Bilingualism Delays The Onset Of Dementia

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The debate Recent studies propose that bilingualism delays the onset of dementia by 4-4.6 years (Bialystok, Craik & Freedman, 2007, Craik, Bialystok & Freedman, 2010, Alladi et al., 2013. Woumans et al., 2015). In Canada, Bialystok, Craik and Freedman (2007) found a 4.1–year delay of dementia onset in bilinguals compared to monolinguals. Unfortunately, the authors do not report effect sizes, making it difficult to interpret the potential impact of these associations. The authors suggest immigration status had no effect on results, supporting this claim with separate analysis of immigrants, which showed an 11.5-year delay of dementia onset in bilinguals compared to monolinguals. However, there is no separate analysis of non-immigrants. Therefore, the overall reported effect may have been driven by the large effect within the immigrant sample. Having said this, immigrant status is not necessary for the effect, as a similar study on non-immigrants found a delay of 4.6 years in bilinguals compared to monolinguals (Woumans et al., 2015). Bak and Alladi (2016) emphasise the importance of cross-cultural research in this field, as attitudes towards bilingualism can significantly influence people’s lives and physicians’ diagnoses of dementia. A recent study in India included illiterates and was representative of a “truly bilingual environment” (Alladi et al., 2013). It found a 4½-year delay in bilinguals compared to monolinguals in Alzheimer’s disease (AD), frontotemporal dementia and vascular dementia (Alladi et al., 2013). As each type of dementia affects the brain and cognition in unique ways, future research should further investigate potential differential effects of bilingualism. The results were also independent of sex, occupation ... ... middle of paper ... ...owever, these results cannot be confidently attributed to bilingualism, as the bilinguals in this study had significantly more years of education than the monolinguals. Similarly, Schweizer, and colleagues (2012) found that bilinguals with AD had greater brain atrophy than monolinguals in brain areas involved in AD diagnosis, despite similar performance on cognitive tests. This result suggests greater amounts of neuropathology is present in the bilingual brain before the of dementia symptoms manifest. However, bilinguals had significantly higher occupational status than monolinguals, which could also account for the results. Future research should continue to investigate structural and metabolic brain differences between monolinguals and bilinguals and could include brain imaging during active tasks, to explore how bilinguals compensate for greater cerebral changes.
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