Prenatal maternal diet and child genetic liability for inflammation are independently linked to ADHD symptoms across development

Background: Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental condition associated with both genetic and prenatal environmental risk factors. Emerging evidence points to chronic low-grade inflammation as a potential shared pathway influencing ADHD symptoms.Methods: Using data from 42,193 children in the Norwegian Mother, Father, and Child Cohort Study (MoBa), we investigated whether maternal diet-induced inflammation during pregnancy (assessed via the Dietary Inflammatory Index, DII) and children’s genetic liability for inflammation (indexed by polygenic scores for C-reactive protein, PGS-CRP) were associated with ADHD symptoms at ages 5, 8, and 14 years. ADHD symptoms were reported by mothers and analyzed using linear mixed-effects models. Covariates included child sex, birth weight and length, maternal smoking, and genetic principal components.Results: Higher maternal DII and higher PGS-CRP were each independently associated with increased ADHD symptoms, particularly inattention, across development. Effect sizes were small but statistically significant. No interaction was observed between genetic and dietary inflammatory risk.Conclusions: Prenatal maternal diet and inherited inflammatory risk factors appear to contribute additively to ADHD symptom development. These findings support the role of inflammation-related mechanisms in ADHD etiology and suggest that prenatal nutrition may be a modifiable risk factor.