Major depressive disorder

5-HTTLPR and MTHFR 677C>T polymorphisms and response to yoga-based lifestyle intervention in major depressive disorder: A randomized active-controlled trial

BACKGROUND

There is growing evidence suggesting that both genetic and environmental factors modulate treatment outcome in, a highly heterogeneous, major depressive disorder (MDD). 5-HTTLPR variant of the serotonin transporter gene (SLC6A4) and MTHFR 677C>T polymorphisms have been linked to the pathogenesis of MDD, and antidepressant treatment response. The evidence is lacking on the clinical utility of yoga in patients with MDD who have 5-HTTLPR and MTHFR 677C>T polymorphisms and less likely to respond to medications (SSRIs).

AIMS

We aimed to examine the impact of YBLI in those who have susceptible 5-HTTLPR and MTHFR 677C>T polymorphisms and are less likely to drug therapy with SSRIs.

SETTINGS AND DESIGN

In a 12 week randomized active-controlled trial, MDD patients (n = 178) were randomized to receive YBLI or drug therapy.

METHODS

Genotyping was conducted using PCR-based methods. The clinical remission was defined as BDI-II score ≤ 9.

STATISTICAL ANALYSIS USED

An intent-to-treat analysis was performed, and the association of genotype with treatment remission consisted of the logistic regression model. A P value of <0.05 was considered statistically significant.

RESULTS

Multivariate logistic regression models for remission including either 5-HTTLPR or MTHFR 677C>T genotypes showed statistically significant odds of remission in YOGA arm vs. DRUG arm. Neither 5-HTTLPR nor MTHFR 677C>T genotype showed any influence on remission to YBLI (P = 0.73 and P = 0.64, respectively). Further analysis showed childhood adversity interact with 5-HTTLPR and MTHFR 677C>T polymorphisms to decrease treatment response in DRUG treatment arm, but not in YOGA arm.

CONCLUSIONS

YBLI provides MDD remission in those who have susceptible 5-HTTLPR and MTHFR 677C>T polymorphisms and are resistant to SSRIs treatment. YBLI may be therapeutic for MDD independent of heterogeneity in its etiopathogenesis.

Efficacy of vortioxetine on the physical symptoms of major depressive disorder

BACKGROUND

Efficacy has been proven for vortioxetine in short-term and long-term treatment of major depressive disorder (MDD), with broad beneficial effects on emotional, physical and cognitive symptoms. Limited specific data on the effects of vortioxetine on depression-related physical symptoms have been published.

METHODS

A meta-analysis was carried out of five short-term multinational, double-blind, placebo-controlled studies. These studies were conducted in a total of 2105 adult MDD outpatients (18-75 years) with a major depressive episode of ⩾3 months' duration. Only patients treated with a dose of 5 or 10 mg vortioxetine (therapeutic doses) or placebo were included in this analysis. Efficacy assessment of vortioxetine on the physical symptoms of depression included all items of the Hamilton Depression Scale (HAM-D) assessing physical symptoms, and all somatic items in the Hamilton Anxiety Scale (HAM-A). A subgroup analysis in MDD patients with coexisting anxiety symptoms (i.e. those with a HAM-A ⩾20 at baseline) was also performed.

RESULTS

A significant improvement ( p<0.05) of vortioxetine versus placebo was observed on all HAM-D items measuring physical symptoms, except for the somatic gastrointestinal symptoms and loss of weight items. Significant effects were also observed on the HAM-A somatic items: general somatic symptoms, gastrointestinal symptoms, and autonomic symptoms. In patients with a high baseline level of anxiety, a significant effect of vortioxetine was also observed on the physical symptoms of depression.

CONCLUSIONS

These analyses indicate that patients with MDD, including those with a high level of anxiety symptoms, have significant improvements in MDD-associated physical symptoms when treated with vortioxetine.

Pets enhance antidepressant pharmacotherapy effects in patients with treatment resistant major depressive disorder

Treatment resistant major depressive disorder (TR-MDD) is a severe disease, with very low remission rates. The resistance to pharmacotherapy leads to the search of non-pharmacological alternative approaches. Animal therapy has been used in patients with psychiatric conditions and the results have been promising. However, there have been no studies in TR-MDD patients with pet adoption. This study assessed the impact of TR-MDD patients adopting a pet. Eighty patients were suggested to adopt a pet, and 33 accepted the challenge. Other 33 patients constituted the control group (did not accept the suggestion of pet adoption and did not already have a pet). All patients maintained their usual pharmacotherapy. All participants were evaluated at baseline, 4, 8 and 12 weeks for depressive symptoms using HAMD17 and GAF. Results show that the pet group had an improvement in HAMD17 and GAF scores as well as higher response and remission rates compared to the control group, where no patient responded or remitted. Therefore, pets can be used as an effective adjuvant to pharmacotherapy with regular medical appointments.

Common variants on 6q16.2, 12q24.31 and 16p13.3 are associated with major depressive disorder

Accumulating evidence suggests that genetic factors have a role in major depressive disorder (MDD). However, only limited MDD risk loci have been identified so far. Here we perform a meta-analysis (a total of 90,150 MDD cases and 246,603 controls) through combing three genome-wide association studies of MDD, including 23andMe (cases were self-reported with a clinical diagnosis or treatment of depression), CONVERGE (cases were diagnosed using the Composite International Diagnostic Interview) and PGC (cases were diagnosed using direct structured diagnostic interview (by trained interviewers) or clinician-administered DSM-IV checklists). Genetic variants from two previously unreported loci (rs10457592 on 6q16.2 and rs2004910 on 12q24.31) showed significant associations with MDD (P < 5 × 10^-8) in a total of 336,753 subjects. SNPs (a total of 171) with a P < 1 × 10^-7 in the meta-analysis were further replicated in an independent sample (GS:SFHS, 2,659 MDD cases (diagnosed with DSM-IV) and 17,237 controls) and one additional risk locus (rs3785234 on 16p13.3, P = 1.57 × 10^-8) was identified in the combined samples (a total of 92,809 cases and 263,840 controls). Risk variants on the identified risk loci were associated with gene expression in human brain tissues and mRNA expression analysis showed that FBXL4 and RSRC1 were significantly upregulated in brains of MDD cases compared with controls, suggesting that genetic variants may confer risk of MDD through regulating the expression of these two genes. Our study identified three novel risk loci (6q16.2, 12q24.31, and 16p13.3) for MDD and suggested that FBXL4 and RSRC1 may play a role in MDD. Further functional characterization of the identified risk genes may provide new insights for MDD pathogenesis.

Imaging genetics paradigms in depression research: Systematic review and meta-analysis

Imaging genetics studies involving participants with major depressive disorder (MDD) have expanded. Nevertheless, findings have been inconsistent. Thus, we conducted a systematic review and meta-analysis of imaging genetics studies that enrolled MDD participants across major databases through June 30th, 2017. Sixty-five studies met eligibility criteria (N = 4034 MDD participants and 3293 controls), and there was substantial between-study variability in the methodological quality of included studies. However, few replicated findings emerged from this literature with only 22 studies providing data for meta-analyses (882 participants with MDD and 616 controls). Total hippocampal volumes did not significantly vary in MDD participants or controls carrying either the BDNF Val66Met 'Met' (386 participants with MDD and 376 controls) or the 5-HTTLPR short 'S' (310 participants with MDD and 230 controls) risk alleles compared to non-carriers. Heterogeneity across studies was explored through meta-regression and subgroup analyses. Gender distribution, the use of medications, segmentation methods used to measure the hippocampus, and age emerged as potential sources of heterogeneity across studies that assessed the association of 5-HTTLPR short 'S' alleles and hippocampal volumes. Our data also suggest that the methodological quality of included studies, publication year, and the inclusion of brain volume as a covariate contributed to the heterogeneity of studies that assessed the association of the BDNF Val66Met 'Met' risk allele and hippocampal volumes. In exploratory voxel-wise meta-analyses, MDD participants carrying the 5-HTTLPR short 'S' allele had white matter microstructural abnormalities predominantly in the corpus callosum, while carriers of the BDNF Val66Met 'Met' allele had larger gray matter volumes and hyperactivation of the right middle frontal gyrus compared to non-carriers. In conclusion, few replicated findings emerged from imaging genetics studies that included participants with MDD. Nevertheless, we explored and identified specific sources of heterogeneity across studies, which could provide insights to enhance the reproducibility of this emerging field.

