He pulls faces. Constant hand gestures. Goes for "the kill" if anyone criticises him. Lewd and sexual comments and actions. Repetitive language.
According to that BBC item, 23k psychiatrists, think Trump is mentally ill? Is he?
His behaviour is bizarre, but is he mentally ill?
Some/all of his "traits" have been likened to autism and there is speculation that his youngest son is autistic. Is Trump?