Trump is irrational, erratic, and prone to outbursts. He squints a lot. He is easily confused. This is all the matter of public record. For many Democrats, it means he has an untreated STD.
The theory can be traced back to the New Republic, where in early 2017 an infectious disease specialist wrote a piece called “A Medical Theory For Donald Trump’s Bizarre Behavior“. Chelsea Handler followed that with an investigation about the possibility on her television show. The pair of high-profile (one for Democrat activists, the other for rank-and-file Democrats) analyses firmly planted the theory as fact in the minds of many, who continue to generate memes promoting it as a certainty two years later.
The basic concept is that Trump, who was sexually promiscuous in the 1970s and 1980s, may have contracted syphilis which went into a dormant stage and is only now appearing.
The belief falls apart with even the most cursory consideration.
First, on the conspiracy side: this theory relies on Trump’s doctors hiding the truth if they know it, or being so incompetent as to never check for the possibility of an STD. While it is very easy to distrust any doctor who would classify a visibly overweight man in terms typically reserved for elite athletes, there is a great distance between “dishonest” and “incompetent”.
Trump, in his statements to Howard Stern, indicated not only that he was sexually active but that he was aware of the dangers in being so. Even while recognizing that at many points in his life his wealth was completely bound in nonliquid assets, he has always had the trappings of great wealth available to him. It is unreasonable to believe he did not seek testing for STDs, or for treatments to be administered if he contracted them.
It is also unreasonable to assume that a diagnosis which seems potentially viable to a doctor who has never personally examined Trump would go unconsidered by the battery of experts who regularly perform checks on any American President. Or, that if such a neurological disease were found and was known to be treatable, such efforts would not be immediately initiated.
There is no indication that Trump has ever stopped sleeping around, whether he was in a marriage or not. He would have had to avoid sex for months or even years while in stages 1 and 2 of the disease, lest he transmit it… or, if he did have sex, the likelihood of transmission would be high. There are no records of any of his partners, wives or otherwise, ever contracting the disease.
Lastly, there is Trump’s history. His bellicose instability is not new, nor is his confusion, or his aversion to reading and study, or any one of a dozen other personality defects which his detractors now use to claim untreated syphilis. He may indeed have a neurological disorder; they are sadly not uncommon at Trump’s age, and some new developments such as his tendency to constantly lean forward have been observed. But his general demeanor has not changed; it has been part of the Trump brand going back into the 1980s. His word salad may be more choppy than ever, but it’s the same style of word salad.
There is a case to be made that he may be even less competent now than he was when he ran for President in 2016. If so, it is not due to syphilis.