Cognitive Adverse Effects of Electroconvulsive Therapy: A Discrepancy Between Subjective and Objective Measures?

The effectiveness of electroconvulsive therapy (ECT) for people with bipolar disorder: is there a specific role?

INTRODUCTION

Electroconvulsive therapy (ECT) has been used for over 80 years to treat various neuropsychiatric conditions, including mood and psychotic disorders. Despite its proven efficacy, ECT remains underutilized and underexplored in patients with bipolar disorder (BD).

AREAS COVERED

This perspective examines the role of ECT in BD, highlighting its effectiveness across depressive, manic, and mixed phases, including those characterized by catatonic or delirious features. Based on these findings, the authors propose a comprehensive transdiagnostic framework to conceptualize ECT-responsive syndromes based on psychomotor, psychotic, and cognitive disturbances. The potential long-term effectiveness of ECT as a mood stabilizer is also suggested, despite the limited amount of literature. Finally, safety issues and alternative options are discussed.

EXPERT OPINION

The shift in ECT usage, from being a first-line treatment for severe affective episodes to a 'last-resort' option for treatment-resistant depression, may have contributed to increased relapse rates and chronicity. Considering ECT at an early stage, potentially even before any medication trials, is recommended for specific clinical conditions associated with BD and marked by objective psychomotor disturbances, acute psychotic symptoms, and severe cognitive alterations.

Investigating the impact of electroconvulsive therapy on brain networks and sleep: an observational study protocol

INTRODUCTION

Electroconvulsive therapy (ECT) is a highly effective treatment for refractory depression, but it may also cause cognitive side effects. Despite decades of use, the mechanisms by which ECT exerts both its antidepressant and cognitive effects are still poorly understood, with the latter substantially limiting referral and adherence to therapy. ECT induces changes in correlated neural activity-functional connectivity-across various brain networks, which may underlie both its clinical efficacy and associated cognitive side effects. Electroencephalography (EEG) could address these knowledge gaps by identifying biomarkers that predict therapeutic outcomes or cognitive side effects. Such developments could ultimately improve patient selection and adherence. Such markers likely span large-scale functional brain networks or temporal dynamics of brain activity during sleep. We hypothesise that enhancement in slow wave sleep mediates the relationship between antidepressant effects and changes in functional connectivity throughout the course of ECT.

METHODS AND ANALYSIS

Disruptions of Brain Networks and Sleep by Electroconvulsive Therapy (DNS-ECT) is an ongoing observational study investigating the impact of ECT on large-scale brain functional networks and their relationships to sleep slow waves, an EEG marker linked to synaptic plasticity. The novelty of this study stems from our focus on the assessment of EEG markers during sleep, wakefulness and ECT-induced seizures over the course of therapy. Graph-based network analyses of high-density EEG signals allow characterisation of functional networks locally in specific subnetworks and globally over large-scale functional networks. Longitudinal assessments of EEG alongside clinical and cognitive outcomes provide a unique opportunity to improve our understanding of the circuit mechanisms underlying the development of cognitive impairments and antidepressant effects incurred during ECT.

ETHICS AND DISSEMINATION

Recruitment for this 5-year study started in March 2023. Dissemination plans include presentations at scientific conferences and peer-reviewed publications. This study has been registered with ClinicalTrials.gov registry under identifier.

TRIAL REGISTRATION NUMBER

NCT05905705.

Who is at risk of long-term subjective memory impairment after electroconvulsive therapy?

BACKGROUND

Electroconvulsive therapy (ECT) is an effective treatment for depression with potential transient cognitive side effects. However, subjective memory impairment can extend over a long period after ECT.

OBJECTIVES

This study aimed to assess potential risk factors for long-term subjective memory impairment 6 months after ECT and to explore if the associations are mediated by depressive symptoms.

METHODS

This registry-based study used the Swedish National Quality Register for ECT and other national registers. Long-term subjective memory worsening was defined as a minimum 2-step worsening on the memory item from the comprehensive psychopathological rating scale (CPRS-M) from before ECT to 6 months after ECT. Changes on the scale were also analyzed in continuous models. Statistical methods used were logistic regression and linear regression analyses in univariable and multivariable models.

RESULTS

The study population consisted of 1498 patients. Subjective memory worsening occurred in 25.2 % of the population. Long-term subjective memory worsening was associated with more depressive symptoms and lower education levels. No association could be found related to ECT technical factors. The associations between age and psychiatric comorbidities with subjective memory worsening were mediated by depressive symptoms.

