From Bound Cells Comes a Sound Mind: The Role of Neuronal Growth Regulator 1 in Psychiatric Disorders

Cell-to-cell adhesion is important for maintenance of brain structure and function. Abnormal neuronal cell adhesion and loss of its connectivity are considered a main cause of psychiatric disorders such as major depressive disorder (MDD). Various cell adhesion molecules (CAMs) are involved in neuronal cell adhesions and thereby affect brain functions such as learning and memory, cognitive functions, and psychiatric functions. Compared with other CAMs, neuronal growth regulator 1 (Negr1) has a distinct functioning mechanism in terms of its cross-talk with cytokine receptor signaling. Negr1 is a member of the immunoglobulin LON (IgLON) family of proteins and is involved in neuronal outgrowth, dendritic arborization, and synapse formation. In humans, Negr1 is a risk gene for obesity based on a genome-wide association study. More recently, accumulating evidence supports that it also plays a critical role in psychiatric disorders. In this review, we discuss the recent findings on the role of Negr1 in MDD, focusing on its regulatory mechanism. We also provide evidence of putative involvement of Negr1 in other psychiatric disorders based on the novel behavioral phenotypes of Negr1 knockout mice.

Antidepressant-like effects of ketamine in a mouse model of serotonergic dysfunction

Traditional monoaminergic treatments of depression frequently exhibit suboptimal tolerability and effectiveness. The 'short' (s) allele variant of 5-HTTLPR is known to compromise transcriptional efficacy of the serotonin transporter (5-HTT) and can reduce treatment response to traditional antidepressants (e.g. selective serotonin reuptake inhibitors or SSRIs). This study sought to establish the 5-HTT knock-out (KO) line as a mouse model of SSRI-resistant depression and assess its response to a novel glutamatergic antidepressant, ketamine, a non-competitive N-methyl-d-aspartate receptor (NMDAR) antagonist. Following acute antidepressant treatment, 5-HTT KO mice and wild-type (WT) controls were subjected to the forced-swim test (FST), one of the most widely used techniques to detect acute antidepressant response. As hypothesised, when assessed 30 min after administration in the FST, the SSRI sertraline (20 mg/kg, i.p.) produced antidepressant-like effects in WT control but not in 5-HTT KO mice. In contrast, ketamine (20 mg/kg, i.p.) induced antidepressant-like effects in both genotypes. 5-HTT KO mice also exhibited a reduced locomotor response to both MK-801 (another NMDAR antagonist) and ketamine, and reduced GluN2A protein levels in the hippocampus, suggesting glutamatergic dysfunction in this model. These results highlight the utility of 5-HTT KO mice as a relevant model of SSRI-resistant depression and demonstrate that ketamine can produce acute antidepressant-like effects in conditions of 5-HTT deficiency. These findings extend existing literature that indicates ketamine is effective in ameliorating symptoms of treatment-resistant depression and may have implications for understanding the cellular and molecular mechanisms underlying the antidepressant effects of ketamine. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

Altered Brain Entropy as a predictor of antidepressant response in major depressive disorder

OBJECTIVE

To explore the alterations and value of brain entropy (BEN) in major depressive disorder (MDD).

METHODS

85 MDD patients and 45 matched normal controls were recruited. MDD was diagnosed based on Diagnostic and Statistical Manual of Mental Disorders, 4th ed (DSM-IV). Symptoms of depression were assessed using the Hamilton depression scale-24 (HAMD-24) at baseline and follow-up (after 8-week treatment). All subjects underwent functional magnetic resonance imaging (fMRI) scans at baseline, and 30 MDD patients completed scans at 8th week. Whole brain BEN maps at each session was calculated using the BEN mapping toolbox.

RESULTS

The 8-week antidepressant treatment improved symptoms for all MDD patients. As compared to normal controls, MDD showed reduced BEN in medial orbitofrontal cortex (MOFC)/subgenual cingulate cortex (sgACC), but increased BEN in motor cortex (MC). In MDD patients, higher baseline BEN in MOFC/sgACC and lower baseline BEN in temporal cortex (TC) were associated with higher baseline HAMD scores; higher baseline BEN in MOFC/sgACC and hippocampus were associated with greater reduction of HAMD scores after 8-week medication; greater reduction of HAMD scores after 8-week medication was correlated with greater BEN reduction in MOFC/sgACC but were correlated with less BEN reduction in MC, TC, fusiform gyrus (FG) and visual cortex (VC).

