Olfaction in First Episode Psychosis Study, Melbourne Neuropsychiatry Centre

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This project involved collection of neuropsychological data from first episode psychosis patients at the Aubrey Lewis unit at Royal Park Hospital. A challenge inherent to understanding schizophrenia is to distinguish between primary and secondary disease processes and their associated symptomatology. Neuropsychological approaches to this challenge are examined in this thesis along with an overview of attempts to identify syndromal patterns. Relationships between these syndromes and their influence on cognitive function are also described, particularly with reference to possible underlying biological compromise. This description forms a rationale for the aims of the thesis that include an examination of cognition as possible marker of functional compromise of circuitry implicated in schizophrenia. Olfactory processing over the course from high risk to chronic schizophrenia is described. Identification of olfactory deficits early in the course of psychosis are found to implicate relatively specific prefrontal circuits that are associated with both syndromal and cognitive patterns of behaviour, after the confounds of acuity, substance abuse, medication and general cognitive ability are taken into account. Patterns of olfactory ability across the spectrum of psychosis are then compared to those found to be characteristic of a temporal lobe epilepsy group with the aim of comparing and contrasting the functional integrity of implicated circuitry in psychosis. Results support the potential for olfactory tasks to be used as probes of function in related circuitry, and particularly for detecting early signs of impending psychotic discharge. While the degree of cognitive deficits may be exacerbated over the course of the illness in accordance with the neurodegenerative hypothesis, identification of patterns of compromised function that implicates the fronto-limbic axis before the first psychotic discharge are also consistent with the neurodevelopmental hypothesis of schizophrenia. This project recruited over 100 participants. Time period: 1994-1999