Effects of electroconvulsive therapy and repetitive transcranial magnetic stimulation on serum brain-derived neurotrophic factor levels in patients with depression

Repetitive Transcranial Magnetic Stimulation-Induced Neuroplasticity and the Treatment of Psychiatric Disorders: State of the Evidence and Future Opportunities

Neuroplasticity, or activity-dependent neuronal change, is a crucial mechanism underlying the mechanisms of effect of many therapies for neuropsychiatric disorders, one of which is repetitive transcranial magnetic stimulation (rTMS). Understanding the neuroplastic effects of rTMS at different biological scales and on different timescales and how the effects at different scales interact with each other can help us understand the effects of rTMS in clinical populations and offers the potential to improve treatment outcomes. Several decades of research in the fields of neuroimaging and blood biomarkers is increasingly showing its clinical relevance, allowing measurement of the synaptic, functional, and structural changes involved in neuroplasticity in humans. In this narrative review, we describe the evidence for rTMS-induced neuroplasticity at multiple levels of the nervous system, with a focus on the treatment of psychiatric disorders. We also describe the relationship between neuroplasticity and clinical effects, discuss methods to optimize neuroplasticity, and identify future research opportunities in this area.

Magnetic Stimulation as a Therapeutic Approach for Brain Modulation and Repair: Underlying Molecular and Cellular Mechanisms

Neurological and psychiatric diseases generally have no cure, so innovative non-pharmacological treatments, including non-invasive brain stimulation, are interesting therapeutic tools as they aim to trigger intrinsic neural repair mechanisms. A common brain stimulation technique involves the application of pulsed magnetic fields to affected brain regions. However, investigations of magnetic brain stimulation are complicated by the use of many different stimulation parameters. Magnetic brain stimulation is usually divided into two poorly connected approaches: (1) clinically used high-intensity stimulation (0.5-2 Tesla, T) and (2) experimental or epidemiologically studied low-intensity stimulation (μT-mT). Human tests of both approaches are reported to have beneficial outcomes, but the underlying biology is unclear, and thus optimal stimulation parameters remain ill defined. Here, we aim to bring together what is known about the biology of magnetic brain stimulation from human, animal, and in vitro studies. We identify the common effects of different stimulation protocols; show how different types of pulsed magnetic fields interact with nervous tissue; and describe cellular mechanisms underlying their effects-from intracellular signalling cascades, through synaptic plasticity and the modulation of network activity, to long-term structural changes in neural circuits. Recent advances in magneto-biology show clear mechanisms that may explain low-intensity stimulation effects in the brain. With its large breadth of stimulation parameters, not available to high-intensity stimulation, low-intensity focal magnetic stimulation becomes a potentially powerful treatment tool for human application.

Acute effects of a session of electroconvulsive therapy on brain-derived neurotrophic factor plasma levels

Brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) are neurotrophins that play critical roles in brain neuronal function. Previous studies have established the association between BDNF and NGF signaling and severe mental disorders, but changes in BDNF plasma levels and electroconvulsive therapy (ECT) response are controversial. The aim of his study was to explore the acute effects of a single session of ECT on these neurotrophins signaling. Plasma levels of BDNF and NGF and their tyrosine kinase-type receptors expression in peripheral blood mononuclear cells (PBMCs) were determined before and two hours after a single ECT session in 30 subjects with a severe mental disorder. Two hours after an ECT session we found a statistically significant decrease of BDNF plasma levels (p=0.007). We did not find significant acute effects on NGF plasma levels or receptors expression in PBMCs. We found a significant inverse correlation between the time of convulsion and BDNF plasma levels decrease (r=-0.041, p=0.024). We have identified a decrease in BDNF plasma levels after 2h of a single ECT session. These results indicate the interest for future research in the role of neurotrophins in the response and safety of ECT.

Challenging the Pleiotropic Effects of Repetitive Transcranial Magnetic Stimulation in Geriatric Depression: A Multimodal Case Series Study

BACKGROUND

Although the antidepressant potential of repetitive transcranial magnetic stimulation (rTMS), the pleiotropic effects in geriatric depression (GD) are poorly investigated. We tested rTMS on depression, cognitive performance, growth/neurotrophic factors, cerebral blood flow (CBF) to transcranial Doppler sonography (TCD), and motor-evoked potentials (MEPs) to TMS in GD.

METHODS

In this case series study, six drug-resistant subjects (median age 68.0 years) underwent MEPs at baseline and after 3 weeks of 10 Hz rTMS on the left dorsolateral prefrontal cortex. The percentage change of serum nerve growth factor, vascular endothelial growth factor, brain-derived growth factor, insulin-like growth factor-1, and angiogenin was obtained. Assessments were performed at baseline, and at the end of rTMS; psychocognitive tests were also repeated after 1, 3, and 6 months.

RESULTS

Chronic cerebrovascular disease was evident in five patients. No adverse/undesirable effect was reported. An improvement in mood was observed after rTMS but not at follow-up. Electrophysiological data to TMS remained unchanged, except for an increase in the right median MEP amplitude. TCD and neurotrophic/growth factors did not change.

CONCLUSIONS

We were unable to detect a relevant impact of high-frequency rTMS on mood, cognition, cortical microcircuits, neurotrophic/growth factors, and CBF. Cerebrovascular disease and exposure to multiple pharmacological treatments might have contributed.

BDNF blood levels after electroconvulsive therapy in patients with mood disorders: An updated systematic review and meta-analysis

OBJECTIVES

Studies have suggested Brain-Derived Neurotrophic Factors (BDNF) increase after electroconvulsive therapy (ECT) although they were methodologically limited and enrolled small sample sizes. We aimed at updating a systematic review and meta-analysis to explore BDNF changes after ECT for the treatment of depression.

METHODS

PubMed, PsycInfo, Embase and Global health were searched (March, 2021). Clinical trials that measured BDNF in the blood before and after ECT in adults (≥ 18 years old) with depression (major depressive disorder or bipolar disorder) were eligible. Data were pooled through random-effects meta-analyses.

RESULTS

Twenty-eight studies involving 778 participants were included. Meta-analysis showed a significant increase in BDNF levels after ECT (Hedges' g = 0.28; 95% CI: 0.10, 0.46) while there was evidence of significant heterogeneity (I² = 67.64%) but not publication bias/small-study effect. Subgroup analyses and meta-regressions were underpowered to detect significant differences. Meta-analysis of depression severity scores demonstrated a considerable larger treatment effect in reducing depressive symptoms after ECT (Hedge's g = -3.72 95% CI: -4.23, -3.21).

CONCLUSION

This updated review showed that BDNF blood levels increased after ECT treatment. However, there was still evidence of substantial heterogeneity and there were limited sample sizes to investigate factors driving the variability of effects across studies. Importantly, the increase in BDNF levels was substantially smaller than the observed in depressive symptomatology, which could be indicative that the former was independent than the latter. Additional studies with larger sample sizes are currently required.

Brain-Derived Neurotrophic Factor (BDNF) as a biomarker of treatment response in patients with Treatment Resistant Depression (TRD): A systematic review & meta-analysis

Multiple lines of evidence have implicated brain-derived neurotrophic factor (BDNF) in treatment-resistant depression (TRD). The aim of this synthesis was to determine the impact of TRD treatments on peripheral BDNF levels, and ascertain whether these changes are associated with antidepressant effects. Thirty-six articles involving 1198 patients with TRD were included herein. Electroconvulsive therapy (ECT), ketamine, and repetitive transcranial magnetic stimulation (rTMS) were the most common TRD treatments investigated. Serum BDNF levels significantly increased in six, two, four and one studies following ECT, ketamine, rTMS and atypical antipsychotics, respectively. The estimated mean baseline serum BDNF concentration in TRD patients ± 95% CI was 15.5 ± 4.34 ng/mL. Peripheral BDNF levels significantly increased overall (Hedges' g ± 95% CI = 0.336 ± 0.302; p < 0.05), but no association with depressive symptoms was found (p ≥ 0.05). These results demonstrate that peripheral measurements of total BDNF (i.e., mature and percursor forms of BDNF) are inadequate predictors of treatment response in TRD patients, and other considerations suggest that this would still apply to separable measurements of mature BDNF and its precursor.