CONCLUSION

The results highlighted MOFC/sgACC BEN as a potential marker for the prediction of MDD diagnosis and treatment effect. MDD might have increased MOFC/sgACC BEN but reduced BEN in visual and sensory-motor circuits corresponding to the imbalanced emotional and sensory-motor information processing. Reversing this unbalanced BEN would improve disease conditions in MDD.

Effects of the LHPP gene polymorphism on the functional and structural changes of gray matter in major depressive disorder

Background

A single-nucleotide polymorphism (SNP) of the LHPP gene (rs35936514) has been reported to be associated with major depressive disorder (MDD) in genome-wide association studies. However, the systems-level neural effects of rs35936514 that mediate the association are unknown. We hypothesized that variations in rs35936514 would be associated with structural and functional changes in gray matter (GM) at rest in MDD patients.

Methods

A total of 50 MDD patients and 113 healthy controls (HCs) were studied. Functional connectivity (FC) was analyzed by defining the bilateral hippocampus as the seed region. Voxel-based morphometry (VBM) was performed to assess the patterns of GM volume. The subjects were further divided into two groups: a CC homozygous group (CC; 24 MDD and 56 HC) and a risk T-allele carrier group (CT/TT genotypes; 26 MDD and 57 HC). A 2×2 analysis of variance (ANOVA: diagnosis × genotype) was used to determine the interaction effects and main effect (P<0.05).

Results

Significant diagnosis × genotype interaction effects on brain morphology and FC were noted. Compared to other subgroups, the MDD patients with the T allele showed an increased hippocampal FC in the bilateral calcarine cortex and cuneus and a decreased hippocampal FC in the right dorsolateral prefrontal cortex (DLPFC), bilateral anterior cingulate cortex (ACC), and medial prefrontal cortex (MPFC), in addition to reduced GM volume in the right DLPFC, bilateral temporal cortex, and posterior cingulate cortex (PCC).

Conclusions

LHPP gene polymorphisms may affect functional and structural changes in the GM at rest and may play an important role in the pathophysiological mechanisms of MDD.

Classification of Depression Patients and Normal Subjects Based on Electroencephalogram (EEG) Signal Using Alpha Power and Theta Asymmetry

Depression or Major Depressive Disorder (MDD) is a mental illness which negatively affects how a person thinks, acts or feels. MDD has become a major disease affecting millions of people presently. The diagnosis of depression is questionnaire based and is not based on any objective criteria. In this paper, feature extracted from EEG signal are used for the diagnosis of depression. Alpha, alpha1, alpha2, beta, delta and theta power and theta asymmetry was used as feature. Alpha1, alpha2 along with theta asymmetry was also used as a feature. Multi-Cluster Feature Selection (MCFS) was used for feature selection when feature combination was used. The classifiers used were Support Vector Machine (SVM), Logistic Regression (LR), Naïve-Bayesian (NB) and Decision Tree (DT). Alpha2 showed higher classification accuracy than alpha1 and alpha power in all applied classifier. From t-test it was found that there was a significant difference in the theta power of left and right hemisphere of normal subjects, but there was no significant difference in depression patients. Average theta asymmetry in normal subjects is higher than MDD patients but the difference in theta asymmetry in normal subjects and MDD patients is not significant. The combination of alpha2 and theta asymmetry showed the highest classification accuracy of 88.33% in SVM.

Psychiatric disorders are a common prognostic marker for worse outcome in patients with idiopathic intracranial hypertension

OBJECTIVE

Idiopathic intracranial hypertension (IIH) is aetiologically unknown disorder that associates with endocrinological disturbances, including dysfunction of hypothalamic-pituitary-adrenal-axis. Neuroendocrinological dysfunctions have also been characterized in psychiatric disorders, and therefore we investigated the presence of psychiatric disorders of patients with IIH in a well-defined cohort.

PATIENTS AND METHODS

A total of 51 patients with IIH were included. Patient demographics, symptoms, imaging data, ophthalmological and clinical findings were collected.