Defective Inflammatory Pathways in Never-Treated Depressed Patients Are Associated with Poor Treatment Response

Inflammation has been involved in the pathophysiology and treatment response of major depressive disorder (MDD). Plasma cytokine profiles of 171 treatment-naive MDD patients (none of the MDD patients received an adequate trial of antidepressants or evidence-based psychotherapy) and 64 healthy controls (HCs) were obtained. MDD patients exhibited elevated concentrations of 18 anti- and proinflammatory markers and decreased concentrations of 6 cytokines. Increased inflammasome protein expression was observed in MDD patients, indicative of an activated inflammatory response. The plasma of MDD patients was immunosuppressive on healthy donor peripheral blood mononuclear cells, inducing reduced activation of monocytes/dendritic cells and B cells and reduced T cell memory. Comparison between 33 non-responders and 71 responders at baseline and 12 weeks revealed that after treatment, anti-inflammatory cytokine levels increase in both groups, whereas 5 proinflammatory cytokine levels were stabilized in responders, but continued to increase in non-responders. MDD patients exhibit remodeling of their inflammatory landscape.

Does Human Experimental Endotoxemia Impact Negative Cognitions Related to the Self?

A role of inflammatory processes in the pathophysiology of depression is increasingly recognized. Experimental endotoxemia offers an established model to induce transient systemic inflammation in healthy humans, and has been proposed as an experimental paradigm of depression. Indeed, different symptoms of depression can be observed during experimental endotoxemia, including negative mood or dysthymia as key symptoms of depression. Hopelessness and low self-esteem constitute common cognitive symptoms in depression, but have not been specifically assessed during endotoxemia. Thus, we pooled data from healthy volunteers who received low-dose endotoxin (i.e., 0.4 or 0.8 ng/kg lipopolysaccharide, LPS) or placebo in three randomized, controlled studies to investigate the effects of LPS on cognitive schemata related to depression. Validated questionnaires were used to assess self-esteem, hopelessness and the vulnerability factor intolerance of uncertainty after intravenous injection of LPS or placebo. Plasma tumor necrosis factor (TNF)-α and interleukin (IL)-6 were repeatedly assessed, along with self-reported mood. Because not all questionnaires were available from primary studies, data were analyzed in two separate data sets: In data set 1, self-esteem and intolerance of uncertainty were assessed in N = 87 healthy volunteers, who randomly received either 0.4 or 0.8 ng/kg LPS or placebo. In data set 2, hopelessness was measured in N = 59 volunteers who randomly received either LPS (0.8 ng/kg) or placebo. In both data sets, LPS-application led to significant increases in TNF-α and IL-6, reflecting systemic inflammation. Positive mood was significantly decreased in response to LPS, in line with inflammation-induced mood impairment. General self-esteem, intolerance of uncertainty and hopelessness did not differ between LPS- and placebo groups, suggesting that these negative cognitive schemata are not responsive to acute LPS-induced systemic inflammation. Interestingly, LPS-treated volunteers reported significantly lower body-related self-esteem, which was associated with increased TNF-α concentration. Thus, certain aspects of self-esteem related to physical attractiveness and sportiness were reduced. It is conceivable that this effect is primarily related to physical sickness symptoms and reduced physical ability during experimental endotoxemia. With respect to cognitive symptoms of depression, it is conceivable that LPS affects cognitive processes, but not negative cognitive schemata, which are rather based on learning and repeated experiences.

Hippocampal Memory Recovery After Acute Stress: A Behavioral, Morphological and Molecular Study

Several studies have shown that a single exposure to stress may improve or impair learning and memory processes, depending on the timing in which the stress event occurs with relation to the acquisition phase. However, to date there is no information about the molecular changes that occur at the synapse during the stress-induced memory modification and after a recovery period. In particular, there are no studies that have evaluated—at the same time—the temporality of stress and stress recovery period in hippocampal short-term memory and the effects on dendritic spine morphology, along with variations in N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subunits. The aim of our study was to take a multidimensional approach to investigate concomitant behavioral, morphological and molecular changes induced by a single restraint stress exposure (2.5 h) and a recovery period of 6 and 24 h in rats. We found that acute stress elicited a reduced preference to explore an object placed in a novel position (a hippocampal-dependent task). These changes were accompanied by increased activity of LIM kinase I (LIMK; an actin-remodeling protein) and increased levels of NR2A subunits of NMDA receptors. After 6 h of recovery from stress, rats showed similar preference to explore an object placed in a novel or familiar position, but density of immature spines increased in secondary CA1 apical dendrites, along with a transient rise in GluA2 AMPA receptor subunits. After 24 h of recovery from stress, the animals showed a preference to explore an object placed in a novel position, which was accompanied by a normalization of NMDA and AMPA receptor subunits to control values. Our data suggest that acute stress produces reversible molecular and behavioral changes 24 h after stress, allowing a full reestablishment of hippocampal-related memory. Further studies need to be conducted to deepen our understanding of these changes and their reciprocal interactions.Adaptive stress responses are a promising avenue to develop interventions aiming at restoring hippocampal function impaired by repetitive stress exposure.

Mapping risk factors for depression across the lifespan: An umbrella review of evidence from meta-analyses and Mendelian randomization studies

The development of depression may involve a complex interplay of environmental and genetic risk factors. PubMed and PsycInfo databases were searched from inception through August 3, 2017, to identify meta-analyses and Mendelian randomization (MR) studies of environmental risk factors associated with depression. For each eligible meta-analysis, we estimated the summary effect size and its 95% confidence interval (CI) by random-effects modeling, the 95% prediction interval, heterogeneity with I², and evidence of small-study effects and excess significance bias. Seventy meta-analytic reviews met the eligibility criteria and provided 134 meta-analyses for associations from 1283 primary studies. While 109 associations were nominally significant (P < 0.05), only 8 met the criteria for convincing evidence and, when limited to prospective studies, convincing evidence was found in 6 (widowhood, physical abuse during childhood, obesity, having 4-5 metabolic risk factors, sexual dysfunction, job strain). In studies in which depression was assessed through a structured diagnostic interview, only associations with widowhood, job strain, and being a Gulf War veteran were supported by convincing evidence. Additionally, 8 MR studies were included and provided no consistent evidence for the causal effects of obesity, smoking, and alcohol consumption. The proportion of variance explained by genetic risk factors was extremely small (0.1-0.4%), which limited the evidence provided by the MR studies. Our findings suggest that despite the large number of putative risk factors investigated in the literature, few associations were supported by robust evidence. The current findings may have clinical and research implications for the early identification of individuals at risk for depression.

Association of Whole-Genome and NETRIN1 Signaling Pathway-Derived Polygenic Risk Scores for Major Depressive Disorder and White Matter Microstructure in the UK Biobank

Background

Major depressive disorder is a clinically heterogeneous psychiatric disorder with a polygenic architecture. Genome-wide association studies have identified a number of risk-associated variants across the genome and have reported growing evidence of NETRIN1 pathway involvement. Stratifying disease risk by genetic variation within the NETRIN1 pathway may provide important routes for identification of disease mechanisms by focusing on a specific process, excluding heterogeneous risk-associated variation in other pathways. Here, we sought to investigate whether major depressive disorder polygenic risk scores derived from the NETRIN1 signaling pathway (NETRIN1-PRSs) and the whole genome, excluding NETRIN1 pathway genes (genomic-PRSs), were associated with white matter microstructure.

Methods

We used two diffusion tensor imaging measures, fractional anisotropy (FA) and mean diffusivity (MD), in the most up-to-date UK Biobank neuroimaging data release (FA: n = 6401; MD: n = 6390).

Results

We found significantly lower FA in the superior longitudinal fasciculus (β = −.035, p_corrected = .029) and significantly higher MD in a global measure of thalamic radiations (β = .029, p_corrected = .021), as well as higher MD in the superior (β = .034, p_corrected = .039) and inferior (β = .029, p_corrected = .043) longitudinal fasciculus and in the anterior (β = .025, p_corrected = .046) and superior (β = .027, p_corrected = .043) thalamic radiation associated with NETRIN1-PRS. Genomic-PRS was also associated with lower FA and higher MD in several tracts.

