Daniel, CL; (2017) Sensory Deprivation as an Experimental Model of Psychosis. Doctoral thesis , UCL (University College London).

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Abstract

The development of novel experimental models of schizophrenia and psychosis are critical to developing a better understanding of these complex and poorly understood disorders. Existing approaches such as animal and drug models have major limitations to their use. An alternative approach to modelling psychosis is proposed, built upon the premise of continuum theory, focusing on ‘high risk’ hallucination prone individuals from within the healthy population. A systematic review considered existing non-pharmacological approaches for inducing psychosis-like experiences (PLE’s) in such individuals. The thesis then addressed how one such method, short-term sensory deprivation, can successfully induce transient psychosis-like experiences (PLE’s) in this population. The Revised Hallucinations Scale (RHS: Morrison et al. 2002) was found to accurately predict individuals most likely to experience PLE’s in sensory deprivation. Individual differences that may contribute to reports of PLE’s were explored: the most powerful predictor of PLE’s in sensory deprivation was verified to be hallucination proneness. Additional personality traits such as fantasy proneness and suggestibility were not implicated. A revised four factor structure for the RHS was also developed, using Exploratory Structural Equation Modelling (ESEM). This model showed improved fit to the original non-replicable factor structure. The ESEM approach is arguably more appropriate than traditional factor analysis for modelling data with high inter-factorial correlations. Quantitative Electroencephalogram (EEG) data was collected in order to establish whether this approach could provide a robust neurophysiological correlate for psychosis-like experiences. Initial pilot data suggested hallucination prone individuals may be characterised by reduced levels of theta, alpha and beta activity, alongside elevated levels of cortical hyper-excitability. These findings support weakened inhibitory processing theories of psychosis. Overall, sensory deprivation was found to have the potential to contribute significantly to our understanding of psychosis, and could be utilised effectively on a stand-alone basis, or as an adjunct to existing animal and drug models.

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