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Dichotic perception and memory capability after electroconvulsive therapy Williams, Karl Munro


To investigate whether electroconvulsive therapy (ECT) is associated with deficits in cognitive functioning, accuracy of dichotic perception and memory was tested in 11 depressed patients before and after treatment with ECT. The performance of these patients was compared with that of remitted and depressed patients who had been treated with ECT at least 6 months previously (N=15), depressed patients who were currently being treated with medication and who had never received ECT (N=15), remitted depressives who had never received ECT (N=17), and normal individuals without history of affective disorder (N=20). Prior to treatment, the patients who were to receive ECT had impaired levels of performance on a test of verbal memory (Logical Memory) and on a test of visuospatial memory (Benton Visual Retention Test). These deficits in performance were apparently attributable to the high level of depression present among those patients. Two weeks after treatment, and despite clinical remission, the ECT patients continued to exhibit diminished levels of performance on the test of verbal memory and also showed significant impairment in the ability to recall autobiographical material. No deficits in performance were detected among the patients who had received ECT at least 6 months previously, and no other differences among groups reached statistical significance. With regard to dichotic perceptual ability, no differences among groups were detected. However, subjects who were currently in treatment with ECT, as well as the depressed subjects overall, failed to demonstrate the degree of ear asymmetry that is normally found on tests of dichotic perception. Possible reasons for this lack of asymmetry are discussed. It is noted that the research evidence that has been accrued to date has tended to support the hypothesis that there is an asymmetry of cerebral hemispheric activation and dominance during certain states of psychopathology. In depression this hemispheric imbalance has usually been found to be one of relative dominance of the right cerebral hemisphere. The results of the present study are taken to provide support for the theory that there are abnormalities of hemispheric lateralization during states of depression. The results of the present study do not provide any evidence of long-term (that is, 6 months or more after treatment) deficits in cognitive functioning associated with ECT.

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