Bilingualism: Lifelong brain benefits
By Makena Wood, B.Sc. Neuroscience student
Bilingualism (the ability to communicate fluently in two languages) has been shown to produce functional, structural and connective differences in the brain, as well as a positive impact on executive function (EF) skills in children and adults (Goksan et al., 2020; Stein, 2012; Wong, 2015). Aside from these important positive changes in brain development, bilingualism can also serve to protect against age-related changes in brain function, and foreign-language training in later life can improve cognitive abilities (Wong et al., 2019). This blog will explore the lifelong benefits of bilingualism and foreign-language learning, and the important differences in these experiences for children, adults, and older adults.
Bilingualism in your brain
There is a wealth of evidence demonstrating significant differences in brain structure between bilinguals and monolinguals (Wong et al., 2015). A unifying principle across many fields of biology, including neuroscience, is that structure reflects function. While studies in humans rarely produce results indicating causation, changes in the structure of areas of the brain of interest to an expected behaviour can often give us strong correlations between the effect of an experience (like bilingualism) on a brain function later in life (like improved executive function). A review article by Wong et al. (2015) details some of these correlations to better understand the relationship between the structural and functional differences observed between monolinguals and bilinguals.
Firstly, Wong et al. (2015) correlate stronger EF in bilinguals with increased gray and white matter volumes, as well as regional activation, in areas of the brain associated with EF (the frontoparietal network and the basal ganglia). On another hand, areas of the brain related to language and phonology (the system of relationships between speech sounds) are also observed to increase in gray matter volume in bilinguals.
Aside from increasing in volume, the brain can also change structurally via the connections it makes with other areas of the brain. Wong et al. (2015) cite work by Garcia-Penton et al. (2014) that identified two main networks with stronger connectivity in bilinguals than monolinguals. The first network with stronger connections in bilinguals is thought to be responsible for contrasting the phonology, syntax, and semantics of different languages, meanwhile the second network with stronger connections in bilinguals is believed to play a general role in visual processing, reading, and semantic processing.
In summary, bilingualism results in an increase in cortical volume in areas of the brain important for language and strengthens connections between these areas of the brain (Wong et al., 2015). We can predict that these changes in structure result in changes in function for bilinguals, and we know that bilingualism positively impacts executive function (Wong et al., 2015).
The effects of learning a second language in early childhood
While it is widely recognized that bilingualism confers an advantage in executive function, it is interesting to consider that bilingualism can occur at different stages in life, and we can estimate that the age of acquisition of a second language would influence related outcomes in the brain (Goksan et al., 2020). For example, an individual could be bilingual from birth (simultaneous exposure to two languages) or could acquire a second language later in life. In their investigation of the effects of early childhood bilingualism, Goksan et al. (2020) identify that early bilingualism (and regular practice) may increase EF performance and connectivity of EF brain regions because more time is spent using more than one language system (Yow & Li, 2015; as cited in Goksan et al., 2020). Further, other studies found that the earlier the age of acquisition of second language, the stronger the connectivity between related regions (Berken et al., 2016; Gullifer et al., 2018; as cited in Goksan et al., 2020). This is to say that, while bilingualism and second language learning can make important differences at many stages of development, it seems as though learning language is a case of ‘the earlier the better’.
Critical periods for language acquisition
The notion of ‘the earlier the better’ aligns well with what we know about critical periods for language acquisition. A critical period refers to the stage in brain development at which a skill is best and most easily learned. Importantly, if acquiring the skill during this time is missed, it can result in impairments related to the skill later in life. Generally, learning a first language is restricted to early childhood, but what can be said about the best time to learn a second language? A large study conducted by Hartshorne et al. (2018) with the aim to identify how grammar-learning ability changes with age in 669,498 native and non-native English speakers provided an estimate of this critical period that appeared to be later than expected; the ability to learn grammar (essential to acquiring a second language) is preserved throughout childhood but declines rapidly in late adolescence. The authors explain that this extended period for acquisition of a second language requires consideration that it has previously been believed that there is an overlap in the age at which native-like attainment of language can be achieved and the age at which learning ability declines (i.e., the final age that language can be attained if learning started earlier may be much later than when learning ability begins to decline). Overall, their results suggest a critical period for second language acquisition that declines steeply around 17.4 years.
