My wife drank short black coffees, drank a glass of red wine at dinner, had a good diet, mainly oily fish, & got early onset dementia at 50.
No-one in her family ever suffered from Alz.
Statistical relationships can be made to show pretty well anything IMHO, I honestly believe the only hope we have is in the stem cell area.
If you like proper, strong coffee (I do for sure), drink it, its a great pick-me-up!