Alzheimers is still not really fully understood (which of course would have to be the crucial first step in trying to find a cure).
But a lot is, and factors that matter seem to very much include LIFESTYLE;
>https://www.nih.gov/has a good article on the subject.
If you read that article you cannot help feeling that it sort of explains why Alzheimers mainly affects the elderly; reduced physical and mental activities.
Some occupational therapists in homes for the elderly have experimented with - yes, really - using a Nintendo Wii therapeutically; it does combine a bit of mental and physical stimulation and entertainment (let's face it, most therapy by repeating the same old things gets boring).