The human brain is vastly complex, compared to that of other species, as it has more neurons to facilitate communication by way of neurogenesis, the process by which new neurons are generated. That being said, humans do not keep all the neurons we make through neurogenesis since our brains exercise a “use it or lose it” principle as we age. This concept refers to our brain reinforcing communication and signal transmission among neural circuits we actively use and that are essential to complete common activities, such as eating or walking. To facilitate this process, our brain will eliminate our existing neuronal connections that are unnecessary to carry out our regular tasks. Although this procedure is generally beneficial, promoting brain efficiency, there is still the risk of excessive neuronal pruning. If this were to occur without any intervention, a person may be at a higher risk of developing cognitive decline symptoms and being diagnosed with memory-related conditions, such as dementia or Alzheimer’s Disease. Such neurodegenerative conditions are especially prevalent among seniors, as aging can bring about a host of comorbidities that are associated with dementia, such as high blood pressure (i.e., hypertension). Additionally, seniors may not be able to engage in the same level of physical activity as they did when they were younger. These conditions contribute to the risk of developing dementia, which thrives off poor nutrition and a lack of exercise.
Such risk factors are important for seniors to consider. This is because Alzheimer’s Disease is caused by an accumulation of amyloid plaques and neurofibrillary tangles (i.e., tau) in the brain. When this happens, neuronal communication becomes disrupted, causing neuronal apoptosis (i.e., neuronal death) and the eventual prognosis of Alzheimer’s Disease. If left untreated, the brain will start to shrink through its pruning process, and the patient is at risk of developing further comorbid conditions, such as depression. Consequently, researchers suggest patients engage in stimulating activities that can strengthen their brain’s neuroplasticity mechanisms to improve memory, executive functioning, and attention. One activity that can help seniors accomplish this is being bi/multilingual and/or engaging in second-language acquisition. Doing so continuously exercises the brain to think and communicate in more than one language. As a result, newly formed brain circuits can facilitate the process of learning a new language that would have otherwise been eliminated by the brain’s use it or lose it principle.
Scientists refer to this linguistic function as a “cognitive reserve,” which means that bilingualism acts as a buffer to cognitive decline. In other words, the onset of dementia becomes delayed in bilingual patients compared to monolingual ones, even if the person has a family history of such inheritable conditions. Researchers speculate this is because bi/multilingual individuals can use their knowledge of different languages to identify a word, even when one language fails them. For example, if a person forgets how to say “apple” in English, they may instead remember how to say it in another language, such as “manzana” in Spanish. This still reveals an understanding of what an apple is, which will continuously strengthen the neural circuits used to make the association. In contrast, a monolingual speaker would have a harder time doing this, as they only know the word “apple,” hence they would not know what else to call the fruit if they were to forget its name.
Furthermore, monolingual and bi/multilinguals utilize different parts of their brains when processing information. Scientists found that bilinguals use the posterior and subcortical brain regions more than monolinguals, who are more reliant on the brain’s frontal circuits. Due to this neurological specialization, monolinguals are at a higher risk of developing dementia at an earlier age as the posterior and subcortical regions, such as Wernike’s and Broca’s areas, are known to influence our working memory and cognitive abilities. In addition, bi/multilinguals have more white and gray matter found within their brains, especially in the left hemisphere. This distinction means that bi/multilingual brains are better at processing information, which is indicative of a robust memory, and engage in faster neuronal communication compared to monolinguals. Such a finding is monumental within the cognitive decline sphere, as practitioners have studied how gray and white matter declines with age, especially when someone has a neurodegenerative condition. Therefore, discovering how impactful language acquisition is within this scope of research has the potential to uncover more information about treatment plans and strategies to mitigate any negative effects of cognitive decline.
This difference between individuals makes sense, as bi/multilingual people have to use the brain regions that would allow them to switch between languages more frequently than monolinguals, who would rely on the one language they are familiar with. This switching practice exercises the brain, strengthening its neuronal communication abilities and brain function. Therefore, the more a person switches between languages, the stronger their brains will be at fighting off neurodegenerative conditions as they are reinforcing their neuronal muscles for synapses to transmit information with one another. Ultimately, neurogenesis would be supported, as the brain subsequently creates new neurons to account for this new information it is receiving, developing the ability to learn and take in data with ease.
Along with physiological alterations, second-language acquisition can help seniors communicate with a diverse array of individuals and family members who speak different languages. This can fortify interpersonal connections and support those who are experiencing cognitive decline. As mentioned above, neurodegenerative conditions are comorbid with neuropsychiatric ones, such as depression and anxiety. One reason for this is that a person living with cognitive decline may feel lonely as their condition might contribute to social isolation and a lack of relationships. This association is so prominent that, in a recent study by the Alzheimer’s Society, approximately 30% of participants with mild to moderate dementia reported moderate loneliness. We should consider these numbers, especially as this study is not accounting for those who experience severe dementia or Alzheimer’s Disease symptoms. With that being said, the more languages a person can speak, the greater the chances they will talk with others and expand their social network. On top of that, the seniors may feel more connected to their cultural roots and community if they are able to speak and understand the language(s) associated with their cultural heritage. Consequently, this may boost their quality of life, lessen their feelings of loneliness, and improve any cognitive decline symptoms.
Despite these advantages that bilingualism and second-language acquisition bring forth, there are not many available studies that investigate if they can be used as an effective treatment plan for dementia. This may be because there is limited research regarding language acquisition in older adults as the current focus is on language acquisition in children, who are believed to be more successful at obtaining language fluency during early development. This mentality is slowly shifting, however, as we start to see more programs being developed for adolescents and young adults to learn second-languages in school and new apps being crafted to help facilitate this process, such as Duolingo. Still, more resources should be made and integrated to better understand how retaining bilingualism and/or learning new languages among seniors can impact cognitive decline. That way, we could come up with new treatment plans for this under-researched population and learn new ways we can obtain language fluency past childhood. From a cost-analysis perspective, this would be exceptionally helpful to examine for patients who cannot afford the traditional treatment plans for cognitive decline, such as medications or therapy. Instead, they could rely on the languages they grew up with or are actively learning, which might serve them in ways a healthy diet or physical exercise cannot.
Overall, there is a clear and positive connection among language acquisition, bi/multilingualism, and cognitive decline. That being so, new patients, caregivers, and neurodegenerative researchers will all benefit from future research conducted within this field. This is especially true as the brain is still a mystery to us with many of its regions still awaiting to be tested and understood by the scientific community.
Sources:
- Use it or lose it: How neurogenesis keeps the brain fit for learning – PMC
- Risk factors for dementia | Alzheimer’s Society
- Alzheimer’s disease – Symptoms and causes – Mayo Clinic
- Study shows learning a second language thwarts onset of dementia – LAS News
- How does the bilingual experience sculpt the brain? – PMC
- Brain Structure in Bilingual Compared to Monolingual Individuals with Alzheimer’s Dementia: Proof of Concept – PMC
- Grey Matter: What It Is & Function
- Alzheimer’s Society funded study reveals a third of people with dementia and two thirds of carers feel lonely
- Bilingualism and Aging: Implications for (Delaying) Neurocognitive Decline – PMC
