Psychiatric disorders before and after inflammatory bowel disease diagnosis: a nationwide cohort study in Sweden 2007-2023.

BACKGROUND AND AIMS: Evidence suggests that patients with inflammatory bowel disease (IBD) are at higher risk of psychiatric disorders, yet temporal pattern of risk elevation before/after IBD diagnosis and role of familial factors remain unclear. METHODS: Swedish IBD patients diagnosed 2007-2023 were compared with reference individuals in a matched population-based cohort and compared with IBD-free full siblings in a sibling-controlled cohort. Primary outcome was any psychiatric disorder, while secondary outcomes included psychotic disorders, mood disorders, anxiety disorders, eating disorders, substance misuse, personality disorders, attention-deficit/hyperactivity disorder, and autism spectrum disorders. We estimated temporal patterns of hazard ratios (HRs) from five years before to ten years after IBD diagnosis by using flexible parametric survival models. RESULTS: The study included 43,862 IBD patients (mean age at diagnosis: 41.6 years; 47.3% female) and 178,821 reference individuals. The HR of any psychiatric disorder started to increase from 2-3 years before IBD diagnosis (e.g., HR=1.15 [95%CI: 1.09-1.21] at -2 years), peaked immediately after IBD diagnosis (HR=1.50 [1.41-1.59] at 0.5 year), and decreased rapidly thereafter but remained increased even at 10 years after diagnosis (HR=1.19 [1.13-1.24]). The increased HR was mainly driven by major depressive disorder, anxiety disorders, and substance misuse. No increase was observed for psychotic disorders, personality disorders, and attention-deficit hyperactivity disorder, although IBD patients were more likely to have autism spectrum disorders shortly after diagnosis and eating disorders from ≥5 years onwards. Similar temporal HR patterns were observed across all subtypes of IBD: Crohn's disease, ulcerative colitis, and IBD-unclassified. Similar risk increases for psychiatric disorders were observed in the sibling-controlled cohort. CONCLUSION: Patients with IBD were at an increased risk of several psychiatric disorders from 2-3 years before diagnosis through up to 10 years after, and this risk increase cannot be fully explained by shared familial factors.