Risk of Schizophrenia Increases After All Child and Adolescent Psychiatric Disorders:A Nationwide Study

Objective: Earlier smaller studies have shown associations between child and adolescent psychiatric disorders and schizophrenia. Particularly, attention-deficit/hyperactivity-disorder and autism have been linked with schizophrenia. However, large-scale prospective studies have been lacking. We, therefore, conducted the first large-scale study on the association between a broad spectrum of child and adolescent psychiatric disorders and the risk of being diagnosed with schizophrenia. Methods: Danish nationwide registers were linked to establish a cohort consisting of all persons born during 1990–2000 and the cohort was followed until December 31, 2012. Data were analyzed using survival analyses and adjusted for calendar year, age, and sex. Results: A total of 25138 individuals with child and adolescent psychiatric disorders were identified, out of which 1232 individuals were subsequently diagnosed with schizophrenia spectrum disorders. The risk of schizophrenia spectrum disorders was highly elevated, particularly within the first year after onset of the child and adolescent psychiatric disorder, and remained significantly elevated >5 years with an incidence rate ratio of 4.93 (95% confidence interval: 4.37–5.54).We utilized the cumulated incidences and found that among persons diagnosed with a child and adolescent psychiatric disorder between the ages 0–13 years and 14–17 years, 1.68% and 8.74 %, respectively, will be diagnosed with a schizophrenia spectrum disorder <8 years after onset of the child and adolescent psychiatric disorder. Conclusions: The risk of being diagnosed with schizophrenia spectrum disorders after a child and adolescent psychiatric disorder was significantly increased particularly in the short term but also in the long-term period