A good example of this is the Amyloid Hypothesis for dementia. All the papers that "proved" this concept have been retracted, but after 8 years. Good work showed that looking at amyloid load in random brains showed no correlation close to 20 years ago, but amyloidists begat more amyloidists, until finally there was a drug that reduces amyloid by 30%. All it did was cause brain bleeds, deaths and no benefit, but the FDA approved it anyway. MDs will still explain how it really "should" work. It was all a cabal of US scientists who dominated all symposia, only inviting speakers who were in their cabal.

Meanwhile, genetic forms of neurodegeneration are highlighting defects in DNA damage repair. So, 25 years and billions wasted while there still are no treatments.