An interview with cognitive neuroscientist Dr. Federico Gallo, who was born and raised in Crema, northern Italy, a town that “acts greater than it actually is” (Federico Gallo). Federico obtained his bachelor’s degree in psychology and cognitive neuroscience from Vita-Salute San Raffaele University in Milan, after which he proceeded to Moscow and Stockholm to complete his Doctorate. Short after defending his PhD in September 2022, Federico was awarded a Maria Skłodowska-Curie Postdoctoral Fellowship, that will span between 2024 and 2026. Ever since his bachelor years, he has been researching the role of life experiences, bilingualism in particular, in postponing and mitigating cognitive aging and dementia. Federico adds, ‘Hopefully, I’ll leave this world a tad better than I found it’.
Erika: A key concept when discussing prevention or mitigation of cognitive aging is that of cognitive reserve. What is cognitive reserve?
Federico: Cognitive reserve is a concept that has been introduced to account for the remarkable interindividual variability typical of cognitive aging. It is an individual “buffer” that allows to delay or mitigate age-related cognitive impairment. It can be defined as the discrepancy between the observed and expected levels of age-related cognitive impairment, given the observed level of age-related neural deterioration.
Erika: According to your article (Jan, 2022), you state that many lifestyle factors have been suggested to promote successful aging by means of cognitive reserve development, and bilingualism has been implicated as one such factor. Can you elaborate?
Federico: Many lifestyle factors have been observed to promote successful aging, some of which are crystalised (i.e., are experienced within a certain life stage), while others are dynamic (i.e., can vary across the whole lifespan). Examples of the first kind are the highest educational attainment or the level of occupational complexity (e.g., manual work vs. cognitively challenging work). Inside the second category, we find physical exercise, healthy dietary habits, size of one’s social network, amount of leisure activities, perceived positive support from one’s inner circle and, of course, bilingualism. However, bilingualism has some unique characteristics among this set of factors:
- It is ubiquitous: other activities may come and go, language is omnipresent;
- It is widespread: more than half of the world’s population is currently estimated to be bilingual;
- It is equitable: education, healthy diet, physical/leisure activities may require resources to be pursued
Erika: Locally, children learn both their national languages, Maltese and English, throughout their schooling years from a very young age. At home, they might be exposed to either language, or to both. Therefore, as a nation, we consider ourselves to be bilingual and according to research, we are at a cognitive advantage. How does acquiring and being proficient in both languages have such a putative beneficial role on executive functioning?
Federico: Widespread evidence shows that both language representations are constantly active in the bilingual brain, irrespectively of contextual needs or conscious intent. In order to successfully juggle their two languages, bilinguals rely on a cognitive device named language control, responsible for avoiding interference from the non-target language, managing conflict between competing alternatives in the two languages and, when needed, switching between them efficiently. The brain network underlying language control largely overlaps with the domain-general executive functions network. Thus, the daily cognitive training experienced by bilinguals results in eventual reinforcement of executive functions, both at the behavioural and at the neural levels.
Erika: Later on in secondary school, students then learn another or 2 foreign languages, usually a choice between German, French, Italian and Spanish. Does acquiring more than two languages, even later in adulthood, further preserve cognitive and linguistic functions as we age?
Federico: As per the question about adulthood, L2 age of acquisition has been repeatedly shown to exert a lesser impact on bilingualism-induced cognitive benefits, as compared to L2 proficiency or L2 exposure. Thus, the answer is yes, how fluent we become in our L2 and how often we use it seem to play a more important part in these beneficial effects.
As per the number of languages spoken, I recall a paper (Davis et al. 2008) in which, in a specific analysis, 3 or more languages spoken predicted a delay in Alzheimer’s Disease onset, while 2 languages did not. In other words, the more, the merrier!
Erika: What fundamental role does executive functioning play in the cognitive aging process?
Federico: Since they are integrative, high level cognitive processes that guide goal-directed and purposeful behaviour, impairments in executive functions can lead to general cognitive decline. At the same time, frontal lobes (that mainly underlie executive functioning) are among the brain regions most early and strongly targeted by age-related deterioration. Many models ascribe a primary role to executive functions in the aging process. Probably the most famous one is the posterior–anterior shift in aging (PASA) model (David et al. 2008). It argues that in the face of age-related efficiency loss in posterior-parietal regions of the brain we observe a shift towards more frontal processing, which is caused by the attempt to compensate for the loss of specific abilities by deploying domain-general, higher level cognitive control.
Erika: Does bilingualism enhance memory skills? If so, how?
Federico: Literature on this topic is not as prolific as for executive functions, but there are a few investigations available:
- Bilinguals were shown to outperform monolinguals on episodic memory ability, both at baseline and across time, in a longitudinal study spanning across 20 years (Ljungberg et al., 2013).
