Bilingualism And Alzheimer'S Disease

As globalization brings more and more diverse cultures together, it also brings along their languages; thus has bilingualism become more and more prevalent in modern-day society. Bilingualism is found to have advantages and disadvantages — while bilingualism can result in a more limited vocabulary, lower fluency in either language, and slower recognition, the advantages are far more paramount (Baumgart and Billick 276). Among these advantages is a particularly astounding benefit: bilingualism has the potential to delay the onset of Alzheimer’s disease through enhanced cognitive reserve. Therefore, while critics may beg to differ, it is evident that this key benefit alone outweighs the minor disadvantages.

Alzheimer’s disease is a type of dementia, meaning that it causes loss of memory and other functions to the point of interfering with daily life. At the same time, Alzheimer’s disease contributes to a majority of dementia cases, which is why it is more well-known than other types of dementia. Even though the majority of cases are age-related, there are numerous instances of individuals below the age of 65 that suffer from the disease; this is known as early-onset Alzheimer’s. It is a progressive disease, meaning that its symptoms worsen over time — it begins with mild memory loss, but in its later stages, it can culminate in an inability to respond to the environment, or to even move. This decline of brain function can unfortunately be indirectly fatal, making Alzheimer’s disease the “sixth leading cause of death in the United States” (“Facts and Figures”). It is clear that the symptoms of the disease are serious, but its pervasiveness is even graver, with a third of seniors dying with some form of dementia, killing more than breast and prostate cancer combined (“Facts and Figures”). It is clear that Alzheimer’s disease is a severe ailment, and for this reason, the fact that something so prevalent as bilingualism can delay its onset is so amazing — it is one step in the right direction for the unfound treatment.

The first time researchers realized that there could be a factor to delay the manifestation of Alzheimer’s disease symptoms was when they found “individuals with no apparent symptoms of dementia who were nonetheless found at autopsy to have brain changes consistent with advanced Alzheimer's disease” (Harvard Health Publishing). Therefore, they concluded that there must have been some sort of “protective factor” that allowed the brain to undergo the physiological damage associated with Alzheimer’s disease, without manifesting the symptoms; thus was coined the term “cognitive reserve. ” Cognitive reserve broadly refers to the flexibility of the brain in performing tasks. This helps stave off symptoms of Alzheimer’s, such as memory loss, by counteracting the physical changes in the brain that Alzheimer’s disease imposes. In this manner, the development of cognitive reserve acts as a reservoir that the disease eats away at, until it is “used up. ” At that point — which is not always reached in life, as in the aforementioned autopsies — the individual would begin to manifest the debilitating symptoms. This is the theoretical mechanism of how cognitive reserve delays the onset of Alzheimer’s.

Where does bilingualism play into the scheme of things? The most consolidated mechanism of bilingualism is known as “joint activation,” meaning that both languages are active and available while the other is being used (Baumgart and Billick 277). Therefore, when a language is either being spoken by or spoken to a fluent bilingual, there is a sort of “attentional control” issue that arises, which can be attributed to some of the inconveniences mentioned earlier. While this can result in lower fluency in both languages compared to monolinguals, this attentional control requires executive control, a complex decision-making process that chooses from the two languages available to the person, and provides them with the word they seek (Baumgart and Billick 277).

Therefore, just as practice makes perfect, the continuous use of executive control strengthens its neural pathways, thereby mitigating slower recognition, while also making the brain better at executive control. Executive control is one of the primary functions used in memory retrieval as well as most other activities, making it important in protecting against Alzheimer’s; hence, better executive control connotes better defense against Alzheimer’s disease. Bilingualism has also garnered much interest as a potential cognitive reserve variable in part because of the fact that it is a primarily environmental factor for which no special education or intelligence is needed, unlike others, such as education, intelligence, socioeconomic status and aerobic fitness (Zheng et al. 10). What is even more interesting are the physiological changes in the brain that bilingualism brings. For example, there is evidence for increased gray matter density in bilinguals relative to monolinguals; this is important as a natural part of aging and Alzheimer’s disease is a decrease in gray matter density, meaning that the brain will be able to stay healthier for longer (Zheng et al. 11).

Furthermore, “there is also evidence for a series of connections between the prefrontal cortex, anterior cingulate cortex, inferior parietal region, and basal ganglia used for bilingual language production” (Baumgart and Billick 278). While these structures are obscure to the average person, it is worth noting that these structures are not physically close to each other in the brain; therefore, it appears that bilingualism exercises a large portion of different parts of the brain, which could explain why it develops cognitive reserve. This also provides reasoning for why a brain with larger cognitive reserve that does show symptoms of Alzheimer’s disease (such as dementia) will be more damaged than one with a smaller cognitive reserve — this “reserve” consists of strengthened neural connections and increased gray matter that work together to maintain function, even with existing damage.

At the same time, these assertions are backed up by numerous studies. A study conducted by Zheng, et al. studied the age of onset of Cantonese/Mandarin bilinguals, and found that this bilingualism postponed the onset of AD symptoms by 5. 5 years (215). Furthermore, in other studies to see how brain structure is affected, the study by Schweizer et al. found greater amounts of brain atrophy in the bilingual group, even though the cognitive function of both the bilingual and monolingual groups were the same (Zheng et al. 216). This shows that even though the bilingual group had undergone more brain damage over time, they had the same cognitive ability as their younger, monolingual counterparts — this agrees with the idea of increased cognitive reserve.

Similarly, research observing how the function differs between the two groups revealed less effective glucose uptake by the bilingual patients (Zheng et al. 216). Glucose uptake shows how active the brain tissue is, and this shows that the brain function is more compromised in the bilingual group, yet they have the same cognitive ability as the monolingual group. Altogether, a lot of research has been conducted to study how these two variables work together, and most of it agreed with the theory; the few others were merely inconclusive, but there were none that showed an adverse effect of bilingualism on the onset of Alzheimer’s disease, supporting the fact that the other disadvantages are less important. I have had multiple experiences with individuals suffering from Alzheimer’s disease, unfortunately. My paternal grandmother had it before her passing, and now my uncle and aunt do too, which aligns with the fact that Alzheimer’s disease has a genetic component. The part that hurt most was watching such bright personalities fade into literal oblivion, and the fact that they were unaware was all the more painful.

My uncle was quadrilingual, in fact; he spoke Urdu, Punjabi, English, and German, so while I do not assert that bilingualism goes as far as to be a cure for Alzheimer’s disease, I cannot say whether or not his cognitive reserve was enhanced. I can say, however, that he developed the disease at 70, while my grandmother developed it much earlier in her life. She was monolingual, and spoke only Punjabi. These experiences go to show how even if something can delay the onset of the terrible ailment that is Alzheimer’s, it gives caretakers hope; even though bilingualism is no cure, the fact that it can delay the onset is a step in the right direction that any small disadvantages are worth.