As a past president of the American Psychiatric Association, I feel strongly that my fellow psychiatrists, and any psychologists or therapists, should stop speculating publicly about President Trump’s mental fitness and stop trying to diagnose possible mental conditions based on their armchair observations.

It’s not that Mr. Trump’s mental fitness should not be evaluated — quite the contrary. All sitting presidents should be evaluated, though most presidential physical exams have included only cursory evaluations of their mental health. When President Trump undergoes his annual medical examination on Friday, his first since taking office, I hope that his assessments include the specific tests that could readily determine if he suffers from a neuropsychiatric condition that could explain his erratic behavior and undermine his ability to perform his duties.

But even if these tests are conducted, it is unlikely that we will learn the results. This would be unfortunate, because speculation about Mr. Trump’s mental fitness appears to be reaching its zenith. It is not just the odd behaviors that have become so common: his obsessive tweeting; his shocking, often contradictory statements; and his instances of confusion (for example, not recognizing Rudy Giuliani sitting across from him at a White House meeting or appearing not to remember the words to the national anthem at a sport event).

Now we have Michael Wolff’s book, “Fire and Fury,” in which the president’s own staff members question Mr. Trump’s stability and cognitive ability. In response to early accounts of the book, the president tweeted in defense of his mental capacities that “actually, throughout my life, my two greatest assets have been mental stability and being, like, really smart.”