Assessment of Schizophrenia in Persons with Severe and Profound Mental Retardation Using the Diagnostic Assessment for the Severely Handicapped-II (DASH-II)

Abstract

The identification and diagnosis of schizophrenia in persons with severe and profound mental retardation has been a controversial issue. Although it has been established that schizophrenia occurs in this clinical population, persons with odd behaviors characteristic of mental retardation or severe behavior disturbances are often diagnosed with schizophrenia and treated with traditional or atypical antipsychotic medications. The present study assessed schizophrenia in a sample of persons with severe and profound mental retardation using the Diagnositic Assessment for the Severly Handicapped-II (DASH-II), a rating scale which contains purely behavioral criteria that are essential features of various DSM-IV disorders. Three groups of participants were compared; (a) those with an independent psychiatric diagnosis of schizophrenia and a significant elevation on the schizophrenia subscale of the DASH-II; (b) those with a significant elevation on this subscale, but no formal diagnosis of schizophrenia; and (c) controls without any elevation of the DASH-II subscales. Results indicated that the three groups were empirically distinguished across the frequency, duration, and severity dimensions of the DASH-II schizophrenia subscale. Item analyses demonstrated that individuals with a diagnosis of schizophrenia and an elevation of the subscale had higher scores on items containing verbal symptoms of the disorder. Implications of these findings are discussed with respect to the diagnosis of schizophrenia in persons with severe and profound mental retardation, with particular emphasis on the efficacy of the DASH-II for assessing the disorder.