Unfortunately not. Current researchers are working on development of biomakers using blood test instead of fluid from the spine for the early detection of alzheimer's. Also working on development of vaccine or medications to modify not to slow dowm the progression of alzheimer's (think of someone who is new onset diabetes or elevated cholesterol which is modifiable).
Not really but maybe. Let's be clear. There's no way to "prevent" alzheimer's disease in the traditional sense like you can prevent some infections w/vaccinations. However, many studies demonstrate a lower population risk in those who eat nutritiously, exercise regularly & maintain a reasonable weight & waist, eg healthy lifestyle. This data is observational & doesn't prove cause & effect. But i believe it gives hope.