The age of Democrat politicians is symptomatic of their absolute lust for power. They refuse to give up their positions even if they have to be wheeled into position.
Perhaps congress should pass a law that says any elected federal official can have their mental competence challenged up to twice a year if they meet certain criteria, including but not limited to advanced age, making bizarre comments (like Guam tipping), conflating/confusing disparate events (Putin invading Korea), and others.
Not sure who would administer the tests, but it would probably have to be a panel of licensed mental health practitioners that aren’t all beholden to one political ideology.
I don’t have a proposed remedy for if the elected official fails their competency test. Various options could be on the table, including suspension or removal requiring a special election for their replacement.