RESULTS

At the time of diagnosis the mean age was 32.5years (SD 10.7), the body mass index was 37.1 kg/m² (SD 7.4), and the opening pressure 29.1 mmHg (SD 6.2). A total of 88.2% of patients were female and 45.1% were diagnosed with a psychiatric co-morbidity prior to IIH diagnosis. The mean follow-up time was 4.4 years (SD 5.4). The overall treatment outcome was significantly poorer on a group of patients with psychiatric diagnosis when compared to individuals without such history (p = 0.001), but there were no differences in the resolution of papilledema (p = 0.405). Patients with IIH and psychiatric disorders had more often empty sella on their imaging at diagnosis when compared to patients without psychiatric co-morbidity (p = 0.044).

CONCLUSION

Psychiatric disorders are highly prevalent in patients with IIH and associate with worse subjective outcomes. These findings advocate for monitoring the mental health of patients with IIH and warrant further multidisciplinary research to understand the potentially underlying psychosocial and neuroendocrinological mechanisms.

Interferon-alpha-induced depression: Comparisons between early- and late-onset subgroups and with patients with major depressive disorder

Interferon (IFN)-alpha, until recently the standard treatment of hepatitis C virus (HCV) infection, is associated with a significant risk of major depressive episode (MDE, or IFN-alpha-induced depression). However, it is little studied the comparisons of clinical manifestations between IFN-alpha-induced depression and major depressive disorder (MDD). In addition, IFN-alpha induces different neuroinflammation and neuroendocrine status throughput the HCV treatment course; however, the clinical presentations have never been compared between early-onset and later-onset IFN-alpha-induced depression. We assessed 200 HCV patients starting IFN-alpha therapy bi-weekly for 24 weeks, with the structured interview for confirmation of diagnosis of IFN-alpha-induced depression and with clinical rating scales for depressive symptoms and neuropsychiatric symptoms. Subjects developed IFN-alpha-induced depression (n = 59, 30%) during the first 6 weeks of IFN-alpha therapy were defined as the early-onset group (n = 32), while those developed depression after the 6th week were defined as the late-onset group (n = 27). A matched group of MDD patients (n = 60) was used to compare specific clusters of depressive symptoms with early- and late-onset IFN-alpha-induced depression. Compared to the matched group of MDD patients, IFN-alpha-induced depression was significantly associated with more somatic symptoms and fewer symptoms of mood, anxiety and negative cognition. More somatic symptoms were also found in those who became clinically depressed at early stage of IFN-alpha therapy. We suggest that the specific somatic features of interferon-alpha-induced depression, and especially of early-onset depression, characterise individuals who are more sensitive to cytokines-induced changes in mood.

Calorie restriction in combination with prebiotic supplementation in obese women with depression: effects on metabolic and clinical response

BACKGROUND

Major depressive disorder (MDD) is a common psychiatric disorder, closely associated with obesity. This study aimed to assess the effects of prebiotics combined with calorie restriction on clinical and metabolic response in obese women with MDD.

METHODS

In an 8-week double-blind placebo-controlled randomized clinical trial, 62 obese women with MDD were equally allocated into either prebiotic (10 g/day Inulin) or placebo (10 g/day Maltodextrin) group. In addition, all the participants were also prescribed a 25% calorie-restricted diet (registration ID: IRCT20100209003320N15). Depression was assessed by Hamilton depression rating scale (HDRS) and Beck depression inventory (BDI-II) pre- and post-intervention. Anthropometric measures, fasting serum levels of glucose, insulin and lipid profile were assessed, and dietary assessments were performed pre- and post-intervention. Insulin resistance was estimated by homeostasis model assessment of insulin resistance (HOMA-IR).

RESULTS

45 patients completed the trial. There were no significant between-group differences for MDD symptoms and other study outcomes, post-intervention. Weight, waist and hip circumferences, systolic blood pressure, and HDRS score significantly decreased in both groups, while fat mass and total cholesterol (TC) declined only in the prebiotic arm. Those who had ≥1.9 kg weight loss showed significantly improved HDRS score, compared to women with <1.9 kg weight reduction, irrespective of the supplement they took.

CONCLUSION

Although prebiotic supplementation had some beneficial metabolic effects, calorie restriction and weight loss seem to play a more important role in improving depressive symptoms among obese women with MDD.

