Early food allergy and other allergic conditions showed a positive association with autism spectrum disorder (ASD) in a large, nationally representative sample of U.S. children, and the association persisted after researchers adjusted for demographic and socioeconomic variables and other types of allergic conditions.
Food allergies were the most common allergic condition found in children with autism, and the association was consistent and significant in all age, sex, and racial/ethnic subgroups in the population-based, cross-sectional analysis of data from the National Health Interview Survey collected between 1997 and 2016.
In an invited commentary published with the study, Christopher J. McDougle, MD, of Massachusetts General Hospital and Harvard Medical School in Boston, explored the researchers' hypothesis that the association may be related to gut-brain-behavior axis abnormalities thought to exist in some children with ASD: "Such an association has been reported in both patients with ASD and animal models of ASD, particularly those with the maternal immune activation model of ASD.
"From a clinical perspective, patients with ASD who are minimally verbal to nonverbal may be unable to describe the pain and discomfort they experience secondary to food allergy and subsequent inflammation in the gastrointestinal tract. Instead, their physical distress may manifest as irritability, aggression, and/or self injury."
The prevalence of ASD among children in the U.S. has increased steadily in recent decades, according to findings from nationally representative surveys, Bao and colleagues noted, explaining that immunologic dysfunction is a potential link between environmental risk factors and ASD.
Symptoms of immune function abnormalities, such as frequent infections and increased prevalence of autoimmune conditions have been frequently reported among children with ASD and maternal infection, inflammatory cytokines, and autoimmune diseases during pregnancy were also associated with ASD in children in some studies.