Posted on Friday, June 3, 02011 by Colin Farlow
Ellen Bialystok, a research professor of psychology at York University in Toronto, claims a polyglot child develops cognitive efficiency from constantly speaking more than one language: "[t]he constant necessity to resist attending to a second language in favor of the one in use, and the need to switch between languages demands more effortful attention than does monolingual speech production, and this greater cognitive demand fosters the development of a higher level of attentional control." 
This affect appears to help stave off the symptoms of Alzheimers. In Bialystok’s study individuals with Alzheimers who had equal levels of outward symptoms were compared. The study essentially shows that people who regularly speak more than one language can perform certain cognitive tasks with significantly less amount of functioning brain matter than can someone who only speaks one language. It seems that bilingualism delays the onset of outward symptoms associated with Alzheimers; provided everything else is equal, those who have the disease and are bilingual will still suffer from brain deterioration, but their symptoms will be less severe. In this sense, bilingualism serves some protection against the effects of Alzheimers.
In a recent New York Times article about her research Bialystok explains, "[t]here’s a system in your brain, the executive control system. It’s a general manager. Its job is to keep you focused on what is relevant, while ignoring distractions. It’s what makes it possible for you to hold two different things in your mind at one time and switch between them. If you have two languages and you use them regularly, the way the brain’s networks work is that every time you speak, both languages pop up and the executive control system has to sort through everything and attend to what’s relevant in the moment. Therefore the bilinguals use that system more, and it’s that regular use that makes that system more efficient."
The claim that bilingualism can actually be advantageous is significant, because in the past bilingualism was generally regarded as a liability. Bialystok notes, "until about the 1960s, the conventional wisdom was that bilingualism was a disadvantage. Some of this was xenophobia. Thanks to science, we now know that the opposite is true." Bialystok describes questions posed to her about which language should be taught to children whose parents speak more than one language, “People e-mail me and say, “I’m getting married to someone from another culture, what should we do with the children?” I always say, “You’re sitting on a potential gift.”
 Schweizer TA, et al., Bilingualism as a contributor to cognitive reserve: Evidence From brain atrophy in Alzheimer's disease, Cortex (2011), doi:10.1016/j.cortex.2011.04.009 (available at http://www.ncbi.nlm.nih.gov/pubmed/21596373)
The author of this post, Colin Farlow, is a 02011 summer intern with the Rosetta Project. He recently graduated from Indiana University, where he studied East Asian Languages and Cultures and Philosophy.