Cerebral folate deficiency (CFD) is a neurological disorder in which the transport of folate (vitamin B9) into the brain is impaired, leading to developmental delays with autistic symptoms including problems with social communication, sensory processing, and repetitive behaviors.[2] Leukovin is an inexpensive generic drug derived from folic acid that bypasses this blockage and increases folate levels in the brain.[1] Three randomized controlled trials of leucovorin for the treatment of autism have shown positive effects on speech, with one-third of children with CFD experiencing improvements in speech and other behaviors in one study led by pediatric neurologist Richard Frye.[1] A folate receptor autoantibody (FRAT) test is available to help identify children who might respond best to leucovorin therapy.[1] Side effects of leucovorin are mild—some children experience hyperactivity in the first few weeks of treatment, which usually subsides within one to two months.[1] The FDA initiated approval of leucovorin calcium tablets for patients with CFD based on an analysis of the scientific literature from 2009–2024.[2]