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

Investigating Neuroplasticity Changes Reflected by BDNF Levels in Astrocyte-Derived Extracellular Vesicles in Patients with Depression

Purpose

To investigate the neuroplasticity hypothesis of depression by measuring brain-derived neurotrophic factor (BDNF) levels in plasma astrocyte-derived extracellular vesicles (ADEVs) and to evaluate their potential as biomarkers for depression compared with plasma BDNF levels.

Patients and Methods

Thirty-five patients with major depressive disorder (MDD) and 35 matched healthy controls (HCs) were enrolled. Plasma ADEVs were isolated using a combination of ultracentrifugation and immunoaffinity capture. Isolated ADEVs were validated using transmission electron microscopy, nanoparticle tracking analysis, and Western blotting. BDNF levels were quantified in both ADEVs and plasma. ALG-2-interacting protein X (Alix) and cluster of differentiation 81 (CD81) levels, two established extracellular vesicle markers, were measured in ADEVs.

Results

After false discovery rate correction, patients with MDD exhibited higher CD81 levels (P FDR = 0.040) and lower BDNF levels (P FDR = 0.043) in ADEVs than HCs at baseline. BDNF levels in ADEVs normalized to CD81 (P FDR = 0.002) and Alix (P FDR = 0.040) remained consistent with this finding. Following four weeks of selective serotonin reuptake inhibitor treatment (n=10), CD81 levels in ADEVs decreased (P FDR = 0.046), while BDNF levels normalized to CD81 increased (P FDR = 0.022). BDNF levels in ADEVs were more stable than in plasma. Exploratory analysis revealed no correlation between BDNF levels in ADEVs and plasma (ρ=0.117, P = 0.334).

Conclusion

This study provides human in vivo evidence supporting the neuroplasticity hypothesis of depression by demonstrating altered BDNF levels in ADEVs. ADEVs may be more suitable for developing biomarkers of depression than plasma-derived biomarkers.

The forensic aspects of suicide and neurotrophin factors: a research study

Introduction: Suicide represents a significant public health problem whose neurobiology is not yet fully understood. In many cases, suicidal behavior and psychiatric spectrum disorders are linked, in particular, to major depression. An emerging pathophysiological hypothesis underlines the role of neurotrophic factors, proteins involved in neurogenesis, in synaptic plasticity in response to stressors. Our research aims to evaluate the degree of expression of brain neurotrophic factor (BDNF) in brain areas involved in depressive disorder in suicidal subjects. Furthermore, we want to evaluate the expression of glial cell line-derived neurotrophic factor (GDNF) in suicidal subjects. Methods: We selected twenty confirmed cases of suicide among subjects with a clinical history of depressive pathology and possible psychopharmacological treatment, compared to ten controls of individuals who died of non-suicidal causes. For all selected cases and controls, immunohistochemical investigations were performed using a panel of antibodies against the BDNF and GDNF antigens on samples from the various brain areas. Results and discussion: The results show that BDNF was under-expressed in the cerebral parenchyma of subjects who died by suicide compared to controls, while there was an overexpression of GDNF in suicide victims, these data could be useful for a clinical application as potential markers for suicidal risk, to assess the severity of depression and development of specific pharmacological therapies for depression.

Sex-controlled differences in sertraline and citalopram efficacies in major depressive disorder: a randomized, double-blind trial

To investigate the response to antidepressants while controlling for sex, which has been controversial, 92 outpatient males and females with major depressive disorder were assigned to sertraline (100 mg/day) or citalopram (40 mg/day) in two strata and were assessed using Hamilton depression rating scale (HDRS) scores and brain-derived neurotrophic factor (BDNF), interleukin (IL)-6 and cortisol serum levels in this 8-week, randomized, parallel-group, double-blind clinical trial. Data of 40 sertraline and 40 citalopram recipients with equal representation of males and females assigned to each medication were analyzed, while their baseline characteristics were not statistically different (P > 0.05). There were no significant differences between sertraline and citalopram recipients in outcome changes (P > 0.05), all of which indicated improvement, but a significant time-treatment-sex interaction effect in BDNF levels was observed (P = 0.035). Regarding this, subgroup analyses illustrated a significantly greater increase in male BDNF levels following sertraline treatment (P = 0.020) with a moderate to large effect size (Cohen's d = 0.76 and ). Significant associations were observed between percentage changes in IL-6 levels and BDNF levels in sertraline recipients (P = 0.033) and HDRS scores in citalopram recipients (P < 0.001). Sex was an effect modifier in BDNF alterations following sertraline and citalopram administration. Further large-scale, high-quality, long-term studies are recommended.

Relationship between inflammatory markers in human olfactory neural progenitor cells and antidepressant response

Response to antidepressants is related to hippocampal neurogenesis integrity, a process mediated by neurotrophins, such as Brain Derived Neurotrophic Factor (BDNF). In turn, pro-inflammatory state appears to reduce neurogenesis, and has been associated with refractory depressive states. We propose to analyze the human neural progenitor cells derived from the olfactory epithelium (HNPCs-OE) as an indicator of neurogenesis in humans. Therefore, we compared the number and content of HNPCs-OE in depressed patients taking antidepressants, according to response to treatment. Twenty depressed patients were followed during eight weeks after antidepressant treatment was prescribed. At the end evaluation they were divided in two groups according to Hamilton depression rating scale (HDRS) scores: responders and non-responders. We compared the number and components of HNPCs-OE between groups and observed an elevation of interleukine-8 in those patients who do not achieve response to treatment, BDNF levels were no related to antidepressant response.

