S100 and impact of ECT on depression and cognition

Blood biomarkers of neuronal injury and astrocytic reactivity in electroconvulsive therapy

Despite electroconvulsive therapy (ECT) being recognized as an effective treatment for major depressive episodes (MDE), its application is subject to controversy due to concerns over cognitive side effects. The pathophysiology of these side effects is not well understood. Here, we examined the effects of ECT on blood-based biomarkers of neuronal injury and astrocytic reactivity. Participants with a major depressive episode (N = 99) underwent acute ECT. Blood was sampled just before (T0) and 30 min after (T1) the first ECT session, as well as just before the sixth session (T2; 48-72 h after the fifth session). Age- and sex-matched controls (N = 99) were recruited from the general population. Serum concentrations of neurofilament light chain (NfL), total tau protein, and glial fibrillary acidic protein (GFAP) were measured with ultrasensitive single-molecule array assays. Utilizing generalized least squares regression, we compared baseline (T0) biomarker concentrations against those of our control group, and calculated the shifts in serum biomarker concentrations from baseline to immediately post-first ECT session (T1), and prior to the sixth session (T2). Baseline analysis revealed that serum levels of NfL (p < 0.001) and tau (p = 0.036) were significantly elevated in ECT recipients compared with controls, whereas GFAP levels showed no significant difference. Relative to T0, serum NfL concentration neither changed at T1 (mean change 3.1%, 95%CI -0.5% to 6.7%, p = 0.088) nor at T2 (mean change -3.2%, 95%CI -7.6% to 1.5%, p = 0.18). Similarly, no change in total tau was observed (mean change 3.7%, 95%CI -11.6% to 21.7%, p = 0.65). GFAP increased from T0 to T1 (mean change 20.3%, 95%CI 14.6 to 26.3%, p < 0.001), but not from T0 to T2 (mean change -0.7%, 95%CI -5.8% to 4.8%, p = 0.82). In conclusion, our findings suggest that ECT induces a temporary increase in serum GFAP, possibly reflecting transient astrocytic activation. Importantly, we observed no indicators of neuronal damage or long-term elevation in any assessed biomarker.

Neurological Damage Measured by S-100b and Neuron-Specific Enolase in Patients Treated with Electroconvulsive Therapy

Electroconvulsive therapy (ECT) is considered one of the most effective treatments for psychiatric disorders. ECT has proven effective in the treatment of depression, mania, catatonia and psychosis. It is presumed that seizures induced during ECT administration cause toxicity and potentially neuronal and glial cell death. A broad range of neurological disorders increase cerebrospinal fluid and serum levels of neuron-specific enolase (NSE) and S-100b protein. This study aims to investigate the effect of ECT on NSE and S-100b levels, which, together, serve as a proxy for neuronal cell damage. Serum concentrations of S-100b and NSE of adult patients who received ECT were measured by immunoluminometric analysis before and after treatment. A two-way ANOVA test was used to estimate the statistical differences in marker concentrations between the subgroups of the study population. Results: A total of 55 patients were included in the analysis: 52.73% (n = 29) were diagnosed with depression, 21.82% (n = 12) with schizophrenia or other psychosis, 16.36% (n = 9) with mania and 9.09% (n = 5) with catatonia. There were no statistically significant changes in NSE (p = 0.288) and S-100b (p = 0.243) levels. We found no evidence that ECT induced neuronal damage based on NSE and S-100b protein levels measured in the serum of patients before and after treatment.

Human in vivo evidence of reduced astrocyte activation and neuroinflammation in patients with treatment-resistant depression following electroconvulsive therapy

AIM

The current study aimed to investigate the neuroinflammatory hypothesis of depression and the potential anti-inflammatory effect of electroconvulsive therapy (ECT) in vivo, utilizing astrocyte-derived extracellular vesicles (ADEVs) isolated from plasma.

METHODS

A total of 40 patients with treatment-resistant depression (TRD) and 35 matched healthy controls were recruited at baseline, and 34 patients with TRD completed the post-ECT visits. Blood samples were collected at baseline and post-ECT. Plasma ADEVs were isolated and confirmed, and the concentrations of two astrocyte markers (glial fibrillary acidic protein [GFAP] and S100β), an extracellular vesicle marker cluster of differentiation 81 (CD81), and nine inflammatory markers in ADEVs were measured as main analyses. In addition, correlation analysis was conducted between clinical features and ADEV protein levels as exploratory analysis.