Conclusions

Our findings indicate that variation in the NETRIN1 signaling pathway may confer risk for major depressive disorder through effects on a number of white matter tracts.

Repetitive transcranial magnetic stimulation in patients with late life depression influences phenylalanine metabolism

Repetitive transcranial magnetic stimulation (rTMS) is used to treat different neuropsychiatric conditions like Parkinson’s disease, essential tremor, stroke, cognitive decline, dementia and depression. rTMS may exert its therapeutic effects by influencing the biochemistry of neurotransmitters. In this exploratory study, safety symptom improvement and changes in the availability of neurotransmitter precursor amino acids were studied following prefrontal cortex (PFC) stimulation using repetitive transcranial stimulation with TheraCell apparatus R (Guth Meditec, Salach, Germany) as an additional treatment in ten patients with late life depression. Treatment was well tolerated with no serious adverse effects being observed. rTMS induced a significant improvement in the symptoms of depression and a significant decrease in the HAMD-7 (p <0.03). At the same time, the serum phenylalanine to tyrosine ratio declined significantly (p <0.04). No significant influence of rTMS on tryptophan breakdown and serum neopterin concentrations was observed. These preliminary findings indicate that rTMS may influence the activity of the enzyme phenylalanine hydroxylase (PAH) which plays a key role in the biosynthesis of neurotransmitter precursors related to neuropsychiatric symptoms in late life depression. However, results were obtained from only 10 patients. Larger studies are therefore required to support these conclusions

Enriched environment prevents oxidative stress in zebrafish submitted to unpredictable chronic stress

Background

The enriched environment (EE) is a laboratory housing model that emerged from efforts to minimize the impact of environmental conditions on laboratory animals. Recently, we showed that EE promoted positive effects on behavior and cortisol levels in zebrafish submitted to the unpredictable chronic stress (UCS) protocol. Here, we expanded the characterization of the effects of UCS protocol by assessing parameters of oxidative status in the zebrafish brain and reveal that EE protects against the oxidative stress induced by chronic stress.

Methods

Zebrafish were exposed to EE (21 or 28 days) or standard housing conditions and subjected to the UCS protocol for seven days. Oxidative stress parameters (lipid peroxidation (TBARS), reactive oxygen species (ROS) levels, non-protein thiol (NPSH) and total thiol (SH) levels, superoxide dismutase (SOD) and catalase (CAT) activities were measured in brain homogenate.

Results

Our results revealed that UCS increased lipid peroxidation and ROS levels, while decreased NPSH levels and SOD activity, suggesting oxidative damage. EE for 28 days prevented all changes induced by the UCS protocol, and EE for 21 days prevented the alterations on NPSH levels, lipid peroxidation and ROS levels. Both EE for 21 or 28 days increased CAT activity.

Discussion

Our findings reinforce the idea that EE exerts neuromodulatory effects in the zebrafish brain. EE promoted positive effects as it helped maintain the redox homeostasis, which may reduce the susceptibility to stress and its oxidative impact.

Imbalance in amino acid and purine metabolisms at the hypothalamus in inflammation-associated depression by GC-MS

Hypothalamic dysfunction is a key factor in depression; increasing evidence highlights neuroinflammation abnormalities as well as imbalances in neurotransmitters and the purinergic system in the pathophysiology of depression. However, little is known about the metabolomic changes in the hypothalamus of depressed patients with neuroinflammation. Herein, taking advantage of the well-established lipopolysaccharide (LPS)-induced depression mouse model, we measured metabolic changes in the hypothalamus using gas chromatography-mass spectrometry (GC-MS). Sucrose preference test (SPT), open field test (OFT), forced swimming test (FST), and tail suspension test (TST) were conducted to assess our depressive model. To better understand the metabolic disturbances occurring in the hypothalamus of depressed mice, multivariate statistics were applied to analyse the clinical significance of differentially expressed metabolites in the hypothalamus of mice with LPS-induced depression. Bioinformatic analysis was conducted to detect potential relationships among the changed metabolites. The data confirmed that mice with LPS-induced depression were good mimics of depression patients in some characteristic symptoms such as decreased sucrose intake and increased immobility. In our study, 27 differentially expressed metabolites were identified in the hypothalamus of mice with LPS-induced depression. Herein, seventeen of these metabolites decreased, whereas 10 metabolites increased. These molecular changes were closely related to perturbations in the amino acid and purine metabolisms. Our data indicate that dysfunction of amino acid and purine metabolisms is one of main characteristics of inflammation-mediated depression. These results provide new insights into the mechanisms underlying depression, which may shed some light on the role of the hypothalamus in the pathogenesis of inflammation-mediated depression.

Association between iron-deficiency anemia and depression: A web-based Japanese investigation

AIM

This web-based survey aimed to examine the relation between iron-deficiency anemia and depression in 11 876 Japanese participants.

METHODS

Participants consisted of 1000 individuals with self-reported history of depression (mean age, 41.4 ± 12.3 years; 499 women) and 10 876 population-based controls (mean age, 45.1 ± 13.6 years; 5185 women). The 6-item Kessler Scale (K6) score was used as a psychological distress scale. The design of the study was cross-sectional.

RESULTS

The rate of self-reported lifetime history of iron-deficiency anemia was higher in the depression group in both men (depression, 7.2%; control, 4.0%; P < 0.001; odds ratio [OR], 1.86; 95% confidence interval [CI], 1.30-2.68) and women (depression, 33.4%; control, 25.8%; P < 0.001; OR, 1.45; 95%CI, 1.19-1.76). The K6 score in participants with self-reported history of iron-deficiency anemia was higher in both the depression (P = 0.004) and control (P < 0.001) groups. In addition, in all participants, the rate of individuals who showed a K6 cut-off score of 13 or more was higher in those with a self-reported history of iron-deficiency anemia (P < 0.001; OR, 1.47; 95%CI, 1.31-1.65). Logistic regression analyses revealed that self-reported history of depression and the K6 score were positively associated with self-reported history of iron-deficiency anemia (all P < 0.01).

CONCLUSION

Self-reported history of iron-deficiency anemia was associated with self-reported history of depression. Furthermore, self-reported history of iron-deficiency anemia was associated with higher psychological distress.

Statistical harmonization corrects site effects in functional connectivity measurements from multi-site fMRI data

Acquiring resting-state functional magnetic resonance imaging (fMRI) datasets at multiple MRI scanners and clinical sites can improve statistical power and generalizability of results. However, multi-site neuroimaging studies have reported considerable nonbiological variability in fMRI measurements due to different scanner manufacturers and acquisition protocols. These undesirable sources of variability may limit power to detect effects of interest and may even result in erroneous findings. Until now, there has not been an approach that removes unwanted site effects. In this study, using a relatively large multi-site (4 sites) fMRI dataset, we investigated the impact of site effects on functional connectivity and network measures estimated by widely used connectivity metrics and brain parcellations. The protocols and image acquisition of the dataset used in this study had been homogenized using identical MRI phantom acquisitions from each of the neuroimaging sites; however, intersite acquisition effects were not completely eliminated. Indeed, in this study, we found that the magnitude of site effects depended on the choice of connectivity metric and brain atlas. Therefore, to further remove site effects, we applied ComBat, a harmonization technique previously shown to eliminate site effects in multi-site diffusion tensor imaging (DTI) and cortical thickness studies. In the current work, ComBat successfully removed site effects identified in connectivity and network measures and increased the power to detect age associations when using optimal combinations of connectivity metrics and brain atlases. Our proposed ComBat harmonization approach for fMRI-derived connectivity measures facilitates reliable and efficient analysis of retrospective and prospective multi-site fMRI neuroimaging studies.

Differences in sleep functioning between individuals with seasonal affective disorder and major depressive disorder in Finland

BACKGROUND

Sleep problems are commonly reported in seasonal affective disorder (SAD) and major depressive disorder (MDD). However, the specific characteristics of sleep difficulties differ. Frequent sleep problems in MDD are insomnia and night awakenings, whereas SAD patients complain of hypersomnia and daytime sleepiness. No previous studies have reported differences in sleep functioning between these two disorders.

