Should candidates be required to go through a physical & mental exam prior to running or being appointed for office? Reagan's Alzheimer's?

Im thinking no here, the medical info would have kept the DNC from fielding a candidate this time, and the psyche exam can get politicized really easily. the diagnostic manual that exists is so ambiguous that literally anyone can be diagnosed with something if they keep talking long enough, and that parameters for those diagnosis are way to subjective. Narcissism alone would wipe out almost everyone who would ever consider running for office.

My concern, is that when elected officials ( Legislative & Judicial ) are usually in there for a LONG, LONG, Long time.
When is it time to tell them to leave?
When they drop dead at their desk? ( i.e. Thurman, President Reagan's Alzheimer's?) ; what happens to a JUDICIAL appointment like the Supreme Court who may have a disease, but does NOT wish to disclose it, and it may render them incapable ?)
Supreme Court Justices are appointed for life, correct?

I am more concerned about whether a candidate is principled and has a strong set of values.

The liberal democrats complained about Trumps mental status. and Trump is a very capable man but these same liberal democrats say nothing about their senile president, Biden. It is obvious that Biden isn't hitting on all cylinders. The democrats are guilty of elder abuse for the way that use the puppet, Biden. I don't like old Joe but I do feel sorry for him.