RESULTS

At baseline, the TRD group exhibited significantly higher levels of two astrocyte markers GFAP and S100β, as well as CD81 compared with the healthy controls. Inflammatory markers interferon γ (IFN-γ), interleukin (IL) 1β, IL-4, IL-6, tumor necrosis factor α, IL-10, and IL-17A were also significantly higher in the TRD group. After ECT, there was a significant reduction in the levels of GFAP, S100β, and CD81, along with a significant decrease in the levels of IFN-γ and IL-4. Furthermore, higher levels of GFAP, S100β, CD81, and inflammatory cytokines were associated with more severe depressive symptoms and poorer cognitive function.

CONCLUSION

This study provides direct insight supporting the astrocyte activation and neuroinflammatory hypothesis of depression using ADEVs. ECT may exert an anti-inflammatory effect through inhibition of such activation of astrocytes.

Blood-brain barrier permeability and electroconvulsive therapy: a systematic review

OBJECTIVE

The cause of cognitive side effects after electroconvulsive therapy (ECT) is largely unknown. Alterations in the blood-brain barrier (BBB) have been considered in several recent ECT studies. We therefore found it worthwhile to perform a systematic review of the literature to examine if electrically induced seizures affect the permeability of the BBB.

METHODS

PubMed/MEDLINE and Embase were searched 16 November 2022. Studies with a direct measurement of BBB permeability in animals treated with modified electroconvulsive stimulation (ECS) and in humans treated with ECT were included. Synthesis of results was narrative due to the low number of studies and differences in study designs.

RESULTS

Four animal and two human (31 participants) studies were included. In animals, two studies found increased BBB permeability to some smaller molecules after modified ECS, while the two other studies found marginally increased or unchanged permeability to albumin after treatment. In contrast, the human studies did not find increased BBB permeability to smaller molecules or albumin after ECT.

CONCLUSION

Animal but not human studies support increased BBB permeability to some smaller molecules after electrically induced seizures. However, this conclusion is confined by the low number of studies and the lack of studies applying state-of-the-art methods. More studies using modern approaches to measuring of BBB permeability are warranted.

FUNDING AND REGISTRATION

The study was founded by Mental Health Services in the Capital Region of Denmark (grant number 61151-05) and was registered on PROSPERO before data extraction was initiated (CRD42022331385).

Peripheral S100B Protein Levels in Five Major Psychiatric Disorders: A Systematic Review

Five major psychiatric disorders: schizophrenia, major depressive disorder, bipolar disorder, autistic spectrum disorder, and attention-deficit/hyperactivity disorder, show a shared genetic background and probably share common pathobiological mechanisms. S100B is a calcium-binding protein widely studied in psychiatric disorders as a potential biomarker. Our systematic review aimed to compare studies on peripheral S100B levels in five major psychiatric disorders with shared genetic backgrounds to reveal whether S100B alterations are disease-specific. EMBASE, Web of Science, and PubMed databases were searched for relevant studies published until the end of July 2023. This study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis Protocols (PRISMA) guidelines. Overall, 1215 publications were identified, of which 111 full-text articles were included in the systematic review. Study designs are very heterogeneous, performed mostly on small groups of participants at different stages of the disease (first-episode or chronic, drug-free or medicated, in the exacerbation of symptoms or in remission), and various clinical variables are analyzed. Published results are inconsistent; most reported elevated S100B levels across disorders included in the review. Alterations in S100B peripheral levels do not seem to be disease-specific.

Serum S100B protein after electroconvulsive therapy in patients with depression

OBJECTIVE

S100B is a glial cell protein with bimodal function. In low concentrations, it exerts neurotrophic effects, but higher levels reflect neuronal distress. Recent research suggests that this molecule may be a biomarker of response to electroconvulsive therapy (ECT). We examined the effect of ECT on serum S100B and its utility as 1) a biomarker of a depressive state and 2) a predictor of ECT response. We also wanted to ensure that ECT does not cause a marked serum S100B elevation, indicating neural distress.

METHODS

We measured serum S100B in 22 in-patients treated with ECT due to depression. Depression severity was assessed using 17-item Hamilton Rating Scale for Depression (HAMD-17). The data were collected before an ECT series, within 1 week after the series (post-ECT), and at a 6-month follow-up. Changes in serum S100B and clinical outcomes were tested using a linear mixed model. A relationship between serum S100B and the clinical outcomes was examined using Spearman's and partial correlation.

RESULTS

Serum S100B did not change significantly immediately after an ECT series or 6 months later. The post-ECT serum S100B change was not associated with the clinical effect (rho = 0.14, n = 22, p = 0.54). The baseline serum S100B did not predict the clinical effect when controlling for age (r = 0.02, n = 22, df = 19, p = 0.92).

CONCLUSION

The study neither supports serum S100B as a state marker of depression nor a predictor of ECT response. No evidence for ECT-related neural distress was found.