METHODS

We interviewed 4554 subjects from the Health 2011 survey and included 4153 individuals in this study. We selected participants who fulfilled the criteria for SAD (n = 223), nonseasonal-MDD (n = 238), SAD + MDD (n = 65), and controls (n = 3627). They completed the World Health Organization Composite International Diagnostic Interview, Munich version (M-CIDI), the Seasonal Pattern Assessment Questionnaire (SPAQ), The Beck Depression Inventory (BDI), the EuroQoL (EQ-5), the Alcohol Use Disorders Identification Test (AUDIT) and several questions about sleeping, based on the Basic Nordic Sleep Questionnaire (BNSQ).

RESULTS

We found Significant differences between groups for "enough sleep", "breathing interruptions during sleep", "tiredness during the day", and "sleeping difficulties". Controls reported better functioning in all sleep variables. SAD + MDD individuals showed more problems in "enough sleep" than SAD, more "breathing interruptions during sleep" than SAD and nonseasonal-MDD, felt more "tired during the day" than SAD and nonseasonal-MDD, and reported more "sleeping difficulties" than SAD and nonseasonal-MDD. Finally, nonseasonal-MDD individuals felt more "tired during the day" than SAD.

CONCLUSION

Individuals with SAD + MDD show generalized sleeping problems. However, when SAD and nonseasonal-MDD appear separately, similar sleep functioning is observed. Nonseasonal-MDD subjects report to be more tired during the day than SAD.

A review of physiological and behavioral monitoring with digital sensors for neuropsychiatric illnesses

Physiological, behavioral, and psychological changes associated with neuropsychiatric illness are reflected in several related signals, including actigraphy, location, word sentiment, voice tone, social activity, heart rate, and responses to standardized questionnaires. These signals can be passively monitored using sensors in smartphones, wearable accelerometers, Holter monitors, and multimodal sensing approaches that fuse multiple data types. Connection of these devices to the internet has made large scale studies feasible and is enabling a revolution in neuropsychiatric monitoring. Currently, evaluation and diagnosis of neuropsychiatric disorders relies on clinical visits, which are infrequent and out of the context of a patient's home environment. Moreover, the demand for clinical care far exceeds the supply of providers. The growing prevalence of context-aware and physiologically relevant digital sensors in consumer technology could help address these challenges, enable objective indexing of patient severity, and inform rapid adjustment of treatment in real-time. Here we review recent studies utilizing such sensors in the context of neuropsychiatric illnesses including stress and depression, bipolar disorder, schizophrenia, post traumatic stress disorder, Alzheimer's disease, and Parkinson's disease.

Genipin normalizes depression-like behavior induced by prenatal stress through inhibiting DNMT1

Synthetic antidepressants in current use for the complex etiopathogeneses of depression have slow response and remission as well as various unpleasant side effects. As a result, it is imperative to develop new antidepressants with more effectiveness and less severe side effects. Recent studies demonstrated that genipin, the aglycon of geniposide, extracted from Gardenia jasminoides Ellis has antidepressive effects. However, knowledge regarding the molecular mechanisms of its antidepressant effects remains limited. Employing a depression-like mouse model, we confirmed that genipin is capable of correcting depressions-like behaviors induced by prenatal stress in offspring from prenatally stressed dams (defined as PRS mice). In further experiments, we found that the effect of genipin on PRS mice occurs through DNA demethylation by inhibiting DNA methyltransferase 1 (DNMT1), normalizing the expression of reduced brain-derived neurotrophic factor (BDNF) in the hippocampus.

How to measure glucocorticoid receptor's sensitivity in patients with stress-related psychiatric disorders

Stress is a state of derailed homeostasis and a main environmental risk factor for psychiatric diseases. Chronic or uncontrollable stress may lead to a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which is a common feature of stress-related psychiatric disorders. One of the key mechanisms underlying a disturbed HPA axis is an impaired function of the glucocorticoid receptor (GR) with an enhanced or reduced feedback sensitivity for glucocorticoids and subsequently altered concentrations of peripheral cortisol. GR function is regulated by a multiprotein complex including the different expression of the hsp90 co-chaperone FK 506 binding protein 51 (FKBP5) that may be genetically determined or acquired in response to stressful stimuli. Specific patterns of a dysregulation of the HPA axis and GR function are found in different stress-related psychiatric entities e.g. major depression, job-related exhaustion or posttraumatic stress disorder. GR challenge tests like the dexamethasone-suppression test (DST), the dexamethasone-corticotropin-releasing hormone (dex-CRH) test or most recently the analysis of the dexamethasone-induced gene expression are employed to sensitively measure HPA axis activity in these disorders. They provide information for a stratification of phenotypic similar but neurobiological diverse psychiatric disorders. In this review we present a synopsis of GR challenge tests with a focus on the application of the DST, the CRH test and the dex-CRH test as well as the dexamethasone-induced gene expression in stress-related psychiatric entities.

Understanding the Neuroepigenetic Constituents of Suicide Brain

Stressful life incidents often cause a predisposition for developing mental disorders such as major depressive disorder (MDD). Impaired neurocognitive and neuro-vegetative functions of the central nervous system are the hallmarks of this mental illness. Blunted responses from emotionally salient regions of the brain including cortex, hippocampus, and amygdala have been associated with MDD-related behavioral changes. Moreover, improper signal processing and neuronal atrophy were held responsible for the overall dysfunctionality of these vulnerable regions in the MDD brain. The prevalence of genetic susceptibility along with adverse environmental stimuli often makes the situation worse for MDD patients, leading to an increased risk of suicidal behavior and eventually death by suicide. Despite considerable efforts to understand the complex neurobiology associated with MDD and suicidal behavior, their pathological determinants remain mostly elusive. Recent research, however, has shown that epigenetic perturbations have a formidable impact on the etiopathogenesis of MDD. Understanding the neuroepigenetic nature of this mental disorder may provide opportunities to devise more effective treatment strategies. Moreover, this can potentially lead to identifying predictive biomarkers associated with suicide risk. The present chapter critically reviews studies pertaining to epigenetic signatures of MDD and suicide brain.

The impact from the aftermath of chronic stress on hippocampal structure and function: Is there a recovery?

Chronic stress results in functional and structural changes to the brain and especially the hippocampus. Decades of research have provided insights into the mechanisms by which chronic stress impairs hippocampal-mediated cognition and the corresponding reduction of hippocampal CA3 apical dendritic complexity. Yet, when chronic stress ends and time passes, which we refer to as a "post-stress rest period," hippocampal-mediated spatial memory deficits begin to improve and CA3 apical dendritic arbors increase in complexity. The processes by which the hippocampus improves from a chronically stressed state are not simply the reversal of the mechanisms that produced spatial memory deficits and CA3 apical dendritic retraction. This review will discuss our current understanding of how a chronically stressed hippocampus improves after a post-stress rest period. Untangling the mechanisms that allow for this post-stress plasticity is a critical next step in understanding how to promote resilience in the face of stressors.

Serotonin 5-HT3 receptor antagonism potentiates the antidepressant activity of citalopram

Activation of serotonin 5-HT₃ receptor (5HT3R) in the locus coeruleus (LC), the principal somatodendritic noradrenergic area, decreases LC firing activity and noradrenaline (NA) release in prefrontal cortex (PFC). Blockade of 5HT3R in coadministration with selective serotonin reuptake inhibitors (SSRIs) has been proposed as a potential strategy to accelerate the onset of action of SSRIs. Dual-probe microdialysis in rats was used to evaluate the involvement of 5HT3R in the in vivo effect exerted by the SSRI citalopram on NA release. Besides, forced swimming test (FST) was carried out in mice to evaluate the antidepressant-like effect of citalopram in combination with a 5HT3R antagonist (Y25130). Systemic administration of the 5HT3R agonist SR57227 (10 mg/kg i.p.) increased NA in LC (Emax = 200 ± 27%) and PFC (Emax = 133 ± 2%). The increase in PFC was enhanced in local presence into LC of Y25130 (50 μM) (Emax = 296 ± 41%) suggesting an inhibitory function on NA release exerted by the activation of 5HT3R located in somatodendritic areas. Citalopram administration (10 mg/kg i.p.) increased NA in LC (Emax = 185 ± 11%) and decreased it in PFC (Emax = -35 ± 7%). Intra-LC (50 μM) or systemic co-administration of Y25130 (10 mg/kg i.p.) with citalopram (10 mg/kg i.p.) switched NA release in the PFC from an inhibition to a stimulatory effect. In mice FST, systemic coadministration of citalopram (2.5 mg/kg i.p.) and Y25130 (10 mg/kg i.p.) potentiated the decrease of immobility time through the increase of both swimming and climbing behaviours. These results suggest that the addition of a 5HT3R antagonist to SSRIs could represent a feasible strategy to improve antidepressant response.

