Bizarre delusions and DSM-IV schizophrenia

The present study investigated whether schizophrenia patients with and without DSM-IV bizarre delusions, categorized as bizarre delusions of Schneiderian first rank symptoms (SBD) and as non-Schneiderian bizarre delusions (non-SBD), differed on demographic or clinical features, in view of the weight given to bizarre delusions in the diagnosis of schizophrenia. One hundred and twenty-nine in-patients with schizophrenia were assessed systematically for both types of bizarre delusions on the five domains of psychopathology of the Positive and Negative Syndrome Scale (PANSS; delusions/hallucinations, thought disorder/disorganization, excitement, negative symptoms and depressive symptoms) and for extrapyramidal side-effects. Inter-rater reliabilities for SBD and non-SBD were assessed and were exceptionally high (kappa value 0.85 and 0.92, respectively). Neither SBD nor non-SBD were associated with any demographic or non-PANSS clinical characteristics tested. However, the presence of non-SBD was significantly associated with more severe psychopathology in all five domains of the PANSS, whereas the presence of SBD was significantly associated with more severe psychopathology in three domains only: delusions/hallucinations, thought disorder/disorganization and depressive symptoms. However, patients with only SBD did not differ from patients with only non-SBD on any demographic or clinical variables, including five psychopathological domains. These findings suggest that, despite showing more severe symptoms, patients with DSM-IV bizarre delusions do not constitute a clinically distinguishable subgroup.