Date of Award


Degree Type


Degree Name

Doctor of Philosophy


The vulnerability model of schizophrenia (Zubin & Spring, 1977) postulates that individuals have a certain level of vulnerability to schizophrenia which is a relatively enduring trait. An episode of schizophrenia is hypothesized to be a function of this level and stressful events, either in the environment or as perceived by the person. One way of investigating this model is to locate both "markers" of vulnerability and episodes by comparing remitted and episodic schizophrenics, to see how they differ (potential episode markers) and how they are similar (potential vulnerability markers).;Schizophrenics in differing phases of illness have demonstrated a letter detection deficit under conditions of rapid processing (Asarnow & MacCrimmon, 1978). It was hypothesized that remitted and episodic paranoid and nonparanoid schizophrenics would all show similar performances when compared to normal controls. This hypothesis was not borne out, as the remitted patients' performance tended to fall in between the episodic and normal groups. Consequently, this deficit was found not to be a reliable vulnerability marker.;A decline in coping skills and cognitive appraisal of stressful events was postulated as marking the onset of an episode of illness. Remitted and episodic paranoid and nonparanoid schizophrenics were hypothesized to differ in terms of how they appraised and coped with a stressor (noise). Remitted schizophrenics were found to be more socially competent than those who were episodic. For the episodics, the paranoids were more competent than the nonparanoids, as predicted, however, the reverse was true for the remitted group. There were consistent patterns of differences in coping strategies and predictions between paranoid and nonparanoids and it appeared that these tendencies to cope in certain ways may have been more long lasting than the episode itself.;Several vulnerability and episode markers other than those predicted emerged from the study, particularly physiological arousal (heartrate) and changes in measured intelligence as episode markers. Potential vulnerability "markers" were more difficult to assess, due to the influence of symptoms, but may be different physiological variables and response styles or coping predictions for certain subtypes of schizophrenics.



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