Les troubles mnésiques au cours de l’électroconvulsivothérapie

Introduction

Electroconvulsive therapy (ECT) is the oldest technique still in use in psychiatry. Nevertheless, its adverse cognitive side effects are frequent, particularly complaints about memory. The main objective of this review is to describe the nature of ECT-related memory disorders, their short- and long-term evolution and associated risk factors, and to propose recommendations for appropriate evaluation and follow-up.

Methods

À systematic review of the literature was conducted in April 2022, using the PRISMA methodology. The English search equations gleaned from the literature published were entered into PubMed and Cochrane using the search queries: ‘cognition’ and ‘electroconvulsive therapy’ or ‘amnesia’ and ‘electroconvulsive therapy’ or ‘adverse effects’ and electroconvulsive therapy’. The search was carried out on literature published between 2000 to 2022.

Results

Our review included 20 articles, including 4 articles on types of memory disorders, 3 articles on mechanisms, 6 articles on risk factors, 3 articles on cognitive testing and 4 articles on treatment. The data indicated impairment of both anterograde and retrograde memory. In the days following the session of ECT, the ability to recall events that occurred post-treatment, as well as general and autobiographical knowledge, was impaired. However, most cognitive functions improve within 4 weeks. Nevertheless, some patients, may show autobiographical memory deficits for from 3 to 6 months after ECT. The duration of the confusion is a predictive factor for the persistence of memory disorders. Subjective complaints are not correlated with objective memory disorders, but rather with the severity of depression. They last longer than objective disorders. The greater the proximity of the events to the ECT, the greater the impairment. In light of the studies included, we found altered hippocampal function and cerebral slowing. Indeed, the presence of EEG theta waves in frontotemporal regions was associated with the duration of post-ictal confusion and retrograde amnesia. There are several factors associated with the onset of memory disorders. These include the nature and charge of the electrical current, electrode placement, frequency of sessions, anaesthetic product administered, as well as individual factors such as age and gender. The use of ultra-short current with right unilateral electrode placement considerably reduces undesirable cognitive effects and preserves efficacy. Different cognitive tests were used, depending on the cognitive domain to be assessed. The Mini-Mental State Examination (MMSE) was the most widely used test for global assessment. Some studies used a cognitive array of tests with evaluation ranging from 1 to 6 months after treatment. Various molecules have been tried during ECT, notably anticholinesterase drugs and piracetam, with no conclusive results. However, the results of trials with ketamine and memantine were encouraging.

Conclusion

Electroconvulsive therapy has been shown to be effective in the treatment of several psychiatric disorders. It is essential, however, to carry out cognitive testing before and after ECT to detect possible memory disorders and to ensure better management.