The revelation came with Trump onstage in Arizona, where he paid tribute to slain right-wing activist Charlie Kirk in a lengthy speech.
At one point he deviated to promise “one of the biggest announcement really, medically, I think in the history of our country”.
“We’re going to be doing it with Bobby (Secretary of Health Robert F Kennedy Jr) and Oz (Administrator of the Centres of Medicare and Medicaid Services Mehmet Oz) and all of the professionals,” he said.
“I think you’re going to find it to be amazing. I think we found an answer to autism.
He said it was likely to be “one of the most important news conferences I’ll ever have”.
“We’re going to be talking in the Oval Office and the White House about autism, how it happens, so we won’t let it happen anymore,” he said.
“And how to get at least somewhat better when you have it so that parents can help their child, their beautiful child. That’s a big one, I’ve been bugging everybody over there get the answer to that.”
He returned to theme by suggesting Kirk would have enjoyed the announcement.
On the weekend, Trump also revealed the Monday announcement at the American Cornerstone Institute’s Founders’ dinner, claiming autism diagnoses were increasing exponentially – an increase medical experts typically put down to improved diagnostic techniques, especially for girls and women.
Kennedy, a vaccine sceptic whose shake-up of health institutions in the US has prompted criticism from some quarters, has previously characterised autism as a chronic disease and an epidemic, rather than a developmental disorder.
The effects of autism can vary widely from person to person.
