There is a lot of evidence that oxidative stress is a major "cause". But one has to look at what causes oxidative stress. There is a lot of scientific literature about this topic.
Dr Dale Bredesen has a method (not a medicine) to successfully treat Alzheimer's: 9 out of 10 patients are cured. He is currently doing a larger study and might be interested in Y Combinator since his method has many variables and he wants to use software to make it available to many doctors.