Neuroinflammation, memory, and depression: new approaches to hippocampal neurogenesis

As one of most common and severe mental disorders, major depressive disorder (MDD) significantly increases the risks of premature death and other medical conditions for patients. Neuroinflammation is the abnormal immune response in the brain, and its correlation with MDD is receiving increasing attention. Neuroinflammation has been reported to be involved in MDD through distinct neurobiological mechanisms, among which the dysregulation of neurogenesis in the dentate gyrus (DG) of the hippocampus (HPC) is receiving increasing attention. The DG of the hippocampus is one of two niches for neurogenesis in the adult mammalian brain, and neurotrophic factors are fundamental regulators of this neurogenesis process. The reported cell types involved in mediating neuroinflammation include microglia, astrocytes, oligodendrocytes, meningeal leukocytes, and peripheral immune cells which selectively penetrate the blood-brain barrier and infiltrate into inflammatory regions. This review summarizes the functions of the hippocampus affected by neuroinflammation during MDD progression and the corresponding influences on the memory of MDD patients and model animals.

Effects of Antidepressant Medication on Brain-derived Neurotrophic Factor Concentration and Neuroplasticity in Depression: A Review of Preclinical and Clinical Studies

Depression is the most prevalent and debilitating disease with great impact on societies. Evidence suggests Brain-Derived Neurotrophic Factor (BDNF) plays an important role in pathophysiology of depression. Depression is associated with altered synaptic plasticity and neurogenesis. BDNF is the main regulatory protein that affects neuronal plasticity in the hippocampus. A wealth of evidence shows decreased levels of BDNF in depressed patients. Important literature demonstrated that BDNF-TrkB signaling plays a key role in therapeutic action of antidepressants. Numerous studies have reported anti-depressant effects on serum/plasma levels of BDNF and neuroplasticity which may be related to improvement of depressive symptoms. Most of the evidence suggested increased levels of BDNF after antidepressant treatment. This review will summarize recent findings on the association between BDNF, neuroplasticity, and antidepressant response in depression. Also, we will review recent studies that evaluate the association between postpartum depression as a subtype of depression and BDNF levels in postpartum women.

Gonadal hormone trigger the dynamic microglial alterations through Traf6/TAK1 axis that correlate with depressive behaviors

Gonadal hormone deficiency is associated with the development of depression, but what mediates this association is unclear. To test the possibility that it reflects neuroimmune and neuroinflammatory processes, we analyzed how gonadal hormone deficiency and replacement affect microglial activation and inflammatory response during the development of depressive symptomatology in gonadectomized male mice. Testosterone level and the ratio of testosterone to estradiol in the serum and brain tissue of mice exposed to 3-35 days of chronic unpredictable stress were much lower than in control animals. Gonadal hormone sustained deficiency in gonadectomized mice and subsequent led to acute inflammation at day 7 following castration. Activating microglia in mice exposed to 7 days of castration subsequently suppressed the proliferation of microglia, such that their numbers in hippocampus and cortex were lower than the numbers in sham-operated mice after 30 days of castration. Here, we showed that gonadal hormone deficiency induces Traf6-mediated microglia activation, a type of inflammatory mediator. Microglia treated in this way for long time showed down-regulation of activation markers, abnormal morphology and depressive-like behaviors. Restoration and maintenance of a fixed ratio of testosterone to estradiol significantly suppressed microglial activation, neuronal necroptosis, dramatically inducing hippocampal neurogenesis and reducing depressive behaviors via the suppression of Traf6/TAK1 pathway. These findings suggest that activated or immunoreactive microglia contribute to gonadal hormone deficiency-induced depression, as well as testosterone and estradiol exert synergistic anti-depressant effects via suppressing microglial activaton in gonadectomized male mice, possibly through Traf6 signaling.

Effects of Antidepressant Treatment on Neurotrophic Factors (BDNF and IGF-1) in Patients with Major Depressive Disorder (MDD)

Major depressive disorder (MDD) remains the subject of ongoing research as a multifactorial disease and a serious public health problem. There is a growing body of literature focusing on the role of neurotrophic factors in pathophysiology of MDD. A neurotrophic hypothesis of depression proposes that abnormalities of neurotrophins serum levels lead to neuronal atrophy and decreased neurogenesis, resulting in mood disorders. Consequently, in accordance with recent findings, antidepressant treatment modifies the serum levels of neurotrophins and thus leads to a clinical improvement of MDD. The purpose of this review is to summarize the available data on the effects of various antidepressants on serum levels of neurotrophins such as brain-derived neurotrophic factor (BDNF) and insulin-like growth factor (IGF-1). In addition, the authors discuss their role as prognostic factors for treatment response in MDD. A literature search was performed using the PubMed database. Following the inclusion and exclusion criteria, nine original articles and three meta-analyses were selected. The vast majority of studies have confirmed the effect of antidepressants on BDNF levels. Research on IGF-1 is limited and insufficient to describe the correlation between different antidepressant drugs and factor serum levels; however, four studies indicated a decrease in IGF-1 after treatment. Preliminary data suggest BDNF as a promising predictor of treatment response in MDD patients. The role of IGF-1 needs further investigation.

Effects of tDCS on neuroplasticity and inflammatory biomarkers in bipolar depression: Results from a sham-controlled study

OBJECTIVES

We investigated the role of peripheral biomarkers associated with neuroplasticity and immune-inflammatory processes on the effects of transcranial direct current stimulation (tDCS), a safe, affordable, and portable non-invasive neuromodulatory treatment, in bipolar depression.

