Gerard makes a good point about the Twenty-Fifth Amendment, but there may a related idea that helps (and shows the limits of the Amendment). Perhaps the President, as with many folks as we age, has a front lobe problem. These ideas apply to many more than the President.
There is some evidence that our frontal lobe decays as we age; when that happens executive control goes down and we are less able to manage many things. This abstract for the paper Aging, Executive Functioning, and Social Control says it all rather well
Aging is associated with atrophy of the frontal lobes of the brain, which are the seat of executive functions. Because successful social functioning often requires executive control, aging can lead to unintended social changes via deficits in executive control. In this article I review evidence that, due to losses in executive control, aging leads to increased prejudice and social inappropriateness and, under certain circumstances, increased depression and problem gambling. I then discuss theory and research suggesting possible interventions that might ameliorate unwanted social changes brought about by executive decline.
Yes. The part of our brain that is “the seat of executive functions, which include tasks such as planning and controlling thought and behavior” decay with age. This change can lead to “poor executive functioning, including reduced ability to inhibit irrelevant or unwanted thoughts.” How does this play out? It seems a variety of things can happen.
Prejudice: “Automatic or unintentional stereotypic thoughts appear to be common in most people (Devine, 1989), and it might be that older adults have greater difficulty inhibiting these stereotypic thoughts despite their efforts to avoid being prejudiced. Thus, older adults might also be more prejudiced than younger adults because they can no longer inhibit their unintentionally activated stereotypes.”
Inhibition and Social Inappropriateness: “findings suggest a dissociation between knowledge of social rules and the ability to follow them that is consistent with other types of frontal lobe damage.”
Inhibition and Depression: As I read the paper, the results are not settled except that “age-related inhibitory deficits might also contribute to late-onset depression by impairing control of excessive rumination (a tendency to focus on one’s problems without engaging in active problem solving,
which exacerbates and prolongs depression).” The paper is clear that the key issue is “those older adults who rely on inhibitory control to stop themselves from ruminating (either chronically or when confronted by negative life events) are likely to develop problems with rumination if they have poor executive control.”
Inhibition and Gambling: Again not conclusive: “Analogous to the case with late-onset depression, poor inhibitory ability is unlikely to lead to gambling problems in all or even most older adults. Rather inhibitory deficits might lead to gambling problems only among those who struggle with their
impulse to gamble. That is, people who gamble and who are impulsive by nature might be at risk for developing gambling problems as they age, due to losses in the ability to restrain their urge to gamble.”
SOLUTIONS: Apparently we are able to exercise and control earlier in the day rather than later.
Another paper notes the limits of the above findings, and both call for longitudinal studies to understand how things change as we age.
Nonetheless, although arm-chair psychology has problems, the list above seems to map rather well to President Trump’s behaviors. None of that excuses them. Unlike our parents, or us as we age, the President’s statements, orders, and actions have consequences that affect hundreds of millions, if not, billions of people. If the above is useful or interesting, I expect someone could and will track the President’s habits and look at time of day. As Gerard noted, it is unlikely these traits will rise to incapacity. And yet, as with our elders and us as we age, at some point, someone gets to run tests and see whether everything is working well. Again for the Office of the President whether we want such tests seems to be answered as no. Both or any party is not to be trusted with such a tool. But that is a problem for another time.