The cognitive benefits of multilingualism may include increased resistance to degenerative diseases like Alzheimers, according to Jared Diamond, writing in Science Magazine. Speaking more than one language will not delay the onset of brain deterioration, but multilingual speakers seem to have the ability to deal with the consequences better and can delay the symptoms by up to four years, according to the Wall Street Journal.
The mental agility required of young people, especially between the ages of 1 and 5, who are learning and practicing more than one language builds up what scientists call “cognitive reserve”. This reserve can be used when the brain is damaged. Speakers of more than one language have developed a mental agility, known as cognitive control that allows them to focus instantly on something else.
Diamond says that on one of his field trips in Papua New Guinea, none of his companions spoke fewer than five languages. One spoke 15 languages. More languages are spoken in the remote, inaccessible valleys of Papua New Guinea than anywhere else on Earth.