T Cell Phenotype and T Cell Receptor Repertoire in Patients with Major Depressive Disorder

While a link between inflammation and the development of neuropsychiatric disorders, including major depressive disorder (MDD) is supported by a growing body of evidence, little is known about the contribution of aberrant adaptive immunity in this context. Here, we conducted in-depth characterization of T cell phenotype and T cell receptor (TCR) repertoire in MDD. For this cross-sectional case–control study, we recruited antidepressant-free patients with MDD without any somatic or psychiatric comorbidities (n = 20), who were individually matched for sex, age, body mass index, and smoking status to a non-depressed control subject (n = 20). T cell phenotype and repertoire were interrogated using a combination of flow cytometry, gene expression analysis, and next generation sequencing. T cells from MDD patients showed significantly lower surface expression of the chemokine receptors CXCR3 and CCR6, which are known to be central to T cell differentiation and trafficking. In addition, we observed a shift within the CD4⁺ T cell compartment characterized by a higher frequency of CD4⁺CD25^highCD127^low/− cells and higher FOXP3 mRNA expression in purified CD4⁺ T cells obtained from patients with MDD. Finally, flow cytometry-based TCR Vβ repertoire analysis indicated a less diverse CD4⁺ T cell repertoire in MDD, which was corroborated by next generation sequencing of the TCR β chain CDR3 region. Overall, these results suggest that T cell phenotype and TCR utilization are skewed on several levels in patients with MDD. Our study identifies putative cellular and molecular signatures of dysregulated adaptive immunity and reinforces the notion that T cells are a pathophysiologically relevant cell population in this disorder.

Functional brain abnormalities in major depressive disorder using the Hilbert-Huang transform

Major depressive disorder is a common disease worldwide, which is characterized by significant and persistent depression. Non-invasive accessory diagnosis of depression can be performed by resting-state functional magnetic resonance imaging (rs-fMRI). However, the fMRI signal may not satisfy linearity and stationarity. The Hilbert-Huang transform (HHT) is an adaptive time-frequency localization analysis method suitable for nonlinear and non-stationary signals. The objective of this study was to apply the HHT to rs-fMRI to find the abnormal brain areas of patients with depression. A total of 35 patients with depression and 37 healthy controls were subjected to rs-fMRI. The HHT was performed to extract the Hilbert-weighted mean frequency of the rs-fMRI signals, and multivariate receiver operating characteristic analysis was applied to find the abnormal brain regions with high sensitivity and specificity. We observed differences in Hilbert-weighted mean frequency between the patients and healthy controls mainly in the right hippocampus, right parahippocampal gyrus, left amygdala, and left and right caudate nucleus. Subsequently, the above-mentioned regions were included in the results obtained from the compared region homogeneity and the fractional amplitude of low frequency fluctuation method. We found brain regions with differences in the Hilbert-weighted mean frequency, and examined their sensitivity and specificity, which suggested a potential neuroimaging biomarker to distinguish between patients with depression and healthy controls. We further clarified the pathophysiological abnormality of these regions for the population with major depressive disorder.

The dynamic characteristics of the anterior cingulate cortex in resting-state fMRI of patients with depression

BACKGROUND

The anterior cingulate cortex (ACC) is part of the limbic system of the brain. It is a bridge between attentional and emotional processing, which is responsible for the integration of visceral, attentional, and affective information. Lesioning of the ACC, which produces striking changes, is used to treat major depression disorder (MDD). Moreover, the brain dynamically integrates and coordinates functions of its different subparts to realize its cognitive capability. Hence, the spatio-temporal community distribution of the ACC is necessary to completely understand MDD.

METHODS

First, community structure detection was used to reveal the community distribution of brain regions. Thereafter, the flexibility, i.e., the frequency of community assignment changes of the ACC in such a community, and the module allegiance matrix (MAM) between the ACC and other brain regions, were analyzed.

RESULTS

Our analysis demonstrated significant differences in the distribution of community assignment and flexibility of the ACC in MDD, compared to healthy controls (HC). The results also showed that the pairwise values of the MAMs between the ACC and the amygdala, insula, precuneus, and thalamus were significantly lower in patients with MDD compared to those in HC.

LIMITATIONS

The data collected is subject to patient-specific noise because (1) the medication effect varies from patient to patient, and (2) with most fMRI studies, the thoughts of the participants during imaging are difficult to control.

CONCLUSION

ACC exhibits abnormal flexibility in community structures in MDD. The pairwise abnormal entries in the MAM for the ACC with four other brain regions, i.e., amygdala, insula, precuneus, and thalamus, quantified the role played by the ACC in MDD.

BDNF Val66Met polymorphism, life stress and depression: A meta-analysis of gene-environment interaction

BACKGROUND

Depression is thought to be multifactorial in etiology, including genetic and environmental components. While a number of gene-environment interaction studies have been carried out, meta-analyses are scarce. The present meta-analysis aimed to quantify evidence on the interaction between brain-derived neurotrophic factor (BDNF) Val66Met polymorphism and stress in depression.

METHODS

Included were 31 peer-reviewed with a pooled total of 21060 participants published before October 2016 and literature searches were conducted using PubMed, Wolters Kluwer, Web of Science, EBSCO, Elsevier Science Direct and Baidu Scholar databases.

RESULTS

The results indicated that the Met allele of BDNF Val66Met polymorphism significantly moderated the relationship between stress and depression (Z=2.666, p = 0.003). The results of subgroup analysis concluded that stressful life events and childhood adversity separately interacted with the Met allele of BDNF Val66Met polymorphism in depression (Z = 2.552, p = 0.005; Z = 1.775, p = 0.03).

LIMITATIONS

The results could be affected by errors or bias in primary studies which had small sample sizes with relatively lower statistic power. We could not estimate how strong the interaction effect between gene and environment was.

CONCLUSIONS

We found evidence that supported the hypothesis that BDNF Val66Met polymorphism moderated the relationship between stress and depression, despite the fact that many included individual studies did not show this effect.

Repeated lipopolysaccharide exposure modifies immune and sickness behaviour response in an animal model of chronic inflammation

Repeated lipopolysaccharide exposure is often used in longitudinal preclinical models of depression. However, the potential phenotypic differences from acute depression-mimicking effects are rarely described. This study compared chronic lipopolysaccharide administration of doses previously used in depression research to a new mode of escalating dose injections. Adult male BALB/c mice ( n=8/group) were injected intraperitoneally with either a single 0.83 mg/kg dose, a repeated 0.1 mg/kg lipopolysaccharide dose or a dose which escalated weekly from 0.33 to 0.83 mg/kg lipopolysaccharide for six weeks. The escalating lipopolysaccharide group demonstrated most features of sickness behaviour such as weight loss and reduction in food intake every week, whilst this effect was not sustained in other groups. Moreover, only in the escalating lipopolysaccharide group did most peripheral plasma cytokines levels, measured using Luminex multiplex technology, such as interleukin-6, tumour necrosis factor α and interleukin-2 remain over three-fold elevated on the sixth week. In addition, exposure to escalating doses led to a reduction of neuroblast maturation in the dentate gyrus relevant for depression neurobiology. Therefore, this mode of injections might be useful in the studies attempting to replicate neurobiological aspects of the chronic inflammatory state observed in mood disorders.

