The Bilingual Advantage:
Alzheimer's Association International Research Grant
Currently, over 55 million individuals in the United States speak a language other than English at home (2007 American Community Survey). While a bilingual population of 20% contributes to controversy in policy, multilingualism may mitigate America's other demographic concerns.
Apart from being a culture of many cultures, the United States is a culture of aging individuals. Currently, the number of U.S. citizens 65 and older numbers 39.6 million, and is predicted to reach 72.1 million by 2030 (USDHS Administration of Aging, Alzheimer’s Association; Supplemental Figure 2). While improved life expectancy reflects strides in medicine, it is invariably accompanied by age-related afflictions. For example, one natural result of old age is brain cell death, which contributes to the elderly’s slower reaction, response, and processing times (Abutalebi et al. 2015). The loss of brain power is only accelerated by dementias such as Alzheimer’s disease (AD). Apart from incurring a health care expenditure of 150 billion each year, there 469,000 new AD cases in 2014, and AD annually claims 27 lives for every 100,000 individuals. Predicting that the rate of AD will increase from 5 million to 13.8 million in 2050 poses an extensive economic and health burden (Alzheimer’s Association). Simultaneously, the accompanying social and psychological impact is undeniable.
Considering the wide-reaching impact of AD in society, we believe research investigating causes and preventative treatments is essential. While neither brain cell death nor disease onset are avoidable, lifestyle choices can delay symptoms (Alzheimer’s Association). These factors include education, occupation, gender, and intellectual stimulation, which contribute to a phenomenon known as “cognitive reserve” (Alzheimer’s Association; Abutalebi et al. 2015). Through intellectually engaging activities, neurons branch out like a tree branches, making contact with other cells, and improving information processing. Thus, when afflicted with dementia, the brain has a “reserve” of more densely connected neurons.
One largely disregarded environmental factor that may contribute to this “cognitive reserve” is bilingualism. A bilingual person continuously selects one language and suppresses the competing language (Weissberger et al. 2015). This form of suppression requires greater executive control from a bilingual, executive control being the mental process that is the final step of common, daily actions: deciding which way to walk, finding where we left our keys, knowing how to plan our day or how to solve a math problem (Heidlymayer et al. 2014; Weissberger et al. 2015). Executive control is examined through reaction speed on a variety of psychological tests (e.g. Flanker test, Stroop test etc.), of which many unequivocally demonstrate a “bilingual advantage” (Heidlymeyer et al. 2014).
How does being bilingual and having improved executive control play into Alzheimer’s disease? Greater executive function may reflect a difference in brain structure between monolinguals and bilinguals. When investigating difference in brain structures between mono- and bilingual patients with the same AD diagnosis, bilinguals had greater cell loss in specific brain regions (Schweizer et al. 2012). Bilingual subjects who displayed greater degeneration than their monolingual counterparts did not appear more impaired in behavioral tasks, despite decreased neural matter. This observation may result from denser connections of brain cells in regions involved with executive control (Abutalebi et al. 2015). Thus, greater “cognitive reserve” may correlate with the observed 4-5 year delay in Alzheimer’s disease in bilingual patients (Bialystok et al. 2007). However, the way in which greater executive control delays Alzheimer’s onset, and its therapeutic implications, is largely unexplored.
However, this protective effect of language is not noted in the Alzheimer’s Association’s annual review publication. Undoubtedly, an investigation of multilingualism’s effect on the onset and course of Alzheimer’s disease is essential to future research. Thus, we are proposing important research which would be of interest to the Alzheimer's Association International Research Grant Program. The resulting data could be disseminated to the Alzheimer’s Association collaborators: the World Wide Alzheimer’s Disease Neuroimaging Initiative, as well as the National Institute on Aging (Alzheimer’s Association – Partnerships).
Specifically, we propose to match mono- and bilinguals on lifestyle (i.e. level of education, occupational status, exercise etc.) and AD advancement based on clinical assessments. Because bilinguals include individuals who grew up in a multilingual household, and those who adopted a second language later in life, participants will complete self-report questionnaires regarding their language status. Further, we will test their executive function through a variety of executive control tasks, targeting information suppression, memory, and attention skills. While participants complete these tasks, brain imaging techniques including magnetic resonance imaging (MRI) will be utilized to assess activated brain regions. Once relevant brain regions are determined, the density and complexity of brain cells will be determined via functional MRI images and neuron tracing programs, to assess marked differences in brain degeneration of mono- and bilingual AD patients. Specifically, we expect to see greater atrophy in aged AD bilinguals despite better performance on behavioral tasks. These results would imply that language training of the elderly may be a viable form of treatment (Antoniou et al. 2013). However, to test whether language training could function as a viable therapeutic measure, monolingual patients would undergo a trial language education for six months. If cognitive improvement and increase in brain volume is observed, we could conclude that language acquisition is not just protective, but possibly regenerative. This would be a ground-breaking observation (see supplemental Figure 1 for a potential therapeutic model).
In summary, strides in research on the link between bilingualism and AD prevention would provide essential economic, social, and health benefits. Finding further therapeutic measures could alleviate the suffering of AD patients, their family members and friends, and reduce the extensive economic cost burdening individual families and the health care system. Additionally, using language-based learning as disease intervention comes at low cost to afflicted individuals. It does not require production of costly medication, avoids deleterious side-effects, and enriches the lives of those engaging their minds.
Additionally, investigating the protective effect of language is vital for clinicians who prescribe treatments, nursing homes, Alzheimer care facilities, and even non-profit organizations targeting education policy such as the National Association for Bilingual Education (NABE). As a result, current Elementary and Secondary School educators could begin stressing second language learning in school-aged children. Knowing another language would not only prepare children for a globalized and interconnected world, but provide neuroprotective advantages.
Ultimately, the proposed research impacts each and every citizen. All are faced with one grim realization: the process of growing old and its associated effects on cognition. Pursuing bilingualism can be cost-effective, foster understanding, and maintain health. It may be as easy as starting with a resounding “Si!”
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Abutalebi, J., Guidi, L., Borsa, V., Canini, M., Della Rosa, P. A., Parris, B. A, & Weekes, B. S. (2015). Bilingualism provides a neural reserve for aging populations. Neuropsychologia, 69, 201-210. doi: 10.1016/j.neuropsychologia.2015.01.040
Administration of Aging. (2012). Future Growth. Retrieved March 9, 2015, from http://www.aoa.acl.gov/Aging_Statistics/Profile/2013/4.aspx
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