Mental disorders in adolescents at familial high-risk of schizophrenia or bipolar disorder and population-based controls: An eight-year follow-up study, The Danish High Risk and Resilience Study, VIA 15

Background Children of parents with schizophrenia (SZ) or bipolar disorder (BP) show elevated rates of mental disorders. Longitudinal studies comparing offspring at familial risk with the background population are lacking. Method This study is an eight-year follow-up of the Danish High Risk and Resilience study. We examined four-year prevalence from age 11 to age15 (n=416), cumulative incidence by age 15 (n=516), persistency of mental disorders from age 11to age 15 (n=396) and global functioning in 15-year-old adolescents with familial high risk of SZ (FHR-SZ) or BP (FHR-BP) compared to population-based controls (PBC). We assessed mental disorders and global functioning with the Kiddie Schedule for Affective Disorders and Schizophrenia - Present and Lifetime Version (K-SADS-PL) and the Childrens Global Assessment Scale (CGAS). Results Four-year prevalence of any mental disorder was higher in FHR-SZ (51.3%, OR=2.39, 95% CI 1.49-3.83) and FHR-BP (45.9%, OR=1.98, 95% CI 1.16-3.37) compared with PBC (30.5%). Cumulative incidence of mental disorders by age 15 was higher in FHR-SZ (67.2%, OR=3.19, 95% CI 2.11-4.82) and FHR-BP (64.4%, OR=2.82, 95% CI 1.75-4.54) than in PBC (39.1%). Adolescents with FHR-SZ showed the highest rate of persistent mental disorders (33.3%), followed by FHR-BP (24.5%), and PBC the lowest (12.9%). Global functioning at age 15 was lower in FHR-SZ than in both FHR-BP and PBC, and FHR-BP showed lower scores compared with PBC. Between-group differences in cumulative incidences of mental disorders and in global functioning scores remained stable across ages 7,11 and 15. Conclusion Adolescents at FHR-SZ or FHR-BP show elevated risks of a range of mental disorders, psychiatric comorbidity, and lower global functioning from childhood to mid-adolescence, not confined to the disorders for which they carry familial risk. This vulnerability underscores the need for early detection and support for FHR offspring and their families.