Randomized study of the therapeutic effect of electroconvulsive therapy, uni- or bilateral, on certain cognitive functions in depression, with electroencephalography monitoring. Preliminary results

Cognitive functions are known to be impaired by ECT. The aim of this study is to differentiate the effects of electroconvulsive therapy on some cognitive functions according to the mode of application of the electrodes. The brief-pulse Thymatron DG apparatus allows to control four electrical parameters and to assess electroencephalographic data. The preliminary sample comprises nine patients suffering of major depressive disorder; they are randomly assigned to the mode of application of the electrodes, bilateral or unilateral to the non dominant hemisphere. Clinical evolution is surveyed by the Montgomery and Asbert Depression Rating Scale. Non mnesic functions are assessed: arousal by CFF (Critical Fusion Frequency), and attentional, motor and decisional abilities by CRT (Choice Reaction Test). Different mnesic function are studied by selective reminding test, cued recall test, block tapping test and picture fragmentation test. After treatment by ECT, verbal mnesic functions assessed by selective reminding test are impaired with the bilateral application. Whereas they are not modified with the unilateral application. The variance of CFF regains a physiological value in the bilateral group, but remains altered in the unilateral.