Bone Spurs
One thing for sure, President Trump can't deny his age. We know the date of his birth since it's a matter of public record, right there on his birth certificate. Which also proves(?) that he was born in the United States of America, but that's another discussion.
We also know that Mr. Trump got a medical waiver from the military draft back in 1968 due to bone spurs. It's clear that those bone spurs have taken their toll on the vain old man. The ducktail toupee, the sunlamps, the mirdle can no longer hide the effects. Top secret documents leaked from the Walter Reed medical center confirm that the disease has metastasized and infected Mr. Trump's cranium. Consequently, the Republican presidential campaign finance committee has authorized the funds needed to fit Mr. Trump with a state of the art prosthetic brain.
Now this is no ordinary prosthetic brain. This brain was developed with the assistance of Russian and Chinese scientists over the course of many years. Innovations in several strategic areas have been brought together to fulfill this goal. Artificial intelligence, gene manipulation, advanced quantum computing, cryptographic communication and big data analytics are just a few of the technologies that have been mastered and brought together, as well as new breakthroughs in neurosurgery, all of which have made this possible.
We can rest assured that the leadership of our great nation is now in the best of hands.