Bilingualism : Brain Boosting Defense Against Alzheimer’s Disease

Source: Knowable Magazine

With the growing prevalence of Alzheimer’s Disease in today’s society, many have begun to look at ways to prevent or delay the onset of memory symptoms that come with this dementia. Multiple studies have shown that bilingualism can delay the onset of Alzheimer’s Disease symptoms by years. Let’s take a look at the current literature surrounding this claim.

What is Bilingualism?

Source: Sloverlinett

Bilingualism is the ability to speak two languages. It is typically acquired in childhood from parents who speak two different languages or children in two different cultural settings (5). This differs from monolinguals, who are people who only speak and understand one language. In this article, we will use two conditions of bilingualism: active and passive. Passive bilinguals are people who can comprehend a second language but have poor or no fluency. Active bilinguals are categorized as people who can speak and comprehend a second language (6). Our focus today is on active bilinguals and their cognitive advantages.

Studies have found that bilingualism can increase one’s cognitive reserve, which is the resilience to brain pathology through neural efficacy and/or the use of compensatory neural networks. Brain resilience is associated with the brain’s ability to maintain cognitive function, which includes brain reserve, cognitive reserve, and brain maintenance.

• Neural reserve: can be associated with the differences in the resilience of existing cognitive networks
• Neural compensation: due to the utilization of alternative networks, cognitive function is maintained during atrophy (brain deterioration)

It has been theorized that neural compensation and increased brain reserve strengthen the brain’s resilience to the symptoms of neurodegeneration through the promotion of neuroplasticity (6). Neuroplasticity is the brain’s ability to form new neuronal connections throughout one’s lifetime. The neurobiological foundation obtained over one’s lifespan is through enriching and stimulating experiences, one of those being learning a second language (7).

Source: Neurodivergent Insights

Benefits of Bilingualism on Cognitive Function

Benefit 1: Neuroprotective through Cognitive Competition

Source: Danish Bhatti

The general consensus is that when one learns a second language, the two languages compete for selection. When the two languages compete, it can contribute to one’s cognitive reserve as being an enriching and challenging experience. This competition leads to bilingualism being neuroprotective (2).

Benefit 2: Increase Brain Matter and Connectivity

Source: Verywell Mind

It has been shown that bilingualism can selectively increase grey matter volume early in second-language acquisition, the product being a new circuit for second-language processing, which can also be used for executive function. Grey matter in the brain contains the majority of the brain’s nerve cells, which are essential for brain function. The theory is that bilinguals circumvent brain damage with these new pathways (2).

Bilingualism is shown to promote white matter integrity, especially in areas related to better proficiency in the second language, especially the superior longitudinal fasciculus, which connects the parietal lobe to the frontal and temporal regions (2,6). White matter connects the grey matter and is the majority of brain volume. More connectivity = improved cognitive function!

Benefit 3: Strengthens Cognitive Circuits and Executive Functioning

Source: Addvantages

Being bilingual can aid in a stronger use of executive function in the brain, which includes suppressing and engaging a specific language. Executive functions include more complex cognitive processing like inhibition, working memory, etc. Code-switching, or switching of languages when engaging in conversation, has been shown to activate the frontal regions of the brain (4). It has also been shown that there is more activation in the posterior and subcortical regions of the brain in bilinguals versus monolinguals. These areas are important for language comprehension and production as well as executive functioning. Learning a second language and learning when to use it increases activation in various areas of the brain, leading to more neural connections and greater cognitive reserve.

It is important to note that the overall concept of learning a second language isn’t the only factor that contributes to the neuroprotective properties of bilingualism, but also the need to navigate new cultural environments (2, 3).

Bilingualism Delays Alzheimer’s Disease

Source: Pace Hospitals

Alzheimer’s Disease is a type of dementia associated with memory loss that affects around 7 million Americans (5). Alzheimer’s dementia typically involves atrophy, or loss of brain cells and their connections in the medial temporal lobe, leading to mild cognitive impairment and subjective cognitive decline (7).

