Bilingualism and brain structure: insights from healthy ageing and progressive neurodegenerative diseases

The study of the effects of bilingualism on brain structure has gained significant traction in the last decade, naturally following from the pioneering work by Ellen Bialystok and others on the effects of bilingualism on cognition. However, and despite the general interest and enthusiasm about the related evidence, the field of bilingualism-induced structural brain plasticity remains young and relatively unexplored, while it has been largely limited to young and healthy populations. This chapter revisits and reviews the evidence about bilingualism-induced neuroplasticity, and the contemporary theories that provide explanations to the available evidence, with a particular focus on the ageing and patient bilingual brain. Specifically, a full account of the reported effects on healthy ageing bilinguals is provided, followed by the limited findings from diseases that cause progressive brain decline, such as mild cognitive impairment, Alzheimer’s and Huntington’s diseases, epilepsy and multiple sclerosis. The chapter concludes with some suggestions for future directions for the field