A Systematic Review of Neuromodulation Treatment Effects on Suicidality

Introduction: Neuromodulation is an important group of therapeutic modalities for neuropsychiatric disorders. Prior studies have focused on efficacy and adverse events associated with neuromodulation. Less is known regarding the influence of neuromodulation treatments on suicidality. This systematic review sought to examine the effects of various neuromodulation techniques on suicidality. Methods: A systematic review of the literature from 1940 to 2020 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guideline was conducted. Any reported suicide-related outcome, including suicidal ideation, suicide intent, suicide attempt, completed suicide in reports were considered as a putative measure of treatment effect on suicidality. Results: The review identified 129 relevant studies. An exploratory analysis of a randomized controlled trial comparing the effects of sertraline and transcranial direct-current stimulation (tDCS) for treating depression reported a decrease in suicidal ideation favoring tDCS vs. placebo and tDCS combined with sertraline vs. placebo. Several studies reported an association between repetitive transcranial magnetic stimulation and improvements in suicidal ideation. In 12 of the studies, suicidality was the primary outcome, ten of which showed a significant improvement in suicidal ideation. Electroconvulsive therapy (ECT) and magnetic seizure therapy was also shown to be associated with lower suicidal ideation and completed suicide rates. There were 11 studies which suicidality was the primary outcome and seven of these showed an improvement in suicidal ideation or suicide intent and fewer suicide attempts or completed suicides in patients treated with ECT. There was limited literature focused on the potential protective effect of vagal nerve stimulation with respect to suicidal ideation. Data were mixed regarding the potential effects of deep brain stimulation on suicidality. Conclusions: Future prospective studies of neuromodulation that focus on the primary outcome of suicidality are urgently needed. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=125599, identifier: CRD42019125599.

Impact of Repetitive Transcranial Magnetic Stimulation (rTMS) on Theory of Mind and Executive Function in Major Depressive Disorder and Its Correlation with Brain-Derived Neurotrophic Factor (BDNF): A Randomized, Double-Blind, Sham-Controlled Trial

BACKGROUND

Studies have implicated hypofrontality in the pathogenesis of impaired theory of mind (ToM) and executive function (EF) in major depressive disorder (MDD). These symptoms are usually resistant to treatment. Repetitive transcranial magnetic stimulation (rTMS) has been shown to reverse hypofrontality. Moreover, BDNF is an effective biomarker of antidepressant effects, but there have been very few studies on the correlation between BDNF and rTMS. We aimed to evaluate the efficacy of 20 sessions of a 10 Hz unilateral rTMS intervention over the left dorsolateral prefrontal cortex (DLPFC) in improving ToM and EF in patients with MDD and its correlation with BDNF.

METHODS

A total of 120 MDD patients were enrolled in this randomized, sham-controlled, double-blind trial. Each participant received 20 sessions of rTMS at 10 Hz frequency through the active or the sham coil over 4 weeks. ToM was assessed with the facial emotion identification test (FEIT) and hinting task (HT). EF was assessed with the Wisconsin card sorting test (WCST). BDNF assessments were carried out at baseline and 2-, 4-, 12-, and 24-week follow-ups.

RESULTS

The improvement in the ToM (FEIT, HT) in the active rTMS group was significantly different from that in the sham rTMS group (F = 18.09, p < 0.001; F = 5.02, p = 0.026). There were significant differences in the WCST (categories completed, response errors, response perseverative errors, non-response perseverative errors) after logarithmic transformation at different time points in the active rTMS group (F = 14.71, p < 0.001; F = 5.99, p = 0.046; F = 8.90, p = 0.031; F = 2.31, p = 0.048). However, there was no significant difference in log transformed BDNF concentration between the two groups (t = 0.07 to t = 1.29, p > 0.05). BDNF was negatively correlated with WCST categories completed at the 24th week (r = -0.258, p = 0.046).

CONCLUSIONS

The results show that rTMS may improve the ToM and EF of patients with MDD and there was no significant correlation with serum BDNF concentration. RTMS can not only be used for treatment of patients with MDD but also has a positive effect on ToM and EF.

Sex differences in the association between serum BDNF and cognitive impairment in schizophrenia patients using various antipsychotics

BACKGROUND

Cognitive impairment is one of the core symptoms of schizophrenia patients. There are often various differences in the efficacy of different antipsychotics in the treatment of cognitive impairment by sex. The purpose of this study was to explore whether there are gender differences in the association between serum BDNF levels and cognitive performance in patients with schizophrenia taking different antipsychotics.

METHODS

We used Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) to assess the cognitive function of three groups of schizophrenia patients (420 on clozapine, 183 on risperidone, 215 on typical antipsychotic drugs) and 467 healthy controls. Positive and Negative Syndrome Scale (PANSS) was used to assess schizophrenia symptoms of patients. Enzyme-Linked ImmunoSorbent Assay was used to measure serum brain-derived neurotrophic factor (BDNF) levels.

RESULTS

Among the patients taking clozapine and typical antipsychotic drugs, the RBANS total score, immediate memory, attention, and delayed memory subscores in females were higher than those in males (all p < 0.05). The RBANS total score and the delayed memory subscores in female patients taking risperidone were higher than those in male patients (all p < 0.05). Significant correlation between BDNF and cognition only existed in male patients taking clozapine, male patients taking risperidone, and male and female patients taking typical antipsychotic drugs (all p < 0.05).

CONCLUSION

Regardless of antipsychotic effect, the cognitive function of female patients is better compared to that of male patients. For male patients, the association between BDNF and cognitive performance exists in each medication group. For female patients, this significant association was only shown in the typical antipsychotic group, but not in the clozapine and risperidone groups.

Exploratory study on neurochemical effects of low-intensity pulsed ultrasound in brains of mice

There is now a relatively large body of evidence suggesting a relationship between dysfunction of myelin and oligodendrocytes and the etiology of several neuropsychiatric disorders, including depression and schizophrenia, and also suggesting that ultrasound methods may alleviate some of the symptoms of depression. We have applied low-intensity pulsed ultrasound (LIPUS) to the brains of mice treated with the demyelinating drug cuprizone, a drug that has been used as the basis for a rodent model relevant to a number of psychiatric and neurologic disorders including depression, schizophrenia, and multiple sclerosis. Prior to conducting the studies in mice, preliminary studies were carried out on the effects of LIPUS in vitro in neuron-like SH-SY5Y cells and primary glial cells. In subsequent studies in mice, female C57BL/6 mice were restrained in plastic tubes for 20 min daily with the ultrasound transducer near the end of the tube directly above the mouse's head. LIPUS was used at an intensity of 25 mW/cm² once daily for 22 days in control mice and in mice undergoing daily repetitive restraint stress (RRS). Behavioral or neurochemical studies were done on the mice or the brain tissue obtained from them. The studies in vitro indicated that LIPUS stimulation at an intensity of 15 mW/cm² delivered for 5 min daily for 3 days in an enclosed sterile cell culture plate in an incubator increased the viability of SH-SY5Y and primary glial cells. In the studies in mice, LIPUS elevated levels of doublecortin, a marker for neurogenesis, in the cortex compared to levels in the RRS mice and caused a trend in elevation of brain levels of brain-derived neurotrophic factor in the hippocampus relative to control levels. LIPUS also increased sucrose preference (a measure of the attenuation of anhedonia, a common symptom of several psychiatric disorders) in the RRS model in mice. The ability of LIPUS administered daily to rescue damaged myelin and oligodendrocytes was studied in mice treated chronically with cuprizone for 35 days. LIPUS increased cortex and corpus callosum levels of myelin basic protein, a protein marker for mature oligodendrocytes, and neural/glial antigen 2, a protein marker for oligodendrocyte precursor cells, relative to levels in the cuprizone + sham animals. These results of this exploratory study suggest that future comprehensive time-related studies with LIPUS on brain chemistry and behavior related to neuropsychiatric disorders are warranted. Exploratory Study on Neurochemical Effects of Low Intensity Pulsed Ultrasound in Brains of Mice. Upper part of figure: LIPUS device and in-vitro cell experimental set-up. The center image is the LIPUS generating box; the image in the upper left shows the cell experiment set-up; the image in the upper right shows a zoomed-in sketch for the cell experiment; the image in the lower left shows the set-up of repetitive restraint stress (RRS) with a mouse; the image in the lower middle shows the set-up of LIPUS treatment of a mouse; the image in the lower right shows a zoomed-in sketch for the LIPUS treatment of a mouse.

