Psychopathological and demographic characteristics of hallucinating patients with schizophrenia and schizoaffective disorder: an analysis based on AMDP data

Hallucinations are at the core of the diagnosis of schizophrenia and schizoaffective disorders, and many neuroscience studies focus on hallucinations. However, there is a lack of data on prevalence, subtyping, and clinical correlates of hallucinations as well as on the comparison of hallucinating schizophrenia versus hallucinating schizoaffective patients. Analysis of all psychopathology evaluations is based on the AMDP scale in a German psychiatric university hospital between 2007 and 2013 regarding patients with schizophrenia or schizoaffective disorder (diagnosed according to ICD-10). Hallucinating versus non-hallucinating patients and age- and gender-matched hallucinating schizophrenic versus schizoaffective patients were compared with regard to key psychopathological and demographic characteristics. Relative to patients with schizoaffective disorder, patients with schizophrenia more often hallucinated at admission (36.6 vs. 16.2 %, RR: 2.3, p < 0.001). By subtype, frequency of hallucinations ranked auditory verbal > other auditory > visual > somatic/tactile > olfactory/gustatory. Hallucinating patients of either disorder were more often affected with respect to delusions (83 vs. 62 % and 81 vs. 48 % among patients with schizophrenia and schizoaffective disorder, respectively [both p < 0.0001]) and anxiety. Hallucinating patients with schizoaffective disorder did not differ from hallucinating patients with schizophrenia. This is one of the few studies providing data on hallucinations in a routine clinical care setting. Hallucinations are a sign and likely a cause of greater illness severity. Patients with schizoaffective disorder less often experience hallucinations than patients with schizophrenia, but if they do, they seem to resemble patients with schizophrenia with regard to illness severity.