Basic cognitive mechanisms in schizophrenia
Schizophrenia is associated with a bewildering array of impairments affecting virtually every aspect of cognitive functioning. These problems may stem from changes in the way in which the brain transmits the most basic of information. Indeed, some of the most interesting observations about schizophrenia come from tasks that have been designed to isolate these rudimentary processes.
For example, in healthy individuals, it is possible to speed up processing of semantic information in a target stimulus by priming the target with another semantically related stimulus. This effect is attributed to information processing mechanisms in semantic memory. In schizophrenia, these priming effects appear to be souped up—they are more powerful and even occur when prime-target pairs are only weakly related. One critical question is whether the mechanism that soups up priming also affects other tasks that are presumed to be sensitive to the same underlying mechanisms.
I think it can. My colleague and I found that automatic memory processes—which are also presumed to depend on semantic memory mechanisms—are increased in schizophrenia, particularly among those patients who have symptoms of thought disorder (Linscott and Knight, 2001). The next critical question is whether those who show souped up priming or souped up automatic memory also show analogous changes in other domains of functioning.
Schizotypy as psychometric risk for schizophrenia
Anomalies in basic cognitive processing in schizophrenia could be due to many things other than schizophrenia itself: the medication used to treat the disorder, hospitalization, or other nonspecific factors associated with being unwell. Equally, if the changes in rudimentary cognitive mechanisms arise after the onset of schizophrenia, there is not much to be gained from studying these processes. Observing changes in basic processes before the onset of schizophrenia provides compelling justification for thinking that such changes may be involved in the development of schizophrenia.
Young adults who exhibit psychometric risk for schizophrenia represent an ideal population in which to explore questions about the significance of changes in basic cognitive processes in schizophrenia. For example, my colleague and I found that automatic memory is also souped up in schizotypy (Linscott and Knight, 2004). However, identifying psychometric risk for schizophrenia is not a straightforward process. Schizotypy is multifaceted and, although there are a few well-established measures of schizotypy, these have their limitations. Also, there are significant ethical issues surrounding the assessment of risk for schizophrenia. My students and I are exploring many different conceptual, measurement, and ethical questions relating to schizotypy.
Linscott, R. J., Allardyce, J., & van Os, J. (2009). Seeking verisimilitude in a class: A systematic review of evidence that the criterial clinical symptoms of schizophrenia are taxonic. Schizophrenia Bulletin, in press, 1-19.
van Os, J., Linscott, R. J., Myin-Germeys, I., Delespaul, P., & Krabbendam, L. (2009). A systematic review and meta-analysis of the psychosis continuum: Evidence for a psychosis proneness-persistence-impairment model of psychotic disorder. Psychological Medicine, 39, 179-195.
Linscott, R. J. (2007). The latent structure and coincidence of hypohedonia and schizotypy and their validity as indices of psychometric risk for schizophrenia. Journal of Personality Disorders, 21, 225-242.
Linscott, R. J., Marie, D., Arnott, K. L., & Clarke, B. L. (2006). Over-representation of Maori New Zealanders among adolescents in a schizotypy taxon. Schizophrenia Research, 84, 289-296.
Linscott, R. J. (2005). Thought disorder, pragmatic language impairment, and generalized cognitive decline in schizophrenia. Schizophrenia Research, 75, 225-232.
Hays, S.-J., Niven, B. E., Godfrey, H. P. D., & Linscott, R. J. (2004). Clinical assessment of pragmatic language impairment: A generalisability study of older people with Alzheimer's disease. Aphasiology, 18, 693-714.
Linscott, R. J., & Knight, R. G. (2004). Potentiated automatic memory in schizotypy. Personality and Individual Differences, 37, 1503-1517.
Linscott, R. J., & Knight, R. G. (2001). Automatic hypermnesia and impaired recollection in schizophrenia. Neuropsychology, 15, 576-585.
Recently completed research students
Richard S. Mullen. (2006). Delusions: Conceptual and phenomenological aspects. (PhD)
Kirsty V. Whitehead. (2006). Precursors for schizophrenia: Are schizotaxia and schizotypy related? (PhD)
Mark W. Lewis. (2005). Prospective memory in schizophrenia and related disorders. (MSc)
Paula G. Watkins. (2005). Representational momentum in individuals at risk for schizophrenia. (MSc)
Bronwyn L. Clarke. (2001). Schizotypy and depressive symptomatology in an adolescent sample. (MSc)