To measure neurological age, the scientists used magnetoencephalography to measure the brain activity of 728 people with varying ages and levels of linguistic ability. They then used AI to process the results to calculate a normal level of brain connectivity at any given age. A second unrelated group of 144 people were then scanned and compared, comprising equal numbers of people speaking one, two, three or four languages.
Dr Lucia Amoruso, from the Basque Center on Cognition, Brain and Language in San Sebastian, said: “In simple terms, people who spoke more languages tended to have brains that looked younger than expected for their chronological age. The effect was not only related to the number of languages spoken. Higher language proficiency and earlier acquisition of a second language were also associated with more delayed brain ageing. This suggests that multilingual experience matters as a gradient: it is not simply about being bilingual or not, but about the depth and duration of language experience.”