Whether ADHD or autism diagnosis affects IBD disease activity (advanced therapies, oral corticosteroids, IBD-related surgery, hospitalization) in patients aged 6–24 years, identified in Danish nationwide registries from 1996–2022.
ADHD/autism was associated with higher 10-year cumulative incidence of severe IBD activity (36.2% vs. 33.7%), higher risk of advanced therapies (aHR 1.2, 95% CI 1.0–1.3), and — in ulcerative colitis — higher colectomy risk (aHR 1.4, 95% CI 1.0–1.8), rising to aHR 1.7 (95% CI 1.1–2.6) in those diagnosed before age 18.
Effect sizes were modest overall, which limits clinical magnitude; the registry-based design cannot fully account for confounding by disease severity at diagnosis, medication adherence, or socioeconomic factors; ADHD and autism were analyzed as a combined group, masking potentially distinct effects of each condition.
Children and young adults with both IBD and ADHD or autism — especially those with ulcerative colitis diagnosed before 18 — are at meaningfully higher risk for colectomy and need for advanced therapies; targeted monitoring and support strategies should be considered for this group.
