The use of the Ego Impairment Index across the schizophrenia spectrum.

The goal of this study was to assess perceptual and thought disturbance, as indexed by the Ego Impairment Index (EII; Perry & Viglione, 1991), a Rorschach-derived measure, across the schizophrenia spectrum. We hypothesized that there would be an increase in EII scores (indicating increased disturbance) across the spectrum from nonpatients to severely disturbed, hospitalized schizophrenia patients. Normal comparison participants (n = 66), students with elevated scores on either the Perceptual Aberration/Magical Ideation or the Physical Anhedonia Scales (n = 24), first-degree relatives of schizophrenia patients (n = 36), participants diagnosed with Diagnostic and Statistical Manual of Mental Disorders (4th ed. [DSM-IV]; American Psychiatric Association, 1994) schizotypal personality disorder (n = 36), outpatient schizophrenia participants (n = 33), and hospitalized schizophrenia patients (n = 56) were studied. As hypothesized, we found increased EII scores in all of the schizophrenia spectrum groups when compared against normal comparison participants. Furthermore, the EII was significantly different between the schizophrenia patients and the other schizophrenia spectrum groups. These findings support the use of the EII as a sensitive measure of perceptual and thought disturbance across the schizophrenia spectrum that yields specific information regarding the type of thinking problems that occur within schizophrenia spectrum subgroups.