The glycine site of NMDA receptors: A target for cognitive enhancement in psychiatric disorders

Cognitive dysfunction is a principal determinant of functional impairment in major depressive disorder (MDD) and often persists during periods of euthymia. Abnormalities in the glutamate system, particularly in N-methyl-d-aspartate receptors (NMDARs) activity, have been shown to contribute to both mood and cognitive symptoms in MDD. The current narrative review aims to evaluate the potential pro-cognitive effects of targeting the glycine site of NMDARs in the treatment of psychiatric disorders, with a special focus on how these results may apply to MDD. Literature databases were searched from inception to May 2018 for relevant pre-clinical and clinical studies evaluating antidepressant and pro-cognitive effects of NMDAR glycine site modulators in both MDD and non-MDD samples. Six glycine site modulators with pro-cognitive and antidepressant properties were identified: d-serine (co-agonist), d-cycloserine (partial agonist), d-alanine (co-agonist), glycine (agonist), sarcosine (co-agonist) and rapastinel (partial agonist). Preclinical animal studies demonstrated improved neuroplasticity and pro-cognitive effects with these agents. Numerous proof-of-concept clinical trials demonstrated pro-cognitive and antidepressant effects trans-diagnostically (e.g., in healthy participants, MDD, schizophrenia, anxiety disorders, major neurocognitive disorders). The generalizability of these clinical studies was limited by the small sample sizes and the paucity of studies directly evaluating cognitive effects in MDD samples, as most clinical trials were in non-MDD samples. Taken together, preliminary results suggest that the glycine site of NMDARs is a promising target to ameliorate symptoms of depression and cognitive dysfunction. Additional rigorously designed clinical studies are required to determine the cognitive effects of these agents in MDD.

Antidepressant outcomes of high-frequency repetitive transcranial magnetic stimulation (rTMS) with F8-coil and deep transcranial magnetic stimulation (DTMS) with H1-coil in major depression: a systematic review and meta-analysis

BACKGROUND

The current study aims to systematically assess and compare the antidepressant outcomes of repetitive transcranial magnetic stimulation (rTMS) with the figure-of-eight (F8)-coil and deep transcranial magnetic stimulation (DTMS) with the H1-coil in studies matched on stimulation frequency in unipolar major depressive disorder (MDD).

METHODS

Electronic search of Medline and PsycInfo identified 19 studies with stimulation frequency of 18-20 Hz using F8-coil (k = 8 randomised sham-controlled trials, RCTs, k = 3 open-label; n = 168 patients) or H1-coil (k = 1 RCT, k = 7 open-label; n = 200). Depression severity (the primary outcome) and response/remission rates (the secondary outcomes) were assessed at session 10.

RESULTS

Effects pooled with random-effects meta-analysis showed a large reduction in depression severity, 29% response, and 15% remission rates after 10 sessions of active stimulation with either coil relative to baseline. Reduction in depression severity was greater in studies with younger patients using either coil. The comparison between coils showed a larger reduction in depression severity in H1-coil vs. F8-coil studies (independent of the study design or the concurrent pharmacotherapy) and a trend towards higher remission rates in F8-coil vs. H1-coils studies. These effects are based on a low volume of studies, are not controlled for placebo, and may not be clinically-relevant. The stimulation protocols differed systematically because stimulation was more focal but less intense (80-110% of the resting motor threshold, MT) in the F8-coil studies and less focal but more intense (120% MT) in the H1-coil studies. Two seizures occurred in the H1-coil studies relative to none in the F8-coil studies.

CONCLUSION

When matched on frequency, the higher-intensity and less focal stimulation with the H1-coil reduces depression more than the lower-intensity and more focal stimulation with the F8-coil. Head-to-head trials should compare the antidepressant outcomes of F8-coil and H1-coil to identify the most optimal stimulation protocols for acute and longer-lasting efficacy.

Altered cellular immune reactivity in traumatized women with and without major depressive disorder

Alterations of the hypothalamic-pituitary-adrenal (HPA) axis such as altered glucocorticoid receptor sensitivity and increased immune reactivity might contribute to the pathogenesis of major depressive disorder (MDD). Exposure to adverse childhood experiences (ACE) precipitates vulnerability to MDD and might be associated with endocrine and immune alterations in the disorder. In order to disentangle the effects of ACE and MDD, we recruited 87 women: n = 23 with MDD and ACE as determined by clinical interview and questionnaires (Structured Clinical Interview for DSM-IV, Early Trauma Inventory, Childhood Trauma Questionnaire), n = 24 with MDD without ACE, n = 21 with ACE but no current or lifetime MDD, and n = 26 healthy women without either MDD or ACE. Glucocorticoid signaling and mitogen-stimulated proliferation were analyzed ex vivo in peripheral blood-derived mononuclear cells. Additionally, mRNA expression of the glucocorticoid and the mineralocorticoid receptor (GR / MR) was assessed. Peripheral GR sensitivity as well as GR and MR expression levels were not significantly different between groups. Women with ACE showed an increased immune response after mitogen stimulation independent of the presence of MDD. Our results provide evidence for a functionally altered ex-vivo immune response in cell cultures from women with a history of ACE. Thus, ACE might contribute to the pathogenesis of MDD through inflammatory pathways.

