The human body is incredibly complex and we have quite limited tools to study it, so we are bound to arrive at wrong conclusions. That by itself is to be expected, but what does really worry me is this missing knowledge updating mechanism. It can take decades for quite a substantial update on what we thought we knew to trickle down from academia to practicing medical professionals.
At this point, if you have any kind of scientific literacy, it might be a good idea to verify whatever your doctor claims.
A recent ep of the Trickle Down podcast (premium offshoot of a show that studies conspiratorial thinking, Q Anon Anonymous), discussed how we learned to treat ulcers with antibiotics and then lost that information for something like fifty years. Changing the scientific understanding of their cause had a Greek doctor going to his country’s health ministry over and over and getting rejected despite results. I think you nailed it.
afaik, there is no reproducible causality for depression; we can't induce it. we only measure it's correlations and have % confidence in hypotheses.