I know a lot of legitimate research supports various versions of the amyloid hypothesis, but I don't buy that these likely fraudsters had minimal impact.
You said that Lesné was "not that highly cited". But his main fraudulent paper was cited 2,300 times, making it the fifth most highly cited Alzheimer's paper since 2006! [1]
Berislav Zlokovic's likely fraudulent papers were cited 11,500 times! [2]
It's hard to imagine these highly papers didn't redirect at least some scientists to do pointless followup studies. Of course, in the counterfactual world the scientists might still have been doing pointless studies, but we'll never know...
Blog post author here. The paper was the 4th most cited paper in Alzheimer's research since 2006. So I feel reasonably confident that if it had never been written, some researchers at the margin would have chosen to work on other hypotheses instead, and perhaps those other avenues would have been more fruitful.
How much time could have been saved towards an effective treatment? It could be as high as a decade, but of course more likely it was zero years. I averaged it out to 1 year.
Now suppose you think that 1 year is orders of magnitude too high, and that in expectation it averages out to a 1 day delay. Even then, I estimate 100,000 QALYs would be lost, making this a tragically high impact case of misconduct.
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Final point: Nobody doubts that science is error correcting. The point is that the errors are corrected far too slowly and many never get corrected at all. It's incredibly hard to develop good theories when you know that 30-50% of the results in your lit review are false.