Mechanisms of repetitive transcranial magnetic stimulation for anti-depression: Evidence from preclinical studies

This review summarizes the anti-depressant mechanisms of repetitive transcranial magnetic stimulation in preclinical studies, including anti-inflammatory effects mediated by activation of nuclear factor-E2-related factor 2 signaling pathway, anti-oxidative stress effects, enhancement of synaptic plasticity and neurogenesis via activation of the endocannabinoid system and brain derived neurotrophic factor signaling pathway, increasing the content of monoamine neurotransmitters via inhibition of Sirtuin 1/monoamine oxidase A signaling pathway, and reducing the activity of the hypothalamic-pituitary-adrenocortical axis. We also discuss the shortcomings of transcranial magnetic stimulation in preclinical studies such as inaccurate positioning, shallow depth of stimulation, and difficulty in elucidating the neural circuit mechanism up- and down-stream of the stimulation target brain region.

Brain-derived neurotrophic factor blood levels after electroconvulsive therapy in patients with major depressive disorder: A systematic review and meta-analysis

Some evidence pointed out that Electro-Convulsive Treatment (ECT) could increase the level of brain-derived neurotrophic factor (BDNF) in depressive patients. However, there are some disagreements. The purpose of the study is through a systematic review and meta-analysis to evaluate BDNF levels after ECT in patients with Major depressive disorder. Two independent researchers searched of published articles in the databases of Cochrane Library, PubMed, MEDLINE, EMBASE and WanFang Data, from January 1990 to March 2019. The following key words were used: "depression" or "depressive disorder", "major depressive disorder", "unipolar depression", "brain-derived neurotrophic factor" or "BDNF", and "electroconvulsive" or "ECT". A total of 22 studies met the inclusion criteria of the meta-analysis and included into our analysis. BDNF levels were increased among patients with MDD after ECT (P = 0.000) in plasma samples. The standardized mean difference (SMD) was 0.695 (95 % CI: 0.402-0.988). We also found BDNF levels increased on one week and one month after finishing ECT (SMD = 0.491, 95 %CI: 0.150,0.833, P = 0.005; and SMD = 0.812, 95 %CI: 0.326,1.298, P = 0.001, respectively). Our findings suggest that BDNF levels may increase after ECT and may possibly be used as an indicator of treatment response after one or more weeks of ECT in patients with depression. However, additional investigation of BDNF levels with different ECT durations are needed in responders and non-responders.

Combination of Human Mesenchymal Stem Cells and Repetitive Transcranial Magnetic Stimulation Enhances Neurological Recovery of 6-Hydroxydopamine Model of Parkinsonian's Disease

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) has been in use for the treatment of various neurological diseases, including depression, anxiety, stroke and Parkinson's disease (PD), while its underlying mechanism is stills unclear. This study was undertaken to evaluate the potential synergism of rTMS treatment to the beneficial effect of human mesenchymal stem cells (hMSCs) administration for PD and to clarify the mechanism of action of this therapeutic approach.

METHODS

The neuroprotective effect in nigral dopamine neurons, neurotrophic/growth factors and anti-/pro-inflammatory cytokine regulation, and functional recovery were assessed in the rat 6-hydroxydopamine (6-OHDA) model of PD upon administration of hMSCs and rTMS.

RESULTS

Transplanted hMSCs were identified in the substantia nigra, and striatum. Enhancement of the survival of SN dopamine neurons and the expression of the tyrosine hydroxylase protein were observed in the hMSCs + rTMS compared to that of controls. Combination therapy significantly elevated the expression of several key neurotrophic factors, of which the highest expression was recorded in the rTMS + hMSC group. In addition, the combination therapy significantly upregulated IL-10 expression while decreased IFN-γ and TNF-α production in a synergistic manner. The treadmill locomotion test (TLT) revealed that motor function was improved in the rTMS + hMSC treatment with synergy.

CONCLUSION

Our findings demonstrate that rTMS treatment and hMSC transplantation could synergistically create a favorable microenvironment for cell survival within the PD rat brain, through alteration of soluble factors such as neurotrophic/growth factors and anti-/pro-inflammatory cytokines related to neuronal protection or repair, with preservation of DA neurons and improvement of motor functions.

BDNF and the Antidepressant Effects of Ketamine and Propofol in Electroconvulsive Therapy: A Preliminary Study

OBJECTIVE

Ketamine and propofol have become increasingly popular in electroconvulsive therapy (ECT) anaesthesia. This study was conducted to examine whether changes in serum levels of brain-derived neurotrophic factor (BDNF) are associated with the antidepressant effects of ketofol, a combination of ketamine and propofol, in ECT for patients with treatment-resistant depression (TRD).

METHODS

Thirty patients with TRD (18-65 years) were enrolled and underwent eight ECT sessions with ketamine (0.5 mg/kg) plus propofol (0.5 mg/kg) (ketofol). Symptom severity was monitored using the 17-item Hamilton Depression Rating Scale (HAMD-17) and the Brief Psychiatric Rating Scale (BPRS), and serum levels of BDNF were examined by enzyme-linked immunosorbent assay (ELISA) at baseline and after 2, 4, and 8 ECT treatments. Serum levels of BDNF were also collected from thirty healthy controls.

RESULTS

At baseline, there were no significant differences in serum levels of BDNF between patients with TRD and healthy controls. The response and remission rates in patients with TRD were 100% (30/30) and 53.3% (16/30) after ECT treatment, respectively. Despite a significant reduction in HAMD-17 and BPRS scores after ECT, no changes in serum levels of BDNF were observed after ECT treatment when compared to baseline. No association was found between serum levels of BDNF and changes in illness severity.

CONCLUSION

Serum levels of BDNF did not represent a suitable candidate biomarker for determining the antidepressant effects of ketofol during ECT for patients with TRD.

Hippocampal volume change following ECT is mediated by rs699947 in the promotor region of VEGF

Several studies have shown that electroconvulsive therapy (ECT) results in increased hippocampal volume. It is likely that a multitude of mechanisms including neurogenesis, gliogenesis, synaptogenesis, angiogenesis, and vasculogenesis contribute to this volume increase. Neurotrophins, like vascular endothelial growth factor (VEGF) and brain-derived neurotrophic factor (BDNF) seem to play a crucial mediating role in several of these mechanisms. We hypothesized that two regulatory SNPs in the VEGF and BDNF gene influence the changes in hippocampal volume following ECT. We combined genotyping and brain MRI assessment in a sample of older adults suffering from major depressive disorder to test this hypothesis. Our results show an effect of rs699947 (in the promotor region of VEGF) on hippocampal volume changes following ECT. However, we did not find a clear effect of rs6265 (in BDNF). To the best of our knowledge, this is the first study investigating possible genetic mechanisms involved in hippocampal volume change during ECT treatment.

Rhythmic low-field magnetic stimulation may improve depression by increasing brain-derived neurotrophic factor

BACKGROUND

Low-field magnetic stimulation (LFMS) has mood-elevating effect, and the increase of brain-derived neurotrophic factor (BDNF) is associated with antidepressant treatment. We evaluated the effects and association with BDNF of rhythmic LFMS in the treatment of major depressive disorder (MDD).

METHODS

A total of 22 MDD patients were randomized to rhythmic alpha stimulation (RAS) or rhythmic delta stimulation (RDS), with 5 sessions per week, lasting for 6 weeks. Outcomes assessments included the 17-item Hamilton Depression Rating Scale (HAMD-17), the Hamilton Anxiety Rating Scale (HAMA), and the Clinical Global Impressions-Severity scale (CGI-S) at baseline and at weeks 1, 2, 3, 4, and 6. Serum BDNF level was measured at baseline and at weeks 2, 4, and 6.