CONCLUSION

Patients can be informed that depressive symptoms are one of the biggest contributing factors to long-term subjective memory impairment after ECT. A successful treatment is therefore important to minimize the long-term experience of memory deficits. The number of sessions or ECT technical factors do not seem to be associated with long-term subjective memory impairment.

Effectiveness of short term acute electroconvulsive therapy at three Brazilian sites: an observational cohort study

BACKGROUND

Electroconvulsive therapy (ECT) remains a target of prejudice, and finding places to administer it remains a challenge. The main reason for the recommendation of ECT is its effectiveness, especially when compared with other treatments for severe and refractory patients.

OBJECTIVES

This study aimed to assess the response rates across a broader patient sample undergoing ECT in three distinct Brazilian states.

DESIGN AND SETTING

This observational cohort study was conducted at the following three sites: Universidade Federal do Tocantins (by partnership with Hospital Geral de Palmas, Palmas-TO), Pax Instituto de Psiquiatria (Goiânia - GO), and Clínica Animus (Joao Pessoa - PB).

METHODS

A total of 212 patients who received ECT at three different Brazilian services were assessed for improvement in symptoms in the first week after treatment and 30 and 60 days after treatment completion.

RESULTS

Safety and efficacy of ECT was well established, as evidenced by the zero mortality rate among the study participants, with side effects observed in only 10.5% of cases. The immediate response rate was impressive at 95.8%, and the response rate after 30 and 60 days was 90.6% and 87.7%, respectively. The regression analysis highlighted session frequency as a key determinant of positive responses.

CONCLUSION

The effectiveness of short term ECT (two months) is one of the greatest among psychiatric treatments. Future research should focus on predictive models for treatment responses to enable personalized approaches.

Trajectory of associative memory impairment during electroconvulsive therapy in depression

Memory impairment is a serious cognitive side effect of electroconvulsive therapy (ECT) in the treatment of major depressive episodes (MDEs) and has garnered widespread attention in clinical practice, but its underlying evolution pattern during the course of ECT remains rarely understood in detail. Associative memory (AM) is a core indicator that reflects memory impairment in ECT. This study aimed to identify the dynamic trajectory of AM impairment and explore associated predictive factors. 405 intensive longitudinal AM data from 81 patients with MDE were collected at the baseline, after the first, third, fifth, and eighth ECT using five sets of face-cued word memory paradigms. Changes in AM score over time were analyzed using a linear mixed effects model. Trajectory subgroups and predictive factors were investigated using growth mixture model and logistic regression. AM score during ECT were significantly lower than at baseline, with the lowest scores observed after the eighth ECT session. Two trajectories of rapid (N = 56, 69.14%) and slow (N = 25, 30.86%) AM impairment were differentiated. Older female with lower education level were significant predictors contributing to more rapid memory impairment for ECT. The evolving pattern of associative memory impairment during ECT appears to occur early and worsen with subsequent treatment. This study may provide the important evidence understanding of the number effect of ECT sessions on memory impairment and suggest individual factors for predicting ECT memory outcome.

Effect of quantitative consciousness index on seizure parameters during electroconvulsive therapy in patients with major depressive disorder

BACKGROUND

Electroconvulsive therapy (ECT) is both an effective treatment for patients with major depressive disorder (MDD) and a noxious stimulus. Although some studies have explored the effect of sedation depth on seizure parameters in ECT, there is little research on the noxious stimulation response to ECT. In this study, we used two electroencephalography (EEG)-derived indices, the quantitative consciousness (qCON) index and quantitative nociceptive (qNOX) index, to monitor sedation, hypnosis, and noxious stimulation response in patients with MDD undergoing acute ECT.

AIM

To evaluate the effect of anesthesia depth based on the qCON and qNOX indices on seizure parameters.

METHODS

Patients with MDD (n = 24) underwent acute bilateral temporal ECT under propofol anesthesia. Before ECT, the patients were randomly divided into three groups according to qCON scores (qCON60-70, qCON50-60, and qCON40-50). Continuous qCON monitoring was performed 3 minutes before and during ECT, and the qCON, qNOX, vital signs, EEG seizure parameters, and complications during the recovery period were recorded. The 24-item Hamilton Rating Scale for Depression, Zung's Self-rating Depression Scale, and Montreal Cognitive Assessment scores were evaluated before the first ECT session, after the fourth ECT session, and after the full course of ECT.

