Relative efficacy of the Sc-O, P-O, P-N, and Sc MMPI scales in differentiating brain-damaged, brain-damaged schizophrenic, schizophrenic, and somatoform disorders in an outpatient setting.

This study examined the efficacy of the Schizophrenic-Organicity (Sc-O), Psychiatric-Organic (P-O), the Pseudo-Neurological (P-N), and the Schizophrenia (Sc) MMPI subscales in differentiating the following four groups of outpatients: brain-damaged (n = 35), brain-damaged schizophrenics (n = 10), non-brain-damaged schizophrenics (n = 15), and somatoform disorders (n = 45). Both unmatched and matched samples were used in the analysis, and cut-off scores were obtained. In an unmatched sample, results suggested that the Sc scale was useful in differentiating brain-damaged schizophrenics from brain-damaged and somatoform disorders. With matched samples, the Sc differentiated brain-damaged schizophrenics well from other clinical groups, while the P-O scale differentiated the non-brain-damaged schizophrenics from brain-damaged and somatoform disorders. Furthermore, the P-N scale discriminated brain-damaged schizophrenics from non-brain-damaged schizophrenics, while the Sc-O scale was no longer significant. Results suggest that caution should be used in generalizing from previous studies (which used inpatient samples) to outpatient populations.