High S100B Levels Predict Antidepressant Response in Patients With Major Depression Even When Considering Inflammatory and Metabolic Markers

BACKGROUND

The relationship between antidepressant response and glial, inflammatory, and metabolic markers is poorly understood in depression. This study assessed the ability of biological markers to predict antidepressant response in major depressive disorder (MDD).

METHODS

We included 31 MDD outpatients treated with escitalopram or sertraline for 8 consecutive weeks. The Montgomery-Åsberg Depression Rating Scale (MADRS) was administered at baseline and at week 4 and 8 of treatment. Concomitantly, blood samples were collected for the determination of serum S100B, C-reactive protein (CRP), and high-density lipoprotein cholesterol (HDL)-C levels. Treatment response was defined as ≥50% improvement in the MADRS score from baseline to either week 4 or 8. Variables associated with treatment response were included in a linear regression model as predictors of treatment response.

RESULTS

Twenty-seven patients (87%) completed 8 weeks of treatment; 74% and 63% were responders at week 4 and 8, respectively. High S100B and low HDL-C levels at baseline were associated with better treatment response at both time points. Low CRP levels were correlated with better response at week 4. Multivariate analysis showed that high baseline S100B levels and low baseline HDL-C levels were good predictors of treatment response at week 4 (R2 = 0.457, P = .001), while S100B was at week 8 (R2 = 0.239, P = .011). Importantly, baseline S100B and HDL-C levels were not associated with depression severity and did not change over time with clinical improvement.

CONCLUSIONS

Serum S100B levels appear to be a useful biomarker of antidepressant response in MDD even when considering inflammatory and metabolic markers.

A critique of narrative reviews of the evidence-base for ECT in depression

There has been recent debate regarding the efficacy of electroconvulsive therapy in the treatment of depression. This has been based on narrative reviews that contradict existing systematic reviews and meta-analyses. In this special article, we highlight the mistakes that occur when interpreting evidence using narrative reviews, as opposed to conventional systematic reviews and meta-analyses.

Rivastigmine for ECT-induced cognitive adverse effects in late life depression (RECALL study): A multicenter, randomized, double blind, placebo-controlled, cross-over trial in patients with depression aged 55 years or older: Rationale, objectives and methods

BACKGROUND

Cognitive side-effects are an important reason for the limited use of electroconvulsive therapy (ECT). Cognitive side-effects are heterogeneous and occur frequently in older persons. To date, insight into these side-effects is hampered due to inconsistencies in study designs and small sample sizes. Among all cognitive side-effects, confusion and delirious states are especially troublesome for patients, relatives and clinicians. In particular inter-ictal delirium-like states are worrisome, since they may lead to premature treatment discontinuation. Besides a need for further insight into determinants of cognitive side-effects of ECT, there is a great need for treatment options.

METHODS AND DESIGN

The Rivastigmine for ECT-induced Cognitive Adverse effects in Late Life depression (RECALL) study combines a multicenter, prospective cohort study on older patients with depression, treated with ECT, with an embedded randomized, placebo-controlled cross-over trial to examine the effect of rivastigmine on inter-ictal delirium. Patients are recruited in four centers across the Netherlands and Belgium. We aim to include 150 patients into the cohort study, in order to be able to subsequently include 30 patients into the trial. Patients are included in the trial when inter-ictal delirium, assessed by the Confusion Assessment method (CAM), or a drop in Mini Mental State Examination (MMSE) score of ≥4 during ECT, develops. In the cohort study, comprehensive measurements of ECT-related cognitive side-effects-and their putative determinants-are done at baseline and during the ECT-course. The primary outcome of the clinical trial is the effectiveness of rivastigmine on inter-ictal delirium-severity, assessed with a change in the Delirium Rating Scale-Revised-98. Secondary outcomes of the clinical trial are several ECT-characteristics and side-effects of rivastigmine.

DISCUSSION

This study is the first clinical trial with a focus on ECT-induced, inter-ictal delirium. The cohort provides the basis for recruitment of patients for the cross-over trial and additionally provides an excellent opportunity to unravel cognitive side-effects of ECT and identify putative determinants. This paper describes the rationale and study protocol.

CLINICAL TRIAL REGISTRATION

EudraCT 2014-003385-24.

