Occurrence and clinical correlates of psychiatric comorbidity in patients with psychotic disorders

Background: The aim of this study was to explore patterns and clinical correlates of psychiatric comorbidity in patients with schizophrenia spectrum disorders and mood spectrum disorders with psychotic features. Method: Ninety-six consecutively hospitalized patients with current psychotic symptoms were recruited and included in this study. Index episode psychotic diagnosis and psychiatric comorbidity were assessed using the Structured Clinical Interview for DSM-III-R-Patient Version (SCID-P). Psychopathology was assessed by the SCID-P, Brief Psychiatric Rating Scale, Scale for the Assessment of Negative Symptoms, and Hopkins Symptom Checklist. Awareness of illness was assessed with the Scale to Assess Unawareness of Mental Disorders. Results: The total lifetime prevalence of psychiatric comorbidity in the entire cohort was 57.3% (58.1% in schizophrenia spectrum disorders and 56.9% in mood spectrum psychoses). Overall, panic disorder (24%), obsessive-compulsive disorder (24%), social phobia (17.7%), substance abuse (11.5%), alcohol abuse (10.4%), and simple phobia (7.3%) were the most frequent comorbidities. Within the group of mood spectrum disorders, negative symptoms were found to be more frequent among patients with psychiatric comorbidity than among those without comorbidity, while such a difference was not detected within the group of schizophrenia spectrum disorders. Social phobia, substance abuse disorder, and panic disorder comorbidity showed the greatest association with psychotic features. An association between earlier age at first hospitalization and comorbidity was found only in patients with unipolar psychotic depression. Patient self-reported psychopathology was more severe in schizophrenia spectrum patients with comorbidity than in those without, while such a difference was less pronounced in mood spectrum psychoses. Conclusion: These findings suggest that psychiatric comorbidity is a relevant phenomenon in psychoses and is likely to negatively affect the phenomenology of psychotic illness. Further studies in larger psychotic populations are needed to gain more insight into the clinical and therapeutic implications of psychiatric comorbidity in psychoses.