The Journal of Neuroscience has recently published a study titled "Lifelong Bilingualism Maintains Neural Efficiency for Cognitive Control in Aging" which shows how bilingualism can help maintain youthful cognitive control abilities in aging.
Two experiments were conducted that included a total of 110 participants. Some of them only spoke one language, while the others had been bilingual since childhood. Brain imaging was used during the test to observe performance in older and younger monolingual and bilingual adults.
The researchers found that even all participants were able to complete the task, the ones who were bilingual were able to do so more quickly.
This is not the first research that shows that being bilingual could help to protect the brain from age-related disease. Other studies published in the last two years show that being able to speak two languages could help delay the onset of diseases in ageing populations, for example Alzheimer's.
Abstract from The Journal of Neuroscience (9 January 2013).
The Journal of Neuroscience: http://www.jneurosci.org/
Read more articles in Trends in cognitive science and in Neurology.