METHODS

This is an exploratory analysis using a dataset from the sham-controlled study the Bipolar Depression Electrical Treatment Trial (BETTER)(clinicaltrials.govNCT02152878). Participants were 52 adults with type I or II bipolar disorder in a moderate-to-severe depressive episode, randomized to 12 bifrontal active or sham tDCS sessions over a 6-week treatment course. Plasma levels of brain derived neurotrophic factor (BDNF), glial cell derived neurotrophic factor (GDNF), interleukins (IL) 2, 4, 6, 8, 10, 18, 33, 1β, 12p70, 17a, interferon gamma (IFN), tumor necrosis factor alpha (TNF) and its soluble receptors 1 and 2, ST2, and KLOTHO were investigated at baseline and endpoint. We performed analyses unadjusted for multiple testing to evaluate whether baseline biomarkers were predictive for depression improvement and changed during treatment using linear regression models.

RESULTS

A time x group interaction (Cohen's d: -1.16, 95% CI = -1.96 to -0.3, p = .005) was found for IL-8, with greater reductions after active tDCS. Higher baseline IL-6 plasma levels was associated with symptomatic improvement after tDCS (F_(1,43) = 5.43; p = .025). Other associations were not significant.

CONCLUSIONS

Our exploratory findings suggested that IL-6 is a potential predictor of tDCS response and IL-8 might decrease after tDCS; although confirmatory studies are warranted due to the multiplicity of comparisons.

Value of peripheral neurotrophin levels for the diagnosis of depression and response to treatment: A systematic review and meta-analysis

The neurotrophin hypothesis indicates that neurotrophic factors are important for the pathophysiology of major depressive disorder (MDD), with alterations in peripheral neurotrophin levels having potential clinical application for MDD. The present meta-analysis aimed to investigate the diagnostic value for MDD of peripheral neurotrophin levels in cross-sectional studies and the association between peripheral neurotrophin levels and the response to antidepressant treatment in longitudinal studies. Published studies in the PubMed and Web of Science databases were systematically searched up to February 2020. The search terms included depressive disorder, neurotrophic factor, serum/plasma and their synonyms. Human studies reporting on BDNF, GDNF, IGF-2, VEGF, NGF, FGF-2, and S100B levels in MDD patients were included. Data comparing MDD patients and healthy controls, and/or between responders and non-responders before and after antidepressant treatment were extracted. A random effects model was used to calculate standardized mean differences. A total of 177 original studies were identified, including 139 cross-sectional and 38 longitudinal studies. Significantly reduced BDNF and NGF levels and significantly elevated IGF-1, VEGF, and S100B levels were reported in MDD patients compared with healthy controls, while GDNF and FGF-2 levels were not significantly different. Furthermore, compared with non-responders, S100B levels at baseline and BDNF levels following treatment were significantly elevated in responders. In addition, there was a significantly elevated level of VEGF after treatment in responders only. In conclusions, alterations in peripheral neurotrophins levels were strongly associated with the biology and the treatment response of MDD. Further investigations are required to examine potential sources of heterogeneity.

Efficacy and acceptability of transcranial direct current stimulation (tDCS) for major depressive disorder: An individual patient data meta-analysis

We evaluated the efficacy and acceptability of transcranial direct current stimulation (tDCS) for treating acute depressive episodes using individual patient data that provide more precise estimates than aggregate data meta-analysis. A systematic review of placebo-controlled trials on tDCS as only intervention was conducted until December-2018. Data from each study was collated to estimate odds ratio (OR) and number needed to treat (NNT) of response and remission, and depression improvement. Endpoints were pre-determined. Nine eligible studies (572 participants), presenting moderate/high certainty of evidence, were included. Active tDCS was significantly superior to sham for response (30.9% vs. 18.9% respectively; OR = 1.96, 95%CI [1.30-2.95], NNT = 9), remission (19.9% vs. 11.7%, OR = 1.94 [1.19-3.16], NNT = 13) and depression improvement (effect size of β = 0.31, [0.15-0.47]). Moreover, continuous clinical improvement was observed even after the end of acute tDCS treatment. There were no differences in all-cause discontinuation rates and no predictors of response were identified. To conclude, active tDCS was statistically superior to sham in all outcomes, although its clinical effects were moderate.

Precision non-implantable neuromodulation therapies: a perspective for the depressed brain

Current first-line treatments for major depressive disorder (MDD) include pharmacotherapy and cognitive-behavioral therapy. However, one-third of depressed patients do not achieve remission after multiple medication trials, and psychotherapy can be costly and time-consuming. Although non-implantable neuromodulation (NIN) techniques such as transcranial magnetic stimulation, transcranial direct current stimulation, electroconvulsive therapy, and magnetic seizure therapy are gaining momentum for treating MDD, the efficacy of non-convulsive techniques is still modest, whereas use of convulsive modalities is limited by their cognitive side effects. In this context, we propose that NIN techniques could benefit from a precision-oriented approach. In this review, we discuss the challenges and opportunities in implementing such a framework, focusing on enhancing NIN effects via a combination of individualized cognitive interventions, using closed-loop approaches, identifying multimodal biomarkers, using computer electric field modeling to guide targeting and quantify dosage, and using machine learning algorithms to integrate data collected at multiple biological levels and identify clinical responders. Though promising, this framework is currently limited, as previous studies have employed small samples and did not sufficiently explore pathophysiological mechanisms associated with NIN response and side effects. Moreover, cost-effectiveness analyses have not been performed. Nevertheless, further advancements in clinical trials of NIN could shift the field toward a more “precision-oriented” practice.

