From the story here:
The participants were given an intelligence test in 1947 at the age of 11 and were retested in their early 70s, between 2008 and 2010. Of the participants, 262 said they were able to communicate in at least one language other than English. Of those, 195 learned the second language before the age of 18, while 65 learned the language after this age.
Researchers found that those who spoke two or more languages had significantly better cognitive abilities in later life, compared to what would be predicted from their performance in the tests at age 11.
