Much of the time, following Trump's train of thought was difficult, if not impossible. In response to a question from the moderator David Muir about whether he regretted anything he'd done during the January 6 insurrection, Trump said:

I have said "blood bash - bath." It was a different term, and it was a term that related to energy, because they have destroyed our energy business. That was where bloodbath was. Also, on Charlottesville, that story has been, as you would say, debunked. Laura Ingraham, Sean Hannity, Jesse - all of these people, they covered it. If they go an extra sentence, they will see it was perfect. It was debunked in almost every newspaper. But they still bring it up, just like they bring 2025 up. They bring all of this stuff up. I ask you this: You talk about the Capitol. Why are we allowing these millions of people to come through on the southern border? How come she's not doing anything - and I'll tell you what I would do. And I would be very proud to do it.

Evading the question is an age-old debate-winning tactic. But Trump's response seems to go beyond evasion. It is both tangential, in that it is completely irrelevant to the question, and circumstantial, in that it is rambling and never gets to a point. Circumstantial and tangential speech can indicate a fundamental problem with an underlying cognitive process, such as logical and goal-oriented thinking. Did Trump realize that his answer was neither germane to the question nor logical?

Trump's speech during the debate was repetitive not only in form but also in content. In psychiatry, the tendency to conspicuously and rigidly repeat a thought beyond the point of relevance, called "perseverance," is known to be correlated with a variety of clinical disorders, including those involving a loss of cognitive reserve.

If a patient presented to me with the verbal incoherence, tangential thinking, and repetitive speech that Trump now regularly demonstrates, I would almost certainly refer them for a rigorous neuropsychiatric evaluation to rule out a cognitive illness. A condition such as vascular dementia or Alzheimer's disease would not be out of the ordinary for a 78-year-old. Only careful medical examination can establish whether someone indeed has a diagnosable illness - simply observing Trump, or anyone else, from afar is not enough. For those who do have such diseases or conditions, several treatments and services exist to help them and their loved ones cope with their decline. But that does not mean any of them would be qualified to serve as commander in chief.

The tables regarding Biden and Trump have taken quite the dramatic turn as Joe proved unable to counter Trump's bombast under the pressure of an intense debate. Tuesday night we witnessed Trump having the same types of difficulty with Harris. And based on the events of the last 60+ days, the GOP should clearly recognize how this is going to end.