RESULTS

A total of 193 ECT sessions were performed on 24 participants. The qCON index significantly affected the EEG seizure duration, peak mid-ictal amplitude, and maximum heart rate during ECT (P < 0.05). The qNOX index significantly affected the post-ictal suppression index (P < 0.05). Age, number of ECT sessions, and anesthetic-ECT time intervals also had a significant effect on EEG seizure parameters (P < 0.05). However, there were no significant differences in complications, 24-item Hamilton Rating Scale for Depression scores, Zung's Self-rating Depression Scale scores, or Montreal Cognitive Assessment scores among the three groups (P > 0.05).

CONCLUSION

Electrical stimulation at a qCON index of 60-70 resulted in better EEG seizure parameters without increasing complications in patients with MDD undergoing bilateral temporal ECT under propofol anesthesia.

The myth of brain damage: no change of neurofilament light chain during transient cognitive side-effects of ECT

Electroconvulsive therapy (ECT) is an effective, safe, and mostly well-tolerated treatment for patients with severe or difficult to treat depression or psychotic disorders. However, a relevant number of patients experience subjective and/or objective cognitive side-effects. The mechanism of these transient deficits is not yet clear. Thus, our study prospectively investigated neurofilament light chain (NfL) concentrations as a highly sensitive biomarker for neuroaxonal damage along with cognitive performance during a course of ECT. Serum NfL concentrations from 15 patients with major depressive disorder receiving ECT were analyzed (1) 24 h before the first ECT, (2) 24 h and (3) 7 days after the last ECT (45 measurements in total). Neuropsychological testing including memory, executive functions and attention was performed at each time-point. NfL concentrations did not change between the three time-points, while a temporary cognitive impairment was found. Even in the subset of patients with the strongest impairment, NfL concentrations remained unchanged. Neuropsychological testing revealed the common pattern of transient cognitive side-effects with reduced performance 24 h post-ECT (global cognition score: p < 0.001; memory: p = 0.043; executive functions: p = 0.002) and return to baseline after 7 days (all p < 0.001). Our study adds to the evidence that neither ECT per se nor the transient cognitive side-effects seem to be associated with an increase of NfL as a marker of neuroaxonal damage. In contrast, we discuss cognitive side effects to be potentially interpreted as a byproduct of ECT's neuroplastic effects.

Unmasking patient diversity: Exploring cognitive and antidepressive effects of electroconvulsive therapy

BACKGROUND

Electroconvulsive therapy (ECT) is an established treatment for depression, but more data on effectiveness and safety in clinical practice is needed. The aim of this register-based study was to investigate short-term effectiveness and cognitive safety after ECT, evaluated by clinicians and patients. Secondary, we investigated predictors for remission and cognitive decline.

METHODS

The study included 392 patients from the Regional Register for Neurostimulation Treatment in Western Norway. Depressive symptoms and cognitive function were assessed with Montgomery-Åsberg Depression Rating Scale and Mini-Mental State Examination (clinician-rated) and Beck Depression Inventory and Everyday Memory Questionnaire (patient-rated). Assessments were done prior to ECT-series and a mean of 1.7 days after (range 6 days before and 12 days after) end of ECT-series. Paired samples t-tests were extended by detailed, clinically relevant subgroups. Predictors were examined using logistic regression.

RESULTS

Clinician- and patient-rated remission rates were 49.5 and 41.0%, respectively. There was a large reduction in depressive symptoms and a small improvement in cognition after ECT, but we also identified subgroups with non-response of ECT in combination with cognitive decline (4.6% clinician-rated, 15.7% patient-rated). Positive predictors for patient- and clinician-rated remission were increasing age, shorter duration of depressive episode, and psychotic features. Antipsychotic medication at the commencement of treatment and previous ECT-treatment gave higher odds of clinician-rated remission, whereas higher pretreatment subjective depression level was associated with lower odds for patient-rated remission. Clinician-rated cognitive decline was predicted by higher pretreatment MMSE scores, whereas psychotic features, increasing age, and greater pretreatment subjective memory concerns were associated with lower odds for patient-rated cognitive decline.

