Foreign language training in seniors to prevent old-age disorders: protocol of a randomized controlled trial

Bilinguals constantly need to mentally juggle multiple languages. This is thought to increase cognitive flexibility (Kroll & Bialystok, 2013), a skill needed to separate numerous languages in one mind (Bice & Kroll, 2015) but also to, adaptively respond to environmental demands. Learning a new language impacts first language processing and storage (Li, Legault, & Litcofsky, 2014). It is for this unique interfering effect that foreign language training is expected to boost cognitive flexibility more than other cognitive training programs. Although there is a wealth of observational studies into bilingual advantages, experimental studies remain scarce.

The objectives of this study are to determine whether a bilingual experience affects cognitive flexibility, its neural underpinnings and emotional health in elderly vulnerable for MCI. We assess the unique role of foreign language training (n=66) compared to music training (n=66) and a social intervention (n=66). Here, we present the method that underlies this study. For three to six months, participants practise the language or musical skills at home five days a week for 45 minutes, and attend classes every fortnight. Participants in the social intervention group will meet every fortnight to attend creative workshops. The language training focusses on speaking and listening and will be free of explicit grammar instruction. Cognitive flexibility is assessed using, among others, a colour-shape switching task and mWCST while measuring brain activity using combined fNIRS/EEG methods.

For the language intervention, but not or less for the control interventions, we expect an increase in cognitive flexibility and its neural underpinnings, indicated by increased power in the theta band network and more activity in the lateral and medial PFC during switching, and positive effects on emotional health. If effective, foreign language learning could serve as an important tool towards healthy aging: it could slow down cognitive aging and reduce vulnerability for depression.