Is Alzheimer's on the rise, or are are simply more people getting diagnosed with it due to increased life expectancy? A quick google search yields avg. age of

Is Alzheimer's on the rise, or are are simply more people getting diagnosed with it due to increased life expectancy? A quick google search yields avg. age of diagnosis to be 80 years; 50 years ago life expectancy in the western world was 70 years, so a bunch of people would've probably passed from Heart Diseases and stroke back then, before getting to the point of dementia. So it's pretty reasonable to assume that more research went towards things like heart diseases, etc. the past 50 years, than towards dementia and the likes. But now, as we see a steady decline in those things (or at least them being the leading cause of death), we see more longevity-related diseases, like cancer and dementia. What I'm trying to get at here is: Yes, maybe there have been ruling forces in academia and research that have stopped alternative theories, but wouldn't a simpler explanation be that there have simply been more pressing issues up until now, and we're now seeing a rise in things like dementia, due to having deal with those previous problems. We have dementia in one side of our family, even though most have gotten it in their late 70s / early 80s, so I obviously hope they come up with something - which I have no doubt will happen, the next decades.