CONCLUSIONS

Our study supports ECT as an effective and safe treatment, although subgroups have a less favorable outcome. ECT should be considered at an early stage for older patients suffering from depression with psychotic features. Providing comprehensive and balanced information from clinicians and patients perspectives on effects and side effects, may assist in a joint consent process.

How electroconvulsive therapy works in the treatment of depression: is it the seizure, the electricity, or both?

We have known for nearly a century that triggering seizures can treat serious mental illness, but what we do not know is why. Electroconvulsive Therapy (ECT) works faster and better than conventional pharmacological interventions; however, those benefits come with a burden of side effects, most notably memory loss. Disentangling the mechanisms by which ECT exerts rapid therapeutic benefit from the mechanisms driving adverse effects could enable the development of the next generation of seizure therapies that lack the downside of ECT. The latest research suggests that this goal may be attainable because modifications of ECT technique have already yielded improvements in cognitive outcomes without sacrificing efficacy. These modifications involve changes in how the electricity is administered (both where in the brain, and how much), which in turn impacts the characteristics of the resulting seizure. What we do not completely understand is whether it is the changes in the applied electricity, or in the resulting seizure, or both, that are responsible for improved safety. Answering this question may be key to developing the next generation of seizure therapies that lack these adverse side effects, and ushering in novel interventions that are better, faster, and safer than ECT.

Trajectories of Efficacy and Cognitive Function During Electroconvulsive Therapy Course in Young Adults with Treatment-Resistant Depression

Objective

Little is known about the effectiveness and cognitive side-effects of electroconvulsive therapy (ECT) in young adults with treatment-resistant depression (TRD). The primary aim of this prospective longitudinal observational trial was to examine the clinical features and cognitive outcomes of young adults with TRD undergoing ECT.

Methods

Changes in depressive symptoms and objective and subjective cognitive function were assessed using repeated evaluation at baseline, after each ECT session, and at one-month follow-up using the Montgomery-Äsberg Depression Rating Scale (MADRS) and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), Forward Digital Span Test (FDST), and part of the Columbia Subjective Side Effects Schedule.

Results

Of 41 inpatients, 35 (85.4%) and 12 (29.3%) met the criteria for response and remission after ECT, respectively. The greatest clinical improvements occurred during the first 3-4 ECT sessions. While 34 patients reported subjective cognitive impairment increased with ECT, immediate and delayed memory (RBANS) significantly increased after ECT, consistent with FDST results. Objective cognition significantly improved during follow-up, but subjective cognition remained impaired.

Conclusion

ECT is effective in young adults with TRD. Although subjective cognitive impairment increased during treatment, objective cognitive impairments were not observed.

Pharmacological interventions to diminish cognitive side effects of electroconvulsive therapy: A systematic review and meta-analysis

OBJECTIVE

The authors conducted a systematic review and meta-analysis of pharmacological interventions to diminish cognitive side effects of ECT.

METHODS

Electronic databases of Pubmed, PsycInfo, Embase and Scopus were searched from inception through 1 April, 2021, using terms for ECT (e.g. electroconvulsive therapy), cognitive outcome (e.g. cogni*) and pharmacological intervention (e.g. calcium channel blocker and general terms, like protein). Original studies with humans receiving ECT were included, which applied pharmacological interventions in comparison with placebo or no additive intervention to diminish cognitive side effects. Data quality was assessed using Risk of Bias and GRADE. Random-effects models were used. PROSPERO registration number was CRD42021212773.

RESULTS

Qualitative synthesis (systematic review) showed 52 studies reporting sixteen pharmacological intervention-types. Quantitative synthesis (meta-analysis) included 26 studies (1387 patients) describing twelve pharmacological intervention-types. Low-quality evidence of efficacy was established for memantine (large effect size) and liothyronine (medium effect size). Very low-quality evidence shows effect of acetylcholine inhibitors, piracetam and melatonin in some cognitive domains. Evidence of no efficacy was revealed for ketamine (very low-quality), herbal preparations with anti-inflammatory properties (very low to low-quality) and opioid receptor agonists (low-quality).

CONCLUSION

Memantine and liothyronine are promising for further research and future application. Quality of evidence was low because of differences in ECT techniques, study populations and cognitive measurements. These findings provide a guide for rational choices of potential pharmacological intervention research targets to decrease the burden of cognitive side effects of ECT. Future research should be more uniform in design and attempt to clarify pathophysiological mechanisms of cognitive side effects of ECT.