The Neurobiological Basis of Cognitive Side Effects of Electroconvulsive Therapy: A Systematic Review

Decades of research have consistently demonstrated the efficacy of electroconvulsive therapy (ECT) for the treatment of major depressive disorder (MDD), but its clinical use remains somewhat restricted because of its cognitive side effects. The aim of this systematic review is to comprehensively summarize current evidence assessing potential biomarkers of ECT-related cognitive side effects. Based on our systematic search of human studies indexed in PubMed, Scopus, and Web of Knowledge, a total of 29 studies evaluating patients with MDD undergoing ECT were reviewed. Molecular biomarkers studies did not consistently identify concentration changes in plasma S-100 protein, neuron-specific enolase (NSE), or Aβ peptides significantly associated with cognitive performance after ECT. Importantly, these findings suggest that ECT-related cognitive side effects cannot be explained by mechanisms of neural cell damage. Notwithstanding, S-100b protein and Aβ40 peptide concentrations, as well as brain-derived neurotrophic factor (BDNF) polymorphisms, have been suggested as potential predictive biomarkers of cognitive dysfunction after ECT. In addition, recent advances in brain imaging have allowed us to identify ECT-induced volumetric and functional changes in several brain structures closely related to memory performance such as the hippocampus. We provide a preliminary framework to further evaluate neurobiological cognitive vulnerability profiles of patients with MDD treated with ECT.

Increased GFAP concentrations in the cerebrospinal fluid of patients with unipolar depression

Inflammatory processes involving altered microglial activity may play a relevant role in the pathophysiology of depressive disorders. Glial fibrillary acidic protein (GFAP) and calcium-binding protein S100B are considered microglial markers. To date, their role has been studied in the serum and tissue material of patients with unipolar depression but not in the cerebrospinal fluid (CSF). Therefore, the aim of the current study was to examine GFAP and S100B levels in the CSF of patients with major depression to better understand their role in affective disorders. In this retrospective study, 102 patients with unipolar depression and 39 mentally healthy controls with idiopathic intracranial hypertension were investigated. GFAP and S100B levels were measured using commercially available ELISA kits. CSF routine parameters were collected during routine clinical care. The mean values of GFAP and S100B were compared using age (and sex) corrected ANOVAs. Matched subgroups were analyzed by using an independent sample t-test. In addition, correlation analyses between GFAP/S100B levels and CSF routine parameters were performed within the patient group. Patients with unipolar depression had significantly higher levels of GFAP than controls (733.22 pg/ml vs. 245.56 pg/ml, p < 0.001). These results remained significant in a sub-analysis in which all controls were compared with patients suffering from depression matched 1:1 by age and sex (632.26 pg/ml vs. 245.56 pg/ml, p < 0.001). Levels of S100B did not differ significantly between patients and controls (1.06 ng/ml vs. 1.17 ng/ml, p = 0.385). GFAP levels correlated positively with albumin quotients (p < 0.050), S100B levels correlated positively with white blood cell counts (p = 0.001), total protein concentrations (p < 0.001), and albumin quotients (p = 0.001) in the CSF. The significance of the study is limited by its retrospective and open design, methodological aspects, and the control group with idiopathic intracranial hypertension. In conclusion, higher GFAP levels in patients with depression may be indicative of altered microglia activity, especially in astrocytes, in patients with unipolar depression. In addition, correlation analyses support the idea that S100B levels could be related to the integrity of the blood-brain/CSF barrier. Further multimodal and longitudinal studies are necessary to validate these findings and clarify the underlying biological processes.

Cytokines changes associated with electroconvulsive therapy in patients with treatment-resistant depression: a Meta-analysis

One third of depressive patients do not achieve remission after several steps of treatment and are considered as treatment resistant. Electroconvulsive therapy (ECT) improves symptoms in 70 to 90% of such cases. Resistant depression is associated with a dysregulation of the immune system with a dysbalance between the pro- and the anti-inflammatory cytokines. Therefore, we aimed to measure the kinetic of cytokines levels before, during and at the end of ECT. To test this hypothesis, we performed a meta-analysis assessing cytokines plasma levels before, during and after ECT in patients with major depressive disorders. After a systematic database search, means and standard deviations were extracted to calculate standardized mean differences. We found that IL-6 levels increased after 1 or 2 ECT session (p = 0.01) then decrease after 4 ECT sessions (p < 0.01) with no difference at the end of ECT (p = 0.94). A small number of studies were included and there was heterogeneity across them. The present meta-analysis reveals that ECT induces an initial increase of IL-6 levels and a potential decrease of TNF-α levels. No changes on IL-4 and IL-10 levels were found. Further work is necessary to clarify the impact of ECT on peripheral cytokines.

S100 calcium-binding protein B in older patients with depression treated with electroconvulsive therapy

BACKGROUND

Increasing evidence suggests that glial mediated disruption of neuroplasticity contributes to depression. S100 calcium-binding protein B (S100B) promotes neuronal protection in nanomolar concentrations. Studies on its possible role as a treatment outcome marker in affective disorders are limited. Recent evidence suggests a putative role for S100B as a state marker of illness activity as it is found elevated in episodes of major depression.

