Is Multilingualism good for cognitive function?

The evidence points that way, though it's not yet conclusive. Multilingualism has one of the more geographically consistent evidence bases in dementia research, though two recent meta-analyses converge on an important nuance: it appears to delay when symptoms appear, not whether dementia develops at all. That's reflected in an evidence score of 67/100 for its role in cognitive function, drawn from 7 studies, with an estimated impact on longevity rated moderate (46/100).