Cognitive processes across the continuum of psychosis

Research suggests psychotic-like experiences (PLEs) are common phenomena and such experiences do not always warrant a clinical diagnosis of psychosis. Nonetheless it has been argued that people who experience PLEs may be at risk of developing psychosis. Consequently, criteria have been developed to identify people experiencing at risk mental states (ARMS) and research trials have been conducted aimed at preventing the development of psychosis. What seems to distinguish the general population from the clinical population is the appraisal of PLEs. Morrison's (2001) cognitive model of psychosis suggests appraisals of PLEs, and subsequent responses adopted, are responsible for the maintenance of distress and disability associated with psychosis. These appraisals and responses are determined by beliefs that are formed through life experiences regarding the self, the world and others (Morrison, 2001). Metacognitive theory would also suggest positive beliefs about PLEs are associated with an increase in such phenomena whereas negative beliefs about PLEs are associated with distress. Five studies were designed to test predictions based on Morrison's (2001) cognitive model in non-clinical (NC) and clinical samples, investigate the continuum view of psychosis, explore experiences of psychopathology across the continuum, investigate how cognitive processes relate to PLEs in clinical and NC samples and examine the role of appraisals and schemas in the relationship between PLEs and associated distress. Studies demonstrated strong evidence to suggest a continuum of psychosis exists, which spans affective states. Continuum studies showed significantly elevated negative metacognitive beliefs and self schemas, plus significantly lower levels of positive self schemas in the clinical populations. Experimental studies reported significant associations between psychotic-like appraisals and distress. Some cognitive processes were found to mediate the relationships between PLEs and distress in the ARMS population. The results provide validation for the continuum view of psychosis, and for both the cognitive model (Morrison, 2001) and the S-REF model (Wells & Matthews, 1994; Wells & Matthews, 1996).EThOS - Electronic Theses Online ServiceGBUnited Kingdo