Language Learning and Alzheimer's

As people get older, they're obviously concerned that they might start showing symptoms of Alzheimer's or dementia. So often you hear that learning another language can help stave off Alzheimer's. Not entirely clear whether this means someone who already is bilingual or multilingual and therefore has these defenses against the onset of Alzheimer's. Or if someone takes up the study of languages in old age or older, when they're older, does that help stave Off Dementia? The gist of it is that learning languages is good for you. Any kind of brain activity is good forYou. Doing Sudoku, playing the piano. Anything that activates the brain cells is better for you than sitting in front of