Association of BDNF, HTR2A, TPH1, SLC6A4, and COMT polymorphisms with tDCS and escitalopram efficacy: ancillary analysis of a double-blind, placebo-controlled trial

OBJECTIVE

We investigated whether single nucleotide polymorphisms (SNPs) associated with neuroplasticity and activity of monoamine neurotransmitters, such as the brain-derived neurotrophic factor (BDNF, rs6265), the serotonin transporter (SLC6A4, rs25531), the tryptophan hydroxylase 1 (TPH1, rs1800532), the 5-hydroxytryptamine receptor 2A (HTR2A, rs6311, rs6313, rs7997012), and the catechol-O-methyltransferase (COMT, rs4680) genes, are associated with efficacy of transcranial direct current stimulation (tDCS) in major depression.

METHODS

Data from the Escitalopram vs. Electrical Current Therapy for Treating Depression Clinical Study (ELECT-TDCS) were used. Participants were antidepressant-free at baseline and presented with an acute, moderate-to-severe unipolar depressive episode. They were randomized to receive escitalopram/tDCS-sham (n=75), tDCS/placebo-pill (n=75), or placebo-pill/sham-tDCS (n=45). General linear models assessed the interaction between treatment group and allele-wise carriers. Additional analyses were performed for each group and each genotype separately.

RESULTS

Pairwise group comparisons (tDCS vs. placebo, tDCS vs. escitalopram, and escitalopram vs. placebo) did not identify alleles associated with depression improvement. In addition, exploratory analyses also did not identify any SNP unequivocally associated with improvement of depression in any treatment group.

CONCLUSION

Larger, combined datasets are necessary to identify candidate genes for tDCS response.

A review of transcranial direct current stimulation (tDCS) for the individualized treatment of depressive symptoms

Transcranial direct current stimulation (tDCS) is a low intensity neuromodulation technique shown to elicit therapeutic effects in a number of neuropsychological conditions. Independent randomized sham-controlled trials and meta- and mega-analyses demonstrate that tDCS targeted to the left dorsolateral prefrontal cortex can produce a clinically meaningful response in patients with major depressive disorder (MDD), but effects are small to moderate in size. However, the heterogeneous presentation, and the neurobiology underlying particular features of depression suggest clinical outcomes might benefit from empirically informed patient selection. In this review, we summarize the status of tDCS research in MDD with focus on the clinical, biological, and intrinsic and extrinsic factors shown to enhance or predict antidepressant response. We also discuss research strategies for optimizing tDCS to improve patient-specific clinical outcomes. TDCS appears suited for both bipolar and unipolar depression, but is less effective in treatment resistant depression. TDCS may also better target core aspects of depressed mood over vegetative symptoms, while pretreatment patient characteristics might inform subsequent response. Peripheral blood markers of gene and immune system function have not yet proven useful as predictors or correlates of tDCS response. Though further research is needed, several lines of evidence suggest that tDCS administered in combination with pharmacological and cognitive behavioral interventions can improve outcomes. Tailoring stimulation to the functional and structural anatomy and/or connectivity of individual patients can maximize physiological response in targeted networks, which in turn could translate to therapeutic benefits.

Brain-Derived Neurotrophic Factor in Brain Disorders: Focus on Neuroinflammation

Brain-derived neurotrophic factor (BDNF) is one of the most studied neurotrophins in the healthy and diseased brain. As a result, there is a large body of evidence that associates BDNF with neuronal maintenance, neuronal survival, plasticity, and neurotransmitter regulation. Patients with psychiatric and neurodegenerative disorders often have reduced BDNF concentrations in their blood and brain. A current hypothesis suggests that these abnormal BDNF levels might be due to the chronic inflammatory state of the brain in certain disorders, as neuroinflammation is known to affect several BDNF-related signaling pathways. Activation of glia cells can induce an increase in the levels of pro- and antiinflammatory cytokines and reactive oxygen species, which can lead to the modulation of neuronal function and neurotoxicity observed in several brain pathologies. Understanding how neuroinflammation is involved in disorders of the brain, especially in the disease onset and progression, can be crucial for the development of new strategies of treatment. Despite the increasing evidence for the involvement of BDNF and neuroinflammation in brain disorders, there is scarce evidence that addresses the interaction between the neurotrophin and neuroinflammation in psychiatric and neurodegenerative diseases. This review focuses on the effect of acute and chronic inflammation on BDNF levels in the most common psychiatric and neurodegenerative disorders and aims to shed some light on the possible biological mechanisms that may influence this effect. In addition, this review will address the effect of behavior and pharmacological interventions on BDNF levels in these disorders.

Plasma biomarkers in a placebo-controlled trial comparing tDCS and escitalopram efficacy in major depression

BACKGROUND

Transcranial direct current stimulation (tDCS) holds promise as a therapeutic intervention for major depressive disorder (MDD). A more precise understanding of its underlying mechanisms may aid in the identification of subsets of patients responsive to tDCS within the context of precision psychiatry.

OBJECTIVE

In this ancillary investigation of the Escitalopram vs. Electrical Current Therapy for Treating Depression Clinical Study (ELECT-TDCS), we investigated whether plasma levels of several cytokines and neurotrophic factors associated with major depression or antidepressant response predicted tDCS effects.

METHODS

We examined, in 236 patients at 3 timepoints during a 10-week treatment course, plasma levels of nerve growth factor (NGF), brain-derived (BDNF), glial-cell line derived neurotrophic factor (GDNF), the interleukins (IL) IL-1ß, IL-6, IL-8, IL-10, IL-12p70, IL-18, IL-33, tumor necrosis factor-alpha (TNF-alpha), and its soluble receptors sTNFr1 and sTNFr2. General linear models and mixed-models analyses of variance were used to respectively assess whether plasma levels of these molecules (1) predicted tDCS antidepressant improvement and (2) changed over time.

