Dysthymia in male adolescents is associated with increased risk of later hospitalization for psychotic disorders: a historical-prospective cohort study

Aim: Retrospective studies indicate that patients with psychotic disorders and schizophrenia often suffer from depressive symptoms before the onset of psychosis. In a historical‐prospective design, we studied the association between dysthymia in adolescence and later hospitalization for psychotic disorders and schizophrenia. Methods: The Israeli Draft Board screens the entire, unselected population of 16–17 years old male adolescents for psychiatric disorders. These adolescents were followed for hospitalization for psychotic disorders and schizophrenia using the Israeli National Psychiatric Hospitalization Case Registry. Of 275 705 male adolescents screened, 1267 (0.5%) were hospitalized for psychotic disorders (International Classification of Diseases ICD]‐10 20.0–29.9), and 757 (0.3%) were hospitalized for schizophrenia (ICD‐10 20.0–20.9) over the next 1–10 years. Results: Of 275 705 male adolescents screened, 513 (0.2%) were diagnosed as suffering from dysthymia by the Draft Board. Of these adolescents, 10/513 (2.0%) were later hospitalized for psychotic disorders (including schizophrenia, HR = 3.967, 95%CI (confidence intervals): 2.129–7.390), and 4/513 (0.8%) were later hospitalized for schizophrenia (HR = 2.664, 95%CI: 0.997–7.116). Conclusions: In this population‐based cohort of male adolescents, dysthymia was associated with increased risk for future psychotic disorders. Dysthymia in some adolescents might be a prodromal symptom, while in others it might be a risk factor for later psychosis. Clinicians assessing dysthymic adolescents should be aware that these symptoms might be part of the prodrome.