It is an easy joke to make. “The president has lost his mind.” In fact, I suspect not a week has passed in the last 50 years when one wag or another didn’t suggest the leader of the day is nuts, or insane or crazy. The joke is even easier to make with the current U.S. president, Donald Trump. He operates so outside of acceptable norms, with behaviour so erratic, unbecoming and unpredictable, that I am sure literally everyone (including his family and his supporters) have said to themselves or out loud, “He’s crazy.”

Asserting a politician has lost his marbles has become so ubiquitous it now merely means you don’t agree with him. I can only recall one instance when a political leader, on this side of the Atlantic or the other, was sincerely accused of suffering from dementia. That was Ronald Reagan, in the final years of his presidency, when he was developing a habit of falling asleep in Cabinet, and showed some obvious signs of memory loss. It appears that in this case the pundits were right. Just a few years after he left the White House, Reagan was diagnosed with Alzheimer’s disease.

From the moment he entered politics, Trump has, on an almost daily basis, said or done something that caused millions to shake their heads and wonder if he was nuts: attacking John McCain for being a prisoner of war; threatening to lock up his opponent; claiming his inauguration was the most-watched in history; yelling at the Australian prime minister. But the tone of that question is beginning to change. People are beginning to wonder if he is genuinely unwell.

We do not judge Trump by the same standard we apply to other politicians. We collectively agree that he is an outlier. If the mayor of New York claimed climate change was a Chinese conspiracy, he would be laughed out of office. Or if the governor of Arizona began to share Muslim conspiracy videos online, people would be immediately concerned.

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We do not even judge Trump by the same standards we would apply to a doddering uncle. If a relative of mine spoke with the same meandering train of thought, telling obvious lies, wandering off into unrelated and self-aggrandizing anecdotes, I would understandably worry that he was not well. But when the president of the United States does it during a press conference with the prime minister of Japan, we simply compare it to his last speech and shrug.

Increasingly, however, when we do compare it to his last speech, or his behaviour even a few months ago, there is a noticeable change. His inability to restrain himself has deteriorated even further. Pulling an example from just last night, when British Prime Minister Theresa May suggested it was wrong for the president to distribute the videos of a highly controversial hate group, he could not restrain himself from immediately rebuking her on Twitter, like she was a failed contestant on The Apprentice. And his lies have become even more bizarre. After acknowledging the video of him bragging about grabbing women by their genitals is real, and even after apologizing for it, Trump has reportedly begun to argue it’s not his voice on the tape.

His own staff are telling reporters that the president has constructed an alternate reality in which he won the popular vote, his polling numbers are great among women, and his administration has passed record amounts of legislation. Which brings us to the absurd place where we have to ask: “Is Trump simply an accelerating liar, or is he suffering from dementia?”

It could be both. His fabrications are well documented (1,628 since inauguration day alone according to fact checkers at the Washington Post). But he is also a 71-year-old man who has one of the world’s most exhausting and stressful jobs. Prevalence of some forms of dementia, among people aged 60 or over in North America, is estimated to be seven per cent. And according to the Alzheimer’s Association, 11 per cent of people 65 or older have the disease. These are not inconsequential numbers.

If Trump’s behaviour and apparent grasp on reality continues to deteriorate, what would happen? After the Kennedy assassination, people realized that if he had been left in a coma, there was no constitutional mechanism to replace him. So Congress passed the 25th amendment, which states that if the vice-president and majority of the Cabinet determine the president is “unable to discharge the powers and duties of his office,” then the vice-president takes over. If the president contests this, then Congress must decide with a two-thirds majority vote.

A group of mental health professionals have already argued the 25th amendment should be enacted because Trump “is too seriously mentally ill to competently discharge his duties as the president,” claiming he is suffering from narcissistic personality disorder.

But there is a political reality that makes this extremely unlikely, if not impossible. The Republican Party controls both houses of Congress, and they would never be willing to mutiny against their president while he still supports their legislative agenda. Moreover, I suspect the Democrats are cynically quite happy to have an addled Trump in office for the time being. His polling numbers continue to fall; he is damaging the Republican Party every day, his continued presence will only help their electoral chances in the 2018 midterm elections, and a President Pence would bring with him both an extremely conservative agenda and the skills to implement it.

In fact, if the president is indeed suffering from dementia, politicians on both sides of the aisle probably are quite happy to leave him in the Oval Office. Which leads to the obvious question: has everyone lost their mind?

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