RESULTS

After correction for multiple comparisons (false discovery rate method), NGF baseline levels predicted early depression improvement for tDCS vs. escitalopram, whilst other biomarkers did not significantly predict treatment improvement. The levels of IL12p70, IL10, IL-1ß, IL-8 and sTNFr1 decreased over time, regardless of allocation group and clinical response.

CONCLUSION

In general, peripheral biomarkers were not associated with the outcome. The post-hoc finding of baseline NGF levels predicting early depression improvement for tDCS should be explored in further studies.

Peripheral biomarkers of major depression and antidepressant treatment response: Current knowledge and future outlooks

BACKGROUND

In recent years, we have accomplished a deeper understanding about the pathophysiology of major depressive disorder (MDD). Nevertheless, this improved comprehension has not translated to improved treatment outcome, as identification of specific biologic markers of disease may still be crucial to facilitate a more rapid, successful treatment. Ongoing research explores the importance of screening biomarkers using neuroimaging, neurophysiology, genomics, proteomics, and metabolomics measures.

RESULTS

In the present review, we highlight the biomarkers that are differentially expressed in MDD and treatment response and place a particular emphasis on the most recent progress in advancing technology which will continue the search for blood-based biomarkers.

LIMITATIONS

Due to space constraints, we are unable to detail all biomarker platforms, such as neurophysiological and neuroimaging markers, although their contributions are certainly applicable to a biomarker review and valuable to the field.

CONCLUSIONS

Although the search for reliable biomarkers of depression and/or treatment outcome is ongoing, the rapidly-expanding field of research along with promising new technologies may provide the foundation for identifying key factors which will ultimately help direct patients toward a quicker and more effective treatment for MDD.

Transcranial Direct Current Stimulation (tDCS): A Promising Treatment for Major Depressive Disorder?

Background: Transcranial direct current stimulation (tDCS) opens new perspectives in the treatment of major depressive disorder (MDD), because of its ability to modulate cortical excitability and induce long-lasting effects. The aim of this review is to summarize the current status of knowledge regarding tDCS application in MDD. Methods: In this review, we searched for articles published in PubMed/MEDLINE from the earliest available date to February 2018 that explored clinical and cognitive effects of tDCS in MDD. Results: Despite differences in design and stimulation parameters, the examined studies indicated beneficial effects of tDCS for MDD. These preliminary results, the non-invasiveness of tDCS, and its good tolerability support the need for further research on this technique. Conclusions: tDCS constitutes a promising therapeutic alternative for patients with MDD, but its place in the therapeutic armamentarium remains to be determined.

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.

Transcranial direct current stimulation of 20- and 30-minutes combined with sertraline for the treatment of depression

BACKGROUND

Transcranial direct current stimulation (tDCS) can be an effective treatment for depression, however, the duration of the stimulation session, among other parameters, needs to be optimized.

METHODS

69 mild to moderately depressed patients (age 37.6±10.5years, 19 men) were randomized into three groups - 30-, 20-minute or sham tDCS. 10 daily sessions of anodal/sham tDCS of the left DLPFC (0.5mA; electrode 3,5×7cm) combined with 50mg/day of sertraline were performed. Mood, cognition and BDNF level were assessed before and after the treatment.

RESULTS

A significant difference between groups was observed in the percent change of the Hamilton Depression Rating Scale (F(2, 66)=10.1; p<0.001). Sham group (43.4%±18.1) had a smaller improvement compared to the 30-minute (63.8%±13.4; 95% CI: 11.23-29.44; p=0.00003) and 20-minute group (53.2%±15.3; 95% CI: 0.21-19.26; p=0.045). 30-minute group had significantly greater percent improvement than 20-minute group (95% CI: 1.74-19.46; p=0.02). Responders constituted 89%, 68%, and 50% and remitters - 70%, 27%, and 35% in the 30-, 20-minute and sham groups, respectively. A significant difference in the number of responders was observed between 30-minute vs. sham group (odds ratio=8; 95% CI, 2.59-24.69; p=0.001), in remission rate - between 30-minute vs. sham (odds ratio=4.40; 95% CI, 2.02-9.57; p=0.02) and vs. 20-minute (odds ratio=6.33; 95% CI, 2.85-14.10; p=0.003) groups. Two hypomania cases and one case of blood pressure elevation were detected in the 20-minute group. Among neuropsychological tests, only the change in Digit Span Backwards test showed a significant interaction between groups (TIME*GROUP; F(2, 65)=6,6, p=0.002); a greater improvement was observed in both active groups compared to sham (p<0.05). The change in BDNF level after the treatment did not show the significant difference between groups.

CONCLUSIONS

tDCS of 20- or 30-minutes combined with sertraline are efficient for the treatment of mild and moderate depression; the effect of 30min stimulation exceeds the one obtained from 20min.

The Comparison of Effectiveness of Various Potential Predictors of Response to Treatment With SSRIs in Patients With Depressive Disorder

The substantial non-response rate in depressive patients indicates a continuing need to identify predictors of treatment outcome. The aim of this 6-week, open-label study was (1) to compare the efficacy of a priori defined predictors: ≥20% reduction in MADRS score at week 1, ≥20% reduction in MADRS score at week 2 (RM ≥ 20% W2), decrease of cordance (RC), and increase of serum and plasma level of brain-derived neurotrophic factor at week 1; and (2) to assess whether their combination yields higher efficacy in the prediction of response to selective serotonin re-uptake inhibitors (SSRIs) than when used singly. Twenty-one patients (55%) achieved a response to SSRIs. The RM ≥20% W2 (areas under curve-AUC = 0.83) showed better predictive efficacy compared to all other predictors with the exception of RC. The identified combined model (RM ≥ 20% W2 + RC), which predicted response with an 84% accuracy (AUC = 0.92), may be a useful tool in the prediction of response to SSRIs.

