About this Research Topic
Scientific advances have led to a remarkable increase in life expectancy over the past century, with global predictions that, by 2050, one in six of us will be aged 65 or over. Nevertheless, quality of life has not kept pace with this increase in longevity, and the burden that age-related cognitive deterioration places on affected individuals, their families, and on healthcare provision is a major societal concern. There is clearly an urgent need to develop ways for protecting and managing cognitive health in the elderly population. Recent research has suggested that factors such as continuing physical activity and cognitive effort may help promote “successful aging” although the viability of activities such as ‘working memory training’ for offsetting the effects of the neurological impairment on cognition has been questioned.
One factor claimed to potentially reduce the deleterious effects of aging on cognition is the process of becoming bilingual. This effect is thought to be driven by the increased inhibitory, attentional and working memory demands associated with operating effectively in bilingual relative to monolingual contexts, which may, over time, promote increased cognitive capacity or ‘cognitive reserve’. Early evidence for the enhancement of cognitive reserve associated with bilingualism stems from retrospective age-of-diagnosis comparisons among bilingual and monolingual patient populations, with the latter reported receiving a clinical diagnosis (typically of Alzheimer’s disease) approximately 4 years earlier. Other research indicates that this protective effect may only operate in particular sections of society, such as immigrant groups or those who had received poor or limited education. More recently, however, other authors published a large-scale study of over 600 patients in India indicating that bilingualism may substantially delay the onset of a range of dementia types, irrespective of immigration status and education. These reports of positive effects, however, are balanced by others producing null or inconsistent findings.
In addition to observations of cognitive benefits associated with bilingualism, there have also been reports of neurological effects. Some authors have provided evidence for less deterioration of white matter integrity and better anterior/posterior functional connectivity in older bilinguals relative to age-matched monolinguals. Similarly, increased tissue density in cortical areas associated with cognitive control/conflict monitoring has been reported in older bilingual (relative to monolingual) participants. Conversely, in bilingual Alzheimer patients with significant structural degeneration, there is some evidence for relatively preserved cognitive function, consistent with bilingualism offering protection against progression of cortical atrophy.
The extent to which such findings may, at least in part, be explained by systematic group differences on extraneous or inadequately controlled covariates, however, remains an issue of ongoing debate.
This research collection aims to gather the most recent empirical research on the effect of multilanguage acquisition across the lifespan. We welcome contributions using different methodologies including behavioral, computational and neuroscientific approaches. We also welcome theoretical contributions that provide a detailed discussion of models or mechanisms that account for the relationship between aging and lifelong multilanguage experience.
Keywords: Bilingualism, Executive Function, Cognitive Reserve, Alzheimer's, Aging
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