Investigating executive control network and default mode network dysfunction in major depressive disorder

Major depressive disorder (MDD) is a mental disorder that causes a persistent feeling of sadness and loss of interest. It affects how you feel, think and behave and can lead to a variety of emotional and physical problems. Previous investigated the MDD has primarily focused on interpreting the abnormal functional connectivity of different brain regions, rather than entire brain networks. Although recent studies have found depression-related abnormalities functional connectivity of the brain networks, it is not clear the certain brain regions or the various functional networks as a whole are involved in the emotional dysregulation of depression. Moreover, abnormal functional connectivity regions are well replicated research, however, default mode network (DMN) and executive control network (ECN) haven't received adequately examined in MDD. To address the above issues, in this paper, we adopt sparse inverse covariance estimation (SICE) approach to investigate the functional connectivity both DMN and ECN. Our experimental results show functional connectivity of ECN have significantly changed in MDD, where the anterior cingulate cortex (ACG.R) region and the thalamus region (THA.R) have shown increased functional connectivity compared with normal control, the superior frontal gyrus (SFGmed.R) region has shown decreased functional connectivity. Moreover, the precuneus lobule (PCUN.L) region and posterior cingulate cortex (PCG.L) of DMN have shown increased functional connectivity. These results may suggest that MDD is associated with large-scale functional networks, rather than the portions of brain regions. These changed functional connectivity may provide more neuroimaging biomarker for MDD diagnosis.

History of major depression is associated with neuropsychiatric symptoms but not systemic inflammation in a cross-sectional study in obese patients

Obesity is a major public health burden associated with neuropsychiatric comorbidities leading to social and occupational impairment. Given the growing prevalence of both obesity and mental disorders worldwide, understanding the risk factors of obesity-related neuropsychiatric comorbidities is crucial to develop preventive strategies and individualized treatments. Recent findings suggest that adiposity-driven inflammation contributes to neuropsychiatric comorbidities in obesity. However, not all obese subjects afflicted with chronic inflammation develop neuropsychiatric symptoms, suggesting additional risk factors. The aim of this study was to investigate the impact of personal history of major depressive disorder (MDD) on obesity-related inflammation and neuropsychiatric symptoms, and their relationship. A case-control study was conducted comparing 66 obese patients (body mass index > 35 kg/m²) and 22 healthy non-obese participants, free of any current neuropsychiatric diseases including MDD. Neuropsychiatric symptoms were assessed using the Neurotoxicity Rating Scale (NRS). Sociodemographic and clinical variables were gathered and blood was collected for the measurement of serum levels of high-sensitivity C-reactive protein (hs-CRP). Multiple regression analyses were performed to assess the contribution of obesity and personal history of MDD to clinical outcomes and inflammatory status in study participants. Hs-CRP levels as well as NRS scores were significantly increased in the obese group. Overall, personal history of depression accounted for increased NRS scores but no significant association was found with inflammatory status. In addition, history of depression did not significantly modulate the relationship of obesity-related inflammation with NRS scores. Interestingly, obese individuals with history of recurrent MDD (n = 13) exhibited higher scores in the cognitive and sickness symptoms dimensions of the NRS compared to obese subjects with history of one depressive episode only. Findings indicate that history of depression contributes to neuropsychiatric symptoms, but not to systemic inflammation, in obese subjects free of current depressive episode. These results provide relevant information on the risk factors that may help identify obese subjects with increased risk of neuropsychiatric comorbidity.

