To determine the usefulness of including a duration criterion in the definition of "negative" symptoms, the prognostic significance of a longitudinally obtained measure of negative symptoms was compared with a cross-sectionally obtained measure. As predicted, the presence of negative symptoms based on longitudinal observation was associated with most aspects of 18-month course in a group of "first-episode" schizophrenic individuals, whereas cross-sectional levels of negative symptoms were not. The findings suggest that negative symptoms, when operationalized as a trait-like phenomenon, help to portend a poor course of illness.
Bibliographical noteFunding Information:
Acknowledgments. The researchr eportedw as supportedb y grant 6610-1691-44a nd a National Health Ph.D. fellowship, both from Canada Health and Welfare National Health Research and Development Program; B.C. Health Research Foundation grant 11(88-2)g; rant MH-44643 from the National Institute of Mental Health; and a Young Investigator Award from the National Alliance for Research in Schizophrenia and Depression. The authors thank Dave Erickson, Kathy Keetley, Neil Kyle, Diane Lambrou, Margaret Moreau, and Geoffrey Smith for their significant contributions to data collection and management.
- onset of illness