Changes in the diagnosed incidence of early onset schizophrenia over four decades

Objective: To explore changes in the diagnosed incidence of early onset schizophrenia (EOS) from 1971 to 2010. Method: Examination of incidence rates of schizophrenia in patients under 18 years of age, using a nationwide, population-based, mental health register. Results: The age-standardized incidence rate (IR) of EOS in the period 19712010 was 3.17 (95% CI: 3.16, 3.18) per 100 000 person years in the age group 018 years, and 9.10 (95% CI: 9.00, 9.21) in the age group 1218 years. In the period 19711993, the age-standardized IR of EOS was 1.80 (95% CI: 1.79, 1.82) per 100 000 person years in the age group 018 years, and 5.02 (95% CI: 4.92, 5.11) in the age group 1218 years. In the period 19942010, the age-standardized IR of EOS was 5.15 (95% CI: 5.10, 5.20) per 100 000 person years in the age group 018 years, and 15.73 (95% CI: 15.22, 16.22) in the age group 1218 years. The IR was higher for males than females in the periods 19711993 and 19712010, but in the period 19942010 the IR was higher for females than males. Conclusion: In recent years, the diagnosed incidence of EOS has increased and the usual male excess has disappeared. The changes in IR could be a result of changes in the diagnostic system, increased awareness of early psychosis or a reflection of actual underlying incidence of the disorder.