Emerging psychopathology and clinical staging in adolescent offspring of parents with bipolar disorder or schizophrenia—A longitudinal study

Objectives: Offspring of parents with bipolar disorder (BDo) and schizophrenia (SZo) are at increased risk for these disorders and general psychopathology. Little is known about their (dis)similarities in risk and developmental trajectories during adolescence. A clinical staging approach may help define the developmental course of illness. Methods: The Dutch Bipolar and Schizophrenia Offspring Study is a unique cross-disorder and prospective cohort study, established in 2010. In total, 208 offspring (58 SZo, 94 BDo, and 56 control offspring [Co]) and their parents participated. Offspring were 13.2 years (SD = 2.5; range: 8–18 years) at baseline and 17.1 years (SD = 2.7) at follow-up (88.5% retention rate). Psychopathology was assessed using the Kiddie Schedule for Affective Disorders and Schizophrenia for School Age Children Present and Lifetime Version, and Achenbach System of Empirically Based Assessment parent-, self- and teacher-reports. Groups were compared on (1) the presence of categorical psychopathology, (2) timing and development of psychopathology using a clinical staging perspective, and (3) dimensional psychopathology using a multi-informant approach. Results: SZo and BDo showed more categorical psychopathology and (sub)clinical symptoms, as compared to Co. SZo have, compared to BDo, an increased risk for developmental disorders, a younger age of onset, and more (sub)clinical symptoms of the mood and behavioral spectrum as reported by multiple informants. Conclusions: Our study shows that the phenotypical risk profile overlaps between SZo and BDo, although an earlier onset of developmental psychopathology was found specifically in SZo, suggesting of a potentially different ethiopathophysiology. Longer follow-up and future studies are needed.