Recent Canadian research notes that knowing two languages always helps, especially in Alzheimer’s.

Researchers at Baycrest's Rotman Research Institute analyzed the records of 211 patients and found that those who spoke more than two languages over the years experienced a delay in the onset of their symptoms by as long as five years.

"We are not claiming that bilingualism in any way prevents Alzheimer's or other dementias, but it may contribute to cognitive reserve in the brain which appears to delay the onset of Alzheimer's symptoms for quite some time," said lead investigator Fergus Craik.

Cognitive reserve refers to compensatory use of other parts of the brain, other than affected regions, and enriched brain vasculature. These are thought to provide a general protective function against the onset of dementia symptoms.

Researchers noted that the Alzheimer’s patients’ brains deteriorated regardless of language skills; however bilingualism appeared to have delayed certain symptoms. Another earlier study led by Ellen Bialystok of York University in 2007 also made similar findings.