Bilingualism and the Brain

This month is Mahuru Māori, where we celebrate not only Te Wiki o Te Reo Māori, but the conscious effort to kōrero in te reo Māori as much as we can for the maramataka month of Mahuru (the Lunar month, from Ākuhata/August 23rd to Hepetema/September 22nd). These initiatives are fun, crucial ways in facilitating language facilitation, but also overwhelmingly highlight that te reo Māori belongs in our communities, i ngā wahi katoa (every single space).

Without touching on politics (an impossible task...), and the way te reo Māori is used as a ‘controversial’ pawn in the space of conservatism, liberalism, nationalism, socialism, and every bit of philosophy in between – we can instead look away from “we shouldn’t have to learn Māori” towards “how is learning te reo Māori beneficial to our roro (brains)?” Cognitively, bilingualism (or knowing two languages), has limited but strongly linked benefits in brain plasticity, attention/language control, and cognitive reserve in aging (Antoniou, 2019; Tao et al., 2021; Gracia-Tabuenca et al., 2024) – This means the practice of knowing two languages can affect the brain’s ability to change and adapt in response to experiences, mental effort in communication, and the brains ability to cope with brain decline from aging or Alzheimer's. The effects are particularly interesting when a person grows up with two languages from birth, but learning a second language later in life can also change the brain. The important thing to note, however, is that bilingualism is not one single experience. Age of acquisition (when we learn it), proficiency (how advanced we are), how often each language is used, and the social contexts in which languages are spoken all matter as factors in seeing these benefits (Gracia-Tabuenca et al., 2024).

The brain therefore must select the language that is appropriate for the situation while reducing interference from the other language. In simple terms, a bilingual brain is constantly asking “so, which language do I need right now?” This is our attention and language control, which demands from our brain attention, inhibition and monitoring, however, bilingual language use can also engage domain-general cognitive functions including focusing attention, managing distractions and switching between tasks (Tao et al., 2021). All of which leads us to a brain that is extra fit to adapt – called brain plasticity.

Brain plasticity is the brain's ability to change and adapt as we learn and experience new things – for example, learning and repeated experiences can change how different areas communicate, how efficiently networks work and, in some circumstances, aspects of the brain's physical structure. Research suggests that bilingual experience may be associated with structural and functional brain plasticity across language and cognitive-control networks (Deluca et al., 2019; Li et al., 2014; Pliatsikas, 2019).

What about brain decline naturally caused by ageing? Cognitive reserve is the brain's ability to continue functioning effectively even when some age-related changes or brain damage are present – it's like having extra capacity or alternative pathways available when the brain's usual pathways become less efficient. Research suggests that lifelong bilingualism may contribute to brain reserve - Bilingual people have, in several studies, shown later onset of dementia symptoms (deterioration in cognitive function beyond expected ageing) and better cognitive functioning than would be expected from some measures of brain structure (Perani & Abutalebi, 2015; Perani et al., 2017; Costumero et al., 2020; Bialystok, 2021).

However, a recent study estimated that bilingualism was associated with a delay in dementia symptom onset of approximately 3.45 years, although evidence that bilingualism actually prevents dementia is much weaker. (Li & Coretta, 2025). This evidence suggests that lifelong language use may help the brain cope more effectively with age-related changes.

Their brain must learn that different people, situations and contexts may require different linguistic systems (languages)! Studies have found differences in visual habituation (process of paying less attention to something once it becomes familiar) and recognition memory in bilingual infants, as well as an ability to distinguish visual changes between languages that monolingual infants did not show in the same way. (Sebastián-Gallés et al., 2012; Singh et al., 2014).

This supports the idea that a child's brain is capable of learning more than one language, and combats the misconception that two languages confuse children. Reviews of infant research suggest that bilingual exposure can maintain flexibility in how children process speech and can alter developmental trajectories without impairing language acquisition overall. (Werker, 2012; Yeh et al., 2026).

Most importantly for us, you don't have to be raised bilingual to experience changes in the brain! Research of second-language learning interventions in later life has mixed results overall, but one study highlighted adults learning a language intensively for six months showed increased connectivity within white-matter pathways involved in language, particularly bilateral temporal-parietal networks involved in semantic processing (connecting words with their meanings) and phonological processing (working with the sounds of language), as well as right temporal-frontal pathways (Wei et al., 2023).

Research in Aotearoa is also beginning to show the educational benefits of bilingual learning in te reo Māori and English. A 2024 study of children aged five to seven in Māori-medium bilingual classrooms found that explicit teaching of phonological awareness (recognising sounds within words and blending these) and vocabulary, supported improvements in phonological awareness, non-word reading and expressive vocabulary. Importantly, growth in te reo Māori was positively associated with growth in English. (Denston et al., 2024). This challenges the idea that developing te reo Māori takes learning away from English, as growth in one language was associated with growth in the other (Denston et al., 2024).

Is learning a second language, like te reo Māori, beneficial to our roro? Forementioned research suggests more than likely. We could also ask if learning te reo Māori benefits our identity, wairua (spirit), community? Also, yes! Māori and Pasifika bilingual speakers have reported stronger ethnic identity centrality, while bilingualism strengthened the relationship between identity and wellbeing for Māori participants. (Matika et al., 2021). Other research in Aotearoa has similarly highlighted the importance of language and cultural identity to wellbeing, particularly for Māori young people (Denston et al., 2022). 

“If you speak more than one language, your brain age, or the health of your brain, is coming in at a couple of years younger than what your chronological (‘actual’) age is - a younger brain means a healthier brain... Learning a second language as a child at school or in your community is good, because it keeps your brain active and stimulated... It's never too early and it's never too late to learn a new language to challenge your brain."

That’s the wero (challenge) for Mahuru Māori i tēnei marama (this month). Keep your roro (brain) stimulated, challenge it to learn some new kupu (words), or even phrases! Jump in the deep end and enrol at Te Wānanga o Aotearoa next year, or a local class to learn a language that is meaningful to you. If you are bilingual already, why not learn a third, fourth language, listen to some music, pick up a quote from a telenovela – you brain just might thank you later.

And a timely reminder, that te reo Māori belongs – Ahakoa kei hea, ahakoa he aha (no matter where, no matter what).  

Kaiya Cherrington

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