2026 will shed light on whether a little-known drug helps with autism
The US government is approving the drug leucovorin to address rising rates of autism, despite limited evidence that it works. This year, results from the largest trial yet should give more insight into its potential
You might not have heard of leucovorin, but it is being championed by the US government to address rising rates of autism
Hannah Beier/Reuters
The US government made waves last year when it announced it would be approving the little-known drug leucovorin for children with cerebral folate deficiency, a condition that appears to be connected to autism.
The decision left many doctors wary because it was based on evidence from just a few small studies. But we could soon receive more insight into the drug’s potential, as results from the largest trial of leucovorin for autism are expected in the first half of 2026.
Autism became a focal point of US health policy in 2025 after President Donald Trump appointed Robert F. Kennedy Jr to lead the country’s top health agencies. Kennedy, who has falsely blamed vaccines for rising autism rates, pledged in April last year that he would identify the causes of autism by the end of September 2025.
That month, the government announced it was planning to approve leucovorin for people with cerebral folate deficiency, a condition some research suggests affects up to 40 per cent of autistic people. It interferes with vitamin B9 uptake in the brain, leading to symptoms similar to some characteristics of autism, such as communication and sensory processing difficulties.
The US Food and Drug Administration declined to comment on where the approval process currently stands.
Leucovorin is already approved for treating some other kinds of vitamin B9 deficiencies, as well as side effects from some cancer medications. A handful of small trials have also suggested it can ease some difficulties experienced by autistic people.
For example, a 2016 study used two daily doses of leucovorin to treat 23 autistic children with language impediments. After 12 weeks, 65 per cent of them saw a clinically meaningful improvement in verbal communication, compared with only about a quarter of 25 children who received a placebo.
“While promising, it is important to note that leucovorin is not a cure for ASD [autism spectrum disorder] and may only lead to improvements in speech-related deficits for a subset of children with ASD,” the US Department of Health & Human Services said in a statement released after the announcement.