On January 29, 2026, the European Journal of Pediatrics formally retracted what had been the largest randomized clinical trial examining folinic acid as an intervention for autism. The reason, according to the journal’s notice, was direct: The study’s data did not support its published conclusions.

Originally released in 2024, the trial reported that 24 weeks of oral folinic acid therapy produced a “significant reduction” in autism symptoms among 77 children. In a field long marked by small samples and heterogeneous outcomes, the study was quickly cited as long-awaited randomized support for a biologically plausible intervention. That support has now been withdrawn.

As clinicians, we are frequently asked about folinic acid by families who are eager for biologically grounded interventions. When the largest randomized trial suggests benefit, it influences recommendations, prescribing patterns, and hope. A retraction forces us to revisit not only the data, but also the assumptions we may have conveyed.

I remember the first time a parent brought this study into the office. The question was simple: “Should we start this?” At the time, the answer felt more straightforward than it does now.

Science vs. hypothesis

Interest in folinic acid is not unfounded. It stems from the folate receptor autoantibody hypothesis, which proposes that certain antibodies impair folate transport into the central nervous system in a way that resembles cerebral folate deficiency. The biological rationale is plausible, and small studies have suggested a signal. But plausibility is not proof.

Before this retraction, the 2024 trial was widely cited as the strongest randomized evidence supporting clinical use. With its removal, the literature returns to a collection of smaller trials with limited power and methodological concerns, including blinding challenges and heterogeneous outcome measures. The hypothesis remains. The evidentiary foundation does not.

A systems question

Scientific retractions are often framed as proof that science corrects itself. That is true. But they are also diagnostic events. In this case, outside researchers identified inconsistencies in the published data tables. When the journal attempted to reproduce the primary outcomes using the authors’ dataset, the results did not hold. The discrepancies were significant enough to invalidate the central claims. Two of the six authors agreed to the retraction, citing unintentional statistical errors.

There has been no public allegation of misconduct. Even so, the inability to reproduce core findings raises uncomfortable questions. How did discrepancies that were visible in published tables pass peer review? What safeguards failed? What does this episode reveal about the pressures surrounding high-interest clinical topics, particularly in areas where families and clinicians are urgently seeking therapeutic options?

In 2025, regulatory guidance surrounding folinic acid expanded, drawing in part on extrapolation from rare folate disorders and limited autism specific evidence. The now retracted trial contributed to the perception that stronger randomized data had finally arrived. Its removal reopens a gap that may have been prematurely declared closed.

The bottom line

This retraction does not prove that folinic acid is ineffective in autism. It does, however, reinforce a central principle of evidence-based medicine. Biologic plausibility and early signals cannot substitute for reproducible, independently verified data.

Autism research operates under extraordinary pressure from families seeking answers, clinicians seeking tools, and researchers seeking breakthroughs. That urgency is understandable. But it is precisely in high-need areas that methodological rigor must remain uncompromising.

If the largest trial in a therapeutic niche cannot withstand basic reproducibility checks, the lesson extends beyond a single paper. In medicine, particularly when treating vulnerable populations, the burden of proof must remain higher than the burden of hope.

Timothy Lesaca is a psychiatrist in private practice at New Directions Mental Health in Pittsburgh, Pennsylvania, with more than forty years of experience treating children, adolescents, and adults across outpatient, inpatient, and community mental health settings. He has published in peer-reviewed and professional venues including the Patient Experience Journal, Psychiatric Times, the Allegheny County Medical Society Bulletin, and other clinical journals, with work addressing topics such as open-access scheduling, Landau-Kleffner syndrome, physician suicide, and the dynamics of contemporary medical practice. His recent writing examines issues of identity, ethical complexity, and patient–clinician relationships in modern health care. Additional information about his clinical practice and professional work is available on his website, timothylesacamd.com. His professional profile also appears on his ResearchGate profile, where further publications and details may be found.