The long-term impact of treatment with electroconvulsive therapy on discrete memory systems in patients with bipolar disorder

Objective: Electroconvulsive therapy (ECT) has been controversially associated with long-lasting memory problems. Verbal learning and memory deficits are commonly reported in studies of people with bipolar disorder (BD). Whether memory deficits can be exacerbated in patients with BD who receive ECT has, to our knowledge, not been systematically examined. We aimed to examine whether long-term effects of ECT on discrete memory systems could be detected in patients with BD. Methods: We studied several domains of memory in 3 groups of subjects who were matched for age and sex: a group of healthy comparison subjects, a group of people with BD who had received ECT at least 6 months before memory assessment and another group with BD that had an equal past illness burden but had never received ECT. Memory was assessed with the California Verbal Learning Test, the Continuous Visual Memory Test and a computerized process dissociation task that examines recollection and habit memory in a single paradigm. Results: Compared with healthy subjects, patients had verbal learning and memory deficits. Subjects who had received remote ECT had further impairment on a variety of learning and memory tests when compared with patients with no past ECT. This degree of impairment could not be accounted for by illness state at the time of assessment or by differential past illness burden between patient groups. Conclusions: From a clinical perspective, it is unlikely that such findings, even if confirmed, would significantly change the risk–benefit ratio of this notably effective treatment. Nonetheless, they may highlight the importance of attending to cognitive factors in patients with BD who are about to receive ECT; further, they raise the question of whether certain strategies that minimize cognitive dysfunction with ECT should be routinely employed in this patient group.