Assessment of schizophrenia in persons with severe and profound mental retardation using the diagnostic assessment for the Severely Handicapped-II (DASH-II)

The identification and diagnosis of schizophrenia in persons with severe an d profound mental retardation has been a controversial issue. Although it h as been established that schizophrenia occurs in this clinical population, persons with odd behaviors characteristic of mental retardation or severe b ehavior disturbances are often diagnosed with schizophrenia and treated wit h traditional or atypical antipsychotic medications. The present study asse ssed schizophrenia in a sample of persons with severe and profound mental r etardation using the Diagnositic Assessment for the Severly Handicapped-II (DASH-II), a rating scale which contains purely behavioral criteria that ar e essential features of various DSM-IV disorders. Three groups of participa nts were compared, (a) those with an independent psychiatric diagnosis of s chizophrenia and a significant elevation oil the schizophrenia subscale of the DASH-II; (b) those with a significant elevation oil this subscale, but no formal diagnosis of schizophrenia; and (c) controls without any elevatio n of the DASH-II subscales. Results indicated that the three groups were em pirically distinguished across the frequency, duration, and severity dimens ions of the DASH-II schizophrenia subscale. Item analyses demonstrated that individuals with a diagnosis of schizophrenia and an elevation of the subs cale had higher scores oil items containing verbal symptoms of the disorder . Implications of these findings are discussed with respect to the diagnosi s of schizophrenia in persons with severe and profound mental retardation, with particular emphasis oil the efficacy of the DASH-II for assessing the disorder.