UBC Theses and Dissertations
A vulnerability-stress model for the course of schizophrenia ? Erickson, David Harry
Despite a prevailing paradigm that emphasizes an interaction of vulnerability and stress to account for the etiology of schizophrenia, diathesis—stress models of subsequent course and outcome of this disorder are rare. Even the simpler stress— process model, where the influence of stressors is mediated by supportive social relationships, has received little attention in studies of the course of schizophrenia. The objective of this study was to assess the following components of a diathesis—stress model as they predict the five-year outcome of first-episode schizophrenia: (1) stressful life events; (2) supportive social relationships; (3) brain lateral ventricle size; and (4) smooth pursuit eye movements. As part of the Greater Vancouver M.A.P. Project, we recruited first-episode DSM-III schizophrenia and affective psychosis patients. At intake to the study, their social relationships, smooth pursuit eye movement function, and brain ventricle size were assessed. Life events in the previous year were measured at intake; events over the following 18 months were assessed in two later interviews. Five years later we assessed outcome, using a global rating of social and occupational functioning. Descriptive results showed substantial variability within the schizophrenia group at intake and outcome. The trajectory of adaptive functioning over time was remarkably similar for the schizophrenic and affective psychosis groups. Of the four hypothesized predictors, only social relationships were associated (p=.O3) with five—year outcome. The number of life events was not associated with five—year outcome, nor was either of the biological risk factors. As a result, the predictor variables could not be combined in either a stress—process model or a vulnerability—stress model of the course of schizophrenia. That social relationship variables are associated with five-year outcome supports earlier findings regarding 18-month outcome, including the differing predictive roles for family and nonfamily relationships. The absence of hypothesized results for the life events data probably indicates that too much time had passed between outcome and the events as measured. Finally, that brain ventricle size and eye-movement dysfunction predict 18-month but not five—year outcome may indicate that impairment due to biological factors is expressed only in the early stages of schizophrenia.
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