Is Something Neurologically Wrong With Donald Trump?

President Donald Trump’s decision to brag in a tweet about the size of his “nuclear button” compared with North Korea’s was widely condemned as bellicose and reckless. The comments are also part of a larger pattern of odd and often alarming behavior for a person in the nation’s highest office.

Trump’s grandiosity and impulsivity has made him a constant subject of speculation among those concerned with his mental health. But after more than a year of talking to doctors and researchers about whether and how the cognitive sciences could offer a lens to explain Trump’s behavior, I’ve come to believe there should be a role for professional evaluation beyond speculating from afar.

I’m not alone. Viewers of Trump’s recent speeches have begun noticing minor abnormalities in his movements. In November, he used his free hand to steady a small Fiji bottle as he brought it to his mouth. Onlookers described the movement as “awkward” and made jokes about hand size. Some called out Trump for doing the exact thing he had mocked Senator Marco Rubio for during the presidential primary—conspicuously drinking water during a speech.

By comparison, Rubio’s movement was smooth, effortless. The Senator noticed that Trump had stared at the Fiji bottle as he slowly brought it to his lips, jokingly chiding that Trump “needs work on his form. Has to be done in one single motion, and eyes should never leave the camera.”

Then in December, speaking about his national-security plan in Washington, D.C., Trump reached under his podium and grabbed a glass with both hands. This time he kept them on the glass the entire time he drank, and as he put the glass down. This drew even more attention. The gesture was like that of an extremely cold person cradling a mug of cocoa. Some viewers likened him to a child just learning to handle a cup.

Then there was an incident of slurred speech. Announcing the relocation of the American embassy in Israel from Tel Aviv to Jerusalem—a dramatic foreign-policy move—Trump became difficult to understand at a phonetic level, which did little to reassure many observers of the soundness