I’m not sure if there are studies comparing PFS CSF levels to others who have taken the medication. It isn’t easy to conduct the study or find control patients willing to participate.
Also not clear to me that Jacobs has done a U-turn. I haven’t look at the paper he published in years, but I think he was suggested certain psychiatric/personality factors would predispose one to developing PFS upon exposure of Propecia treatment. It is controversial because it sounds like he is suggesting PFS is not physiological, but it really isn’t the same thing. Given so many factors impact the human endocrine system (bio/psycho/social), it isn’t too unreasonable to think that some guys would be less able to withstand the shock of taking Propecia. It is also why this has gone under the radar so long.