The 45th President's unconventional behavior has roiled the national consciousness and provoked intense concern. As a psychiatrist, I have repeatedly been asked to comment on his conduct and render my opinion as to whether it could be due to a mental disorder. I have steadfastly resisted, citing the "Goldwater Rule"—the name given to Section 7.3 of the American Psychiatric Association's Code of Ethics, which states that it's inappropriate for psychiatrists to opine on public figures that they do not have direct knowledge of or authority to diagnose. (The rule derives from the 1964 presidential campaign, during which the now-defunct Fact magazine published a survey of psychiatrists that concluded that the Republican candidate, Senator Barry Goldwater, was "psychologically unfit" to be President, with comments calling him a "dangerous lunatic" and "emotionally unstable." When it became apparent that the survey and article was politically motivated, and after Goldwater lost the election, he sued the magazine's editor for libel and won. Hence the rule.)

However, there is another, more compelling reason why psychiatrists and other medical professionals should refrain from ad hoc clinical characterizations of the POTUS. The appropriate authority to supersede the electoral process and pass judgment on the competence of the President does not rest with the medical profession, but with the federal government as per the Constitution. The 25th Amendment provides for succession if "the President dies, resigns or is unfit to discharge her/his duties." It has four sections: 1) when the President dies or resigns, 2) when the Vice President dies or resigns, 3) when the President requests to transfer authority due to temporary incapacitation. The 4th section is meant to be invoked when the President is incapable of discharging his or her duties, but is unable or unwilling to acknowledge this or to provide the written declaration voluntarily transferring powers called for by Section 3. In such instances, it is up to the Vice President, together with a "majority of either the principal officers of the executive departments or of such other body as Congress may by law provide," to declare the President "unable to discharge the powers and duties of his office" by submitting a written declaration to the President on behalf of the Senate and the Speaker of the House of Representatives.

While the primary responsibility for adjudicating the President's competence may rest with the federal government and is guided by a constitutional amendment, medical opinion, presumably, must play a role in this process. However, it is the cited members of the government, not physicians, who should orchestrate the process.

But herein lies the problem. If the mechanism for ensuring the competence of POTUS rests with an inherently political body (federal government comprised by members of different political parties), how can the process be responsibly carried out free of partisan influence and political motivation?

Shortly after President Trump's inauguration, I ran into the distinguished journalist and author Walter Isaacson at the University Club in New York City. I suggested to him that the news media should focus on the 25th Amendment and how it would be applied in the event that public reaction to President Trump reached a tipping point. After pausing to reflect on the 25th Amendment, he emphatically stated that its invocation would never happen because of the political complexities.

The fact that there are no procedures or guidelines for orchestrating section 4 of the 25th Amendment seems incredible. No one would argue with the possibility of a president experiencing a brain disorder that affected mental functions and behavior. Psychosis, dementia, depression and addiction all can occur to middle-aged adults and could be severe enough to impair their ability to discharge their duties. Therefore, it would seem to behoove us to develop the procedures to be followed, including any requisite medical evaluation, in the event that the need to invoke section 4 of the 25th Amendment became so overwhelming as to supersede the political gauntlet.

In an attempt to simulate what this process would entail, I engaged seven of my colleagues, who are experts in disorders of the brain (neurologic and psychiatric), in a meeting to discuss this matter as a thought exercise. We presumed that our charge would be to evaluate the POTUS and determine (to the best of our ability), 1) whether he suffered from a medical condition affecting mental function and behavior; and 2) whether, and to what degree, the severity of the condition affected his ability to carry out the responsibilities of the office. The first step ordinarily would be to conduct physical and mental status exams and carry out relevant diagnostic tests (blood, neuro-cognitive, brain scans, and genotyping). However, since this was not possible, we had to rely on information in the public domain that we could glean from biographies, news reports, video interviews and media appearances, and social media. (Disclaimer: such publicly available information has not been validated or certified, thus the impressions derived from it cannot be considered conclusive.)

Based on these, we posited that President Trump came from a stable intact family, had a non-traumatic upbringing and normal development, during which he sustained no serious illness. He was intelligent, gregarious and had a strong, exuberant personality. While he was willful, headstrong, and self-important, he tolerated the discipline and graduated from the military school and college to which he was sent. Throughout his life he has been dedicated to his family, his three marriages notwithstanding, and, regardless of what one might think of his business practices and achievements, he has been professionally successful. He is hardworking, possesses great energy and stamina, and is rumored to be a "short sleeper" (someone who constitutionally requires less sleep than their peers). These assets have served Trump well throughout his life.

However, what has prompted concern about Trump's mental health is not his assets but his intemperate, erratic, bombastic, and self-interested behavior. None of these qualities by themselves warrants a diagnosis of mental disorder, but it is their aggregation and severity that raises the question.

