Besides, I do not think that depression should keep someone from being PM. It didn’t keep Churchill from being a great one.
We have come a long way in my lifetime in recognizing that mental diseases have a chemical component. The drugs that have been developed to bring those chemical imbalances back to a normal range have helped millions of people.
I agree that taking medication for certain types of mental illness is not a contraindication for serving in high office. It would worry me to have someone diagnosed with OCD in such an office though. It can have truly bizarre effects on behavior, decision-making, and prioritization, and is difficult to fully control with medication.