The 25th Amendment, proposed by Congress and ratified by the states in the aftermath of the assassination of President John F. Kennedy, provides the procedures for replacing the president or vice president in the event of death, removal, resignation, or incapacitation. The Watergate scandal of the 1970s saw the application of these procedures, first when Gerald Ford replaced Spiro Agnew as vice president, then when he replaced Richard Nixon as president, and then when Nelson Rockefeller filled the resulting vacancy to become the vice president...
https://www.law.cornell.edu/constitution/amendmentxxv
Does "incapacitation" also include mental incapacity? We have a POTUS who has called himself the "Chosen one", the King of Israel, sought to purchase a major territory of another sovereign nation, called it a "nasty" response when they said it was "absurd" and actually called off a visit to that country out of pure pettiness. This aside from the numerous other deranged utterances made over the years. So.. at what point can the 25th be invoked? Does it only apply to physical capacity?