Memory changes after unilateral electroconvulsive therapy with different electrode positions.

Abstract

In the course of a series into the effects of unilateral electroconvulsive therapy on memory functions,double-blind cross-over intraindividual comparison were performed after the second and third treatment in patients suffering from depressive syndrome. The main aim of the project, which is still in course, was to explore the possibility of a further reduction of the side-effects of this antidepressant method. Three separate comparisons were performed between unilateral nondominant temporo-parietal ECT and (a) unilateral dominant temporo-parietal ECT, (b) unilateral non-dominant fronto-parietal ECT, (c) unilateral non-dominant fronto-fronto ECT (Figure 1). The treatments were given under total anaesthesia and with subtotal muscle relaxation. Four memory tests were administered three hours after the second and the third ECT, the treatment methods being allocated at random. The 30 Word-Pair Test is mixed audio-visual recall verbal test. The 30 Figure Test is mainly visual recognition test with items which can be easily verbally patterned. Further, two visual recognition tests, the 30 Face Test and the 30 Geometrical Figure Test, composed of not easily verbalized items were administered. For each test, three memory scores were obtained, immediate memory score (IMS, immediately after the presentation of the items, three hours after ECT), delayed memory score (DMS, three hours after IMS) and their differenc, forgetting score (FS). IMS is considered to be a function of the hypothetical memory variable, learning, and FS a function of the variable retention. DMS is related to both learning and retention. When non-dominant and dominant temporo-parietal ECT are compared, there are, after non-dominant ECT, significantly lower IMS and DMS in the 30 Face Test but only lower IMS in the 30 Geometrical Figure Test. The difference in DMS for the 30 Word-Pair Test is in the opposite direction (Figure 2). In the comparison between non-dominant temporo-parietal vs non-dominant fronto-frontal ECT, a slightly, non-significant, lower IMS in the 30 Face Test is apparent (Figure 4). Other important trends are not found in any of the studies (Figures 2-4). The results show that differential effects are obtained with different memory material when dominant and non-dominant electrode positions are used in unilateral ECT. The results are discussed in relation to the question whether high level perceptive function or memory is involved in the encoding-storage of complex non-verbal material in the non-dominant hemisphere.