RESULTS

HAMD-17, HAMA, and CGI-S scores were significantly reduced with both RAS and RDS. RAS patients had numerically greater reductions in HAMD-17 scores than RDS patients (8.9 ± 7.4 vs. 6.2 ± 6.2, effect size [ES]=0.40), while RDS patients had greater improvement in HAMA scores (8.2 ± 8.0 vs. 5.3 ± 5.8, ES=0.42). RAS was associated with clinically relevant advantages in response (54.5% vs. 18.2%, number-needed-to-treat [NNT]=3) and remission (36.4% vs. 9.1%, NNT=4). BDNF increased significantly during the 6-week study period (p&lt;0.05), with greater increases in RAS at weeks 4 and 6 (ES=0.66-0.76) and statistical superiority at week 2 (p=0.034, ES=1.23). Baseline BDNF in the 8 responders (24.8±9.0 ng/ml) was lower than in the 14 nonresponders (31.1±7.3 ng/ml, p=0.083, ES=-0.79), and BDNF increased more in responders (8.9±7.8 ng/ml) than in nonresponders (1.8±3.5 ng/ml, p=0.044). The change in BDNF at week 2 was the most strongly predicted response (p=0.016).

CONCLUSIONS

Rhythmic LFMS was effective for MDD. BDNF may moderate/mediate the efficacy of LFMS.

Brain-derived neurotrophic factor as a possible predictor of electroconvulsive therapy outcome

While brain-derived neurotrophic factor (BDNF) has been shown to predict response to pharmacotherapy in depression, studies in electroconvulsive therapy (ECT) are small and report conflicting results. This study assesses the association between pre-treatment BDNF levels and ECT outcome in severe late-life unipolar depression (LLD). The potential of BDNF as a clinical predictor of ECT outcome was subsequently evaluated. Characteristics associated with low and high BDNF subgroups were determined as well. Ninety-four patients diagnosed with LDD referred for ECT were included. Fasting serum BDNF levels were determined before ECT. Remission and response, measured with the Montgomery-Åsberg Depression Rating Scale, were the outcomes. The association between BDNF and ECT outcome was analysed with logistic regression and Cox regression. The clinical usefulness of BDNF was evaluated using the receiver operating characteristic (ROC) curve. Associations between clinical characteristics and low versus high BDNF levels were examined with T tests, chi-squared tests and Mann-Whitney tests. The odds of remission decreased with 33% for every five units increase of BDNF levels (OR 0.67, 95% confidence interval 0.47-0.96; p = 0.03); however, neither the association with time to remission nor the associations with response nor the adjusted models were significant. The area under the ROC (0.66) implied a poor accuracy of BDNF as a clinical test. Clinical characteristics associated with BDNF were inclusion site, physical comorbidities and duration of the index episode. To conclude, although there is an association between pre-treatment BDNF levels and ECT outcome, BDNF cannot be considered an eligible biomarker for ECT outcome in clinical practice.

Effect of electroconvulsive therapy on brain-derived neurotrophic factor levels in patients with major depressive disorder

OBJECTIVES

Brain-derived neurotrophic factor (BDNF) has been associated with depression and its treatment response. The aim of the present study was to explore the effect of electroconvulsive therapy (ECT) on serum and plasma BDNF levels and change of Montgomery-Asberg Depression Rating Scale (MADRS) and their associations in patients with major depressive disorder (MDD).

METHODS

The study included thirty patients suffering from MDD. Their serum and plasma BDNF levels were examined before ECT (baseline) and after the first, fifth, and last ECT session. The severity of the depression and the response to ECT were measured with MADRS.

RESULTS

Electroconvulsive therapy caused no significant changes in serum BDNF levels. Plasma BDNF levels decreased during the fifth ECT session between the baseline and the 2-hr samples (p = 0.019). No associations were found between serum or plasma BDNF levels and remission. The correlations between plasma and serum BDNF levels in each measurement varied between 0.187 and 0.636.

CONCLUSIONS

Neither serum nor plasma BDNF levels were systematically associated with the clinical remission. However, the plasma BDNF levels somewhat varied during the ECT series. Therefore, the predictive value of BDNF for effects of ECT appears to be at least modest.

Both Serum Brain-Derived Neurotrophic Factor and Interleukin-6 Levels Are Not Associated with Therapeutic Response to Lamotrigine Augmentation Therapy in Treatment-Resistant Depressive Disorder

BACKGROUND/AIMS

Serum levels of brain-derived neurotrophic factor (BDNF) and interleukin-6 (IL-6) were prospectively monitored in relation with therapeutic response to lamotrigine augmentation therapy in 46 (15 males and 31 females) inpatients with treatment-resistant depressive disorder during an 8-week treatment with lamotrigine using an open-study design.

METHODS

The subjects were 46 depressed patients who had already shown insufficient response to at least 3 psychotropics including antidepressants, mood stabilizers, and atypical antipsychotics. The diagnoses were major depressive disorder (n = 19), bipolar I disorder (n = 6), and bipolar II disorder (n = 22). The final doses of lamotrigine were 100 mg/day for 26 subjects who were not taking valproate and 75 mg/day for 20 subjects taking valproate, respectively. Depressive symptoms were evaluated by the Montgomery-Åsberg Depression Rating Scale (MADRS) before and after the 8-week treatment. Blood sampling was performed before the start of lamotrigine treatment and at week 8. Serum BDNF and IL-6 levels were measured using quantitative sandwich enzyme immunoassays.

RESULTS

No significant changes in serum BDNF or IL-6 levels during the 8-week lamotrigine treatment were observed in the total of subjects, responders or nonresponders. There was no significant correlation between the changes in serum BDNF or IL-6 levels and the percent improvement in MADRS scores in the overall subjects.

CONCLUSION

The present study suggests that the acute effect of lamotrigine augmentation therapy for a major depressive episode is not related to either BDNF or IL-6, at least in patients with treatment-resistant depressive disorder.

Cranial electrotherapy stimulation affects mood state but not levels of peripheral neurotrophic factors or hypothalamic- pituitary-adrenal axis regulation

Cranial electrotherapy stimulation (CES) is reported to aid in relieving symptoms of depression and anxiety, though the mechanism underlying this effect remains unclear. Therefore, the present study aimed to evaluate changes in the hypothalamic-pituitary-adrenal (HPA) axis response and levels of neurotrophic factors, as well as changes in mood state, in patients undergoing CES therapy. Fifty healthy postmenopausal women were randomly assigned to either a Sham CES group (n = 25) or an Active CES group (n = 25). CES treatment was conducted in 20-minute sessions, three times per week for 8 weeks, using a micro current cranial electrotherapy stimulator. Blood samples were collected prior to and following the 8-week treatment period for measurement of cortisol, adrenocorticotropic hormone (ACTH), brain-derived neurotrophic factor (BDNF), and nerve growth factor (NGF) levels. Changes in mood state were also examined at the time of blood collection using the Profile of Mood States (POMS). No significant differences in cortisol, ACTH, BDNF, or NGF were observed between the two participant groups (p > 0.05) following the treatment period. However, those in the Active CES group exhibited significantly decreased Tension-Anxiety and Depression-Dejection scores on the POMS relative to pre-treatment scores (p < 0.05). Furthermore, Depression-Dejection scores following treatment were significantly lower in the Active CES group than in the Sham CES group (p < 0.05). No significant differences were observed in any other POMS scores such as Anger-Hostility, Vigor-Activity, Fatigue-Inertia, and Confusion-Bewilderment (p > 0.05). These results suggest that 8 weeks of CES treatment does not induce changes in blood levels of neurotrophic factors or HPA-axis-related hormones, though such treatment may be effective in treating symptoms of anxiety and depression.

Increased serum levels of sortilin-derived propeptide after electroconvulsive therapy in treatment-resistant depressed patients

PURPOSE

Sortilin-derived propeptide (PE) and its synthetic analog spadin show strong antidepressant activity in rodents and, therefore, could be used as a biomarker to evaluate the clinical efficacy of antidepressant treatments. The aim of this study was to determine whether electroconvulsive therapy (ECT) modulates serum PE concentration in patients with treatment-resistant depression (TRD).

PATIENTS AND METHODS

Forty-five patients with major depressive disorder, who met the Diagnostic and Statistical Manual of Mental Disorders-IV criteria, were selected for this study.

