A metacognitive account for the relationship between neurocognition and functional outcome in first-episode psychosis

Neurocognitive and functional outcome deficits have long been acknowledged in schizophrenia and are considered a core feature of the disorder. Neurocognition has been found to account for functional disability to a greater extent than psychopathology however much of the variance in functional outcome still remains unexplained. How functional outcome is measured also requires clarification. By investigating the relationship between neurocognition and functional outcome in First-Episode Psychosis (FEP), much can be learnt about the trajectory of disability and the course of illness in schizophrenia. Metacognition, or thinking about thinking, has been proposed as a mediating variable between neurocognition and functional outcome. Despite different theoretical backgrounds, authors generally converge on there being higher-order, explicit, conscious metacognitive knowledge and lower-order, implicit metacognitive processes. How these relate to each other requires clarification. The prefrontal cortex (PFC) has been implicated in higher order thought and metacognitive processing, and deficits have been observed in PFC Grey Matter (GM) volume in schizophrenia. These metacognitive deficits may contribute to the relationship between cognitive ability and community functioning. A preliminary meta-analysis demonstrated that a moderate effect size is found between neurocognition and metacognition and a moderate effect size exists between metacognition and functional outcome. The present thesis investigated whether metacognition mediates the relationship between neurocognition and functional outcome in FEP (N=80). Path models were created to investigate the different relationships between neurocognition, metacognition and both capacity to perform everyday tasks and objective functioning in the community. A secondary Voxel-based Morphometry (VBM) analysis was also conducted investigating perceptual metacognitive accuracy and its relationship to GM volume in both FEP (N=41) and a matched healthy control sample (N=21). Current findings support the model that metacognition and negative symptoms mediate the relationship between neurocognition and functional capacity in FEP. Path models also demonstrated a significant mediation effect of metacognition between neorocognition and objective function, and functional capacity and objective function. Significant group differences were found between FEP and controls in perceptual metacognitive accuracy however no significant relationship was found between metacognition and GM volume in the PFC. The present thesis suggests that metacognitive deficits are present at first episode and may account for the relationship between cognitive ability and functioning in the community. Findings also suggest that cognitive remediation programmes may wish to focus on metacognition to maximise the transfer of cognitive skills to community functioning. The findings also suggest the presence of two metacognitive processing routes; explicit, declarable, higher-order knowledge and implicit, intuition-based, lower-order experience which can be accounted for by Nelson and Narens (1990) metacognitive model.