Reviewing the Impact of Gluten-Free Diets on Child and Adolescent Psychiatric Disorders.

Gluten-free diets (GFDs) are increasingly used by families as a complementary intervention for pediatric psychiatric disorders despite limited evidence supporting their efficacy. Proposed mechanisms include immune-mediated inflammation, altered gut-brain signaling, and increased intestinal permeability that may influence neuropsychiatric function. This review aimed to systematically evaluate the evidence for GFD use in children and adolescents with psychiatric disorders without diagnosed celiac disease. A structured literature search was conducted using Ovid Medical Literature Analysis and Retrieval System Online (MEDLINE), PsycINFO, and ClinicalTrials.gov to identify English-language studies published between January 2000 and August 2024. Studies involving participants ≤20 years old with a psychiatric disorder who underwent a GFD intervention for at least six weeks were reviewed. Studies involving diagnosed celiac disease, acute medical illness, or non-gluten dietary interventions were excluded. Study characteristics, intervention details, and psychiatric outcomes were extracted and qualitatively synthesized. Four studies met inclusion criteria, including three studies in autism spectrum disorder (ASD) and one case report in schizophrenia. Across ASD studies, evidence was mixed. Two randomized controlled trials found no significant improvement in core ASD symptoms compared with control diets, although one reported significant reductions in gastrointestinal symptoms and modest behavioral improvements. A prospective observational study reported numerical improvements in gastrointestinal complaints, caregiver-reported behavior, and autism-related symptom scores in a subset of participants; however, changes in autism symptom scores did not reach statistical significance. The schizophrenia case report described substantial improvement and eventual resolution of psychotic symptoms following initiation of a GFD in an adolescent with non-celiac gluten sensitivity. No eligible studies were identified for attention-deficit/hyperactivity disorder (ADHD), anxiety disorders, obsessive-compulsive disorder (OCD), mood disorders, disruptive behavior disorders, Tourette syndrome, post-traumatic stress disorder (PTSD), or substance use disorders. Overall, the available evidence was limited by small sample sizes, short intervention periods, methodological heterogeneity, and moderate-to-high risk of bias. Current evidence supporting GFD use in pediatric psychiatric disorders is sparse and heterogeneous. While some children may experience improvements in gastrointestinal symptoms and associated behavioral difficulties, there is insufficient evidence to support routine implementation of a GFD for core psychiatric symptoms. The near absence of studies outside ASD highlights a significant gap in the literature. Larger, well-designed randomized controlled trials are needed to clarify efficacy, identify potential biological responders, and determine whether subsets of children with gluten sensitivity or immune dysregulation may derive meaningful benefit from dietary gluten restriction.