingual did not result in better performance on executive control tasks or contribute to enhanced cognitive reserve among older participants in Wales, and thus is unlikely to confer benefits with regard to preventing AD in the Welsh context. A possible explanation for the unexpected observation of a monolingual advantage may lie in the nature of the sociolinguistic context and its influence on cognitive processing in the bilingual group.