Therapeutic Strategies for Treatment of Inflammation-related Depression

BACKGROUND

Mounting evidence demonstrates enhanced systemic levels of inflammatory mediators in depression, indicating that inflammation may play a role in the etiology and course of mood disorders. Indeed, proinflammatory cytokines induce a behavioral state of conservation- withdrawal resembling human depression, characterized by negative mood, fatigue, anhedonia, psychomotor retardation, loss of appetite, and cognitive deficits. Neuroinflammation also contributes to non-responsiveness to current antidepressant (AD) therapies. Namely, response to conventional AD medications is associated with a decrease in inflammatory biomarkers, whereas resistance to treatment is accompanied by increased inflammation.

METHODS

In this review, we will discuss the utility and shortcomings of pharmacologic AD treatment strategies focused on inflammatory pathways, applied alone or as an adjuvant component to current AD therapies.

RESULTS

Mechanisms of cytokine actions on behavior involve activation of inflammatory pathways in the brain, resulting in changes of neurotransmitter metabolism, neuroendocrine function, and neuronal plasticity. Selective serotonin reuptake inhibitors exhibit the most beneficial effects in restraining the inflammation markers in depression. Different anti-inflammatory agents exhibit AD effects via modulating neurotransmitter systems, neuroplasticity markers and glucocorticoid receptor signaling. Anti-inflammatory add-on therapy in depression highlights such treatment as a candidate for enhancement strategy in patients with moderate-to-severe depression.

CONCLUSION

The interactions between the immune system and CNS are not only involved in shaping behavior, but also in responding to therapeutics. Even though, substantial evidence from animal and human research support a beneficial effect of anti-inflammatory add-on therapy in depression, further research with special attention on safety, particularly during prolonged periods of antiinflammatory co-treatments, is required.

A study in the general population about sadness to disentangle the continuum from well-being to depressive disorders

OBJECTIVE

Sadness is both a common experience in general population and one of the main criteria of major depressive disorder (MDD). We tested the hypothesis of a depressive continuum using sadness as an intermediate experience between well-being and disorder.

METHODS

A French cross-sectional Mental Health survey in General Population interviewed 38,694 individuals. We examined prevalences and compared sociodemographic correlates and psychiatric disorders of individuals in 3 independent groups 1) MDD, 2) sadness without MDD, and 3) controls.

RESULTS

The prevalence of sadness was of 29.8% in the whole sample and of 93% in subjects suffering from MDD (n = 4976). The "sadness" group shared the same sociodemographic patterns as the "MDD" group. All psychiatric disorders assessed (i.e. bipolar disorder, anxiety disorder, alcohol use disorder, psychotic disorder and suicide attempts) were significantly associated with both "sadness" and "MDD" groups compared to "controls". Individuals with sadness, compared to those with MDD, were significantly less likely to meet the criteria for all psychiatric disorders. MDD's sensitivity of sadness was 94,2%.

LIMITATIONS

Even though we used a quota sampling method, the sample was not strictly representative of the general population.

CONCLUSION

Sadness validates the depressive continuum hypothesis, since it is more frequent in the general population than MDD itself and at the same time shares with MDD the same sociodemographic and clinical correlates. A gradual association from controls to MDD was observed for psychiatric comorbidities. Finally, the high sensitivity of sadness may suggest its use to screen at-risk individuals converting from well-being to full psychiatric disorders.

Negative Autobiographical Memory in Depression Reflects Elevated Amygdala-Hippocampal Reactivity and Hippocampally Associated Emotion Regulation

BACKGROUND

Dysregulated autobiographical recall is observed in major depressive disorder (MDD). However, it is unknown whether people with MDD show abnormalities in memory-, emotion-, and control-related brain systems during reactivity to and regulation of negative autobiographical memories.

METHODS

We used functional magnetic resonance imaging to identify neural mechanisms underlying MDD-related emotional responses to negative autobiographical memories and the ability to downregulate these responses using a cognitive regulatory strategy known as reappraisal. We compared currently depressed, medication-free patients with MDD (n = 29) with control participants with no history of depression (n = 23).

RESULTS

Relative to healthy control participants, medication-free MDD patients reported greater negative emotion during recall but relatively intact downregulation success. They also showed elevated amygdala activity and greater amygdala-hippocampal connectivity. This connectivity mediated the effect of MDD on negative emotional experience. When reappraising memories (vs. recalling from an immersed perspective), the MDD and control groups showed comparable recruitment of the prefrontal, parietal, and temporal cortices, and comparable downregulation of the amygdala and anterior hippocampus. However, MDD patients showed greater downregulation of the posterior hippocampus, and the extent of this downregulation predicted successful reduction of negative affect in MDD patients only.

CONCLUSIONS

These data suggest amygdala-hippocampal connectivity and posterior hippocampal downregulation as brain mechanisms related to elevated emotional reactivity and atypical emotion regulation in MDD.

Patients with anxious depression: overview of prevalence, pathophysiology and impact on course and treatment outcome

PURPOSE OF REVIEW

Major depressive disorder with a comorbid anxiety disorder or with significant anxiety symptoms (here called anxious depression) is common and has been associated with poor clinical course trajectories. However, various dichotomous as well as dimensional definitions have been used to label anxious depression and it remains unclear to which extent these result in inconsistent findings. This review provides an overview of recent literature on the impact of anxiety in depressed patients on clinical course trajectories, treatment outcomes, and underlying neurobiological dysregulations.

RECENT FINDINGS

Anxious depression seems associated with poorer clinical course trajectories and treatment nonresponse as compared with 'pure' depression, regardless of which definition is used. Recent studies have attempted to determine specific efficacy of novel pharmacological treatments for anxious depressed patients, but have not been conclusive because of the insufficient number of studies and differences in definitions and assessment of anxious depression. Neurobiology studies suggest that anxious depression is associated with increased immune dysregulation, more cortical thinning, and corticolimbic dysfunctions as compared with 'pure' depression.

SUMMARY

Anxious depression appears to be a common and clinically relevant subtype of depression as it predicts poorer course trajectories. As populations with anxious depression may benefit from specific treatment regimens, further research is necessary to better delineate its definition and neurobiology. The relatively new Diagnostic and Statistical Manual of Mental Disorders-5 anxious distress specifier is a welcome development and should be further investigated and compared against other anxiety constructs.

Associations between stress and depression symptom profiles vary according to serotonin transporter polymorphism in rural Australians

PURPOSE

Depression remains difficult to treat in all cases, and further investigation of the role of genetic and environmental factors may be valuable. This study was designed to investigate the association between the short (s) versus non-short (non-s) 5HTTLPR variants, presence of childhood stressors and recent life stressors, and depression, and to do so at two levels that would expose the associations between total depression scores and also individual depression items.

MATERIALS AND METHODS

Two hundred and forty-nine volunteers from one of the Australian Electoral Office electorates covering a large rural land area completed a series of questionnaires about childhood and recent life stress and depression, and provided a buccal cell sample for genotyping the 5-HTTLPR polymorphism into s versus non-s carriers.

RESULTS

Although there were no significant differences in the depression scores of the s-carriers versus the non-s carriers, each subtype of the 5-HTTLPR polymorphism showed different patterns of association between childhood stress and depression symptoms, and between recent life stress and depression symptoms.

CONCLUSION

Individualization of therapy for depression may be achieved through consideration of the specific associations that patients exhibit between life stress, 5-HTTLPR polymorphism, and depression symptomatology.

Downregulation of microRNA‑124‑3p suppresses the mTOR signaling pathway by targeting DDIT4 in males with major depressive disorder

Recent investigations have suggested that microRNAs (miRNAs or miRs) are involved in several pathways that may contribute to the pathomechanism of major depressive disorder (MDD). Sex may not only act as a demographic factor in clinical practive, but may also play a vital role in the molecular heterogeneity of MDD. Although many molecular changes correlated with MDD are found in males, the molecular mechanisms of MDD remain poorly understood. The present study performed bioinformatics analysis to investigate the pathomechanism of MDD in males. The present study identified miR‑124‑3p as one of the most dysregulated miRNAs in MDD, with decreased expression in the post‑mortem BA44 brain area of male patients with MDD. In addition, miR‑124‑3p targets DNA damage‑inducible transcript 4 (DDIT4) and specificity protein 1 (SP1), a DDIT4 transcription factor, in the validated target module of the miRWalk 2.0 database. This is concurrent with an increase in the expression level of DDIT4, which is an inhibitor of the mammalian target of rapamycin (mTOR) signaling pathway. It was also demonstrated that miR‑124‑3p expression was positively associated with mTOR signaling and this relationship was dependent on the tuberous sclerosis proteins 1/2 complex. Taken together, these results provided a novel insight on miR‑124‑3p involvement in the biological alterations of male patients with MDD and suggested that this miRNA may also serve as a male‑specific target for antidepressant treatment.

