What Is Leucovorin, the Unproven Autism Drug Backed by Trump Officials?

According to Martin Makary, head of the US Food and Drug Administration (FDA), Leucovorin drugs will help “hundreds of thousands of children” autistic. But one day after Makary praised Leucovorin’s powers during a White House event, some specialists warn that science to justify Makary’s enthusiasm is far from solid.

These researchers say that the effectiveness of the drug has not been established, that scientists do not know how many drugs to give or how people should take them, and that security data are lacking. According to the current FDA plans, leucuvorine will only be available for a minority of autistic people.

All of this has led to a general confusion, say that clinicians, who are also worried about the expectations created by Makary and other officials from the American President Donald Trump.

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“I heard many families,” said psychologist Catherine Lord at the University of California in Los Angeles. “The major thing they say is,” What is it? ” What are we doing? »»

“I do not want to get the hopes of everyone that this is a magic remedy,” said Rebecca Schmidt, a molecular epidemiologist at the University of California in Davis. “It’s not for everyone.”

Vitamin under the spotlight

During an announcement on September 22, Makary announced the upcoming approval of Leucovorine, a form of folate vitamin, saying that it “would open the door to the first processing route recognized by the FDA for autism”. People with low folate levels in the protective liquid surrounding the brain and the spine can sometimes present features associated with autism, including challenges in social communication. This condition, called brain deficiency in folate, could be due to rogue antibodies that attack the body’s own proteins – in this case, proteins that import the folate into the brain.

There have been clinical trials of Leucovorine, also called folinic acid, in autism, but studies to date have been weak. For example, a recent clinical trial has scored about 80 children aged 2 to 10 and provided folinic acid supplements to about half of the participants. Neither the participants nor their doctors knew who received the supplement and who received a placebo. Participants who received the supplement brought in greater improvements in social interactions and linguistic skills than those who received the placebo.

After the publication of the test, some researchers subsequently raised concerns about the subtlety of the evaluation of these improvements and that the study was too small to detect subtle differences in response.

Call for greater tests

But size is not the only thing that matters in clinical trials, explains Dan Rossignol, a family doctor in Aliso Viejo, California, who studied data on Leucuvorine and sometimes prescribes it to autistic children. The effect of leucuvorine in the tests was large enough to be apparent even with a small number of participants, he said. More specifically, Rossignol highlights an early clinical study of Leucovorine, in which only 48 children participated, but some have experienced marked improvements in a standardized speech assessment.

“But that would be great if more studies were done with more children,” he said. “Then we could unravel the children who react better.” As a general rule, the studies submitted for the approval of the FDA of an autism medication could have data from hundreds of children, he says, but it was difficult to collect funds for greater trials. Rossignol says that he and a colleague had discussions with the administration of American president Donald Trump to plead in favor of Leucovorine.

The Trump administration said on Monday the National Institutes of Health Plans of the United States to monitor the effects of the expected approval of the FDA and to study the broader benefits of Leucuvorine in people with autistic people. No details have been published on how these studies will be designed.

Not a magic solution

Whatever the effectiveness of therapy, it will not be a panacea. The approval proposed by the FDA, which has not yet been finalized, would only apply to people with low folate levels in the liquid surrounding the brain and spinal cord. This represents around 7 to 30% of autistic people, according to the way in which folate levels are measured, explains Alycia Halladay, director of sciences of the Autism Sciences Foundation in New York. “Families are in Facebook groups saying,” We can get a prescription now, “she says. “And that’s not what will happen.”

Autism is complex and supposed to be caused by a wide range of factors. No single therapy is likely to apply to all autistic people. “If someone tells you that he has found a magic shot remedy for autism, doubt it,” said Halladay. “There will be no cause and unique treatment.”

The lack of data from the big trials means that doctors will not have much to do to determine the dose to be prescribed, or how long children should take leucuvorine before deciding if it works or does not work, explains Halladay. “We hope he will end up being advice,” she says. Rossignol says that most clinical studies of Leucovorine in autistic children have used the same dose, which could provide a starting point for doctors.

Leucuvorine has long been used to alleviate certain side effects of chemotherapy and immune suppression treatments and seems to be sure in this context. But there is little data to confirm that it is safe for autistic children, explains Schmidt. “I do not know any evidence showing real evil,” she said. “But there is not much evidence in this population either.”

Schmidt is particularly concerned about the fact that the speakers could start to take leucuvorine. “We know less appropriate doses and things like that during pregnancy,” she says.

False positive

Meanwhile, some autistic families have been asking for leucuvorine for years, sometimes shopping for doctors who will prescribe them despite the FDA lack of approval as an autistic drug. Rossignol says that people came from 80 countries to visit his clinic and that her two autistic children have benefited from leucurine treatment.

Lord says that she knows the neurologists who have agreed to prescribe the drug despite the reluctance of a lack of data, because at least they know that they can monitor the safety of the drug in their patients. And Lord remembers when the results of small clinical trials of other autistic interventions over the past years energized the autism community, to give disappointment when major studies have proven that the results were false positive.

“It is very easy to obtain results of false positives in autism research,” explains James Cusack, Managing Director of Autistica, a charity in the autistic UK of research and the campaign in London, which is autistic. “The threshold to demonstrate something is effective is very, very high in autism.”

Everyone autistic does not seek treatment. Some autistic groups and people would like there to be treatments, says Cusack, and “their voice is important in all this discussion”. But many people find the story and fear around autism that is generated by the Trump administration stigmatizing and negative, he says: “The whole thing is a distraction, a waste of time, resources and efforts.”

CUSACK says that the urgent objective should be to recognize the inequalities that autistic people experience and find ways to ensure that autistic people get health care, mental health assistance and employment support.

With additional reports by Helen Pearson

This article is reproduced with permission and was first publication September 23, 2025.