chance that if you are under 50 you have much lower odds of ending up with Alzheimer's than your parents do. Unfortunately, even if the current crop of drugs is successful they will be used to prevent the disease or delay it. There will still not be much that can be done by the time someone is experiencing memory or cognition decline.
We aren't there yet, and we need to continue putting more than the current 1.4 billion per year into research, but we are getting there finally (we spend $16,000 on care for Alzheimer's for every $100 we spend on research for a cure or prevention).