Efficacy of oral folinic acid supplementation in children with autism spectrum disorder: a randomized double-blind, placebo-controlled trial

Oral folinic acid has shown potential to improve symptoms in children with autism spectrum disorder (ASD). However, randomized controlled trials (RCTs) are limited. This double-blind, placebo-controlled RCT aimed to compare changes in Childhood Autism Rating Scale (CARS) scores in children with ASD aged 2-10 years, among folinic acid (2 mg/kg/day, maximum of 50 mg/day) and placebo groups at 24 weeks, in comparison with baseline. Both the groups received standard care (ABA and sensory integration therapy). Secondary objectives included changes in behavioral problems measured by the Child Behavior Checklist (CBCL) and serum levels of anti-folate receptor autoantibodies and folic acid, correlated with changes in autism symptom severity. Out of the 40 participants recruited in each group, 39 and 38 participants completed the 24-week follow-up in the folinic acid and placebo groups, respectively. The change in CARS score was higher in the folinic acid group (3.6 +/- 0.8) compared to the placebo group (2.4 +/- 0.7, p < 0.001). Changes in CBCL total score and CBCL internalizing score were also better in the folinic acid group (19.7 +/- 9.5 vs. 12.6 +/- 8.4 and 15.4 +/- 7.8 vs. 8.5 +/- 5.7, p < 0.001 for both). High-titer anti-folate receptor autoantibodies were positive in 32/40 and 33/40 cases in the folinic acid and placebo groups, respectively (p = 0.78). In the placebo group, improvement in CARS score was comparable regardless of autoantibody status (p = 0.11), but in the folinic acid group, improvement was more pronounced in the high-titer autoantibody group (p = 0.03). No adverse reactions were reported in either group. Conclusions: Oral folinic acid supplementation is effective and safe in improving ASD symptoms, with more pronounced benefits in children with high titers of folate receptor autoantibodies. What is Known:<br /> center dot Folate receptor autoantibodies are more prevalent in children with autism spectrum disorder (ASD) compared to typically developing children.<br /> center dot Folate receptor autoantibodies play a significant role in the neuropathogenesis of autism spectrum disorder.<br /> What is New:<br /> center dot Add-on oral folinic acid supplementation is safe and effective in reducing the severity of symptoms in children with ASD.<br /> center dot The clinical benefits are more pronounced in children with high titers of folate receptor autoantibodies.