Meta-analyses of comparative efficacy of antidepressant medications on peripheral BDNF concentration in patients with depression

Background

Brain derived neurotrophic factor (BDNF) is one of the most important regulatory proteins in the pathophysiology of major depressive disorder (MDD). Increasing numbers of studies have reported the relationship between serum/plasma BDNF and antidepressants (ADs). However, the potential effects of several classes of antidepressants on BDNF concentrations are not well known. Hence, our meta-analyses aims to review the effects of differential antidepressant drugs on peripheral BDNF levels in MDD and make some recommendations for future research.

Methods

Electronic databases including PubMed, EMBASE, the Cochrane Library, Web of Science, and PsycINFO were searched from 1980 to June 2016. The change in BDNF levels were compared between baseline and post-antidepressants treatment by use of the standardized mean difference (SMD) with 95% confidence intervals (CIs). All statistical tests were two-sided.

Results

We identified 20 eligible trials of antidepressants treatments for BDNF in MDD. The overall effect size for all drug classes showed that BDNF levels were elevated following a course of antidepressants use. For between-study heterogeneity by stratification analyses, we detect that length of treatment and blood samples are significant effect modifiers for BDNF levels during antidepressants treatment. While both SSRIs and SNRIs could increase the BDNF levels after a period of antidepressant medication treatment, sertraline was superior to other three drugs (venlafaxine, paroxetine or escitalopram) in the early increase of BDNF concentrations with SMD 0.53(95% CI = 0.13–0.93; P = 0.009).

Conclusions

There is some evidence that treatment of antidepressants appears to be effective in the increase of peripheral BDNF levels. More robust evidence indicates that different types of antidepressants appear to induce differential effects on the BDNF levels. Since sertraline makes a particular effect on BDNF concentration within a short amount of time, there is potential value in exploring its relationship with BDNF and its pharmacological mechanism concerning peripheral blood BDNF. Further confirmatory trials are required for both observations.

Investigational drugs for treating major depressive disorder

INTRODUCTION

Treatment of patients suffering from major depression could be highly challenging for psychiatrists. Intractability as well as relapse is commonly seen among these patients, leading to functional impairment and poor quality of life. The present review discusses some of the novel investigational drugs that are under pre-clinical or clinical phases in the treatment of major depression. Areas covered: Molecules belonging to different classes such as triple reuptake inhibitors, opioid receptors, ionotropic and metabotropic glutamate receptors, and neurotrophin in the treatment of major depression are covered in this article. Expert opinion: Although the historical discovery of earlier antidepressant molecules (iproniazid and imipramine) is through serendipitous discovery, the present research focuses on discovering novel molecules based on our current pathophysiological knowledge of the disease condition. The fast-acting antidepressant property of N-methyl-d-aspartate (NMDA) receptor molecules, including ketamine is an exciting area of research. Other drug molecules such as amitifadine (triple reuptake inhibitor), ALKS-5461 (kappa receptor antagonist and mu opioidergic receptor agonist), rapastinel (NMDA glutamatergic receptor modulator) are under Phase-III clinical trials and could be approved in the near future for the treatment of major depression.

Transcranial Direct Current Stimulation Use in the Treatment of Neuropsychiatric Disorders: A Brief Review

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that has grown in popularity over the past two decades as an alternative treatment option for various neuropsychiatric disorders. tDCS modulates cortical excitability through the application of a weak direct current to the scalp via electrodes placed over cortical regions of interest. It has been shown to be a promising and relatively safe treatment tool with few adverse events. In this article, we will briefly review the efficacy of tDCS in depression, bipolar disorder, schizophrenia, and obsessive-compulsive disorder. We will also discuss biomarkers of tDCS efficacy in depression, as it is the most studied neuropsychiatric disorder using tDCS application. We will then offer suggestions for future directions. Although efficacy results show promise, more studies with larger samples and longer treatment periods are needed to better understand the benefits of using tDCS as an alternative treatment option for neuropsychiatric disorders.

A prospective, longitudinal study of platelet serotonin and plasma brain-derived neurotrophic factor concentrations in major depression: effects of vortioxetine treatment

BACKGROUND

Various antidepressants occupy brain serotonin transporter (SERT), decrease platelet serotonin (5-HT) concentration, and normalize reduced plasma brain-derived neurotrophic factor (BDNF) concentrations in depressed patients. Vortioxetine is a recently introduced antidepressant with a multimodal mechanism of action. In addition to SERT inhibition, vortioxetine acts via different 5-HT receptors. To further elucidate its mechanism of action, we have investigated the effects of vortioxetine on platelet 5-HT and plasma BDNF concentrations in patients with major depression.

METHODS

Platelet 5-HT and plasma BDNF concentrations were determined in 44 healthy subjects at baseline and in 44 depressed patients before and after 4 weeks of treatment with vortioxetine (5-15 mg daily). Platelet 5-HT concentration was determined using the ortho-phthalaldehyde-enhanced fluorometric method, and plasma BDNF concentration using a commercial enzyme-linked immunosorbent assay (Quantikine ELISA, R&D Systems).

RESULTS

At baseline, platelet 5-HT concentrations did not differ between depressed and control subjects, but plasma BDNF values were lower (p = 0.011; ω = 0.80) in depressed patients than in healthy subjects. Vortioxetine treatment significantly (p < 0.0001; ω = 0.80) decreased platelet 5-HT concentration and significantly (p = 0.004; ω = 0.80) increased plasma BDNF concentration in depressed patients compared to their baseline values. Age, gender, and smoking were not significantly associated with platelet 5-HT and plasma BDNF concentrations.

