Federal officials once championed leucovorin as an autism breakthrough. The agency’s actual approval tells a far more limited story.
The Food and Drug Administration has approved a new use for leucovorin, a lab-made form of vitamin B9 — but the approval has nothing to do with autism, despite months of high-profile claims to the contrary from top federal health officials.
The agency’s Tuesday announcement authorizes leucovorin specifically for the treatment of cerebral folate deficiency, a rare neurological condition in which vitamin B9 levels in the brain fall dangerously low. It is estimated to affect roughly one in one million people.
A Gap Between Rhetoric and Reality
The approval stands in sharp contrast to statements made by President Donald Trump and FDA Commissioner Marty Makary last September, when both officials framed leucovorin as a promising weapon against autism symptoms. Makary declared the agency was moving to relabel the drug so it could be available to children with autism, claiming hundreds of thousands of young patients stood to benefit. Trump echoed those remarks, telling the public the updated label would reflect potential benefits in reducing autism symptoms.
A senior FDA official walked back those statements on Monday, acknowledging that the agency lacks sufficient evidence to establish leucovorin’s effectiveness as an autism treatment. The official noted that patients interested in the drug should consult their physicians, who retain the authority to prescribe it off-label.
Leucovorin’s Actual Uses
In standard clinical practice, leucovorin is used primarily to help cancer patients tolerate chemotherapy or to boost its potency. Its new approved indication — cerebral folate deficiency — is a condition that, while sharing some surface-level overlapping traits with autism, such as challenges with social communication, sensory processing, and repetitive behaviors, is thought to affect only a small fraction of those on the autism spectrum.
Some researchers have explored a possible link between cerebral folate deficiency and autism, but the scientific community has remained cautious, noting that any connection is far from established.
Leucovorin Prescriptions Surged After Trump’s Announcement
The political messaging had measurable consequences. Prescriptions of leucovorin for children jumped 71 percent in the roughly two and a half months following Trump’s September remarks, according to data published last week in The Lancet. Some physicians had already been prescribing it off-label based on findings from a small number of trials conducted mostly outside the United States.
One of those trials, published in the European Journal of Pediatrics, was retracted in January after the study’s authors discovered significant errors in their underlying data — a development that further eroded confidence in the existing evidence base.
Experts Warn of Harm from Mixed Messaging
Researchers and advocates in the autism community reacted to Tuesday’s announcement with a mixture of relief and frustration. Alycia Halladay, chief science officer at the Autism Science Foundation, described the FDA’s approval as fundamentally different from what the administration had signaled in September — a total disconnect, in her words.
Halladay warned that the damage may already be done, noting that prescription numbers have already spiked and are unlikely to reverse course simply because the approval is more narrowly defined than originally implied.
David Mandell, a psychiatry professor at the University of Pennsylvania, said the FDA’s latest communication compounds an already confusing and distressing information environment for families of autistic children. The back-and-forth over what treats, causes, or does not cause autism, he argued, fails the very people it purports to help.
What Comes Next for Autism Research
Despite his criticism, Mandell expressed relief that leucovorin was not approved as a broad autism treatment, pointing to the thinness of the existing data and early signals that ongoing clinical trials are not producing promising results for the condition.
The episode underscores a broader tension in federal health policy: the pressure to deliver hope to families navigating complex neurological conditions, and the scientific obligation to base treatment decisions on rigorous, reproducible evidence. For the millions of families affected by autism, what happened with leucovorin is a cautionary tale about the consequences of getting that balance wrong.
Meanwhile, advocates say the conversation around autism treatment needs to be grounded in transparency, careful science, and above all, the interests of the patients and families at its center — not the political moment.
Source: NBC News
