Follow
https://www.wsj.com/amp/articles/can-you-keep-your-brain-fit-with-duolingo-babbel-and-other-language-apps-606de053?mod=latest_headlines
"being bilingual was correlated with a four-to-six-year delay in dementia symptoms"
非中原地区方言加普通话算不算bilingual，这些地区的老年痴呆会不会少发一点？
