INTRODUCTION: Self-disorders (SD) have been described as a core feature of schizophrenia both in classical and recent psychopathological literature. However, the specificity of SD for the schizophrenia spectrum disorders has never been demonstrated in a diagnostically heterogeneous sample, nor has the concurrent validity of SD been examined.

AIM: (1) To examine the specificity of Examination of Anomalous Self-Experiences (EASE) measured SD to the schizophrenia spectrum disorder in first contact inpatients, (2) to explore the internal consistency and factorial structure of the EASE, (3) to assess the concurrent validity of SD by exploring correlations between SD and the canonical psychopathological dimensions of schizophrenia, (4) to explore relations of SD to intelligence, sociodemographic, and extrinsic illness characteristics.

METHODS: A total of 100 consecutive first admission patients underwent a comprehensive psychopathological examination and an assessment of SD with the EASE scale. The diagnostic distribution of the EASE scores was tested with ANOVA, whereas the relations between the EASE scores and other symptomatic dimensions of schizophrenia were tested with Spearman's rho. A potential factorial structure and the internal consistency of the EASE scale were also examined.

RESULTS: SD aggregated significantly in the schizophrenia spectrum disorders, with no differences between schizophrenia and schizotypal disorders. EASE scores correlated moderately with canonical psychopathological dimensions of schizophrenia. Factor analysis of the EASE disclosed only one factor and the internal consistency of the EASE was excellent.

CONCLUSIONS: SD aggregate selectively in the schizophrenia spectrum disorders, with similar levels in schizophrenia and schizotypy. The study lends validity to the view of SD as an experiential vulnerability phenotype of the schizophrenia spectrum disorders.