Do you have a source for this claim? There are plenty of mental health disorders (in the DSM-V) that are tied to one gender or another. Whether these are grounded in some physiological basis or serve to re-affirm social expectations is a whole other story.
I think you're probably right but on your link there I see a review article (from the US) criticizing the lack of diversity in studies. It is followed by papers from countries like Uzbekistan, Iran, Iraq, Mexico, Austria, Korea. A few from Italy. The US certainly seems under-represented.
It doesn't need to be from the research experience. Research is not a straight line from A to B. One has to form wrong hypotheses, discard them completely, improve upon them, etc. Some paths are from A are MORALLY forbidden from pursuing.