BILINGUALISM AND ITS ADVANTAGES: A BRIEF REVIEW OF RECENT FINDINGS

Definition of Bilingualism

Bilingualism is the condition of knowing two languages rather than one. For the purpose of this presentation this author only addresses the situation where the bilingual has native or native-like fluency in both languages. In bilinguals two language systems both overlap and are separate. The bilingual uses two language systems in a variety of ways depending on the linguistic and communicative demands of each situation. A bilingual may have relatively greater fluency with the formal or informal style in either language. S/he may speak, but not read or write, in one of the languages. A bilingual can switch back and forth from one language to another at will and effortlessly. Factors that affect what language is used and when include what language is spoken in the home (versus language of instruction at school, language spoken in the neighborhood or by friends, language used by the media), age of emigration to an area where the home language is not widely spoken, parental attitudes towards maintenance of the native language, social status of the native language, and even politically motivated pressures.

How to Become Bilingual

People may become bilingual either by acquiring two languages at the same time in childhood (birth)

Growing up in societies where bilingualism is societal

Growing up in a bilingual family (parents speak 2 different languages)

or by learning a second language sometime after acquiring their first language. Many bilingual people grow up speaking two languages.

In school and/or living in a different country/region

Advantages of Bilingualism

The question of whether bilingualism can influence cognitive functions in healthy aging as well as in brain diseases is currently a topic of an intense debate. While controversy exists regarding the cognitive effects of bilingualism, a growing body of literature appears to support certain clear-cut advantages.

PART 1. Protection against dementing illnesses: Lifelong bilingualism may delay dementia onset.

The dramatic increase in the proportion of elderly people in the world population has led to a growing importance of age-related diseases, in particular dementing illnesses. Importantly, this development is not confined to the western world. Dementia is recognized as a major health issue in India, China and many other countries across all continents. It has been described as a “public health priority” by the WHO and became the topic of the December 2013 G8 economic superpowers in London (UK). During the past ten years a number of researchers have examined closely the possibility that dementing conditions may be staved off by non-pharmacologic means. A brief review is provided here.

Bialistock et al (2007) examined the effect of lifelong bilingualism on maintaining cognitive functioning and delaying the onset of symptoms of dementia in old age. The sample was selected from the records of 228 patients referred to a Canadian Memory Clinic with cognitive complaints. The final sample consisted of 184 patients diagnosed with dementia, 51% of whom were bilingual. The bilinguals showed symptoms of dementia 4 years later than monolinguals, all other measures being equivalent. Additionally, the rate of decline in Mini-Mental State Examination (MMSE) scores over the 4 years subsequent to the diagnosis was the same for a subset of patients in the two groups, suggesting a shift in onset age with no change in rate of progression.

Perani and Abutalebi (2015) recently studied CT scans of 85 older patients with Alzheimer’s; 45 spoke both German and Italian and 40 spoke only one of the two languages. Bilinguals outperformed single- language speakers in short- and long- term memory tasks, scoring on average three to eight times higher — even though their scans showed more severe deterioration in brain metabolism. They reported that bilingual individuals were on average five years older than their monolingual peers. Brain scans provided a clue as to why this might be: Those who spoke more than one language were thought to have better functional connectivity in frontal brain regions, presumably allowing them to maintain better cognition despite their disease.

Commenting on Perani’s findings, Heather Snyder, director of medical and scientifc operations at the Alzheimer’s Association said “It’s that idea of cognitive engagement — continuing to use it or you lose it” [...] “People who are bilingual and are going back and forth with two different languages throughout their day are activating a specifc way of thinking that’s making those brain connections.”

Findings suggested that in bilingual patients with Alzheimer’s dementia, neuronal loss is accompanied by compensatory increase of connectivity, allowing bilingual patients to maintain high neuropsychological performance and cognitive functioning longer than monolingual patients.

Perani and Abutalebi (2015) concluded that lifelong bilingualism appears to encourage a powerful cognitive reserve delaying the onset of dementia by approximately 4 years. As to the causal mechanism, because speaking more than one language heavily relies upon executive control and attention, brain systems handling these functions are more developed in bilinguals resulting in increases of gray and white matter densities that may help protect from dementia onset. These neurocognitive benefits are even more prominent when second language proficiency and exposure are kept high throughout life.

Alladi and his colleagues (2013) conducted the largest study so far documenting a delayed onset of dementia in bilingual patients and the first one to show this delayed onset separately in different dementia subtypes. It was the first study reporting a bilingual advantage in those who are illiterate, suggesting that education is not a sufficient explanation for the observed difference. Overall, bilingual patients developed dementia 4.5 years later than the monolingual ones. A significant difference in age at onset was found across Alzheimer disease dementia as well as frontotemporal dementia and vascular dementia. This was also observed in illiterate patients. There was no additional benefit to speaking more than 2 languages. The bilingual effect on age at dementia onset was shown independently of other potential confounding factors such as education, sex, occupation, and urban vs rural dwelling of subjects. The findings were interpreted in the context of the bilingual advantages in attention and executive functions.