In light of this, we systematically considered which conditions described in the Diagnostic Statistical Manual of Mental Disorders could most plausibly account for his behavior. They were: Bipolar Disorder, Intermittent Explosive Disorder, Substance Use Disorder, Narcissistic Personality Disorder (or some variant personality disorder), Attention Deficit Disorder, and a form of early stage Dementia. Whether it is reassuring or surprising, we could not endorse any diagnosis with a high degree of confidence. In fact, most could readily be ruled out. Bipolar Disorder was unlikely because it usually emerges in the third or fourth decade of life and, while Trump may be grandiose and emotionally volatile, he has reached his 8th decade without exhibiting the characteristic euphoric excitement and hyperactivity or agonizing depression associated with the illness. He also does not meet criteria for Intermittent Explosive Disorder despite his emotionality and combative nature, as he has neither assaulted nor been physically aggressive toward anyone (even if his rhetoric may be inflammatory).

Substance Abuse was eliminated because Trump is a teetotaler in reaction to his older brother's alcoholism. A diagnosis of Personality Disorder (narcissistic or otherwise), while plausible, is of limited significance, as they lack well-established scientific validity and their diagnostic boundaries are indistinct. Moreover, if Trump did indeed warrant a diagnosis of a Narcissistic—or any other type of—Personality Disorder, he would be one of the many successful habitués of centers of power like Washington, DC, and New York who would also seem to fit the diagnostic criteria.

Attention Deficit Disorder was a possibility given Trump's penchant for short meetings and conversations, limited concentration span, and aversion to reading. However, this condition usually arises during youth, and, if severe, should have affected his education, and, presumably, would have been diagnosed and treated.

The diagnosis that seemed most plausible was incipient dementia (possibly Alzheimer's, Fronto-Temporal, or less likely, cerebrovascular). Trump is 71 years old, and despite having no serious prior illness, he does not exercise (apart from playing golf) and does not lead a particularly healthy lifestyle or follow a healthy diet. At 6'2" and 236 pounds, he has a body mass index over 30, which places him in the mildly obese category. This could predispose him to cerebrovascular disease (when trouble with the cardiovascular system affects the brain). Of note is the fact that the President's father developed what was diagnosed as Alzheimer's disease in his 80's.

An interesting observation that adds credence to the possibility of an evolving dementia came from an analysis of Trump's speech patterns at different stages of his life published by various sources. By comparing his interviews and speeches from earlier decades to recent communications, they found marked differences in his speech patterns. In addition to the cardinal symptoms of memory loss, dementia can cause the range of a person's vocabulary and speech syntax to constrict. President Trump's tendency to speak in simple phrases and sentences, frequent repetition of words, and occasional neologisms, served him well during the campaign, but could be a telling and worrisome sign of impending dementia. Dementias are also associated with the disinhibition or emotions and impulses, and coarsening of personality traits, which President Trump has demonstrated in abundance. Of course, this potential diagnosis can readily be confirmed or dispelled by obtaining several medical tests. These results would be critical to know, as they not only would explain if a brain disorder accounted for the President's questionable behavior, but also whether this could be expected to worsen.

While our thought exercise was unable to render a clear or definitive diagnosis, this does not mean that President Trump gets a clean bill of health, because we were lacking sufficient information that should be available but could only be obtained if President Trump agreed to allow it to be obtained. We respectfully disagree with the current situation, because given the enormous authority of the Presidency, and potential consequences of its misuse, we believe that a person's, in this case the POTUS's, legal right to privacy, is outweighed by the public's right to know about the President's competence.

The main purpose of having a mechanism to ensure the POTUS's competence is to determine whether any pattern of questionable behavior is caused by illness or simply bad behavior. (Presidential misbehavior is nothing new. Witness Nixon's effort to rig the election, Clinton's promiscuity, Reagan's Iran Contra.) In the case of misbehavior, the constitutional remedies are through the ballot box and impeachment. But for brain disorders that affect behavior, it's the 25th Amendment. And while we may agree on the logic and relevance of this constitutional process, the devil will be in the details of how and by what procedures should it be implemented. The complexity and difficulty of this task notwithstanding, if our legal system can develop a process for determining a person's competence to stand trial—and criteria for verdicts of not guilty by reason of insanity for even the most serious of crimes—we should be able to do the same to assure the fitness for office of those aspiring to or occupying the most powerful position on earth.

Jeffrey Lieberman, MD, is Chair of Psychiatry at Columbia University Columbia University Medical Center and Psychiatrist in Chief of the New York Presbyterian Hospital as well as past President of the APA. He is author of Shrinks: The Untold Story of Psychiatry (Little Brown, 2015).