I suspect if/when they find out what causes Alzheimer's it will be multifactorial. Not any single one smoking gun, but a combination of environmental plus genetic contributors. But that is just a guess.

One problem with research on the subject is much of the money spent will be on drugs to treat the symptoms of the disease rather than on what causes it and how to prevent ever getting it. Because that is where the money is, selling a pill to treat it. Lots more money to be made treating disease rather than preventing it. So that is where much of the focus is.

One positive about the research he is talking about is at least it is looking potentially at a contributing factor which could become part of a prevention program. Lots better to prevent something happening rather than have it happen and try to treat it. Have a diabetic friend that had a toe cut off yesterday. Would have been much better to have prevented the diabetic damage rather than try to fix it after the fact.