Generally, you rely on experts.

Who typically became experts by adhering to the conventional wisdom set by gatekeepers.

"Science advances one funeral at a time" feels apt.

Sadly, the problem isn't confined to Alzheimer's.

Whenever only a few people decide what is "right," the same pattern of stifled innovation will generally manifest itself not by design or from malice, but because it's hard for a small group to be 100% right on what works and what doesn't -- especially on matters as inscrutable as neuroimmune diseases.