Leucovorin: A Potential Solution for Rising Autism Rates Hannah Beier/Reuters
The U.S. government ignited discussions last year by deciding to approve leucovorin, a lesser-known drug aimed at children with brain folate deficiency, a condition believed to correlate with autism.
This controversial decision alarmed many healthcare professionals, given that it was founded on limited evidence from just a handful of small studies. However, the largest clinical trial focusing on leucovorin’s effectiveness in treating autism is anticipated to yield results in early 2026, potentially providing clearer insights.
Autism became a priority in U.S. health strategy in 2025, following President Donald Trump’s appointment of Robert F. Kennedy Jr. as head of the nation’s health agency. Kennedy, who has previously linked increasing autism rates to vaccinations, committed to identifying autism’s causes by the end of September 2025.
Concurrently, the government signaled intentions to approve leucovorin use in patients with cerebral folate deficiency—a condition studies suggest affects nearly 40% of individuals on the autism spectrum, hindering effective vitamin B9 uptake in the brain and resulting in symptoms akin to autism traits, such as communication struggles and sensory processing issues. See more on this topic.
The U.S. Food and Drug Administration has refrained from commenting on the approval process’s current status.
Leucovorin is already sanctioned for treating various vitamin B9 deficiencies and mitigating side effects from certain cancer treatments. Preliminary studies hint it could alleviate some challenges faced by individuals with autism.
For instance, a 2016 survey assessed twice-daily leucovorin administration in 23 autistic children experiencing language impairments. After 12 weeks, 65% demonstrated significant improvements in verbal communication, contrasting sharply with approximately 25% of the 25 children who received a placebo.
“While these findings are hopeful, it’s crucial to clarify that leucovorin does not treat Autism Spectrum Disorder (ASD). It may merely enhance language capabilities in a subset of children with ASD,” stated the U.S. Department of Health and Human Services in their recent announcement.
Some researchers express skepticism regarding the U.S. government’s choice to endorse leucovorin, citing the limited and inconsistent evidence from current studies testing its efficacy on a small cohort of autistic children. Experts like Alicia Halladay from the Autism Science Foundation have voiced such concerns.
Meanwhile, Dr. Richard Fry and his team at Rossignol Medical Center in Arizona are in the process of studying leucovorin in a larger group of 80 children, aged between 2.5 to 5 years. While it is a more substantial trial, some advocate for even larger samples. This study aims to elucidate the drug’s efficacy in a more meaningful way.
Half of the participants will receive the drug for 12 weeks, while the rest will be given a placebo. All participants will then continue on leucovorin for an additional 12 weeks to gather more safety data.
Researchers are collecting feedback from parents on changes in social communication, as well as monitoring other autism-related indicators including irritability, hyperactivity, sensory sensitivities, and repetitive behaviors.
This trial aims to enhance understanding of whether leucovorin has an effect on autism in children and to address ongoing concerns regarding its safety profile.
Despite being considered a safe drug overall, its side effects—particularly in children with autism—remain largely uncharted territory. “The number of families involved in this analysis is still limited, underscoring the need for comprehensive safety assessments,” expressed Halladay.
Throughout the trial, Fry and colleagues will monitor potential side effects bi-weekly for the first 12 weeks and subsequently on a four-week basis, while regularly collecting blood samples to assess changes in blood clotting, immune responses, and overall organ function.
Assuming leucovorin proves beneficial, its mechanisms—beyond merely boosting vitamin B9 levels in the brain—will be explored through scans taken pre- and post-trial.
“We are unsure of the exact effects of leucovorin, but our hypothesis suggests it may enhance brain connectivity,” Fry stated.
However, opinions differ regarding the implications of these findings. “At present, there are no therapies addressing core autism symptoms. Existing medications only serve as temporary solutions for symptoms,” Fry noted. “Leucovorin might be a pioneering therapy potentially treating foundational mechanisms of autism.”
Conversely, Professor Halladay cautions that even an expanded sample of 80 children is still insufficient for making informed conclusions, particularly considering the trial is taking place at a single Arizona location. “This represents progress, but further research involving diverse populations at multiple sites is essential,” she advised.
Stay informed on the latest developments regarding leucovorin and its implications for autism treatment.
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Source: www.newscientist.com