CONCLUSION

Despite a novel mechanism of action, vortioxetine shares some common effects with other antidepressants. This study is the first to show that, in addition to clinical improvement, 4 weeks of treatment with vortioxetine (5-15 mg daily), decreased platelet 5-HT and increased plasma BDNF concentrations in depressed patients.

Seeking an objective diagnosis of depression

Major depressive disorder (MDD: unipolar depression) is widely distributed in the USA and world-wide populations and it is one of the leading causes of disability in both adolescents and adults. Traditional diagnostic approaches for MDD are based on patient interviews, which provide a subjective assessment of clinical symptoms which are frequently shared with other maladies. Reliance upon clinical assessments and patient interviews for diagnosing MDD is frequently associated with misdiagnosis and suboptimal treatment outcomes. As such, there is increasing interest in the identification of objective methods for the diagnosis of depression. Newer technologies from genomics, transcriptomics, proteomics, metabolomics and imaging are technically sophisticated and objective but their application to diagnostic tests in psychiatry is still emerging. This brief overview evaluates the technical basis for these technologies and discusses how the extension of their clinical performance can lead to an objective diagnosis of MDD.

p11 mediates the BDNF-protective effects in dendritic outgrowth and spine formation in B27-deprived primary hippocampal cells

BACKGROUND

p11 (S100A10) is a key regulator of depression-like behaviors and antidepressant drug response in rodent models. Recent studies suggest that p11 mediates the behavioral antidepressant action of brain-derived neurotrophic factor (BDNF) in rodents. BDNF improves neural plasticity, which is linked to the cellular actions of antidepressant drugs. In the present study, we investigated whether p11 regulated BDNF action on neural plasticity in vitro.

METHODS

We generated primary hippocampal cultures. p11 expression, total dendritic length, and spine density were investigated under toxic conditions induced by B27 deprivation, which causes hippocampal cell death.

RESULTS

B27 deprivation significantly decreased p11 expression. Treatment with BDNF significantly prevented the B27 deprivation-induced decrease in p11 levels in a concentration-dependent manner, whereas these concentrations had no effect on control cultures. B27 deprivation significantly reduced the total length of hippocampal dendrites and spine density. BDNF increased the total dendritic length and spine density in conditions with or without B27. Furthermore, p11 knockdown through small interfering RNA (siRNA) transfection blocked these effects. The overexpression of p11 in B27-deprived cells increased the total dendritic length and spine density, and treatment with BDNF potentiated these effects.

LIMITATION

This study should be confirmed in animal models of depression.

CONCLUSION

Taken together, our data suggest that BDNF-induced improvement in neural plasticity may depend on the regulation of p11 in hippocampal cells with B27 deprivation. These results provide evidence to strengthen the theoretical basis of a role for p11 in BDNF-induced antidepressant action.

Plasma levels of soluble TNF receptors 1 and 2 after tDCS and sertraline treatment in major depression: Results from the SELECT-TDCS trial

BACKGROUND

The cytokine hypothesis of depression postulates that the pathophysiology of this illness incorporates an increased production of pro-inflammatory cytokines, which leads to an over-activation of the hypothalamic-pituitary-adrenal axis as well as monoaminergic disturbances. Nevertheless, it remains unclear whether the amelioration of depressive symptoms could decrease cytokine levels. Notwithstanding antidepressant drug therapy might exert anti-inflammatory effects, the effects of non-invasive neuromodulatory approaches like transcranial direct current stimulation (tDCS) on pro-inflammatory cytokine networks are largely unknown.

METHODS

We evaluated, in the Sertraline vs. Electric Current Therapy for Treating Depression Clinical Study (SELECT-TDCS) trial, whether the plasma levels of the soluble TNF receptors 1 and 2 (sTNFRs) changed after antidepressant treatment in a sample of 73 antidepressant-free patients with unipolar depressive disorder in an episode of at least moderate intensity.

RESULTS

Although both tDCS and sertraline exerted antidepressant effects, the plasma levels of sTNFRs did not change over time regardless of the intervention and clinical response. Also, baseline sTNFRs levels did not predict antidepressant response.

LIMITATIONS

Our negative findings could be a type II error, as this trial did not use an equivalence design.

CONCLUSIONS

To conclude, in this novel placebo-controlled trial prospectively evaluating the changes of sTNFRs in depressed patients, we found that these molecules are not surrogate biomarkers of treatment response of tDCS, whose antidepressant effects occurred regardless of normalization of immunological activity.

The Escitalopram versus Electric Current Therapy for Treating Depression Clinical Study (ELECT-TDCS): rationale and study design of a non-inferiority, triple-arm, placebo-controlled clinical trial

CONTEXT AND OBJECTIVE

Major depressive disorder (MDD) is a common psychiatric condition, mostly treated with antidepressant drugs, which are limited due to refractoriness and adverse effects. We describe the study rationale and design of ELECT-TDCS (Escitalopram versus Electric Current Therapy for Treating Depression Clinical Study), which is investigating a non-pharmacological treatment known as transcranial direct current stimulation (tDCS).

DESIGN AND SETTING

Phase-III, randomized, non-inferiority, triple-arm, placebo-controlled study, ongoing in São Paulo, Brazil.

METHODS

ELECT-TDCS compares the efficacy of active tDCS/placebo pill, sham tDCS/escitalopram 20 mg/day and sham tDCS/placebo pill, for ten weeks, randomizing 240 patients in a 3:3:2 ratio, respectively. Our primary aim is to show that tDCS is not inferior to escitalopram with a non-inferiority margin of at least 50% of the escitalopram effect, in relation to placebo. As secondary aims, we investigate several biomarkers such as genetic polymorphisms, neurotrophin serum markers, motor cortical excitability, heart rate variability and neuroimaging.

