[W]e know there is little relationship between the amount of amyloid in one’s brain and your memory function. In fact, those “super-agers”—your 95-year-old great-great-aunt who finishes the crossword puzzle in 20 minutes, is president of the bridge club and has a better golf handicap than you—may have just as many amyloid plaques in her brain as AD patients.
Another AD researcher, Rudolph Tanzi, recently made the same point, suggesting that it's the inflammation caused by these plaques in some patients that leads to dementia:
http://www.aarp.org/health/brain-health/info-2016/alzheimers...