Reviewing the neurobiology of electroconvulsive therapy on a micro- meso- and macro-level

Predicting responses of neuromodulation and psychotherapies for major depressive disorder: A coordinate-based meta-analysis of functional magnetic resonance imaging studies

This meta-analysis synthesized resting-state functional connectivity (FC) patterns associated with treatment responses in Major Depressive Disorder (MDD). We evaluated studies from 2013 to 2023 that reported pre-treatment FC (i.e., 'biomarker' analysis) and/or treatment-induced FC alterations (i.e., 'longitudinal effects') in three treatments (i.e., transcranial magnetic stimulation, electroconvulsive therapy, psychotherapy), and further associated these patterns with gene expression, neurotransmitter distributions, and symptomatology. From 57 studies covering 1726 patients, the 'biomarker' results revealed significant rs-FC patterns in the Default Mode Network (DMN) and Frontoparietal Network (FPN). 'Longitudinal effects' were characterized by altered DMN connectivity. Psychotherapy primarily affected the visual network and DMN. Gene expression profiles explained 38.5 % and 56.0 % of the variance in 'biomarker' and 'longitudinal' results, respectively. The meta-analysis correlated with neurotransmitter distributions (e.g., serotonin, dopamine) and MDD-related terms ('interaction', 'emotional', 'negative'). These findings indicate that baseline FC within the DMN and FPN is crucial for predicting treatment responses, and the core mechanisms may involve restoring the DMN. This work may enhance our understanding of MDD pathophysiology and help guide personalized interventions.

Mapping electroconvulsive therapy induced neuroplasticity: Towards a multilevel understanding of the available clinical literature - A scoping review

Since its introduction in 1938, the precise mechanism underlying the efficacy of electroconvulsive therapy (ECT) in treating severe psychiatric disorders remains elusive. This paper presents a comprehensive scoping review aimed to collate and summarize findings from clinical studies on neuroplastic changes induced by ECT. The review categorizes neuroplasticity into molecular, structural, and functional domains, offering a multilevel view of current research and its limitations. Molecular findings detail the varied responses of neurotrophic factors and neurotransmitters post-ECT, highlighting inconsistent evidence on their clinical relevance. Structural neuroplasticity is explored through changes in brain volume, cortical thickness, and white matter properties, presenting ECT as a potent stimulator of brain architecture alterations. Functional plasticity examines ECT's impact on brain function through diverse neuroimaging techniques, suggesting significant yet complex modifications in brain network connectivity and activity. The review emphasizes the multilevel nature of these neuroplasticity levels and their collective role in ECT's therapeutic outcomes. Methodological considerations-including sample size, patient heterogeneity, and variability in assessment timing-emerge as recurring themes in the literature, underscoring the need for more consistent and rigorous research designs. By outlining a cohesive framework of changes in neuroplasticity due to ECT, this review provides initial steps towards a deeper comprehension of ECT's mechanisms.

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.

Inflammatory markers associated with electroconvulsive therapy response in patients with depression: A meta-analysis

Electroconvulsive therapy (ECT) is an effective intervention for severe unipolar and bipolar depression, yet its drawbacks often lead to its underutilization. Accurate prediction of ECT outcomes is crucial for optimizing patient care and increasing remission rates. This study synthesized existing evidence on the relationship between baseline inflammatory markers and ECT outcomes. Additionally, we explored whether changes in these markers during ECT correlated with symptom improvement. A correlation meta-analysis was conducted according to the PRISMA statement, including a total of fourteen studies (n = 556 patients). The analyses revealed that higher baseline CRP and IL-6 levels were significantly associated with greater depressive symptom reduction post-ECT. Additionally, our findings suggested that increases in kynurenine metabolites and IL-8 during treatment correlated with improved depressive symptoms, offering insights into the mechanistic aspects of depression and ECT. In conclusion, peripheral inflammation in depression, as measured by CRP and IL-6, is associated with better ECT outcomes and may guide treatment stratification. Further research on a broader range of cytokines and kynurenine metabolites is needed to confirm these findings.

Molecular Positron Emission Tomography and Single-Photon Emission Computed Tomography Imaging for Understanding the Neurobiological Mechanisms of Electroconvulsive Therapy: A Scoping Review

ABSTRACT

Electroconvulsive therapy (ECT) effectively treats severe psychiatric disorders such as depression, mania, catatonia, and schizophrenia. Although its exact mechanism remains unclear, ECT is thought to induce neurochemical and neuroendocrine changes. Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) have provided vital insights into ECT's neurobiological effects. This scoping review investigates the role of molecular imaging in understanding these effects. A systematic search across PubMed, EMBASE, Web of Science, Cochrane, and Scopus databases yielded 857 unique records, from which 45 peer-reviewed articles in English with longitudinal PET or SPECT measures in ECT patients were included. The review identifies 2 main research directions: ECT's impact on brain activity and neurotransmitters. Initial research assessed regional cerebral blood flow and regional glucose metabolism during ictal (during ECT), postictal (within 24 hours), short-term (within a week), and long-term (beyond a week) follow-up as markers of brain activity. Initial findings showed an anterior-posterior regional cerebral blood flow gradient during the ictal phase, with subsequent normalization of hypoperfusion in frontal and parietal regions, and persistent long-term effects. Later, research shifted to the monoamine hypothesis of depression, examining ECT's impact on serotonin and dopamine systems via PET imaging. Results on receptor availability post-ECT were mixed, showing both reductions and no significant changes, indicating variable effects. This scoping review further highlights the need to explore new targets, tailor methodologies for patient populations, and foster multicenter studies. Although SPECT has been valuable, advances in PET imaging now make it preferable, offering unparalleled insights into ECT's molecular and neurobiological mechanisms.