RESULTS

We did not observe any difference in the PE levels between TRD patients and controls (z=0.10, P=0.92), but we found a strong significant increase between the PE levels measured just before (T0) and about 1 month (T2) after ECT (z=-2.82, P=0.005). A significant difference between T0 and T2 was observed only in responders (z=-2.59, P=0.01), whereas no effect was found in nonresponders (z=-1.27, P=0.20). Interestingly, we found a significant correlation between the increase in PE levels and decrease in Montgomery -Åsberg Depression Rating Scale scores for the total patient sample (P=0.03).

CONCLUSION

This study indicates for the first time that ECT affects serum PE concentration in responders and, therefore, could contribute to the evaluation of the therapy success.

How Electroconvulsive Therapy Works?: Understanding the Neurobiological Mechanisms

Electroconvulsive therapy (ECT) is a time tested treatment modality for the management of various psychiatric disorders. There have been a lot of modifications in the techniques of delivering ECT over decades. Despite lots of criticisms encountered, ECT has still been used commonly in clinical practice due to its safety and efficacy. Research evidences found multiple neuro-biological mechanisms for the therapeutic effect of ECT. ECT brings about various neuro-physiological as well as neuro-chemical changes in the macro- and micro-environment of the brain. Diverse changes involving expression of genes, functional connectivity, neurochemicals, permeability of blood-brain-barrier, alteration in immune system has been suggested to be responsible for the therapeutic effects of ECT. This article reviews different neurobiological mechanisms responsible for the therapeutic efficacy of ECT.

Randomized controlled trial of repetitive transcranial magnetic stimulation combined with paroxetine for the treatment of patients with first-episode major depressive disorder

Repetitive transcranial magnetic stimulation (rTMS) has been introduced as a new and effective treatment option for major depression. This paper examined the effectiveness of rTMS on first episode depressed patients when combined with antidepressant drugs. A random sample of forty-three first-episode depressed patients received active or sham rTMS to the left dorsolateral prefrontal cortex, and concomitantly took paroxetine for 4 weeks, and paroxetine monotherapy for 4 weeks afterwards. Response was defined as a ≥50% decrease on the total Hamilton Depression Rating Scale (HDRS) from the baseline, and remission was defined as an HDRS total residual score <8. The dosage of paroxetine was the average dose per day in each week. Repeated-measures ANOVA revealed a significant improvement in the HDRS with active compared with sham rTMS from the end of the 1st week to the 4th week. At the end of the 4th week, response rate was 95.5% with active and 71.4% with sham rTMS, remission rate was 68.2% with active and 38.1% with sham rTMS, while these significant differences disappeared at the endpoint of the study. These findings indicate that rTMS at 10-Hz accelerated the onset of action and augmented the response to paroxetine for first-episode depressed patients.

Consequences of brain-derived neurotrophic factor withdrawal in CNS neurons and implications in disease

Growth factor withdrawal has been studied across different species and has been shown to have dramatic consequences on cell survival. In the nervous system, withdrawal of nerve growth factor (NGF) from sympathetic and sensory neurons results in substantial neuronal cell death, signifying a requirement for NGF for the survival of neurons in the peripheral nervous system (PNS). In contrast to the PNS, withdrawal of central nervous system (CNS) enriched brain-derived neurotrophic factor (BDNF) has little effect on cell survival but is indispensible for synaptic plasticity. Given that most early events in neuropsychiatric disorders are marked by a loss of synapses, lack of BDNF may thus be an important part of a cascade of events that leads to neuronal degeneration. Here we review reports on the effects of BDNF withdrawal on CNS neurons and discuss the relevance of the loss in disease.

Effect of Deep Intramuscular Stimulation and Transcranial Magnetic Stimulation on Neurophysiological Biomarkers in Chronic Myofascial Pain Syndrome

OBJECTIVE

The aim was to assess the neuromodulation techniques effects (repetitive transcranial magnetic stimulation [rTMS] and deep intramuscular stimulation therapy [DIMST]) on pain intensity, peripheral, and neurophysiological biomarkers chronic myofascial pain syndrome (MPS) patients.

DESIGN

Randomized, double blind, factorial design, and controlled placebo-sham clinical trial.

SETTING

Clinical trial in the Laboratory of Pain and Neuromodulation at Hospital de Clínicas de Porto Alegre (NCT02381171).

SUBJECTS

We recruited women aged between 19- and 75-year old, with MPS diagnosis.

METHODS

Patients were randomized into four groups: rTMS + DIMST, rTMS + sham-DIMST, sham-rTMS + DIMST, sham-rTMS + sham-DIMST; and received 10 sessions for 20 minutes each one (rTMS and DIMST). Pain was assessed by visual analogue scale (VAS); neurophysiological parameters were assessed by transcranial magnetic stimulation; biochemical parameters were: BDNF, S100β, lactate dehydrogenase, inflammatory (TNF-α, IL6, and IL10), and oxidative stress parameters.

RESULTS

We observed the pain relief assessed by VAS immediately assessed before and after the intervention (P < 0.05, F(1,3)= 3.494 and F(1,3)= 4.656, respectively); in the sham-rTMS + DIMST group and both three active groups in relation to sham-rTMS + sham-DIMST group, respectively. There was an increase in the MEP after rTMS + sham-DIMST (P < 0.05). However, there was no change in all-peripheral parameters analyzed across the treatment (P > 0.05).

CONCLUSION

Our findings add additional evidence about rTMS and DIMST in relieving pain in MPS patients without synergistic effect. No peripheral biomarkers reflected the analgesic effect of both techniques; including those related to cellular damage. Additionally, one neurophysiological parameter (increased MEP amplitude) needs to be investigated.

Increased BDNF levels after electroconvulsive therapy in patients with major depressive disorder: A meta-analysis study

OBJECTIVE

We performed a systematic review and meta-analysis to estimate brain-derived neurotrophic factor (BDNF) level in patients with major depressive disorder (MDD) after electroconvulsive therapy (ECT).

METHOD

A comprehensive search of the Cochrane Library, MEDLINE, LILACS, Grey literature, and EMBASE was performed for papers published from January 1990 to April 2016. The following key terms were searched: "major depressive disorder", "unipolar depression", "brain-derived neurotrophic factor", and "electroconvulsive therapy".

RESULTS

A total of 252 citations were identified by the search strategy, and nine studies met the inclusion criteria of the meta-analysis. BDNF levels were increased among patients with MDD after ECT (P value = 0.006). The standardized mean difference was 0.56 (95% CI: 0.17-0.96). Additionally, we found significant heterogeneity between studies (I² = 73%).

CONCLUSION

Our findings suggest a potential role of BDNF as a marker of treatment response after ECT in patients with MDD.

Effects of modified electroconvulsive therapy on the electroencephalogram of schizophrenia patients

Background

This study aimed to investigate the modified electroconvulsive therapy (MECT) on the electroencephalogram (EEG) of schizophrenia patients. A total of 26 schizophrenia patients who received MECT were recruited. EEG recording was initiated at 30 min before 1st and 6th MECT and terminated on the 2nd day. Images without artifacts were selected for the analysis of δ, θ, α1, α2 and β bands. The wave energy at each frequency, index of waves at different bands from the same lead, index of waves at the same band from different leads, time of epileptic discharge, time of resting state, and time to the stable EEG were determined and compared.

Results

The energy of slow waves increased. α waves reduced, but θ waves increased in the frontotemporal area. The index of θ waves increased. After resting state, brainwaves first occurred in the frontal area. Significant difference was observed in the time to waves returning to normal (P = 0.05).

Conclusions

After MECT, the θ waves in the same lead increases, and its energy also elevates; α wave in the frontotemporal area reduces; there is transient reduction in cerebral function during MECT. After electric resting state, brainwaves mainly occur in the frontal area, and the time to brainwaves returning to normal reduces over time after MECT.

Electroconvulsive therapy (ECT) and aerobic exercise training (AET) increased plasma BDNF and ameliorated depressive symptoms in patients suffering from major depressive disorder

BACKGROUND

To treat patients suffering from major depressive disorder (MDD), research has focused on electroconvulsive therapy (ECT) and aerobic exercise training (AET). Brain derived neurotrophic factor (BDNF) seems to be key in MDD. The aims of the present study were therefore two-fold, to investigate in a three-arm interventional study the differential effects of ECT, ECT plus AET, and AET alone in patients suffering from TR-MDD on 1. depressive symptoms and 2. plasma BDNF (pBDNF).

