There is strong evidence to suggest that bilingualism has a positive effect on the adult brain. However, the impact of bilingualism in children has yet to be explored.
A recent study by the Universities of Reading and Georgetown is the first of its kind to target this issue; the joint team of international researchers performed a comprehensive study, where the brains of 41 children and adolescents aged 3-21 were scanned and analysed. Brain scans were then grouped into two categories of either bilingual or monolingual children, and subsequently compared. The study found that children who are bilingual reach adulthood with more gray and white matter as they undergo less brain deterioration, compared to children who grew up similarly but only spoke one language.
Gray matter is the area of the brain where the neuron bodies are found. An area of gray matter of particular importance is the cortex, or the outer edge of the brain. Gray matter, along with other areas of the brain, deteriorates as we age. This deterioration is seen through the shrinkage of the cortex. In order to measure gray matter deterioration, researchers often measure the volume, thickness and the surface area of the cortex; a depletion of these parameters over time is indicative of brain deterioration. These three matrices were analysed through brain scans of both monolingual and bilingual children and it was found that, despite gray matter beginning to deteriorate from a relatively early age, bilingual children showed less deterioration (hence, thicker and more voluminous cortices).
Upon a comprehensive analysis of several areas of gray matter in both mono- and bilingual children’s brains, the researchers found that specific areas showed less deterioration. These include the frontal (found on the forefront of the brain as highlighted in blue in the image below) and the parietal (the upper back portion of the brain, highlighted in yellow) regions of the cortex, which contribute to linguistics and articulatory functions.
Similarly, the researchers also found that white matter (the area of the brain in which the connections between neurons are found) was modified by bilingualism. Generally, white matter can be altered with experience and skill acquisition; it has been found that learning and maintaining new skills can lead to increased integrity of white matter, indicating optimized neuronal connections. The study found that bilingual children had increased white matter integrity, which suggests a higher affinity to language learning and control. Increased integrity of white matter obtained during childhood or adolescence may also preserve into adulthood.
The differences between the brains of monolingual and bilingual children suggest that bilingualism positively impacts brain development, which has extended benefits into adulthood. These results reinforce the advantages of bilingualism, while also providing the most comprehensive analysis of bilingualism effects in children, to date. Yet, further studies are required to establish the exact patterns of deterioration in both bilingual and monolingual children. Increasing sample size and reducing confounding factors may also be beneficial, particularly the ages at which the children acquire their second language, or their level of knowledge in their second language. Overall, this study is in line with existing evidence in adults that suggests that speaking more than one language positively affects the developing brain by reducing brain loss and deterioration.
Study: Pliatsikas, C., Meteyard, L., Veríssimo, J. et al. The effect of bilingualism on brain development from early childhood to young adulthood. Brain Struct Funct 225, 2131–2152 (2020). https://doi.org/10.1007/s00429-020-02115-5
Photo credit: Université du Luxembourg.
Featured photo credit: Mosaic, G. Vince (2016).