A new study published this month in the journal Psychology and Aging, shows that people who speak two languages from the age of 10 are more resistant to mental deterioration associated with aging. The study focuses on the fact that "crystallized intelligence", or early-learned habitual knowledge, is better retained than other intellectual capabilities. The findings seem to indicate that having two distinct cognitive resources for organizing information about the world trains the bilingual mind to focus on multiple stimuli with more ease, and to respond to their environment more efficiently.

The report cites 3 studies that used a stimulus test designed to distract the subjects, and found that bilingual subjects were better able to process multiple competing stimuli and to solve distinct problems more quickly. The study also found that as these subjects aged, they suffered less of the cognitive decline found in their monolingual counterparts.

The reports authors suggest that the brain process used in order to focus on one stimulus while putting aside irrelevant atmospheric information may be the same one used in operating within one language, even in the presence of another. Long-term bilingual people have consistent experience in alternating between competing cognitive environments, responding to different sets of stimuli, and maintaining within each cognitive system the coherence necessary for fluency.

The bilingual individuals studied had all used their two languages daily from the age of 10, leading to the analysis that the second language must start early and be a solid cognitive structure by the time the mind matures. But whatever the implications of the starting point, the report clearly shows that bilingual fluency offers many benefits for intellectual longevity. [For more: APA]