Non-psychotic psychiatric disorder and subsequent risk of schizophrenia: Cohort study

Abstract

Background. Those with schizophrenia often give a history of premorbid non-psychotic psychiatric disorder. Aims. To investigate the association between non-psychotic psychiatric disorders and the later development of schizophrenia. Method. Men aged 18 or 19 years, conscripted to the Swedish army in 1970 (n=50 054) were linked to the Swedish National Psychiatric Case Register. Results. There was an increased risk of schizophrenia in those with ICD-8 diagnoses of neurosis (OR-4.6, 95% CI 3.2-6.9), personality disorder (OR=8.2, 95% CI 5.4-12.3), alcohol abuse (OR=5.5, 95% CI 1.7-17.5) or substance abuse (OR=14.0, 95% CI 7.8-25.0) at age 18. Of those who developed schizophrenia, 38% (95% CI 32-45) received a diagnosis of non-psychotic psychiatric disorder at age 18. Only those with personality disorder had a significantly increased risk of schizophrenia (OR=2.4, 95% CI 1.1-5.2) with onset after age 23. Conclusions. Personality factors could represent an underlying vulnerability to schizophrenia. Other diagnoses occurring before schizophrenia may reflect a prodromal phase of the illness. Declaration of interest. Supported by the Swedish Medical Research Council and the Soderberg-Konigska Foundation. No conflict of interest.