So they modify their claim: Biden is addled and wandering, except when he is given some sort of medication, perhaps a stimulant, that reverses that effect. And here we are, with Trump and those seeking his reelection to the White House demanding that Biden submit to some sort of drug test before this week’s first presidential debate, purportedly in effort to sniff out this theoretical drug.

Experts who spoke with The Washington Post, though, confirm that no such medicine exists.

At the outset, we should recognize that this claim is generally not offered seriously. It is, instead, an effort to escape the aforementioned contradiction, a way to hold both that Biden is incapable of serving as president and yet, unquestionably at times, not demonstrating any such impairment. What’s more, the demand that Biden undergo a drug test is itself not serious. It is, instead, meant to create a condition that allows Trump and his allies to continue to claim that any strong performance from Biden is a function of medication. The result is win-win for Trump, who can blame any loss on this wonder drug.

If you haven’t been paying close attention to the debate (such as it is) over this idea, consider a snippet of conversation that aired on Fox Business on Tuesday morning.

Host Maria Bartiromo — no stranger to conspiratorial argumentation — hosted Rep. Eric Burlison (R-Mo.) where she offered an observation made by Rep. Ronny Jackson (R-Tex.).

“Jackson says Biden will have been at Camp David for a full week before the debate,” Bartiromo said, “and that they’re probably experimenting with getting doses right. Giving him medicine ahead of the debate.”

Burlison agreed that this was possible, though he offered that it might be more innocuous than medication. Perhaps, he said, Biden’s team is “jack[ing] him up on Mountain Dew.”

Jackson, you will recall, was Trump’s personal doctor while Trump was in the White House. He is not an expert on cognition or cognition-related illnesses, though he is familiar with drug prescription.

“Nothing like that exists,” Thomas Wisniewski, director of the NYU Langone Alzheimer’s Disease Research Center, told The Washington Post by phone. “There are no medications or stimulants that can reverse a dementing process transiently.”

“All of those sorts of things can perhaps make an individual more alert, but quite often that can just exacerbate their confusion, as well,” he added. “They can be more stimulated, but they are not going to be behaving in a more cogent or normal fashion as a result of being stimulated by anything. Very often it’s the reverse.”

Adam Brickman, associate professor of neuropsychology at Columbia University Irving Medical Center, concurred with that assessment.

“I’m not aware of any medications that would reverse or mask cognitive decline,” Brickman said. What’s more, he noted that “the association between energy and cognition is a very weak one. In other words, someone could have low energy but totally intact cognition and vice versa.”

Both doctors noted that such a medication would be of enormous benefit. Reversing cognitive decline, after all, would mean turning back the damage done from diseases that impair cognition in the first place. It would be akin not just to treating the pain of a broken bone but, instead, to directly healing the break itself. Sadly, no such drug for cognition exists.

Again, the argument that Biden is or could be receiving targeted treatment to improve his mental state fails multiple logical tests. Why, for example, would he not simply take this medication all the time? Why would he need to retest his dosage for a debate after giving a lengthy State of the Union address? The answer is that there is no good answer, that the intent of the allegations is simply to maintain the political argument that Biden is mentally deficient even in the face of his performing above expectations in a debate.

Not that that argument is itself well-grounded, as Brickman noted.

“It’s not possible to conclude or to determine whether someone has subtle cognitive change without doing a true clinical evaluation,” he said. “So to judge whether there’s an underlying disease or neurodegenerative condition based on public speeches or interactions that are captured by the press is irresponsible.”

Wisniewski offered a more succinct dismissal of the claims being made by Trumpworld.

“It’s spurious,” he said. “It’s nonsensical.”

In other words, if Biden fares better in the debate this week, it’s not because of a secret Camp David drug-dosing regimen that enabled the administration to mask Biden’s physical degeneration. It’s because Biden out-debated the guy who won’t accept that that’s possible.