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Title: Physiological and psychological assessment of schizophrenia and affective disorders
Author: Roxborough, Hilary M.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1989
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The study examined data on the physiological and psychological changes which occur in schizophrenia and the affective disorders. The main physiological variable studied was the P300, a component of Event Related Potentials (ERPs), which has been hypothesized to reflect a manifestation of information processing involving the matching of incoming stimuli with the subject's cognitive set. Information processing deficits have also been implicated in schizophrenia and in the affective disorders. The specific aims were: a) to compare the P300 components of the ERPs in clinical groups (schizophrenia, bipolar depression and unipolar depression) and non-patient groups (normal controls and relatives of schizophrenic patients) b) to identify dysfunctional cognitive styles which correlate with abnormalities in P300 latency and amplitude c) to consider whether the cognitive and physiological abnormalities correlate with structural changes measured by Magnetic Resonance Imaging (MRI) in the schizophrenic patients d) to consider whether another physiological variable (Eye Tracking Dysfunction, ETD) which is also involved in information processing differentiates the groups and correlates with cognitive function and structural change. Three studies were conducted. In the first study, physiological responses (P300 and ETD) and psychological performance related to the formation and use of cognitive sets were identified in 24 schizophrenic, 10 bipolar manic, 10 bipolar depressed, 10 unipolar depressed and 24 control subjects. P300 latencies were found to be significantly different in the schizophrenic and bipolar groups compared with the control subjects. Deficits in cognitive function in these patient groups correlated significantly with increased P300 latencies, indicating that schizophrenic and bipolar subjects experience dysfunctions in cognitive sets which are reflected in their physiological functioning. Three sub-groups were identified in the schizophrenic population: one showed no physiological abnormalities; of the two which had physiological abnormalities, one group showed a strong correlation between P300 latency and tests which are sensitive to frontal lobe function, and the other group showed consistent significant correlations between P300 latency and performance in memory tests. In the second study, MRI measures of structural change were correlated with physiological and cognitive scores, to validate the specific deficits identifed in the schizophrenic population. Thirty schizophrenic patients and thirty control subjects were assessed. The data indicated that the schizophrenic subjects who showed physiological abnormalities had frontal lobe or hippocampal impairment or both. A decline in IQ with illness was found in the group which showed frontal lobe impairment. The same psychological tests were applied to schizophrenic patients' relatives (n = 30). Relatives with prolonged P300 latencies showed deficits in frontal lobe and hippocampal function which were similar to those found in the patients. The third study compared the P300 amplitude and latency of visual ERPs to emotive stimuli in 15 depressed, 15 recovered depressed and 15 control subjects. The physiological data were correlated with ratings of severity of depression, depressogenic attitudes and personality variables. Significant differences were found between the depressed and control subjects in the physiological and psychological data. A significant relationship between the physiological and psychological measures was established. This study supported cognitive theories of depression by showing a negative set in information processing. The results from the three studies supported the hypothesis that P300 abnormalities reflect dysfunctions in cognitive set.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available