RESULTS

Proving that tDCS is similarly effective to antidepressants would have a tremendous impact on clinical psychiatry, since tDCS is virtually devoid of adverse effects. Its ease of use, portability and low price are further compelling characteristics for its use in primary and secondary healthcare. Multimodal investigation of biomarkers will also contribute towards understanding the antidepressant mechanisms of action of tDCS.

CONCLUSION

Our results have the potential to introduce a novel technique to the therapeutic arsenal of treatments for depression.

Combined neuromodulatory interventions in acute experimental pain: assessment of melatonin and non-invasive brain stimulation

Transcranial direct current stimulation (tDCS) and melatonin can effectively treat pain. Given their potentially complementary mechanisms of action, their combination could have a synergistic effect. Thus, we tested the hypothesis that compared to the control condition and melatonin alone, tDCS combined with melatonin would have a greater effect on pain modulatory effect, as assessed by quantitative sensory testing (QST) and by the pain level during the Conditioned Pain Modulation (CPM)-task. Furthermore, the combined treatment would have a greater cortical excitability effect as indicated by the transcranial magnetic stimulation (TMS) and on the serum BDNF level. Healthy males (n = 20), (aged 18-40 years), in a blinded, placebo-controlled, crossover, clinical trial, were randomized into three groups: sublingual melatonin (0.25 mg/kg) + a-tDCS, melatonin (0.25 mg/kg) + sham-(s)-tDCS, or sublingual placebo+sham-(s)-tDCS. Anodal stimulation (2 mA, 20 min) was applied over the primary motor cortex. There was a significant difference in the heat pain threshold (°C) for melatonin+a-tDCS vs. placebo+s-tDCS (mean difference: 4.86, 95% confidence interval [CI]: 0.9 to 8.63) and melatonin+s-tDCS vs. placebo+s-tDCS (mean: 5.16, 95% CI: 0.84 to 8.36). There was no difference between melatonin+s-tDCS and melatonin+a-tDCS (mean difference: 0.29, 95% CI: -3.72 to 4.23). The mean change from the baseline on amplitude of motor evocate potential (MEP) was significantly higher in the melatonin+a-tDCS (-19.96% ± 5.2) compared with melatonin+s-tDCS group (-1.36% ± 5.35) and with placebo+s-tDCS group (3.61% ± 10.48), respectively (p < 0.05 for both comparisons). While melatonin alone or combined with a-tDCS did not significantly affect CPM task result, and serum BDNF level. The melatonin effectively reduced pain; however, its association with a-tDCS did not present an additional modulatory effect on acute induced pain.

BDNF blood levels after non-invasive brain stimulation interventions in major depressive disorder: a systematic review and meta-analysis

OBJECTIVES

To evaluate whether the antidepressant effects of novel non-invasive brain stimulation (NIBS) therapies are associated with neurotrophic effects, indexed by peripheral brain-derived neurotrophic factor (BDNF) levels.

METHODS

Systematic review and meta-analysis. We included trials published in PubMed/Medline from the first date available to June 2014 measuring BDNF blood levels before and after repetitive transcranial magnetic stimulation or transcranial direct current stimulation in depression.

RESULTS

Eight datasets (n = 259) were included. These studies enrolled mostly treatment-resistant depression patients, who received daily stimulation sessions on the left dorsolateral prefrontal cortex. BDNF did not increase after NIBS (Hedges' g = 0.03, 95% CI = -0.21 to 0.27), even when examining each intervention separately. Meta-regressions did not identify the influence of any clinical and demographic predictors on the outcome. Finally, Begg's funnel plot did not suggest publication bias and results were robust according to sensitivity analysis.

CONCLUSIONS

Peripheral BDNF levels do not increase after NIBS in depression. Such biomarker might, therefore, not be suitable to index NIBS antidepressant response. Further trials are needed, particularly exploring non-medicated populations, performing subsequent BDNF assessments in a larger timeframe and employing more intensive NIBS treatment protocols.

Assessment of non-BDNF neurotrophins and GDNF levels after depression treatment with sertraline and transcranial direct current stimulation in a factorial, randomized, sham-controlled trial (SELECT-TDCS): an exploratory analysis

The neurotrophic hypothesis of depression states that the major depressive episode is associated with lower neurotrophic factors levels, which increase with amelioration of depressive symptoms. However, this hypothesis has not been extended to investigate neurotrophic factors other than the brain-derived neurotrophic factor (BDNF). We therefore explored whether plasma levels of neurotrophins 3 (NT-3) and 4 (NT-4), nerve growth factor (NGF) and glial cell line derived neurotrophic factor (GDNF) changed after antidepressant treatment and correlated with treatment response. Seventy-three patients with moderate-to-severe, antidepressant-free unipolar depression were assigned to a pharmacological (sertraline) and a non-pharmacological (transcranial direct current stimulation, tDCS) intervention in a randomized, 2 × 2, placebo-controlled design. The plasma levels of NT-3, NT-4, NGF and GDNF were determined by enzyme-linked immunosorbent assay before and after a 6-week treatment course and analyzed according to clinical response and allocation group. We found that tDCS and sertraline (separately and combined) produced significant improvement in depressive symptoms. Plasma levels of all neurotrophic factors were similar across groups at baseline and remained significantly unchanged regardless of the intervention and of clinical response. Also, baseline plasma levels were not associated with clinical response. To conclude, in this 6-week placebo-controlled trial, NT-3, NT-4, NGF and GDNF plasma levels did not significantly change with sertraline or tDCS. These data suggest that these neurotrophic factors are not surrogate biomarkers of treatment response or involved in the antidepressant mechanisms of tDCS.