The Nuance of Bilingualism as a Reserve Contributor: Conveying Research to the Broader Neuroscience Community

Abstract

The neurological notion of “reserve” arises from an individually observable dissociation between brain health and cognitive status. According to the cognitive reserve hypothesis, high-reserve individuals experience functional compensation for neural atrophy and, thus, are able to maintain relatively stable cognitive functioning with no or smaller-than-expected impairment. Several lifestyle factors such as regular physical exercise, adequate and balanced nutrition, and educational attainment have been widely reported to contribute to reserve and, thus, lead to more successful trajectories of cognitive aging (CA). In recent years, it has become clear that bilingualism is also a potential reserve contributor. Yet, there is little communication between the neuroscience of bilingualism research community and researchers working in the field of CA more generally, despite compelling reasons for it. In fact, bilingualism tends to be overlooked as a contributory factor in the CA literature, or reduced to a dichotomous trait, despite it being a complex experience. Herein, we discuss issues that are preventing recognition of bilingualism as a reserve contributor across all literatures, highlight the benefits of including language experiences as a factor of interest across research disciplines, and suggest a roadmap to better integrate bilingualism and aging moving forward. We close with calls toward a model of aging that examines the contributions across lifestyle factors, including that of bilingual experience.

Protective effect of bilingualism on aging, MCI, and dementia: A community‐based study

“…58 Previous research revealed superior executive function and experience-dependent plasticity in older bilinguals, resulting in a greater cognitive reserve. 56 In our cohort, healthy older bilinguals with NCI had better general cognitive abilities compared to monolinguals, independent of the social determinants of health, such as age, sex, education, socioeconomic status, and occupation. Bilingual speakers scored better on attention, memory, fluency, language, and visuospatial subdomains of ACE-III compared to monolinguals.…”

“…55 This is attributed to increased neuronal plasticity and better cognitive reserve resulting from practicing more than one language across the lifespan. 13,56 This is the first study investigating the impact of bilingualism on the prevalence of both dementia and MCI in a large population. We addressed the key methodological problems in earlier clinic and community studies to a greater extent in the current study.…”

“…Overall findings indicate that bilingualism promotes healthy aging and protects against cognitive decline and dementia, which might be due to additional cognitive benefits noted in bilingual speakers 55 . This is attributed to increased neuronal plasticity and better cognitive reserve resulting from practicing more than one language across the lifespan 13,56 …”

“…55 This is attributed to increased neuronal plasticity and better cognitive reserve resulting from practicing more than one language across the lifespan. 13 , 56 …”

Executive functions are modulated by the context of dual language use: diglossic, bilingual and monolingual older adults

“…Similarly, the life-long experience of bilingualism has been suggested to be one of those challenging experiences that may bring about adaptations in cognition (Anderson, Mak, Keyvani Chahi & Bialystok, 2018;Bialystok, Craik, Klein & Viswanathan, 2004) and the brain (DeLuca, Rothman, Pliatsikas, 2020), and may lead to enhanced cognitive abilities in older adults (Bialystok et al, 2004;Samuel, Roehr-Brackin, Pak & Kim, 2018). It has even been suggested that the benefits of bilingualism in older age extend to increased cognitive flexibility and delay the onset of dementia symptoms (Bialystok, 2021;Craik, Bialystok & Freedman, 2010), both of which can be considered forms of cognitive reserve (Voits, DeLuca & Abutalebi, 2022a). It has been shown that both languages are constantly active, and competing, in the bilingual mind (Bialystok, Craik & Luk, 2012;Carlson & Meltzoff, 2008), a situation that requires bilinguals to inhibit the nontarget language and use the target language.…”