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

Background Those with schizophrenia often give a history of premorbid non-p sychotic psychiatric disorder. Aims To investigate the association between non-psychotic psychiatric disor ders 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 di agnoses 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 abu se (OR=14.0, 95% CI 7.8-25.0) at age 18. Of those who developed schizophren ia. 38% (95% CI 32-45) received a diagnosis of non-psychotic psychiatric di sorder at age 18. Only those with personality disorder had a significantly increased risk of schizophrenia (OR=2.4. 95% Cl 1.1-5.2) with onset after a ge 23. Conclusions Personality factors could represent an underlying vulnerability to schizophrenia. Other diagnoses occurring before schizophrenia may refle ct a prodromal phase of the illness. Declaration of interest Supported by the Swedish Medical Research Council a nd the Soderberg-Konigska Foundation. No conflict of interest.