The effect of continuation and maintenance electroconvulsive therapy on cognition: A systematic review of the literature and meta-analysis

Highlights

• ECT is an effective treatment for depression, mania, and refractory schizophrenia

• ECT continued for at least 2 months constitutes a valuable treatment option

• Little is known of its long-term effects, particularly on cognitive performance

• We performed a systematic review and meta-analysis to answer this question

• Continuation and maintenance ECT do not appear detrimental for cognition

Abstract

Background

Electroconvulsive therapy (ECT) is an effective treatment for depression, mania, and refractory schizophrenia. Its tolerability profile is established for acute treatment, but less is known regarding the effects of longer treatment courses, particularly on cognitive performance.

Objectives

To assess the effect of the long-term ECT on cognition.

Methods

We searched CINAHL, EMBASE, PsychInfo and Pubmed, for the period between January 1, 2010, and June 30, 2022, in English or French, for randomized controlled trials, prospective or retrospective studies of ECT continued for at least 2 months for the treatment of mood or schizophrenic disorders and which measured cognition before and at the end of treatment. Non-peer reviewed records were excluded. The Cochrane Risk of Bias tool was used to assess study quality. Classical meta-analyses, with heterogeneity statistics (tau², I²) were complemented with three level-meta-analysis and Bayesian Meta-analyses.

Results

Nine studies were included in the narrative and quantitative review. Controlled comparison at 6 months (k = 6, n = 334) and at 12 months (k = 3, n = 56), within-subject comparisons at 6 (k = 6, n = 218) and 12 months (k = 4, n = 147) showed no detrimental effect of maintenance or continuation ECT on cognition, with little to no heterogeneity. Bayesian analysis further confirmed that data better supported the no effects hypothesis.

Limitations

Insufficient data resulted in imprecision in estimates.

Conclusions

Continuation and maintenance ECT do not appear detrimental for cognitive performance. However, the low number of studies limit the interpretation of the results.

Introduction

Electroconvulsive therapy (ECT) is an effective treatment for specific psychiatric disorders. Although usually reserved for conditions where pharmacological treatment has failed, it can be a first-line treatment for clinical situations where there is a need for rapid intervention, for example where suicidal risk is high or in older adults where the psychiatric condition may have a deleterious impact on a precarious physical status or where it may be preferable to avoid pharmacological treatment, for example during pregnancy and in older adults (Van der Wurff et al., 2003; Ward et al., 2018). ECT is effective as monotherapy and in combination with pharmacotherapy, to treat resistant depressive symptoms in diverse populations (Heijnen et al., 2010; UK Ect Review Group, 2003). It is worthwhile to note that while ECT literature has been recently criticized for lacking adequate placebo comparison (Read et al., 2020; Read and Arnold, 2017), meta-analytic comparisons of response rates show that ECT (whether alone or in combination with pharmacotherapy) is superior to pharmacotherapy alone (Song et al., 2015). A meta-analysis has also demonstrated that ECT efficacy is superior to that of Transcranial Magnetic Stimulation, another nonpharmacological intervention (Berlim et al., 2013). Thus, there are several robust lines of evidence that ECT is more effective (and has faster onset of action) than other treatments (for a more in depth discussion on the robustness of ECT research, see (Andrade, 2021)).

Furthermore, when faced with challenging treatment-resistant conditions, clinicians resort to pharmacological combinations, which increase the side effect burden. This becomes all the more evident in chronic treatment-resistant disorders, where long-term side effects become worrisome (Ionescu et al., 2015). Conversely, the safety profile of an acute course of ECT allows it to be used in acute clinical settings, as even the most prevalent tolerability concern, cognitive side effects, has sufficient evidence of being restricted to a few days post-ECT. Landry et al. (Landry et al., 2021) performed a meta-analysis of the cognitive effects of an acute course of ECT, for any psychiatric disorder, in the short (1 to 28 days after last ECT session) and long term (>1 month after last ECT session). Results showed autobiographical memory, verbal fluency and verbal memory performance declined in the short-term, but improved in the long term, along with global cognition and executive functions.

Although there is evidence that ECT is well tolerated in the short term, little is known about the cognitive tolerability profile of repeated and long-term administration of ECT. As severe pathologies can be chronic and relapsing, and an acute course of ECT does not necessarily result in sustained remission or prevent relapses (Jelovac et al., 2013), continuation and maintenance ECT have been increasingly used as a means of prolonging the benefits of acute treatment. In this approach, patients who achieved response after an acute course of ECT (namely, a course of 8 to 12 sessions, given over the period of 4 to 12 weeks, for an index episode), continue to receive ECT sessions, with an increasing interval between each session, over the course of 6 months (continuation ECT, cECT) or more, possibly indefinitely (maintenance ECT, mECT), in combination with pharmacological or psychotherapeutic treatment or as a monotherapy (Gill and Kellner, 2019).

In a literature review, Petrides et al. (2011) reviewed 32 studies published from 1998 to 2009 to delineate evidence-based guidelines for the use of longer duration ECT treatment for mood disorders. They found that adverse events were similar to those of an acute course ECT, with encouraging absence of long-term adverse effects on cognition. However, no pooled effect size of the impact of ECT on cognition was reported.

Consequently, we aimed to test the following hypothesis: maintenance and continuation electroconvulsive therapy have no effect on cognitive performance in adults with major depressive disorder, bipolar disorder, schizophrenia or schizoaffective disorder according to the results obtained from randomized controlled trials, retrospective and prospective cohort studies.

The knowledge of the extent of cognitive impairment associated with long-term ECT will provide important information for clinicians faced with choosing an appropriate maintenance treatment following an acute course of ECT.