- Senior bilinguals were shown to outperform monolingual peers in executive-mediated memory recall tasks (Wodniecka et al, 2010) and executive-mediated working memory tasks (Bialystok et al, 2014).
- Senior bilinguals actively using their L2 were shown to outperform bilingual peers not exposed to their L2 and monolingual peers on semantic memory performance Arce et al., 2019).
Erika: Several investigations report that bilinguals outperform monolinguals in various executive functions tasks across the lifespan. Can you elaborate?
Federico: As expected given the mechanisms mentioned above, bilingual seniors have been repeatedly reported to exhibit better executive functioning, in a variety of tasks that include, but are not limited to, the Simon Task, the Flanker Task and the Stroop Task (e.g., Abutalebi et al., 2015; Bialystok et al., 2004, 2008; Bialystok, Poarch, et al., 2014; Del Maschio et al., 2018; Estanga et al., 2017; Gold et al., 2013; López Zunini et al., 2019; Incera, 2018). Similar effects have been reported for bilingual young adults, although findings being more inconsistent in this age group, probably due to confounding effects related to cognitively training activities other than bilingualism.
Erika: In your paper (Jan, 2022), you talk about the bilingual individual having this simultaneous activation of competing information, which leads to conflict, which is to be solved by the speaker. What is this conflict you mention?
Federico: Let’s make the case of an English monolingual speaker, aiming to produce the word “cat”. During this task, they will encounter interference by phonologically similar words, e.g., hat, bat, and also from semantically similar words, e.g., dog, mouse. As we can all testify, solving this interference quickly and accurately is not a big challenge for us. Now imagine a bilingual speaker during the same task: they will experience twice the interference, also arising from L2 counterparts of the target word and its alternatives. Beside this semantic level, competition between L1 and L2 also happens at the phonological level (imagine how the sound “a” is pronounced differently in, e.g., English and Italian), and the syntactic level, with alternative word order/grammatical structure choices available.
Erika: According to research, people who speak more than one language and who develop dementia tend to experience a later onset of this neurological disorder than those who are monolingual. Do you agree and how is this so?
Federico: Several investigations report that bilinguals, on average, develop mild cognitive impairment (MCI) 7-8 years later, and dementia 5-7 years later, than monolinguals. It has been observed that, for comparable levels of age-related neural deterioration, bilinguals are able to maintain better cognitive performance levels than monolinguals. This is probably to be ascribed to the bilingualism-induced training mentioned above, which results in structural and functional benefits for the executive brain network.
Erika: Why, in your opinion, is it important for educators to know the benefits of bilingualism?
Federico: We live in an aging world. Average life expectancy is constantly increasing, thus age-related cognitive decline is becoming a more and more central issue in our society. Indeed, dementia incidence is growing, but pharmacological solutions to age-related brain pathology are still unsatisfactory. Thus, finding non-pharmacological, lifestyle ways to prevent cognitive aging, as bilingualism, could hold a two-fold advantage: on the one hand, this type of research may equip governments with a tool to improve older adults’ quality of life. At the same time, it may provide a roadmap to ease the pressure on healthcare systems and public funds, which are well known to be disproportionally burdened by expenses devoted to older strata of the population. Thus, with this in mind, educators could prioritise bilingual programmes and related initiatives, and be aware of the potential a well-taught second-, third-, or fourth-language course may hold for the future of individuals and societies.
References
Arce Rentería, M., Casalletto, K., Tom, S., Pa, J., Harrati, A., Armstrong, N., … & Zahodne, L. (2019). The contributions of active Spanish-english bilingualism to cognitive reserve among older hispanic adults living in California. Archives of Clinical Neuropsychology, 34(7), 1235-1235.
Bialystok, E., Poarch, G., Luo, L., & Craik, F. I. (2014). Effects of bilingualism and aging on executive function and working memory. Psychology and aging, 29(3), 696.
Davis, S. W., Dennis, N. A., Daselaar, S. M., Fleck, M. S., & Cabeza, R. (2008). Que PASA? The posterior–anterior shift in aging. Cerebral cortex, 18(5), 1201-1209.
Gallo, F., Kubiak, J. & Myachykov, A. (2022). Add Bilingualism to the Mix: L2 proficiency modulates the effect of cognitive reserve proxies on executive performance in healthy aging. Frontiers in Psychology, Vol. 13. Pp. 1 – 8.
Ljungberg, J. K., Hansson, P., Andrés, P., Josefsson, M., & Nilsson, L. G. (2013). A longitudinal study of memory advantages in bilinguals. PloS one, 8(9), e73029.
Wodniecka, Z., Craik, F. I., Luo, L., & Bialystok, E. (2010). Does bilingualism help memory? Competing effects of verbal ability and executive control. International Journal of Bilingual Education and Bilingualism, 13(5), 575-595.