Lifelong Exposure to Multilingualism: New Evidence to Support Cognitive Reserve Hypothesis

Abstract

ObjectiveInvestigate the protective effect of multilingualism on cognition in seniors.MethodsAs part of the MemoVie study conducted on 232 non-demented volunteers aged 65 and more, neurogeriatric and neuropsychological evaluations were performed. Participants were classified as presenting either cognitive impairment without dementia (CIND) or being free of any cognitive impairment (CIND-free). Language practices, socio-demographic data and lifestyle habits were recorded. In this retrospective nested case-control design, we used as proxies of multilingualism: number of languages practiced, age of acquisition and duration of practice, emphasizing the temporal pattern of acquisition, and the resulting practice of several languages sequentially or concomitantly during various periods of life. This special angle on the matter offered to our work a dimension particularly original and innovative.Results44 subjects (19%) had CIND, the others were cognitively normal. All practiced from 2 to 7 languages. When compared with bilinguals, participants who practiced more than 2 languages presented a lower risk of CIND, after adjustment for education and age (odds ratio (OR) = 0.30, 95% confidence limits (95%CL) = [0.10–0.92]). Progressing from 2 to 3 languages, instead of staying bilingual, was associated with a 7-fold protection against CIND (OR = 0.14, 95%CL = [0.04–0.45], p = 0.0010). A one year delay to reach multilingualism (3 languages practiced being the threshold) multiplied the risk of CIND by 1.022 (OR = 1.022, 95%CL = [1.01–1.04], p = 0.0044). Also noteworthy, just as for multilingualism, an impact of cognitively stimulating activities on the occurrence of CIND was found as well (OR = 0.979, 95%CL = [0.961–0.998], p = 0.033).ConclusionThe study did not show independence of multilingualism and CIND. Rather it seems to show a strong association toward a protection against CIND. Practicing multilingualism from early life on, and/or learning it at a fast pace is even more efficient. This protection might be related to the enhancement of cognitive reserve and brain plasticity, thereby preserving brain functions from alterations during aging.

Beyond a simple “yes” and “no”

“…Similar results were reported in cognitive aging (n=232) (Perquin et al, 2013) and dementia (n=134) (Woumans et al, 2014). Thirdly, in large parts of the world bilingualism is the rule rather than exception.…”

The Impact of L2 Learning on Cognitive Aging

“…They proposed for the first time that the more languages old people spoke on regular basis, the higher their cognitive levels would be [21]. It is known as the cumulative effect of languages, which is consistent with the results of Luxembourg's study that mastering one more language would increase the probability of protection against cognitive impairment by more than four times (of course, a threshold existed) and the earlier they became multilingual, the greater the protection would be [25]. It is a pity that this research didn't involve monolinguals, which makes impossible the comparison between monlolinguals and bilinguals or multilinguals (people speaking more than two languages).…”

The Relationship of Bilingualism Compared to Monolingualism to the Risk of Cognitive Decline or Dementia: A Systematic Review and Meta-Analysis

“…One study had a 14% follow-up rate and did not compare those who dropped out and those who did not [12]. The other was cross-sectional and found being multilingual rather than bilingual was protective, giving an odds ratio of 0·3 for cognitive impairment (95% Confidence Interval 0·10-0·92) after adjustment for education and age [13]. Both studies found that knowing and using more than two languages seems to confer a cognitive advantage and multi-lingualism may differ from bilingualism but there is not enough evidence as yet to draw definitive conclusions.…”