Treatment resistant depression: A multi-scale, systems biology approach

An estimated 50% of depressed patients are inadequately treated by available interventions. Even with an eventual recovery, many patients require a trial and error approach, as there are no reliable guidelines to match patients to optimal treatments and many patients develop treatment resistance over time. This situation derives from the heterogeneity of depression and the lack of biomarkers for stratification by distinct depression subtypes. There is thus a dire need for novel therapies. To address these known challenges, we propose a multi-scale framework for fundamental research on depression, aimed at identifying the brain circuits that are dysfunctional in several animal models of depression as well the changes in gene expression that are associated with these models. When combined with human genetic and imaging studies, our preclinical studies are starting to identify candidate circuits and molecules that are altered both in models of disease and in patient populations. Targeting these circuits and mechanisms can lead to novel generations of antidepressants tailored to specific patient populations with distinctive types of molecular and circuit dysfunction.

Environmental enrichment modulates the response to chronic stress in zebrafish

Several studies have shown that manipulations to the housing environment modulate the susceptibility to stress in laboratory animals, mainly in rodents. Environmental enrichment (EE) is one such manipulation that promotes neuroprotection and neurogenesis, besides affecting behaviors such as drug self-administration. Zebrafish are a popular and useful animal model for behavioral neuroscience studies; however, studies evaluating the impact of housing conditions in this species are scarce. In this study, we verified the effects of EE on behavioral (novel tank test) and biochemical (cortisol and reactive oxygen species (ROS)) parameters in zebrafish submitted to unpredictable chronic stress (UCS). Consistent with our previous findings, UCS increased anxiety-like behavior, cortisol and ROS levels in zebrafish. EE for 21 or 28 days attenuated the effects induced by UCS on behavior and cortisol, and prevented the effects on ROS levels. Our findings reinforce the idea that EE exerts neuromodulatory effects across species, reducing vulnerability to stress and its biochemical impact. Also, these results indicate that zebrafish is a suitable model animal to study the behavioral effects and neurobiological mechanisms related to EE.

Mitochondria, Microglia, and the Immune System-How Are They Linked in Affective Disorders?

Major depressive disorder (MDD) is a severe mood disorder and frequently associated with alterations of the immune system characterized by enhanced levels of circulating pro-inflammatory cytokines and microglia activation in the brain. Increasing evidence suggests that dysfunction of mitochondria may play a key role in the pathogenesis of MDD. Mitochondria are regulators of numerous cellular functions including energy metabolism, maintenance of redox and calcium homeostasis, and cell death and therefore modulate many facets of the innate immune response. In depression-like behavior of rodents, mitochondrial perturbation and release of mitochondrial components have been shown to boost cytokine production and neuroinflammation. On the other hand, pro-inflammatory cytokines may influence mitochondrial functions such as oxidative phosphorylation, production of adenosine triphosphate, and reactive oxygen species, thereby aggravating inflammation. There is strong interest in a better understanding of immunometabolic pathways in MDD that may serve as diagnostic markers and therapeutic targets. Here, we review the interaction between mitochondrial metabolism and innate immunity in the pathophysiology of MDD. We specifically focus on immunometabolic processes that govern microglial and peripheral myeloid cell functions, both cellular components involved in neuroinflammation in depression-like behavior. We finally discuss microglial polarization and associated metabolic states in depression-associated behavior and in MDD.

Gap junction channels as potential targets for the treatment of major depressive disorder

BACKGROUND

Major depressive disorder (MDD) remains a major public health problem worldwide. The association between MDD and the dysfunction of gap junction channels (GJCs) in glial cells, especially astrocytes, is still controversial.

OBJECTIVE

This review provides an overview of the role of astrocyte GJCs in LMDD.

RESULTS

Exposure to chronic unpredictable stress caused a reduction in connexin expression in the rat prefrontal cortex, a result that is consistent with clinical findings reported in postmortem studies of brains from MDD patients. Chronic antidepressant treatment in these rats increased the expression of connexins. However, pharmacological GJC blockade in normal rodents decreased connexin expression and caused depressive-like behaviors. Furthermore, GJC dysfunction affects electrical conductance, metabolic coupling and secondary messengers, and inflammatory responses, which are consistent with current hypotheses on MDD. All these results provide a comprehensive overview of the neurobiology of MDD.

CONCLUSION

This review supports the hypothesis that the regulation of GJCs between astrocytes could be an underlying mechanism for the therapeutic effect of antidepressants.

The effects of six-day SSRI administration on diurnal cortisol secretion in healthy volunteers

RATIONALE

Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis has been widely reported in depression, and evidence suggests that selective serotonin reuptake inhibitors (SSRIs) might exert their therapeutic effects through altering cortisol secretion.

OBJECTIVE

This study assessed the effects of SSRI administration on diurnal cortisol secretion in healthy volunteers.

METHODS

Sixty-four healthy men and women were randomised to receive either 10 mg escitalopram or placebo for six days in a double-blind fashion. On day six of medication, saliva samples were obtained at home for measurement of diurnal cortisol parameters (cortisol slope, cortisol awakening response, total daily cortisol output).

RESULTS

Women receiving escitalopram had significantly steeper cortisol slopes across the day compared with those receiving placebo (F(1, 36) = 7.54, p = 0.009). This alteration in cortisol slope was driven by increases in waking cortisol levels (F(1, 35) = 9.21, p = 0.005). Escitalopram did not have any significant effect on the cortisol awakening response or the total daily cortisol output.

CONCLUSIONS

Flattened cortisol slopes have been seen in depression. The results of this study suggest that escitalopram might exert its therapeutic effect in women in part through correction of a flattened diurnal cortisol rhythm.

Major depression and its treatment: microRNAs as peripheral biomarkers of diagnosis and treatment response

PURPOSE OF REVIEW

Major depressive disorder (MDD) is among the most prevalent and disabling medical conditions worldwide. Despite its considerable burden, our understanding of its pathophysiology remains rudimentary, and a validated biomarker has yet to be identified. Antidepressants are the most common treatment for MDD, yet roughly one-third of patients experience an inadequate response. Thus, there is a great need for not only identifying biomarkers of MDD but also those that can predict and monitor or just monitor response to treatment.

RECENT FINDINGS

MicroRNAs (miRNAs) act as endogenous fine-tuners and on-off switches of gene expression. Several lines of evidence now suggest that miRNAs are involved in the pathogenesis of neuropsychiatric disorders. As such, miRNAs offer great hope as biomarkers of disease and response to treatment.

SUMMARY

In this review, we discuss the growing field, investigating peripheral miRNAs as potential biomarkers of major depression and treatment response. A noninvasive and validated biomarker of MDD or treatment response will help clinicians guide treatment selection. Ultimately, these findings provide important steps in the development of early diagnostic tools, preventive strategies, and effective pharmacological treatment for psychiatric disorders.

