Damaging my mind is my biggest fear. I had a simple surgery a year ago(shoulder arthroscopy), and I specifically said that I don't agree to general anesthesia or any kind of sedatives, because even a small probability of a small brain damage isn't worth it for me.
Doctors tried to push me into accepting the general anesthesia, saying that it's the only option(and that we lose brain cells every day really, so who cares). I went to a different clinic where a doctor agreed to do the surgery under local anesthetics and without sedation without any problems. Said someting along the lines "don't worry, man, your brain is gonna be fine."
He failed to mention that local anesthesia can also lead to neurotoxicity, and I was too ignorant to know about it(for some reason I assumed that local anesthetics are harmless, and didn't do my research).
During the surgery I felt the symptomps(dizziness, difficulty speaking), consistent with neurotoxicity caused by local anesthetics.
I don't notice any permanent damage, though I doubt that I'd be able to tell. 6 months after the surgery I have developed tinnitus, but I can't tell if it's connected to it or not.
Anyway, my point is that no way in hell would I agree to the surgery if I'd have known the risks.
Also, before that, doctors pushed me into unnecessarily taking general anesthesia for a routine procedure. They convinced me that it can't be harmful, and I was too young and socially awkward to ask more questions or argue.
I also fear dental anesthetics. There is research indicating that they can cause neurotoxocity. I can easily sit through filling regular cavities(with a dental laser it really isn't that painful), but I'm not sure what I would do if I have to get root canal. I would take any option over anesthesia, but I don't know of any alternative.
Some doctors say that it's just an irrational fear. But given that there's some research saying that even dental anesthesia can cause neurotixicity, I'm not sure what's so irrational about not wanting my brain cells to die. My brain is what matters to me the most in the world, far more than anything else, it has infinite value, because that's literally "me", so even small chance of small damage is worth avoiding at all cost(in my value system).
It's infuriating how casual doctors are about such risks, especially in cases when they can be avoided. I understand taking necessary risks when it's a life-saving surgery, but when you have alternatives, I think patient should be able to make an informed choice.