AIM

To investigate whether higher S100B is associated with favourable treatment outcome following electroconvulsive therapy (ECT) and to further explore whether S100B reflects a state marker of depression activity.

METHODS

Serum S100B samples, at baseline and post-ECT and clinical assessments including Montgomery Åsberg Rating scales were collected in 91 older depressed patients (mean age: 73.0 years), referred for ECT. Change in pre- and post-ECT S100B was compared between remitters and nonremitters. Logistic and Cox regression analyses were used to determine whether S100B was associated with remission of depression.

RESULTS

Patients with S100B levels in the intermediate tertile, that is, between 33 ng/L and 53 ng/L, had higher odds on remission, odds ratio: 5.5 (95%Confidence Interval (CI): 1.55-19.20, p = <0.01), and were more likely to remit from depression over time, hazard ratio: 1.96 (95%CI: 1.04-3.72, p = 0.04), compared with patients in the lowest tertile. There was no significant decrease in levels of S100B after ECT in both remitters and nonremitters.

CONCLUSION

Our findings demonstrate that patients with higher S100B levels at baseline were more likely to remit from depression suggesting an association between higher S100B and responsiveness to ECT. Next, S100B levels do not decrease after remission, suggesting S100B is not a state marker of depression. S100B is not capable of predicting treatment outcome by itself, further research may combine outcome markers.

Effects of electroconvulsive therapy in the systemic inflammatory balance of patients with severe mental disorder

AIM

There is a great interest in the role of the immune system and the inflammatory balance as key mechanisms involved in the pathophysiology of severe mental disorders. Previous studies have indicated that electroconvulsive therapy (ECT) produces changes in certain inflammatory mediators or in the immune system response. This study aimed to explore the effects of ECT on the nuclear transcription factor κB (NFκB) pathway, a main regulatory pathway of the inflammatory/immune response.

METHODS

Thirty subjects with a severe mental disorder receiving treatment with ECT in our center were included. Thirteen systemic biomarkers related to the NFκB pathway were analyzed right before and 2 h after a single ECT session.

RESULTS

An ECT session significantly decreased the expression of NFκB (P = 0.035) and of the inducible nitric oxide synthase (P = 0.012), and the plasma levels of nitrites (P = 0.027), prostaglandin E₂ (P = 0.049), and 15-deoxy-PGJ₂ (P < 0.001). Decrease in plasmatic levels of nitrites was greater in females than in males (P = 0.021). A positive correlation between the ECT stimulus load and changes in the expression of NFkB was found (P = 0.036). Thiobarbituric acid reactive substance levels were decreased in treatment responders and increased in non-responders (P = 0.047).

CONCLUSION

Our study shows the effects that a single session of ECT produces on a canonical regulatory pathway of the inflammatory/innate immune system and the inflammatory balance. These biomarkers could be useful as treatment response targets and could help to clarify the biological basis of ECT action. These findings warrant greater attention in future investigations and in the translational significance of these data.

BDNF Genotype and Baseline Serum Levels in Relation to Electroconvulsive Therapy Effectiveness in Treatment-Resistant Depressed Patients

OBJECTIVES

Electroconvulsive therapy (ECT) represents one of the most effective therapies for treatment-resistant depression (TRD). The brain-derived neurotrophic factor (BDNF) is a neurotrophin implicated in major depressive disorder and in the effects of different therapeutic approaches, including ECT. Both BDNF peripheral levels and Val66Met polymorphism have been suggested as biomarkers of treatment effectiveness. The objective of this study was to test the potential of serum BDNF levels and Val66Met polymorphism in predicting ECT outcome in TRD patients.

METHODS

Seventy-four TRD patients scheduled to undergo ECT were included in the study. Illness severity was assessed through the Montgomery and Asberg Depression Rating Scale before beginning ECT (T0), the day after the end of ECT (T1), and 1 month after the end of ECT (T2). At T1, patients were classified as responders/nonresponders and remitters/nonremitters, whereas at T2, they were classified as sustained responders/nonresponders and sustained remitters/nonremitters. Serum concentrations of BDNF were measured at T0, and the BDNF Val66Met polymorphism was genotyped.

RESULTS

No difference in BDNF concentrations was observed in responders versus nonresponders, in remitters versus nonremitters, in sustained responders versus sustained nonresponders, and in sustained remitters versus sustained nonremitters. No association of Val66Met polymorphism was detected with both the response and the remission status.

CONCLUSIONS

Baseline serum BDNF levels and the BDNF Val66Met polymorphism showed no clinical utility in predicting ECT outcome in TRD patients.

