Roxborough, Hilary Mary

2018-01-31T11:36:30Z

2018-01-31T11:36:30Z

1989

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 P3, 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 P3 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 P3 latency and amplitude

c) to consider whether the cognitive and physiological abnormalities correlate with structural change 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 (P3 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. P3 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 P3 latencies, indicating that schizophrenic and bipolar subjects experience dysfunctions in cognitive set which are reflected in their physiological funtioning. Two sub -groups were identified in the schizophrenic population: one group showed a strong correlation between P3 latency and tests which are sensitive to frontal lobe function, and the other group showed a significant correlation between P3 latency and performance in verbal recall.

In the second test, MRI measures of structural change were correlated with physiological and cognitive scores, to validate the specific deficits identified 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 sub -group which showed most frontal lobe impairment. The same psychological tests were applied to schizophrenic patients' relatives (n =30). Relatives with prolonged P3 latencies showed deficits in frontal lobe and hippocampal function which were similar to those found in the patients.

The third study compared the P3 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. The study supported cognitive theories of depression by showing a negative set in information processing.

The results from the three studies supported the hypothesis that P3 abnormalities reflect dysfunctions in cognitive set.

http://hdl.handle.net/1842/27314

The University of Edinburgh

Annexe Thesis Digitisation Project 2017 Block 16

Already catalogued

Physiological and psychological assessment of schizophrenia and affective disorders

Thesis or Dissertation

PhD Doctor of Philosophy