Attentional bias modification reduces clinical depression and enhances attention toward happiness

Difficulty in clinical antidepressant treatment leads to the pursuit of alternative treatments, such as cognitive-behavior therapy (CBT). CBT combined with regular antidepressants have indicated an optimal therapeutic effect in clinic. Attentional bias is important in the occurrence and remission of depression, however, few studies have explored the effect of attentional bias modification (ABM) on depression, and inconsistent results have been obtained due to the heterogeneity in the targeted populations, training tasks, strategies, and materials. Hence, the current study aimed to explore the therapeutic effect of ABM on depression in clinical depression. Study I was designed to explore the optimal training methods regarding task (dot-probe vs. cue-target), material (faces vs. self-referent words), and strategy (mixed ABM toward positive and away from negative stimuli vs. positive ABM toward positive stimuli) in unselected undergraduates once daily for 10 days (N = 309). Study II was carried out to observe the effect of 10 days ABM toward positive and away from negative faces (based on Study I) on clinical depression (N = 32). Depression level was assessed via a self-reporting questionnaire and a structured interview, while attentional bias was tested by cue-target task and attention to positive and negative inventory (APNI). In unselected undergraduates (Study I), two strategies significantly reduced the self-reporting depression scores: mixed ABM toward positive stimuli and away from negative stimuli with emotional faces, and positive ABM toward positive materials only with self-referent words. In patients with major depressive disorder (MDD) (Study II), the mixed ABM with emotional faces resulted in enhanced attentional bias toward happy materials in the cue-target task and APNI, which predicted a delayed depression reduction in clinical depression at the one-month follow-up investigation. Our finding confirms the literature and broadens the knowledge with the evidence of the optimal therapeutic effect of ABM combined with regular antidepressants in clinical depression. The findings that a quick enhancement in positive attentional bias, predicting a later therapeutic effect on clinical depression reduction, indicate a potential mechanism that could underlie the therapeutic process of ABM in depression. The findings that two training strategies are effective in depression reduction suggest that different strategies should be utilized to treat different types of depression. This study offers a potential way to cure depression and could be further practiced in clinic.

Severity-dependent and -independent brain regions of major depressive disorder: A long-term longitudinal near-infrared spectroscopy study

BACKGROUND

Long-term longitudinal studies are necessary to establish neuroimaging indicators which contribute to the detection of severity changes over time in patients with major depressive disorder (MDD).

METHODS

One hundred sixty-five patients with MDD underwent clinical assessments and near-infrared spectroscopy (NIRS) examination at the initial evaluation (T0). After 1.5 years, 45 patients who visited for the follow-up evaluation (T1.5) were included in the analysis. The authors conducted analyses using the 17-item Hamilton Rating Scale for Depression (HAMD) scores and mean oxy-hemoglobin concentration ([oxy-Hb]) changes during a cognitive task in NIRS at T0 (T0_HAMD, T0_[oxy-Hb]) and at T1.5 (T1.5_HAMD, T1.5_[oxy-Hb]), and their intra-individual longitudinal changes (ΔHAMD = T1.5_HAMD - T0_HAMD, Δ[oxy-Hb] = T1.5_[oxy-Hb] - T0_[oxy-Hb]).

RESULTS

For severity-dependent regions, the Δ[oxy-Hb] in the right inferior frontal gyrus (IFG) was negatively correlated with the ΔHAMD. For severity-independent regions, the intra-class correlation coefficients between T0_ and T1.5_[oxy-Hb] were moderate in the bilateral middle frontal gyri (MFG).

LIMITATIONS

The percentage of patients included in the follow-up examination was relatively small.

CONCLUSIONS

Brain activation in the right IFG and the bilateral MFG as measured by NIRS may differentially indicate clinical severity and trait-related abnormalities in MDD.

A P2X7 receptor antagonist reverses behavioural alterations, microglial activation and neuroendocrine dysregulation in an unpredictable chronic mild stress (UCMS) model of depression in mice

A polymorphism in the P2RX7 gene that encodes for the P2X7 ionotropic ATP-gated receptor (P2X7R) protein has been shown to be associated with an increased risk for developing depressive illnesses. However, the role of P2X7R in depression is still unclear. To better understand the role of P2X7R and its subsequent impact on microglial activation, we compared the effect of the P2X7R antagonist Brilliant Blue G (BBG) with that of fluoxetine in an unpredictable chronic mild stress (UCMS) model of depression in mice. Our results indicate that BBG (50 mg/kg body weight in 0.9% NaCl, 10 ml/kg/day) successfully reversed the degradation of coat states and nest-building scores induced by exposure to UCMS, similar to the conventional antidepressant fluoxetine (15 mg/kg body weight in 0.9% NaCl, 10 ml/kg/day). BBG also reversed the UCMS-induced microglial activation in cortical and hippocampal regions and the basal nuclei of mouse brains and corrected the UCMS-induced hypothalamo-pituitary-adrenal (HPA) axis dysregulation. In contrast to fluoxetine, however, BBG treatment did not increase the density of doublecortin-positive cells in the dentate gyrus, indicating that BBG had no impact on hippocampal neurogenesis. These results suggest that P2X7R is involved in recovery from depressive-like states caused by exposure to UCMS in a mechanism that involves restoration of the HPA axis but not hippocampal neurogenesis. These results add to the evidence that P2X7R antagonist agents may have potential value in the pharmacological management of depression.