Astrocyte, a Promising Target for Mood Disorder Interventions

Mood disorders have multiple phenotypes and complex underlying biological mechanisms and, as such, there are no effective therapeutic strategies. A review of recent work on the role of astrocytes in mood disorders is thus warranted, which we embark on here. We argue that there is tremendous potential for novel strategies for therapeutic interventions based on the role of astrocytes. Astrocytes are traditionally considered to have supporting roles within the brain, yet emerging evidence has shown that astrocytes have more direct roles in influencing brain function. Notably, evidence from postmortem human brain tissues has highlighted changes in glial cell morphology, density and astrocyte-related biomarkers and genes following mood disorders, indicating astrocyte involvement in mood disorders. Findings from animal models strongly imply that astrocytes not only change astrocyte morphology and physiological characteristics but also influence neural circuits via synapse structure and formation. This review pays particular attention to interactions between astrocytes and neurons and argues that astrocyte dysfunction affects the monoaminergic system, excitatory–inhibitory balance and neurotrophic states of local networks. Together, these studies provide a foundation of knowledge about the exact role of astrocytes in mood disorders. Importantly, we then change the focus from neurons to glial cells and the interactions between the two, so that we can understand newly proposed mechanisms underlying mood disorders, and to identify more diagnostic indicators or effective targets for treatment of these diseases.

Subjective memory complaints after electroconvulsive therapy: systematic review

Aims and methodFew studies have looked at subjective memory impairment from electroconvulsive therapy (ECT) after treatment completion. We aimed to systematically review all available evidence for subjective post-treatment effects. RESULTS: We included 16 studies in this review. There was considerable between-study heterogeneity in clinical population, ECT modality and assessment scales used. The most common assessment scale (eight studies) was the Squire Subjective Memory Questionnaire. The majority of studies reported an improvement in subjective memory after ECT, which correlated with improved depression scores. Subjective complaints were fewer in studies that used ultra-brief pulse ECT. Longer pulse widths were associated with more subjective complaints, as was female gender and younger age of treatment in the largest study.Clinical implicationsThere is considerable heterogeneity between studies, limiting meaningful conclusions. Ultra-brief pulse ECT appears to result in fewer subjective complaints.Declaration of interestNone.

S100B, Homocysteine, Vitamin B12, Folic Acid, and Procalcitonin Serum Levels in Remitters to Electroconvulsive Therapy: A Pilot Study

Background

Electroconvulsive therapy (ECT) is one of the most effective treatment options for refractory depressed patients. To date, there are only a few predictors of response.

Aim

The aim was to identify predictive biomarkers of remission to ECT on a molecular level.

Methods

11 patients suffering from a major depressive episode—according to the Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV)—underwent 10 ECT sessions. Blood samples were taken, and the depression severity was assessed before, one hour and 24 hours after sessions 1, 4, 7, and 10 using the Montgomery Asberg Depression Rating Scale (MADRS). A MADRS total score < 12 was interpreted as remission.

Results

Patients remitting under ECT had significantly higher homocysteine (p < 0.001), S100B (p < 0.001), and procalcitonin (PCT) (p = 0.027) serum levels. On the contrary, serum levels of vitamin B12 (p < 0.001) and folic acid (p = 0.007) were significantly lower in remitters compared to those in nonremitters. Levels remained unchanged throughout the whole ECT course.

Conclusions

Our findings indicate that lower levels of vitamin B12 and folic acid associated with higher levels of homocysteine, S100B, and PCT point to a subgroup of depressed patients sensitive to ECT. Due to the limited sample size, further studies are required to replicate our findings.

Potential Mechanisms Underlying the Therapeutic Effects of Electroconvulsive Therapy

In spite of the extensive application of electroconvulsive therapy (ECT), how it works remains unclear. So far, researchers have made great efforts in figuring out the mechanisms underlying the effect of ECT treatment via determining the levels of neurotransmitters and cytokines and using genetic and epigenetic tools, as well as structural and functional neuroimaging. To help address this question and provide implications for future research, relevant clinical trials and animal experiments are reviewed.

