Depression predicts persistence of paranoia in clinical high-risk patients to psychosis: results of the EPOS project.

BACKGROUND The link between depression and paranoia has long been discussed in psychiatric literature. Because the causality of this association is difficult to study in patients with full-blown psychosis, we aimed to investigate how clinical depression relates to the presence and occurrence of paranoid symptoms in clinical high-risk (CHR) patients. METHODS In all, 245 young help-seeking CHR patients were assessed for suspiciousness and paranoid symptoms with the structured interview for prodromal syndromes at baseline, 9- and 18-month follow-up. At baseline, clinical diagnoses were assessed by the Structured Clinical Interview for DSM-IV, childhood adversities by the Trauma and Distress Scale, trait-like suspiciousness by the Schizotypal Personality Questionnaire, and anxiety and depressiveness by the Positive and Negative Syndrome Scale. RESULTS At baseline, 54.3 % of CHR patients reported at least moderate paranoid symptoms. At 9- and 18-month follow-ups, the corresponding figures were 28.3 and 24.4 %. Depressive, obsessive-compulsive and somatoform disorders, emotional and sexual abuse, and anxiety and suspiciousness associated with paranoid symptoms. In multivariate modelling, depressive and obsessive-compulsive disorders, sexual abuse, and anxiety predicted persistence of paranoid symptoms. CONCLUSION Depressive disorder was one of the major clinical factors predicting persistence of paranoid symptoms in CHR patients. In addition, obsessive-compulsive disorder, childhood sexual abuse, and anxiety associated with paranoia. Effective pharmacological and psychotherapeutic treatment of these disorders and anxiety may reduce paranoid symptoms in CHR patients.