METHODS

60 patients with MDD (mean age: 31 years; 31.6% female patients) were randomly assigned either to the ECT, ECT + AET, or AET condition. The AET condition consisted of treadmill exercise for 45 min, three times a week. Both depression severity and pBDNF levels were assessed at baseline and 4 weeks later. All patients were further treated with an SSRI standard medication.

RESULTS

pBDNF levels increased over time in all three study conditions, though, highest increase was observed in the ECT + EAT condition, and lowest increase was observed in the AET condition. Depressive symptoms decreased in all three conditions over time, though, strongest decrease was observed in the ECT + AET condition. The combination of ECT + AET led to significantly greater remission rates than in either the ECT or AET alone conditions. BDNF levels were not associated with symptoms of depression.

CONCLUSIONS

The pattern of results suggests that ECT, AET and particularly their combination are promising directions for the treatment of patients suffering from MDD, and that it remains unclear to what extent pBDNF is key and a reliable biomarker for MDD.

Induction of Neurorestoration From Endogenous Stem Cells

Neural stem cells (NSCs) persist in the subventricular zone lining the ventricles of the adult brain. The resident stem/progenitor cells can be stimulated in vivo by neurotrophic factors, hematopoietic growth factors, magnetic stimulation, and/or physical exercise. In both animals and humans, the differentiation and survival of neurons arising from the subventricular zone may also be regulated by the trophic factors. Since stem/progenitor cells present in the adult brain and the production of new neurons occurs at specific sites, there is a possibility for the treatment of incurable neurological diseases. It might be feasible to induce neurogenesis, which would be particularly efficacious in the treatment of striatal neurodegenerative conditions such as Huntington's disease, as well as cerebrovascular diseases such as ischemic stroke and cerebral palsy, conditions that are widely seen in the clinics. Understanding of the molecular control of endogenous NSC activation and progenitor cell mobilization will likely provide many new opportunities as therapeutic strategies. In this review, we focus on endogenous stem/progenitor cell activation that occurs in response to exogenous factors including neurotrophic factors, hematopoietic growth factors, magnetic stimulation, and an enriched environment. Taken together, these findings suggest the possibility that functional brain repair through induced neurorestoration from endogenous stem cells may soon be a clinical reality.

Neurobiological mechanisms of repetitive transcranial magnetic stimulation of the dorsolateral prefrontal cortex in depression: a systematic review

Depression is one of the most prevalent mental illnesses worldwide and a leading cause of disability, especially in the setting of treatment resistance. In recent years, repetitive transcranial magnetic stimulation (rTMS) has emerged as a promising alternative strategy for treatment-resistant depression and its clinical efficacy has been investigated intensively across the world. However, the underlying neurobiological mechanisms of the antidepressant effect of rTMS are still not fully understood. This review aims to systematically synthesize the literature on the neurobiological mechanisms of treatment response to rTMS in patients with depression. Medline (1996-2014), Embase (1980-2014) and PsycINFO (1806-2014) were searched under set terms. Three authors reviewed each article and came to consensus on the inclusion and exclusion criteria. All eligible studies were reviewed, duplicates were removed, and data were extracted individually. Of 1647 articles identified, 66 studies met both inclusion and exclusion criteria. rTMS affects various biological factors that can be measured by current biological techniques. Although a number of studies have explored the neurobiological mechanisms of rTMS, a large variety of rTMS protocols and parameters limits the ability to synthesize these findings into a coherent understanding. However, a convergence of findings suggest that rTMS exerts its therapeutic effects by altering levels of various neurochemicals, electrophysiology as well as blood flow and activity in the brain in a frequency-dependent manner. More research is needed to delineate the neurobiological mechanisms of the antidepressant effect of rTMS. The incorporation of biological assessments into future rTMS clinical trials will help in this regard.

Brain-Derived Neurotrophic Factor and Antidepressive Effect of Electroconvulsive Therapy: Systematic Review and Meta-Analyses of the Preclinical and Clinical Literature

Emerging data suggest that Electro-Convulsive Treatment (ECT) may reduce depressive symptoms by increasing the expression of Brain-Derived Neurotrophic Factor (BDNF). Yet, conflicting findings have been reported. For this reason we performed a systematic review and meta-analysis of the preclinical and clinical literature on the association between ECT treatment (ECS in animals) and changes in BDNF concentrations and their effect on behavior. In addition, regional brain expression of BDNF in mouse and human brains were compared using Allen Brain Atlas. ECS, over sham, increased BDNF mRNA and protein in animal brain (effect size [Hedge’s g]: 0.38―0.54; 258 effect-size estimates, N = 4,284) but not in serum (g = 0.06, 95% CI = -0.05―0.17). In humans, plasma but not serum BDNF increased following ECT (g = 0.72 vs. g = 0.14; 23 effect sizes, n = 281). The gradient of the BDNF increment in animal brains corresponded to the gradient of the BDNF gene expression according to the Allen brain atlas. Effect-size estimates were larger following more ECT sessions in animals (r = 0.37, P < .0001) and in humans (r = 0.55; P = 0.05). There were some indications that the increase in BDNF expression was associated with behavioral changes in rodents, but not in humans. We conclude that ECS in rodents and ECT in humans increase BDNF concentrations but this is not consistently associated with changes in behavior.

Electroconvulsive therapy improves clinical manifestations of treatment-resistant depression without changing serum BDNF levels

Electroconvulsive therapy (ECT) is effective in treatment-resistant depression (TRD). It may act through intracellular process modulation, but its exact mechanism is still unknown. Animal research supports a neurotrophic effect for ECT. We aimed to investigate the association between changes in serum brain-derived neurotrophic factor (sBDNF) levels and clinical improvement following ECT in patients with TRD. Twenty-one patients with TRD (2 men, 19 women; mean age, 63.5 years; S.D., 11.9) were assessed through the Hamilton Depression Rating Scale (HDRS), the Brief Psychiatric Rating Scale (BPRS), and the Clinical Global Impressions scale, Severity (CGIs) before and after a complete ECT cycle. At the same time-points, patients underwent blood withdrawal for measuring sBDNF levels. ECT significantly reduced HDRS, BPRS, and CGIS scores, but not sBDNF levels. No significant correlation was found between sBDNF changes, and each of HDRS, BPRS, and CGIs score changes. sBDNF levels in TRD patients were low both at baseline and post-ECT. Our results do not support that improvements in TRD following ECT are mediated through increases in sBDNF levels.

Possible Mechanisms Underlying the Therapeutic Effects of Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) is an effective method used to diagnose and treat many neurological disorders. Although repetitive TMS (rTMS) has been used to treat a variety of serious pathological conditions including stroke, depression, Parkinson’s disease, epilepsy, pain, and migraines, the pathophysiological mechanisms underlying the effects of long-term TMS remain unclear. In the present review, the effects of rTMS on neurotransmitters and synaptic plasticity are described, including the classic interpretations of TMS effects on synaptic plasticity via long-term potentiation and long-term depression. We also discuss the effects of rTMS on the genetic apparatus of neurons, glial cells, and the prevention of neuronal death. The neurotrophic effects of rTMS on dendritic growth and sprouting and neurotrophic factors are described, including change in brain-derived neurotrophic factor concentration under the influence of rTMS. Also, non-classical effects of TMS related to biophysical effects of magnetic fields are described, including the quantum effects, the magnetic spin effects, genetic magnetoreception, the macromolecular effects of TMS, and the electromagnetic theory of consciousness. Finally, we discuss possible interpretations of TMS effects according to dynamical systems theory. Evidence suggests that a rTMS-induced magnetic field should be considered a separate physical factor that can be impactful at the subatomic level and that rTMS is capable of significantly altering the reactivity of molecules (radicals). It is thought that these factors underlie the therapeutic benefits of therapy with TMS. Future research on these mechanisms will be instrumental to the development of more powerful and reliable TMS treatment protocols.