Protein S-100 and neuron-specific enolase serum levels remain unaffected by electroconvulsive therapy in patients with depression

The mechanism of the reversible cognitive deficits that might occur within an electroconvulsive therapy (ECT) treatment has not been clarified in a substantial way yet. Although the data available so far do not point towards a cause due to any structural or diffuse damage, further clarification, especially of the role of S-100 seems to be necessary before robust conclusions can be drawn. Serum levels of protein S-100 and neuron-specific enolase (NSE) were analysed in 19 patients with depression, who received ECT. The sampling was adjusted for the short half-life of protein S-100. Several outcome parameters such as Hamilton Depression Rating Scale and Mini-mental state examination before and after the ECT, response and remission to the treatment were recorded. S-100 and NSE levels at baseline, 30 and 60 min after the third session and after the end of the ECT remained stable. S-100 and NSE levels were neither associated with antidepressant response or remission nor with alterations in the cognitive performance. Although aiming for detecting potential rise in these established brain damage markers, an increase due to ECT was not observed, which is in line with the previous studies concerning the safety of ECT on a cellular basis.

Neuron specific enolase and serum remain unaffected by ultra high frequency left prefrontal transcranial magnetic stimulation in patients with depression: a preliminary study

Serum levels of neuron specific enolase (NSE) and protein S-100 were analysed in 22 patients with depression, who got repetitive transcranial magnetic stimulation (rTMS) for 3 weeks with ultra high frequency stimulation or sham. NSE and S-100 at baseline and after 3 weeks did not differ between the groups. Neither in the ultra high frequency group, nor in the sham group a difference between baseline and end could be found. No evidence for a significant rise in brain damage markers in rTMS was found in this preliminary study.

Antidepressants act directly on astrocytes: evidences and functional consequences

Post-mortem histopathological studies report on reduced glial cell numbers in various frontolimbic areas of depressed patients implying that glial loss together with abnormal functioning could contribute to the pathophysiology of mood disorders. Astrocytes are regarded as the most abundant cell type in the brain and known for their housekeeping functions, but as recent developments suggest, they are also dynamic regulators of synaptogenesis, synaptic strength and stability and they control adult hippocampal neurogenesis. The primary aim of this review was to summarize the abundant experimental evidences demonstrating that antidepressant therapies have profound effect on astrocytes. Antidepressants modify astroglial physiology, morphology and by affecting gliogenesis they probably even regulate glial cell numbers. Antidepressants affect intracellular signaling pathways and gene expression of astrocytes, as well as the expression of receptors and the release of various trophic factors. We also assess the potential functional consequences of these changes on glutamate and glucose homeostasis and on synaptic communication between the neurons. We propose here a hypothesis that antidepressant treatment not only affects neurons, but also activates astrocytes, triggering them to carry out specific functions that result in the reactivation of cortical plasticity and can lead to the readjustment of abnormal neuronal networks. We argue here that these astrocyte specific changes are likely to contribute to the therapeutic effectiveness of the currently available antidepressant treatments and the better understanding of these cellular and molecular processes could help us to identify novel targets for the development of antidepressant drugs.

Proteomic changes induced by anaesthesia and muscle relaxant treatment prior to electroconvulsive therapy

PURPOSE

Electroconvulsive therapy (ECT) is a psychiatric treatment in which seizures are electrically induced in patients. Prior to treatment, patients are usually given short-acting anaesthetics and muscle relaxants to avoid harm, e.g. musculoskeletal injury, during the convulsions. However, most molecular studies investigating the mechanism of action of ECT have not explored the potential effects of the pre-treatment with anaesthetic and/ or muscle relaxant.

EXPERIMENTAL DESIGN

We have carried out a targeted proteome analysis using multiplex immunoassay platform of serum samples before and 10 min after initiating the administration of the anaesthetic methohexital(®) and the muscle relaxant succinylcholine(®) to eight major depressive disorder patients undergoing ECT.

RESULTS

Twenty-six out of 142 analysed molecules showed significant differences in abundance after the methohexital/succinylcholine treatment. Importantly, eight of these molecules (fatty acid-binding protein, insulin, interleukin (IL)1β, IL-10, IL-4, prolactin, S100 calcium-binding protein B and tumor necrosis factor α) have been associated previously with effects of ECT.

CONCLUSIONS AND CLINICAL RELEVANCE

These findings indicate that caution should be used when interpreting results in existing and future proteome-based biomarkers studies on the effects of ECT in neuropsychiatric disease or the use of anaesthetic/muscle relaxant in major surgical operations related to different therapeutic areas.

Mood disorders are glial disorders: evidence from in vivo studies

It has recently been suggested that mood disorders can be characterized by glial pathology as indicated by histopathological postmortem findings. Here, we review studies investigating the glial marker S100B in serum of patients with mood disorders. This protein might act as a growth and differentiation factor. It is located in, and may actively be released by, astro- and oligodendrocytes. Studies consistently show that S100B is elevated in mood disorders; more strongly in major depressive than bipolar disorder. Successful antidepressive treatment reduces S100B in major depression whereas there is no evidence of treatment effects in mania. In contrast to the glial marker S100B, the neuronal marker protein neuron-specific enolase is unaltered. By indicating glial alterations without neuronal changes, serum S100B studies confirm specific glial pathology in mood disorders in vivo. S100B can be regarded as a potential diagnostic biomarker for mood disorders and as a biomarker for successful antidepressive treatment.

