Exploring Language Learning as a Potential Tool against Cognitive Impairment in Late-Life Depression: Two Meta-Analyses and Suggestions for Future Research

Abstract

Late-life depression (LLD) affects about an eighth of community-dwelling seniors. LLD impacts well-being, with loneliness and small social networks being typical. It has also been linked to cognitive dysfunction and an increased risk of developing dementia. Safety and efficacy of pharmacological treatments for LLD have been debated, and cognitive dysfunction often persists even after remission. Various cognitive interventions have been proposed for LLD. Among these, one has received special attention: foreign language learning could serve as a social intervention that simultaneously targets brain structures affected in LLD. Lifelong bilingualism may significantly delay the onset of cognitive impairment symptoms by boosting cognitive reserve. Even late-life foreign language learning without lifelong bilingualism can train cognitive flexibility. It is then counterintuitive that the effects of language learning on LLD have never been examined. In order to create a theoretical basis for further interdisciplinary research, this paper presents a status quo of current work through two meta-analyses investigating cognitive functioning in LLD on the one hand and in senior bilinguals or seniors following a language course on the other hand. While LLD was consistently associated with cognitive dysfunction, inconsistent results were found for bilingualism and language learners. Possible reasons for this and suggestions for future research are subsequently discussed.

Keywords: bilingualism; cognitive function; language learning; late-life depression; meta-analysis; seniors; systematic review.

Figure 1

PRISMA flow diagram of the screening process for late-life depression (left) and bilingualism (right).

Figure 2

Forest plot for cognitive functioning in late-life depression showing individual and pooled effect sizes. A positive standardized mean difference indicates a higher average score for the depressed group.

Figure 3

Forest plot for cognitive functioning in older bilinguals showing individual and pooled effect sizes. A positive standardized mean difference indicates a higher average score for the bilingual group.

Figure 4

Funnel plots for studies on late-life depression (left) and bilingualism (right). An asymmetrical distribution suggests publication bias.