In the last 25 years, tens of billions almost all spent chasing the amyloid beta hypothesis, with other theories getting the short end of the stick.
It didn't start changing until outside researchers wrote a major editorial about how bad it was in Nature.
The biggest alternative is the infection hypothesis - amyloid beta is left by our immune reaction to diseases that manage to get into the brain. If that idea had been pursued for 25 years, we might actually know by now what the real connections are with HSV1 (warts), gum disease, and so on.
That presumes there is a treatment, and the proposal to research it would have been funded, and it would have been found to be effective. But yes, research dollars are somewhat of a fixed pie, and there are always people who don't get a slice.
It didn't start changing until outside researchers wrote a major editorial about how bad it was in Nature.
The biggest alternative is the infection hypothesis - amyloid beta is left by our immune reaction to diseases that manage to get into the brain. If that idea had been pursued for 25 years, we might actually know by now what the real connections are with HSV1 (warts), gum disease, and so on.