Enduring psychological sequelae of electroconvulsive therapy
The aim of this research was to examine whether electroconvulsive therapy (ECT) has any enduring effects on cognition when it is used to treat depressed patients. The literature concerning the effects of depression, psychotropic medication, and ECT on cognition, was reviewed. Animal analogue experiments and human clinical studies were reviewed with particular attention to followup studies. Within the clinical psychometric studies, four major aspects of cognitive function - perception, performance speed, learning and memory - were critically analyzed. An empirical prospective study, avoiding the methodological inadequacies of the previous work and extending the length of follow up, is described. The above mentioned aspects of cognitive function were compared in carefully matched groups of ECT and non-ECT treated depressives on admission, at four months and at seven months. Matched volunteer subjects were assessed to ascertain normal levels and variation of each of the psychometric tests employed, and to ascertain reliability. Three new tests were validated by correlational reference to established tests and to independent neuroradiological assessments of structural cerebral abnormalities. ECT caused little impairment at four months and no impairment at seven months as indicated by the comprehensive cognitive test battery. Severity of depression had a marked effect on cognitive function. Within the ECT group, bilateral ECT caused more impairment than unilateral ECT one week after a course of treatment, but three months later the differences had disappeared. Both forms of treatment were equally antidepressant. These results are discussed in terms of potential methodological criticisms and other sources of error. A synthesis is attempted to relate this study's findings to the subjective complaints of a proportion of previously treated patients. The implications of this study to clinical practice and further research are put forward.