Abutalebi et al., (2014) reported that in English/Cantonese speakers when they retire, those who   maintained high usage of a second language showed neuroprotective effects in terms of increased grey matter in certain brain areas that may eventually protect against cognitive decline. The authors concluded that if we are to profit from the protective effects that bilingualism provides, governments and health systems should activate social programs and interventions to support the maintenance of the second language among senior citizens.

Estanga et al. (2017) broke new ground by combining cognitive and biological approaches to the study of the possible effects of bilingualism on dementia onsel. Based on the data from the Guipuzkoa Alzheimer Project, they reported that, compared with monolinguals, early bilinguals are not only characterized by a better cognitive performance in several domains and a lower prevalence of Alzheimer's disease but also by lower levels of t-tau in their cerebrospinal fluid. They suggested that sustained activation of noradrenergic signaling pathways associated with bilingualism could provide a possible mechanism linking results of their study with previous observations of delayed onset of dementia in bilinguals (Bak and Robertson 2017).

Constantly switching between two languages appears to make the brain work harder leading to structural changes in the brain, creating a “neural reserve”, and rendering the bilingual brain more resilient against aging (Gold, 2015). It appears that the more bilingual people switch from one language to another during their lifetimes, the more their brains are prepared to alternate pathways that maintained thinking skills even as Alzheimer’s damage accumulates.

The potential social and economic benefits of delaying the onset of dementing illnesses (in particular Alzheimer’s Disease) are very significant and have been addressed recently and reviewed (e.g.Bialistock et al., 2016; Brookmeyer et al., 2007; Gingrich, 2015).

Conclusion

With the population aging and a dramatic increase in the number of senior citizens, public health systems will be increasingly burdened with the need to deal with the care and treatment of individuals with dementia. Scientific evidence demonstrates how a particular experience, bilingualism, appears to protect cognitive function in older age and delay onset of symptoms of dementia. The potential savings in both human costs in terms of demented patients and economic considerations in terms of public money if symptoms of dementia can be postponed are considerable.

REFERENCES

Abutaleb,i J., Canini, M., Della Rosa, P.A., et al. (2014). Bilingualism protects anterior temporal lobe integrity in aging. Neurobiol Aging 35, 2126-33.

Alladi S, Bak TH, Duggirala V, et al. (2013) Bilingualism delays age at onset of dementia, independent of education and immigration status. Neurology ;81:1938-1944.

Bialistock, E., Fergus, I.M.,Craik, M. F. (2007). Bilingualism as a protection against the onset of symptoms of dementia. Neuropsychologia, 45- 2, 2007, pp 459-464

Bialystok, E., Abutalebi J., Bak, T.H., Burke, D.M., and  Kroll, J.F. (2016) Aging in Two Languages: Implications for Public Health Ageing Res Rev. Pp.27: 56–60.

Brookmeyer, R, Johnson, E., Ziegler-Graham, K., and Arrighi, H.M. (2007). Forecasting the global burden of Alzheimer's disease. Alzheimers Dement. 3(3):186-91.

Estanga A, Ecay-Torres M, Ibañez A, Izagirre A, Villanua J, Garcia-Sebastian M, Iglesias Gaspar MT, Otaegui-Arrazola A, Iriondo A, Clerigue M, Martinez-Lage P. (2017) Beneficial effect of bilingualism on Alzheimer's disease CSF biomarkers and cognition. Neurobiol Aging 50:144-151

Perani, D., Abutalebi, J. (2015). Bilingualism, dementia, cognitive and neural reserve. Current Opinion in Neurology: December 2015 - Volume 28 - Issue 6 - p 618–625

Gingrich N. Double the N.I.H. budget. New York Times. 2015 Apr 22; 2015

Gold, B.T. (2015) Lifelong bilingualism and neural reserve against Alzheimer's disease: A review of findings and potential mechanisms. Behavioural Brain Research, 281, pp. 9-15

WHY WE CREATED THE SPANISH NEUROPSYCHOLOGICAL EXAMINATIONS

The project to create a book of cognitive test norms specifically for Spanish-speaking populations had two purposes: The first one was to address the fact in the United States neuropsychology professionals are frequently called to evaluate monolingual Spanish-speaking immigrants or individuals whose knowledge of English is not sufficient to warrant an examination in this language. The second, probably more obvious purpose, was to provide Spanish speaking colleagues in Spanish-speaking countries some appropriately normed tools of neuropsychological assessment. Indeed, when this project was started in the 1990’s there were few Spanish language instruments both the United States and in Spanish speaking countries. Use of translated English language instruments and norms collected with English speakers with Spanish speaking patients was rampant -a practice lacking scientific plausibility and of questionable ethical grounding.

The project consisted of selecting tests with a good track record in the field of clinical neuropsychology, adapting them to respond to language and cultural demands, and collecting data from individuals free of neurological or psychiatric illness in the border area of the United States and Mexico on the one hand and Madrid, Spain on the other.

The project also wanted to address a population that is seldom looked at by neuropsychologists: individuals with extreme low levels of education. Indeed, while neuropsychological testing has developed chiefly in English-speaking areas and with individuals with relatively high levels of formal education (10 or more years of schooling), a large number of countries in the world have populations with an average of six or fewer years of formal schooling. Investigation on the effects of this lack of formal education on cognition has been largely ignored by the scientific community. There are, of course, exceptions. These will be considered here in future additions to this blog.