Possible Mechanisms Underlying the Therapeutic Effects of Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) is an effective method used to diagnose and treat many neurological disorders. Although repetitive TMS (rTMS) has been used to treat a variety of serious pathological conditions including stroke, depression, Parkinson's disease, epilepsy, pain, and migraines, the pathophysiological mechanisms underlying the effects of long-term TMS remain unclear. In the present review, the effects of rTMS on neurotransmitters and synaptic plasticity are described, including the classic interpretations of TMS effects on synaptic plasticity via long-term potentiation and long-term depression. We also discuss the effects of rTMS on the genetic apparatus of neurons, glial cells, and the prevention of neuronal death. The neurotrophic effects of rTMS on dendritic growth and sprouting and neurotrophic factors are described, including change in brain-derived neurotrophic factor concentration under the influence of rTMS. Also, non-classical effects of TMS related to biophysical effects of magnetic fields are described, including the quantum effects, the magnetic spin effects, genetic magnetoreception, the macromolecular effects of TMS, and the electromagnetic theory of consciousness. Finally, we discuss possible interpretations of TMS effects according to dynamical systems theory. Evidence suggests that a rTMS-induced magnetic field should be considered a separate physical factor that can be impactful at the subatomic level and that rTMS is capable of significantly altering the reactivity of molecules (radicals). It is thought that these factors underlie the therapeutic benefits of therapy with TMS. Future research on these mechanisms will be instrumental to the development of more powerful and reliable TMS treatment protocols.

Pharmacogenetics in electroconvulsive therapy and adjunctive medications

Electroconvulsive therapy (ECT) has shown apparent efficacy in treatment of patients with depression and other mental illnesses who do not respond to psychotropic medications or need urgent control of their symptoms. Pharmacogenetics contributes to an individual's sensitivity and response to a variety of drugs. Clinical insights into pharmacogenetics of ECT and adjunctive medications not only improves its safety and efficacy in the indicated patients, but can also lead to the identification of novel treatments in psychiatric disorders through understanding of potential molecular and biological mechanisms involved. In this review, we explore the indications of pharmacogenetics role in safety and efficacy of ECT and present the evidence for its role in patients with psychiatric disorders undergoing ECT.

Brain-derived neurotrophic factor and subcallosal deep brain stimulation for refractory depression

OBJECTIVES

Subcallosal cingulate (SCC) deep brain stimulation (DBS) is a promising experimental treatment for treatment-resistant depression (TRD). Given the role of brain-derived neurotrophic factor (BDNF) in neuroplasticity and antidepressant efficacy, we examined the effect of SCC-DBS on serum BDNF in TRD.

METHODS

Four patients with TRD underwent SCC-DBS treatment. Following a double-blind stimulus optimization phase of 3 months, patients received continuous stimulation in an open label fashion for 6 months. Clinical improvement in depressive symptoms was evaluated bi-weekly for 6 months using the Hamilton Depression Rating Scale (HDRS). Mature serum BDNF levels were measured before and 9-12 months after surgery.

RESULTS

Three patients responded to SCC-DBS: two showed full clinical response (50% reduction in HDRS scores) and one had partial response (35% reduction in HDRS scores) at the clinical endpoint. Interestingly, all four patients showed reduction in serum BDNF concentration from pre-DBS baseline.

CONCLUSIONS

SCC-DBS for TRD may be associated with decreased levels of serum BDNF. Longitudinal studies with multiple measurements in a larger sample are required to determine the role of BDNF as a biomarker of SCC-DBS antidepressant efficacy.

The neuroprotection of repetitive transcranial magnetic stimulation pre-treatment in vascular dementia rats

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive technique that could interfere cortical excitability though brief electric currents induced by alternating magnetic fields from the inductive coil. Currently, it has been applied in many fields of basic and clinical neuro-research. The aims of the present study are to investigate the effect of rTMS pre-treatment on cognitive function in vascular dementia (VaD) rats and further explore the molecular mechanism of rTMS neuroprotection on VaD. We found that rTMS pre-treated VaD rats showed significantly better memory and learning abilities in Morris water maze test compared to the untreated group. Moreover, the mRNA and protein expression levels of BDNF, TrkB, and SYN were significantly higher in the rTMS pre-treated group, indicating that rTMS pre-treatment has neuroprotective effect for VaD, which may have resulted from the increased level of BDNF, TrkB, and SYN in the hippocampal CA1 area.

BDNF serum levels and promoter methylation of BDNF exon I, IV and VI in depressed patients receiving electroconvulsive therapy

We examined potential changes in brain-derived neurotrophic factor (BDNF) serum levels and promoter methylation of the BDNF gene in 11 patients with treatment-resistant major depressive disorder during a series of electroconvulsive therapy (ECT). Blood samples were taken before, 1 and 24 h after ECT treatment sessions 1, 4, 7 and 10. Patients remitting under ECT had significantly lower mean promoter methylation rates, especially concerning the exon I promoter, compared to non-remitters (both p < 0.002). These findings may point to a depression subtype in which ECT is particularly beneficial.

Electroconvulsive therapy improves clinical manifestation with plasma BDNF levels unchanged in treatment-resistant depression patients

Electroconvulsive therapy (ECT) is the most effective treatment in treatment-resistant depression; it may modulate intracellular processes in such patients. This study aimed to investigate the association between changes in plasma brain-derived neurotrophic factor (BDNF) levels and the clinical improvements after ECT for patients with treatment-resistant depression. Fifty-five inpatients with treatment-resistant depression were recruited. The severity of depression was measured using the 17-item Hamilton Rating Scale for Depression (HAMD-17) and the Clinical Global Impression-Severity (CGI-S) before ECT, after every 3 sessions of ECT, and at the end of ECT. Plasma BDNF levels were measured in all subjects before and after ECT. The severity of depression was significantly reduced on the HAMD-17 (p < 0.001) and the CGI-S (p < 0.001) after the end of ECT. There were no significant differences in plasma BDNF levels after ECT (p = 0.615). No significant correlation was found between changes in plasma BDNF levels and changes in HAMD-17 scores (r = 0.188, p = 0.169). Our results do not support the hypothesis that improvements in treatment-resistant depression patients after ECT are due to changes in BDNF levels.

RETRACTED: Electroconvulsive therapy and aerobic exercise training increased BDNF and ameliorated depressive symptoms in patients suffering from treatment-resistant major depressive disorder

BACKGROUND

To treat patients suffering from treatment-resistant major depressive disorder (TR-MDD), research has focused on electroconvulsive therapy (ECT) and aerobic exercise training (AET). Brain derived neurotrophic factor (BDNF) seems to be key in MDD. The aims of the present study were therefore two-fold, to investigate in a three-arm interventional study the differential effects of ECT, ECT plus AET, and AET alone in patients suffering from TR-MDD on 1. depressive symptoms and 2.

BDNF METHODS

60 patients with TR-MDD (mean age: 31 years; 31.6% female patients) were randomly assigned either to the ECT, ECT + AET, or AET condition. The AET condition consisted of treadmill exercise for 30 min, three times a week. Both depression severity and BDNF levels were assessed at baseline and 4 weeks later. All patients were further treated with an SSRI standard medication.

RESULTS

BDNF levels increased over time in all three study conditions. After completion of the intervention program, the ECT group showed significantly higher BDNF levels compared to the ECT + AET and the AET conditions. Depressive symptoms decreased in all three conditions over time. The combination of ECT + AET led to a significantly greater decrease than in either the ECT or AET alone conditions. BDNF levels were not associated with symptoms of depression.

CONCLUSIONS

The pattern of results suggests that ECT, AET and particularly their combination are promising directions for treatment patients suffering from TR-MDD, and that it remains unclear to what extent BDNF is key and a reliable biomarker for TR-MDD.

BDNF plasma levels after antidepressant treatment with sertraline and transcranial direct current stimulation: results from a factorial, randomized, sham-controlled trial

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation intervention that modifies cortical excitability according to the stimulation parameters. Preclinical and clinical studies in healthy volunteers suggest that tDCS induces neuroplastic alterations of cortical excitability, which might explain its clinical effects in major depressive disorder (MDD). We therefore examined whether tDCS, as compared to the antidepressant sertraline, increases plasma brain-derived neurotrophic factor (BDNF) levels, a neurotrophin associated with neuroplasticity. Patients (n=73) with major depressive disorder were randomized to active/sham tDCS and sertraline/placebo (four groups) in this 6-week, double-blind, placebo-controlled trial. We measured BDNF plasma levels at baseline and endpoint, observing no significant changes of BDNF levels after treatment. In addition, no significant changes were observed in responders and non-responders as well as no relationships between BDNF levels and clinical and psychopathological variables related to depression. Thus, in one of the few placebo-controlled trials evaluating BDNF changes over an antidepressant treatment course, we did not observe BDNF increase regardless of clinical improvement in depressed patients. Regarding tDCS, BDNF plasma levels might not be a good candidate biomarker to evaluate depression improvement or be a predictor of response in patients treated with tDCS, as our results showed that BDNF increase was not necessary to induce clinical response. Finally, our findings do not support a relationship between BDNF and improvement of depression.

