In February, 2009, the British medical journal Brain published an article on the intersection of health and politics titled “Hubris Syndrome: An Acquired Personality Disorder?” The authors were David Owen, the former British Foreign Secretary, who is also a physician and neuroscientist, and Jonathan Davidson, a professor of psychiatry and behavioral sciences at Duke University, who has studied the mental health of politicians. They proposed the creation of a psychiatric disorder for leaders who exhibited, among other qualities, “impetuosity, a refusal to listen to or take advice and a particular form of incompetence when impulsivity, recklessness and frequent inattention to detail predominate.”

Owen and Davidson studied the behavior and medical records of dozens of American and British political leaders, from Prime Minister Herbert Asquith, who took office in 1908, to President George W. Bush, who left office in 2009. Across that century, they identified a tendency among some otherwise high-achieving individuals to close themselves off from critics and to overestimate their odds of success. Neville Chamberlain wrongly believed that he could appease Hitler; Tony Blair supported the invasion of Iraq even after his envoy informed him that the plan had “no leadership, no strategy, no coördination,” among other defects. When a leader succumbs to hubris syndrome, the authors wrote, his experience at the top has distorted his personality and decision-making.

“The Greeks warned us about it,” Owen told me recently, when I called him at home, in Britain. “When you see it, you’ve got to be very conscious that you may be watching somebody who is intoxicated with power.” After training as a doctor, Owen spent thirty-two years in politics, heading the Foreign Office from 1977 to 1979, and he developed a fascination with the ways in which C.E.O.s, dictators, and parliamentarians who are otherwise successful in their professions can be warped by the pressures and self-glorification presented by power. “It takes one to know one,” he said, dryly. “For a lot of us who are in leadership roles, the problem with the word ‘narcissism’ is that it has a very Freudian linkage and, if you use it, people will shy away from it.”