Electroconvulsive therapy modulates loudness dependence of auditory evoked potentials: a pilot MEG study

Introduction

Electroconvulsive therapy (ECT) remains a critical intervention for treatment-resistant depression (MDD), yet its neurobiological underpinnings are not fully understood. This pilot study aims to investigate changes in loudness dependence of auditory evoked potentials (LDAEP), a proposed biomarker of serotonergic activity, in patients undergoing ECT.

Methods

High-resolution magnetoencephalography (MEG) was utilized to measure LDAEP in nine depressed patients receiving right unilateral ECT. We hypothesized that ECT would reduce the LDAEP slope, reflecting enhanced serotonergic neurotransmission. Depression severity and cognitive performance were assessed using the 24-item Hamilton Depression Rating Scale (HDRS24) and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), respectively.

Results

Contrary to our hypothesis, findings indicated a significant increase in LDAEP post-ECT (t 8 = 3.17, p = .013). The increase in LDAEP was not associated with changes in depression severity or cognitive performance.

Discussion

The observed increase in LDAEP suggests a more complex interaction between ECT and neurobiological systems, rather than a direct reflection of serotonergic neurotransmission. Potential mechanisms for this increase include ECT's impact on serotonergic, dopaminergic, glutamatergic, and GABAergic receptor activity, neuroplasticity involving brain-derived neurotrophic factor (BDNF), and inflammatory modulators such as TNF-α. Our results highlight the multifaceted effects of ECT on brain function, necessitating further research to elucidate these interactions.

Characterization of gray matter volume changes from one week to 6 months after termination of electroconvulsive therapy in depressed patients

BACKGROUND

Increased gray matter volume (GMV) following electroconvulsive therapy (ECT) has been well-documented, with limited studies reporting a subsequent decrease in GMV afterwards.

OBJECTIVE

This study characterized the reversion pattern of GMV after ECT and its association with clinical depression outcome, using multi-site triple time-point data from the Global ECT-MRI Research Collaboration (GEMRIC).

METHODS

86 subjects from the GEMRIC database were included, and GMV in 84 regions-of-interest (ROI) was obtained from automatic segmentation of T1 MRI images at three timepoints: pre-ECT (T0), within one-week post-ECT (T1), and one to six months post-ECT (T2). RM-ANOVAs were used to assess longitudinal changes and LMM analyses explored associations between GMV changes and demographical and clinical characteristics.

RESULTS

63 of the 84 ROIs showed a significant increase-and-decrease pattern (RM-ANOVA, Bonferroni corrected p < 0.00059). Post hoc tests indicated a consistent pattern in each of these 63 ROIs: significant increase from T0 to T1inGMV, followed by significant decrease from T1 to T2 and no difference between T0 and T2, except for both amygdalae, right hippocampus and pars triangularis, which showed the same increase and decrease but GMV at T2 remained higher compared to T0. No consistent relationship was found between GMV change pattern and clinical status.

CONCLUSION

The GEMRIC cohort confirmed a rapid increase of GMV after ECT followed by reversion of GMV one to six months thereafter. The lack of association between the GMV change pattern and depression outcome scores implies a transient neurobiological effect of ECT unrelated to clinical improvement.

Semiconducting polymer dots for multifunctional integrated nanomedicine carriers

The expansion applications of semiconducting polymer dots (Pdots) among optical nanomaterial field have long posed a challenge for researchers, promoting their intelligent application in multifunctional nano-imaging systems and integrated nanomedicine carriers for diagnosis and treatment. Despite notable progress, several inadequacies still persist in the field of Pdots, including the development of simplified near-infrared (NIR) optical nanoprobes, elucidation of their inherent biological behavior, and integration of information processing and nanotechnology into biomedical applications. This review aims to comprehensively elucidate the current status of Pdots as a classical nanophotonic material by discussing its advantages and limitations in terms of biocompatibility, adaptability to microenvironments in vivo, etc. Multifunctional integration and surface chemistry play crucial roles in realizing the intelligent application of Pdots. Information visualization based on their optical and physicochemical properties is pivotal for achieving detection, sensing, and labeling probes. Therefore, we have refined the underlying mechanisms and constructed multiple comprehensive original mechanism summaries to establish a benchmark. Additionally, we have explored the cross-linking interactions between Pdots and nanomedicine, potential yet complete biological metabolic pathways, future research directions, and innovative solutions for integrating diagnosis and treatment strategies. This review presents the possible expectations and valuable insights for advancing Pdots, specifically from chemical, medical, and photophysical practitioners' standpoints.

Electroconvulsive Therapy Modulates Loudness Dependence of Auditory Evoked Potentials: A Pilot MEG Study

Electroconvulsive therapy (ECT) remains a critical intervention for treatment-resistant depression (MDD), yet its neurobiological underpinnings are not fully understood. This pilot study utilizes high-resolution magnetoencephalography (MEG) in nine depressed patients receiving right unilateral ECT, to investigate the changes in loudness dependence of auditory evoked potentials (LDAEP), a proposed biomarker of serotonergic activity, following ECT. We hypothesized that ECT would reduce the LDAEP slope, reflecting enhanced serotonergic neurotransmission. Contrary to this, our findings indicated a significant increase in LDAEP post-ECT ( t 8 = 3.17, p = .013). The increase in LDAEP was not associated with changes in depression severity or cognitive performance, as assessed by the Hamilton Depression Rating Scale (HAMD-24) and Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). We discussed potential mechanisms for the observed increase, including ECT's impact on serotonergic, dopaminergic, glutamatergic, and GABAergic receptor activity, neuroplasticity involving brain-derived neurotrophic factor (BDNF), and inflammation modulators such as TNF- alpha . Our results suggest a complex interaction between ECT and these neurobiological systems, rather than a direct reflection of serotonergic neurotransmission.