My Dad passed away from from dementia, and he was deep into it before the tests finally officially confirmed it. Literally EVERYONE around him absolutely knew it, but so much of the test had to do with numbers - telling time, adding numbers, etc. - that he did deceptively good on it. He never had a problem with numbers, right up to the end. He had been a Mathmatics major in college, and was hard-wired for numbers. Even dementia couldn't disturb that. I saw a 60 minutes piece on Tony Bennett, and he was exactly the same way with music.

So just because you pass the test, doesn't mean you aren't already showing strong symptoms of dementia. I've never taken the test, and neither has my mother. You only take it when someone suggests that it's a good idea because you've been showing symptoms. Of Trump is taking it, it's probably because those around him are becoming alarmed at his behavior.