Electroconvulsive therapy and biomarkers of neuronal injury and plasticity: Serum levels of neuron-specific enolase and S-100b protein

Electroconvulsive therapy (ECT) is considered an effective and safe treatment in major depressive disorders. However, the possibility that it may induce cognitive adverse effects observed in selected patients has raised a concern that ECT may induce neuronal damage. The biomarkers of brain damage, neuron-specific enolase (NSE) and S-100b protein (S-100b), were measured in serum before and after ECT to determine whether this treatment induces neuronal injury or glial activation. ECT was administered to 10 patients with major depressive disorder. The serum samples were analyzed before (baseline) and after ECT at 1 h, 2 h, 6 h, 24 h and 48 h. The severity of depression was scored with the Montgomery-Asberg Depression Rating Scale (MADRS) and Beck Depression Inventory (BDI) pre-to-post ECT. There were no statistically significant changes in the median concentrations of NSE or S-100b at various time points before or after ECT. However, there were substantial elevations in the levels of S-100b in four patients. High levels of S-100 at 2 and 6 h correlated with the response to the treatment. These results suggest that ECT does not produce neuronal injury. The transient increase in the levels of S-100b reflecting activation of glial cells may play a part in mediating the antidepressant effects of ECT.

Neonatal S100B protein levels after prenatal exposure to selective serotonin reuptake inhibitors

OBJECTIVE

This study investigated neonatal S100B levels as a biomarker of prenatal selective serotonin reuptake inhibitor (SSRI) exposure.

METHODS

Maternal (delivery; N = 53) and neonatal (cord; N = 52) serum S100B levels were compared between prenatally SSRI-exposed (maternal, N = 36; neonatal, N = 37; duration: 230 +/- 71 days) and nonexposed (maternal, N = 17; neonatal, N = 15) groups. Measures of maternal depression and anxiety symptoms were assessed during the third trimester (33-36 weeks), and neonatal outcomes, including Apgar scores, birth weight, gestational age at birth, and symptoms of poor neonatal adaptation, were recorded.

RESULTS

S100B levels were significantly lower in prenatally SSRI-exposed neonates than in nonexposed neonates, controlling for gestational age and third-trimester maternal mood (P = .036). In contrast, SSRI-exposed mothers had significantly higher maternal serum S100B levels, compared with nonexposed mothers (P = .014), even controlling for maternal mood in the third trimester. S100B levels were not associated with maternal or neonatal drug levels, duration of prenatal exposure, demographic variables, or risk for poor neonatal adaptation.

CONCLUSIONS

Prenatal SSRI exposure was associated with decreased neonatal serum S100B levels, controlling for prenatal maternal mood. Neonatal S100B levels did not reflect neonatal behavioral outcomes and were not related to pharmacologic indices. These findings are consistent with prenatal alcohol and cocaine exposures, which also alter central serotonin levels.

Serum markers support disease-specific glial pathology in major depression

BACKGROUND

Recently, it was shown by histopathological studies that mood disorders are characterized by disease-specific glial pathology.

METHODS

To validate this hypothesis in vivo we measured weekly and simultaneously serum levels of the neuronal marker neuron-specific enolase and S100B, a protein expressed in astro- and oligodendroglia in the human brain, in 10 patients with major depressive disorder and 10 age- and gender-matched control subjects. Furthermore, we conducted a systematic, quantitative meta-analysis of all published studies on S100B involving 193 patients suffering from mood disorders and 132 healthy control subjects by calculating effect sizes.

RESULTS

S100B was elevated at admission and discharge in our patients with major depression compared with control subjects, whereas there were no significant differences for neuron-specific enolase. During treatment S100B decreased slightly, although this effect was not significant. It had no significant impact on neuron-specific enolase. The meta-analysis revealed that serum levels of S100B are consistently elevated in mood disorders during acute major depressive or manic episodes. Additionally, it demonstrated that serum S100B decreases during antidepressive treatment reliably if clinical improvement is sufficient.

LIMITATIONS

As the study measured only serum S100B, future (cell culture) studies have to elucidate molecular mechanisms of this protein in mood disorders. Moreover, results have to be replicated in a larger patient group.

CONCLUSIONS

S100B may represent a biomarker for mood disorders, particularly major depression, and their treatment. Together with unaltered levels of neuron-specific enolase, our results support in vivo the histopathologically generated hypothesis of disease-specific glial pathology in mood disorders.