My entire research (work life) was centered on Alzheimer's disease and related neurological disorders so I have a good overview of the field (and have contributed to it a bit as well). Despite much improved knowledge on mechanisms and causes sadly there has been very little to show for cures.
And now the incidence is dropping seemingly all on its own:
"The incidence rate of dementia in Europe and North America has declined by 13% per decade over the past 25 years, consistently across studies. Incidence is similar for men and women, although declines were somewhat more profound in men. These observations call for sustained efforts to finding the causes for this decline, as well as determining their validity in geographically and ethnically diverse populations."
Neurology August 04, 2020; 95 (5)
Even if we don't know why its a good thing!