Bilingualism has been shown to delay the onset of Alzheimer’s symptoms by 4–5 years compared to monolinguals. When comparing monolinguals and bilinguals with the same symptoms, bilinguals will often have more brain damage, especially in the hippocampus, which is a key region for memory (2,6,7). This demonstrates how bilinguals can withstand the effects of increased brain damage longer than monolinguals due to their increased cognitive reserve.

A study conducted by Alladi et al. found that in India, there was a 4-year delay in symptoms from 391 bilinguals versus 257 monolinguals, independent of education, gender, occupation, etcetera (2). The large-scale delay found in 300+ people goes to show how effective learning a second language may be in preserving the brain’s integrity.

A cross-sectional MRI study conducted in Spanish dementia patients showed that bilinguals had decreased brain volume versus monolinguals, both displaying similar cognitive symptoms (higher atrophy at the same cognitive level). More specifically, there was lower functional tissue volume especially seen in areas relating to bilingualism, such as the cingulate gyrus, which helps regulate emotions and decision-making, and the striatum, involved in movement and reward processing (6). These brain regions are essential in executive functions, which people with bilingualism constantly use.

The structural adaptations and consistent use of these areas can contribute to one’s cognitive reserve, aiding in bilingual individual’s resilience to neurodegeneration. By having lower functional tissue volume (lower brain matter) in these areas in bilingual patients with similar symptoms as monolingual patients, we can see how these areas, used more in bilinguals, are equally efficient as in monolinguals, even with lower volume.

Source: Costumero et al.

It is important to note that bilingualism does not affect incidence rates of Alzheimer’s disease, but other sets of symptoms, meaning that it can aid in slowing down Alzheimer’s symptoms, but not completely prevent the disease (2). There are also differing results on the neuroprotective properties of bilingualism in various individuals (2). Additionally, studies have reported inconsistent results regarding the neuroprotective properties of bilingualism in various populations, potentially due to differences in study design and participant demographics

Can You Start Now?

Source: Uncaged

Yes! It is never too late to begin learning a new language. The frequency and application of the language are more effective than at what age you learned the second language (4). Finding activities that challenge and stimulate your brain, such as learning a second language can improve your cognitive reserve, leading to resilience against brain pathology such as Alzheimer’s Disease. (6) Embracing bilingualism not only enriches personal and cultural experiences but also serves as a proactive defense for your brain’s long-term health.

Works Cited

1. Alzheimer’s Association. (2023). Alzheimer’s disease facts and figures. https://www.alz.org/alzheimers-dementia/facts-figures
2. Anderson, J. A. E., Hawrylewicz, K., & Grundy, J. G. (2020). Does bilingualism protect against dementia? A meta-analysis. Psychonomic bulletin & review, 27(5), 952–965. https://doi.org/10.3758/s13423-020-01736-5
3. Bak TH, Long MR, Vega-Mendoza M, Sorace A (2016) Novelty, Challenge, and Practice: The Impact of Intensive Language Learning on Attentional Functions. PLoS ONE 11(4): e0153485. https://doi.org/10.1371/journal.pone.0153485
4. Bilingualism Delays the Onset of Alzheimer’s Symptoms. (2020). Uclahealth.org; UCLA Health. https://www.uclahealth.org/departments/neurology/about-us/neurology-lab-profiles/bilingualism-delays-onset-alzheimers-symptoms
5. Britannica, T. Editors of Encyclopaedia (2024, November 13). bilingualism. Encyclopedia Britannica. https://www.britannica.com/topic/bilingualism
6. Costumero, V., Marin-Marin, L., Calabria, M. et al. A cross-sectional and longitudinal study on the protective effect of bilingualism against dementia using brain atrophy and cognitive measures. Alz Res Therapy 12, 11 (2020). https://doi.org/10.1186/s13195-020-0581-1
7. Coulter, K., & Phillips, N. A. (2024). Bilinguals show evidence of brain maintenance in Alzheimer’s disease. Bilingualism: Language and Cognition, 1–10. doi:10.1017/S1366728924000221