Volkswacht Bodensee - RFK Jr pushes fringe claim linking autism to circumcision

The claim was swiftly derided by experts who said the main study cited by proponents of this theory was strewn with errors and it was yet another example of Kennedy's penchant for "pseudoscience."

"Don't take Tylenol if you're pregnant and when the baby is born, don't give it Tylenol," Trump said during a Cabinet meeting.

"There's two studies that show children who are circumcised early have double the rate of autism," chimed in Kennedy, adding: "It's highly likely because they're given Tylenol."

"None of this makes sense," Helen Tager-Flusberg, a professor at Boston University and autism expert, told AFP.

"None of the studies have shown that giving Tylenol to babies is linked to a higher risk for autism once you can control for all the confounding variables," she said.

Pregnant women are also advised by medical associations to take pain medication including acetaminophen -- the active ingredient in Tylenol -- in moderation when needed, contrary to Trump's advice to "tough it out."

While a few studies have suggested a possible association with acetaminophen in pregnancy, no causal link has ever been proven. The most rigorous analysis to date -- published last year in JAMA and using siblings as controls -- found no link at all.

As for the circumcision theory, the most widely cited paper, published by Danish researchers in 2015, was "riddled with flaws" that were pointed out by other scientists at the time, David Mandell, a psychiatrist at the University of Pennsylvania's Perelman School of Medicine, told AFP.

Specifically, he said, the study relied on a tiny sample of Muslim boys circumcised in hospitals rather than at home -- the dominant cultural practice.

Because those children were hospitalized, Mandell said, it was likely they were "otherwise medically compromised," which could explain higher rates of neurodevelopmental disorders.

"A more recent review of studies in this area finds no association between circumcision and any adverse psychological effects," he added.

Kennedy -- a former environmental activist and lawyer who spent decades spreading vaccine misinformation before being appointed Trump's health secretary -- has made uncovering the root causes of autism a central focus, while cutting research grants in other areas.

He has hired vaccine conspiracy theorist David Geier, previously disciplined for practicing medicine without a license and for testing unproven drugs on autistic children, to investigate alleged links between vaccines and autism -- a connection debunked by dozens of prior studies.

I.Stoeckli--VB