That's not going to happen, but that's okay. Testing wouldn't be conclusive, shouldn't be the basis for disqualifying someone for the presidency and wouldn't tell us anything we don't already know.
Even without experts weighing in, the public has more than a reasonable basis to question Trump's mental capacity to serve as the country's leader. After all, he is famously impulsive, dishonest, thin-skinned and unpredictable. Such characteristics would impair any chief executive; in a president, they are a threat to the country.
The publication of Michael Wolff's "Fire and Fury: Inside the Trump White House" last week reignited concern about Trump's cognitive function. In response, the president took to Twitter to defend his mental fitness, describing himself as a "very stable genius." But his boastful cognitive self-assessment stands in stark contrast to his often rambling and incoherent statements, ultra-short attention span, repetitive speech pattern and rather impoverished vocabulary — all of which understandably invite worry by any layperson about his cognitive state.
So what would an expert mental fitness evaluation add to our understanding of Trump? Typically, a psychiatric evaluation involves an in-depth interview, history taking and collection of laboratory data that might reveal hidden biological contributors to various abnormal mental states. This approach is particularly useful in diagnosing more subtle forms of psychiatric illness, such as mild anxiety, depressive states, or covert drug or alcohol abuse, which can color one's perception of the world and bias behavior.
But such an interview for Trump would likely be uninformative and largely irrelevant. The reason is that mental illness per se is not a bar to being president. In fact, one study based on biographical data suggests that mental illness is hardly a stranger to the White House: 18 of America's first 37 presidents met criteria for a psychiatric disorder during their lifetimes — 10 of whom showed signs of mental illness while in the White House.
The study found that Abraham Lincoln, one of the greatest presidents, met the criteria for disabling depression; Lyndon B. Johnson had bipolar disorder; Richard Nixon abused alcohol; Ulysses S. Grant was an alcoholic. Clearly, a psychiatric disorder in a sitting president doesn't guarantee that a president is unfit to serve.
What about conducting neurocognitive testing on Trump? Such tests could quantitatively assess cognitive functions such as attention, memory, verbal comprehension and analytical reasoning. But even mild deficits in attention or short-term memory would hardly disqualify a president from service. A president with attention-deficit/hyperactivity disorder or dyslexia, for example, would manifest predictable deficits on neuropsychological testing, but no one would argue that this would be a dealbreaking impairment.
Sure, some speculate that Trump is showing signs that can be indications of dementia affecting the prefrontal cortex, given his poor impulse control and difficulty constructing a logical argument. Perhaps, but these traits apparently have been characteristic of Trump's behavior for quite some time. And when you see such enduring behavior in the average person, it makes dementia questionable.
The same limitations hold for brain imaging. You can have abnormalities on sensitive tests such as a brain MRI that do not correlate well with mental states or behavior. You'd be surprised how bad a scan can look for a perfectly functional person.
There is another reason my colleagues should be hesitant to provide a diagnosis from afar or encourage Congress and the Cabinet to remove Trump under the 25th Amendment. All our diagnoses are clinical in nature, requiring some degree of subjective judgment. Unlike, say, an EKG or cholesterol level, which speak for themselves, our opinions are unlikely to be free of personal or political bias any more than those of the Supreme Court justices.
Much of the public would inevitably view expert intervention as a politically motivated attempt to disqualify a sitting president, whether true or not. That is something our profession must avoid, unless we have knowledge and insight that were inaccessible and vital to the public's well-being, which is clearly not the case with Trump.
In the end, neither the public nor Congress needs the advice of us psychiatric experts. The most accurate measure of a person's fitness, whether mental or physical, is observable function in the real world — not the results of a fancy test or expert opinion. The fact is that Americans already have all the data they need to judge Trump's fitness.
After all, do you really need a physicist to explain what will happen to you if you walk in front of a speeding train?
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