BDNF blood levels after electroconvulsive therapy in patients with mood disorders: a systematic review and meta-analysis

OBJECTIVES

To evaluate whether electroconvulsive therapy (ECT), a very effective non-pharmacological treatment for mood disorders, induces neurotrophic effects, indexed by the measurement of peripheral brain-derived neurotrophic factor (BDNF) levels.

METHODS

Systematic review and meta-analysis of clinical trials published in PubMed/Medline from the first date available to October 2013. We included studies measuring pre- and post-BDNF blood levels under ECT in patients with mood disorders in the acute depressive episode.

RESULTS

Eleven studies (n = 221 subjects) were eligible. These studies enrolled subjects with unipolar, bipolar and psychotic depression and varied regarding electrode placement (unipolar vs. bipolar) and previous use of pharmacotherapy. Nonetheless, BDNF significantly increased after ECT (Hedges' g pooled, random-effects model of 0.354; 95% CI = 0.162-0.546). The results were robust according to sensitivity analysis and Begg's funnel plot did not suggest publication bias. Meta-regression results did not show association of the outcome with any clinical and demographic variable, including depression improvement.

CONCLUSIONS

Our meta-analysis indicates that, similar to pharmacological interventions, peripheral BDNF increases after ECT treatment. The lack of correlation between BDNF increasing and depression improvement suggests that ECT induces neurotrophic effects regardless of clinical response in depression.

Serum BDNF concentrations as peripheral manifestations of depression: evidence from a systematic review and meta-analyses on 179 associations (N=9484)

Meta-analyses, published in 2008-2010, have confirmed abnormally low serum brain-derived neurotrophic factor (BDNF) concentrations in depressed patients and normalization of this by antidepressant treatment. These findings are believed to reflect peripheral manifestations of the neurotrophin hypothesis, which states that depression is secondary to an altered expression of BDNF in the brain. Since the publication of these meta-analyses, the field has seen a huge increase in studies on these topics. This motivated us to update the evidence on the aforementioned associations and, in addition, to compile the data on serum BDNF concentrations in relation to the symptom severity of depression. Using a manifold of data as compared with earlier meta-analyses, we find low serum BDNF concentrations in 2384 antidepressant-free depressed patients relative to 2982 healthy controls and to 1249 antidepressant-treated depressed patients (Cohen's d=-0.71 and -0.56, P-values <0.0000001). When publication bias is accounted for, these effect-sizes become substantially smaller (d=-0.47 and -0.34, respectively, P-values<0.0001). We detect between-study heterogeneity in outcomes for which only year of publication and sample size are significant moderators, with more recent papers and larger samples sizes in general being associated with smaller between-group differences. Finally, the aggregated data negate consistent associations between serum BDNF concentrations and the symptom severity of depression. Our findings corroborate the claim that altered serum BDNF concentrations are peripheral manifestations of depression. However, here we highlight that the evidence for this claim is slimmer as was initially thought and amidst a lot of noise.

Serial repetitive transcranial magnetic stimulation (rTMS) decreases BDNF serum levels in healthy male volunteers

Although repetitive transcranial magnetic stimulation (rTMS) is established in the treatment of depression, there is little knowledge about the underlying molecular mechanisms. In the last decade, the neurotrophic hypothesis of depression entailed a plethora of studies on the role of neurogenesis-associated factors in affective disorders and rTMS treatment. In the present study, we hypothesised a sham-controlled increase of peripheral brain-derived neurotrophic factor (BDNF) levels following serial rTMS stimulations in healthy individuals. We investigated the influence of a cycle of nine daily high-frequency (HF)-rTMS (25 Hz) stimulations over the left dorsolateral prefrontal cortex (DLPFC) on serum levels of BDNF in 44 young healthy male volunteers. BDNF serum concentrations were measured at baseline, on day 5 and on day 10. Overall, the statistical analyses showed that the active and sham group differed significantly regarding their responses of BDNF serum levels. Contrary to our expectations, there was a significant decrease of BDNF only during active treatment. Following the treatment period, significantly lower BDNF serum levels were quantified in the active group on day 10, when compared to the sham group. The participants' smoking status affected this effect. Our results suggest that serial HF-rTMS stimulations over the left DLPFC decrease serum BDNF levels in healthy male volunteers. This provides further evidence for an involvement of BDNF in clinical rTMS effects.

Therapeutic effects of repetitive transcranial magnetic stimulation in an animal model of Parkinson's disease

Repetitive transcranial magnetic stimulation (rTMS) is used to treat neurological diseases such as stroke and Parkinson's disease (PD). Although rTMS has been used clinically, its underlying therapeutic mechanism remains unclear. The objective of the present study was to clarify the neuroprotective effect and therapeutic mechanism of rTMS in an animal model of PD. Adult Sprague-Dawley rats were unilaterally injected with 6-hydroxydopamine (6-OHDA) into the right striatum. Rats with PD were then treated with rTMS (circular coil, 10 Hz, 20 min/day) daily for 4 weeks. Behavioral assessments such as amphetamine-induced rotational test and treadmill locomotion test were performed, and the dopaminergic (DA) neurons of substantia nigra pas compacta (SNc) and striatum were histologically examined. Expression of neurotrophic/growth factors was also investigated by multiplex ELISA, western blotting analysis and immunohistochemistry 4 weeks after rTMS application. Among the results, the number of amphetamine-induced rotations was significantly lower in the rTMS group than in the control group at 4 weeks post-treatment. Treadmill locomotion was also significantly improved in the rTMS-treated rats. Tyrosine hydroxylase-positive DA neurons and DA fibers in rTMS group rats were greater than those in untreated group in both ipsilateral SNc and striatum, respectively. The expression levels of brain-derived neurotrophic factor, glial cell line-derived neurotrophic factor, platelet-derived growth factor, and vascular endothelial growth factor were elevated in both the 6-OHDA-injected hemisphere and the SNc of the rTMS-treated rats. In conclusion, rTMS treatment improved motor functions and survival of DA neurons, suggesting that the neuroprotective effect of rTMS treatment might be induced by upregulation of neurotrophic/growth factors in the PD animal model.

Additional ECT increases BDNF-levels in patients suffering from major depressive disorders compared to patients treated with citalopram only

BACKGROUND

In patients suffering from major depressive disorders (MDD), improvements in MDD are related to increased activation of brain-derived neurotrophic factor (BDNF), an endogenous protein that facilitates neural functioning. To treat patients suffering from severe MDD, electroconvulsive therapy (ECT) is considered an efficacious and safe intervention, though the impact of ECT on plasma BDNF levels has thus far barely been investigated. The aim of the present study was therefore to assess plasma BDNF levels and depression of patients suffering from severe MDD treated with additional ECT compared to patients treated with citalopram only.

METHODS

A total of 40 patients (mean age: M = 31.45 years; females 30%) suffering from MDD and all receiving 40 mg/d citalopram were assigned either to a control group (N = 20), or to a target group (N = 20) undergoing additional 12 sessions of ECT. Plasma BDNF and symptom severity were assessed at baseline and four weeks later.

RESULTS

Plasma BDNF increased in both groups over time, though the significant Time by Group-interaction revealed an increase of 101% in the target group as compared to the control group. Symptom severity significantly decreased in both groups over time, though without being related to plasma BDNF levels.

CONCLUSIONS

Data from the present study suggest that, in patients suffering from severe MDD, treatment with citalopram was associated both with an increase of plasma BDNF and amelioration of depression, while additional ECT was associated with even higher plasma BDNF levels. Further studies should focus on possible cognitive and behavioral consequences.