Inflammatory Measures in Depressed Patients With and Without a History of Adverse Childhood Experiences

Background: Major depressive disorder (MDD) is a complex psychiatric condition with different subtypes and etiologies. Exposure to adverse childhood experiences (ACE) is an important risk factor for the development of MDD later in life. Evidence suggests that pro-inflammatory processes may convey this risk as both MDD and ACE have been related to increased levels of inflammation. In the present study, we aimed to disentangle the effects of MDD and ACE on inflammation levels. Methods: Markers of inflammation (plasma interleukin(IL)-6 and high sensitive C-reactive protein (hsCRP) concentrations, white blood cell (WBC) count and a composite inflammation score (CIS) combining all three) were assessed in 23 MDD patients with ACE, 23 MDD patients without ACE, 21 healthy participants with ACE, and 21 healthy participants without ACE (mean age: 35 ± 11 (SD) years). None of the patients and participants was taking psychotropic medication. ACE was assessed with the Early Trauma Inventory (ETI) and was defined as moderate to severe exposure to sexual or physical abuse. Results: Group differences in the different inflammatory measures were observed. MDD patients with ACE showed significantly higher IL-6 concentrations (p = 0.018), higher WBC counts (p = 0.003) and increased general inflammation levels as indicated by the CIS (p = 0.003) compared to healthy controls. In contrast, MDD patients without ACE displayed similar inflammation levels to the control group (p = 0.93). Conclusion: We observed elevated inflammation in MDD patients with a history of ACE, which could indicate a subtype of "inflammatory depression". Accordingly, MDD patients with ACE might potentially benefit from anti-inflammatory therapies.

The depressive-like behaviors of chronic unpredictable mild stress-treated mice, ameliorated by Tibetan medicine Zuotai: involvement in the hypothalamic-pituitary-adrenal (HPA) axis pathway

BACKGROUND

Zuotai, a famous Tibetan medicinal mixture containing metacinnabar, is traditionally used for the purpose of tranquilizing minds and soothing nerves. However, it still lacks substantial experimental data for it to be approved for use.

AIM

This study was designed to assess the effects of Zuotai on depressive-like symptoms in a chronic unpredictable mild stress (CUMS) mouse model, and to explore its potential mechanism, particularly the hypothalamic-pituitary-adrenal (HPA) axis pathway.

MATERIALS AND METHODS

First, Kunming mice were exposed to the CUMS procedure and simultaneously administered Zuotai or imipramine (positive control) by gavage continuously for 6 weeks. Then, depressive-like behaviors of mice in each group were tested with the sucrose preference test, forced swimming test, tail suspension test, and open field test. Meanwhile, the three key neuroendocrine hormones (corticotropin releasing hormone, adrenocorticotropic hormone and corticosterone) in HPA axis pathway, and the level of the emotion-related monoamine neurotransmitters (5-hydroxytryptamine and norepinephrine) were measured using enzyme-linked immunosorbent assay. Furthermore, total mercury in the hypothalamus and hippocampus were determined using an automatic, direct mercury analyzer.

RESULTS

Zuotai or imipramine significantly increased the body weight and the sucrose preference ratio in sucrose preference test, and dramatically improved motor activity in forced swimming test, tail suspension test, and open field test in CUMS mice. Zuotai or imipramine remarkably decreased levels of corticotropin-releasing hormone, adrenocorticotropic hormone, and corticosterone in the HPA axis, and increased levels of 5-hydroxytryptamine and norepinephrine in the serum in CUMS mice. However, a small amount of mercury was deposited in the hypothalamus and hippocampus in Zuotai-treated mice, which may pose a potential risk to the central nervous system.

CONCLUSION

Zuotai has a strong ability to ameliorate depressive-like behaviors in CUMS-treated mice through inhibition of the HPA axis and upregulation of monoamine neurotransmitters. These findings provide new insight into the pharmacological effect of Zuotai on depression.

Cognitive Behavioral Therapy Is Associated With Enhanced Cognitive Control Network Activity in Major Depression and Posttraumatic Stress Disorder

BACKGROUND

Both major depressive disorder (MDD) and posttraumatic stress disorder (PTSD) are characterized by depressive symptoms, abnormalities in brain regions important for cognitive control, and response to cognitive behavioral therapy (CBT). However, whether a common neural mechanism underlies CBT response across diagnoses is unknown.

METHODS

Brain activity during a cognitive control task was measured using functional magnetic resonance imaging in 104 participants: 28 patients with MDD, 53 patients with PTSD, and 23 healthy control subjects; depression and anxiety symptoms were determined on the same day. A patient subset (n = 31) entered manualized CBT and, along with controls (n = 19), was rescanned at 12 weeks. Linear mixed effects models assessed the relationship between depression and anxiety symptoms and brain activity before and after CBT.

RESULTS

At baseline, activation of the left dorsolateral prefrontal cortex was negatively correlated with Montgomery–Åsberg Depression Rating Scale scores across all participants; this brain–symptom association did not differ between MDD and PTSD. Following CBT treatment of patients, regions within the cognitive control network, including ventrolateral prefrontal cortex and dorsolateral prefrontal cortex, showed a significant increase in activity.

CONCLUSIONS

Our results suggest that dimensional abnormalities in the activation of cognitive control regions were associated primarily with symptoms of depression (with or without controlling for anxious arousal). Furthermore, following treatment with CBT, activation of cognitive control regions was similarly increased in both MDD and PTSD. These results accord with the Research Domain Criteria conceptualization of mental disorders and implicate improved cognitive control activation as a transdiagnostic mechanism for CBT treatment outcome.

Are adverse childhood experiences and depression associated with impaired glucose tolerance in females? An experimental study

Adverse childhood experiences (ACE) enhance the risk for mental disorders, e.g. major depressive disorder (MDD). Increasing evidence suggests an association between ACE and impaired physical health, e.g. metabolic syndrome. The aim of this study was to assess several metabolic risk markers in healthy individuals with and without ACE and depressed patients with and without ACE. We examined glucose and insulin release in the oGTT in 33 women with MDD and ACE, 47 women with MDD without ACE, 21 women with ACE but no current or lifetime MDD and 36 healthy women without either MDD or ACE. Several metabolic markers such as triglycerides, cholesterol, LDL, HDL, HbA1c, BMI and waist to hip ratio were assessed. The four groups did neither differ in insulin release and glucose concentrations in the oGTT nor with respect to other metabolic variables. Depressed patients with and without psychotropic medication did not differ in any outcome variable, but there was a trend towards higher glucose concentrations in the oGTT in patients with current psychotropic medication. In this physically healthy sample neither ACE nor MDD were associated with metabolic risk factors. Thus, metabolic alterations might not directly be linked to ACE and depression.

Recent Advances in Non-invasive Brain Stimulation for Major Depressive Disorder

Non-invasive brain stimulation (NBS) is a promising treatment for major depressive disorder (MDD), which is an affective processing disorder involving abnormal emotional processing. Many studies have shown that repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) over the prefrontal cortex can play a regulatory role in affective processing. Although the clinical efficacy of NBS in MDD has been demonstrated clinically, the precise mechanism of action remains unclear. Therefore, this review article summarizes the current status of NBS methods, including rTMS and tDCS, in the treatment of MDD. The article explores possible correlations between depressive symptoms and affective processing, highlighting the relevant affective processing mechanisms. Our review provides a reference for the safety and efficacy of NBS methods in the clinical treatment of MDD.

Salvianolic acid B promotes microglial M2-polarization and rescues neurogenesis in stress-exposed mice

Although accumulating evidence suggests that activated microglia are associated with deficits in neurogenesis and contribute to the physiopathology of major depressive disorder, the role of microglia in treating depression remains poorly understood. Our previous study showed that salvianolic acid (SalB) has the regulation of neuroinflammatory responses and antidepressant-like effects. Here, we hypothesized that SalB's therapeutic effects occur because it modulates microglial phenotypes that are associated with neurogenesis. To test this hypothesis, we treated CMS-exposed C57BL/6 mice with SalB (20mg/kg, intraperitoneally, once daily) for 3weeks and investigated microglial phenotypic profiles and hippocampal neurogenesis. The results showed that the SalB treatment skewed M1 microglial polarization toward M2 activation in the hippocampus and cortex and remedied CMS-induced deficits in hippocampal neurogenesis. SalB (40µM) inhibited LPS-stimulated microglial M1 activation as well as induced M2 activation in vitro, and the cultured microglia with the SalB treatment showed enhanced neural precursor cell proliferation, differentiation, and survival. SalB treatment also ameliorated the depressive-like behaviors of the CMS-treated mice in sucrose preference, forced swimming, and tail suspension tests. These findings suggest a possible antidepressive mechanism for anti-inflammatory agents that is correlated with microglial polarization and hippocampal neurogenesis and which may provide a new microglia-targeted strategy for depression therapy.