Bilingualism 'can increase mental agility':
ScienceDaily (Aug. 3, 2012) — Bilingual children outperform children who speak only one language in problem-solving skills and creative thinking, according to research led at the University of Strathclyde.
A study of primary school pupils who spoke English or Italian- half of whom also spoke Gaelic or Sardinian- found that the bilingual children were significantly more successful in the tasks set for them. The Gaelic-speaking children were, in turn, more successful than the Sardinian speakers.
The differences were linked to the mental alertness required to switch between languages, which could develop skills useful in other types of thinking. The further advantage for Gaelic-speaking children may have been due to the formal teaching of the language and its extensive literature.