I just heard a brilliant lecture on the subject of the above title by Dr. Prof. Rudolph Tanzi of the Harvard Medical School and chairs of many Aging Research labs and Institutes. I suggest you use the link https://en.wikipedia.org/wiki/Rudolph_E._Tanzi to have a glance of his numerous (first) contributions to research/discoveries in this area. Last night he just gave the last of the six lectures on the Brain Research Series of Lectures at Brookhaven. His lecture fulfills my prime criterion of a good lecture: Accessible to a general audience and yet impressive to experts.  

As a complete novice and layman on this subject, here is what I got out of the lecture using a metaphor. Imagine a beautiful forest of trees (you brain). The forest is populated with a lot of tourists with matches. Suppose each tourist lights a match and disposes of the match carelessly. Many of these lit matches will start small fires. But no one notices these small fires until the whole forest is burning with a raging inferno. Now the firefighting brigades move in trying to extinguish the wildfire. They may succeed and put out the fire or they may not. In any case parts or the whole forest is lost forever. This is the situation with Alzheimer disease. By the time symptoms’ of the disease are noticeable, the patient (like the forest) is already at the forest wild fire stage. Treatments even successful will be too late. In fact, Alzheimer diseases actually start decades earlier at the match lighting stage but completely un-noticed. It is here that treatments should be administered if diagnosed and if possible. What kind of treatment? It is here that Tanzi's research and other research are now directed. How?: identify the tourist (through genetics) with matches. give each of them ordinary tin cans or glass jars so that lit matches can be disposed of securely regardless how many matches are there. In actual practice this means cycle through combination of available ordinary medicines (tin cans and glass jars) in pharmacies to evaluate their efficacy in treating these precursors to causing Alzheimer disease which is manifested by the inflammation of brain neurons and synapses that kill them. They have already (i.e., currently) scored some successes in lab animals and are awaiting approval for human trials. Thus, we are on the precipice of a major revolution in the advance of practical treatments of the disease. In the meantime what can each of us do to help protect ourselves. His recommendation is SHIELD which stand for: SLEEP, HANDLING stress,  INTERACT socially, EXERCISE, LEARN new things, and DIET. Each one of these activities promote brain health and prevents/isolates those Alzheimer causing matches.  

I'll try to find out if the 1.5 hour lecture is recorded and if so what is the link. 

PS. In fact Dr.Tanzi are so convinced about the efficacy of these drug combinations that he is willing to give out the information even before FDA approval so long the patient is willing to accept the disclaimer that they are doing so at their own risks..