How a bilingual brain changes over the lifespan
Another important facet of bilingualism is how the systems and skills it helps to establish in childhood continue to develop through childhood and into adulthood.
Throughout childhood, bilingual children experience greater improvements in inhibition (a skill mediated by EF) compared to monolingual children (Park et al., 2018). It has been hypothesized that this is because inhibition is the skill used by bilinguals to prevent interference between their two languages during use (Green, 1998; as cited in Park et al., 2018).
Into adulthood, we see that a bilingual advantage in EF is preserved and is greater for groups of older adults compared to younger adults (Bialystok et al., 2014). Another incredible advantage of bilingualism in older adulthood is its contribution to cognitive reserve (Bialystok, 2021) Cognitive reserve is a term that describes the brain’s ability to preserve its cognitive function while the associated physical structure may be deteriorating. The same hypothesis that contributes to increased inhibition in childhood (stimulation of multiple attentional processes) helps to create the foundation of cognitive reserve to be used in later life (Bialystok, 2021).
Can learning a second language be beneficial in later life?
If you’re engaging with this blog as an adult with children, allow it to encourage you to involve your child in second-language learning as early as possible given the above discussion. However, if you’re engaging with this blog as an adult or older adult out of personal interest and are not bilingual, then there is still opportunity for this blog to be of use to you. While your brain cannot jump backwards in time to reap the benefits of acquiring a second language in early childhood as described above, there are certainly different and equally important benefits to practicing a second language later in life. A study by Wong et al. (2019) aimed precisely to address the benefits of foreign-language learning as an intervention for cognitive decline. Their results demonstrated that intensive foreign-language training significantly improves measures of cognitive function and working memory; moreover, they discuss that, compared to other cognitive training for older adults (for example, puzzling), foreign-language learning facilitates other activities like communication and traveling. Finally, they note that foreign-language learning may also represent a cognitive-reserve building activity, a similar type of advantage compared to lifelong bilingualism, although surely different in mechanism and in magnitude.
Hopefully this blog has helped to explain the incredible role of bilingualism in supporting executive function, and has encouraged you to consider implementing second language learning for yourself or your child given the diverse ability of acquiring a second language to alter brain outcomes. Check out buildingbrains.ca/blog for other topics related to improving EF and supporting EF trajectory across the lifespan.
References
Bialystok, E. (2021). Bilingualism: Pathway to cognitive reserve. Trends in Cognitive Sciences, 25, 355-364. https://doi.org/10.1016/j.tics.2021.02.003
Bialystok, E., Poarch, G., Luo, L., & Craik, F. I. M. (2014). Effects of bilingualism and aging on executive function and working memory. Psychology and Aging, 29, 696-705. https://doi.org/10.1037/a0037254
Goksan, S., Argyri, F., Clayden, J. D., Liegeois, F., & Wei, L. (2020). Early childhood bilingualism: Effects on brain structure and function. F1000 Research, 9, 1-25. https://doi.org/10.12688/f1000research.23216.1
Hartshorne, J. K., Tenenbaum, J. B., Pinker, S. (2018). A critical period for second language acquisition: Evidence from 2/3 million English speakers. Cognition, 177, 263-277. https://doi.org/10.1016/j.cognition.2018.04.007
Park, J., Weismer, S. E., & Kaushanskaya, M. (2018). Changes in executive function over time in bilingual and monolingual school-aged children. Developmental Psychology, 54, 1842-1853. https://doi.org/10.1037/dev0000562
Stein, M., Federspiel, A., Koenig, T., Wirth, M., Strik, W., Wiest, R., Brandeis, D., & Dierks, T. (2012). Structural plasticity in the language system related to increased second language proficiency. Cortex, 48, 458-465. https://doi.org/10.1016/j.cortex.2010.10.007
Wong, B., Yin, B., & O’Brien, B. (2015). Neurolinguistics: Structure, function, and connectivity in the bilingual brain. BioMed Research International, 2016, 1-22. https://doi.org/10.1155/2016/7069274
Wong, P. C. M., Ou, J., Pang, C. W. Y., Zhang, L., Tse, C. S., Lam, L. C. W., & Antoniou, M. (2019). Language training leads to global cognitive improvement in older adults: A preliminary study. Journal of Speech, Language, and Hearing Research, 62, 2411-2424. https://doi.org/10.1044/2019_JSLHR-L-18-0321