Family History as an Important Factor for Stratifying Participants in Genetic Studies of Major Depression

Depression is estimated to affect 350 million people worldwide. The World Mental Health Survey conducted in 17 countries found that, on average, about one in 20 people reported having an episode of depression in the previous year. Although depression has been shown to be moderately heritable by studies conducted in the past, the search for its so-called missing heritability has so far been unsuccessful. The difficulty in identifying common genetic variants predisposing to depression could be due to large sample sizes needed to detect small effects on genetic risk and the heterogeneous nature of major depressive disorder (MDD). The aim of our study was to determine whether there was a connection between a family history of depression in MDD patients and the presence of putative risk variants in the well-studied SLC6A4, COMT and PCLO genes. We analyzed 133 patients with MDD (30.0% with a positive family history for MDD and 70.0% sporadic cases) and compared them to 279 healthy controls. When comparing all the depressed patients to controls, no significant differences in genotype and allele distributions were detected. After stratifying patients according to their family history, the PCLO rs2522833 C allele was shown to be significantly less common in patients with a positive family history (p = 0.001), indicating a possible difference in the genetic structure of MDD between familial and sporadic cases and a less important role of the common genetic risk variants for the development of MDD in familial cases.

Ketamine influences the locus coeruleus norepinephrine network, with a dependency on norepinephrine transporter genotype - a placebo controlled fMRI study

Background

Ketamine is receiving increasing attention as a rapid-onset antidepressant in patients suffering from major depressive disorder (MDD) with treatment resistance or severe suicidal ideation. Ketamine modulates several neurotransmitter systems, including norepinephrine via the norepinephrine transporter (NET), both peripherally and centrally. The locus coeruleus (LC), which has high NET concentration, has been attributed to brain networks involved in depression. Thus we investigated the effects of single-dose of racemic ketamine on the LC using resting state functional MRI.

Methods

Fifty-nine healthy participants (mean age 25.57 ± 4.72) were examined in a double-blind, randomized, placebo-controlled study with 7 Tesla MRI. We investigated the resting state functional connectivity (rs-fc) of the LC before and one hour after subanesthetic ketamine injection (0.5 mg/kg), as well as associations between its rs-fc and a common polymorphism in the NET gene (rs28386840).

Results

A significant interaction of drug and time was revealed, and post hoc testing showed decreased rs-fc between LC and the thalamus after ketamine administration compared with baseline levels, including the mediodorsal, ventral anterior, ventral lateral, ventral posterolateral and centromedian nuclei. The rs-fc reduction was more pronounced in NET rs28386840 [AA] homozygous subjects than in [T] carriers.

Conclusions

We demonstrated acute rs-fc changes after ketamine administration in the central node of the norepinephrine pathway. These findings may contribute to understanding the antidepressant effect of ketamine at the system level, supporting modes of action on networks subserving aberrant arousal regulation in depression.

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Ketamine decreased connectivity between locus coeruleus and bilateral thalamus in resting state fMRI.

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This reduction of rs-fc between LC and thalamus was dependent on norepinephrine transporter genotype.

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The central effects of ketamine involve norepinephrine and attention networks.

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Antidepressive effects of ketamine may involve LC attention system.

Role of a VGF/BDNF/TrkB Autoregulatory Feedback Loop in Rapid-Acting Antidepressant Efficacy

Members of the neurotrophin family and in particular brain-derived neurotrophic factor (BDNF) regulate the response to rapid- and slow-acting chemical antidepressants and voluntary exercise. Recent work suggests that rapid-acting antidepressants that modulate N-methyl-D-aspartate receptor (NMDA-R) signaling (e.g., ketamine and GLYX-13) require expression of VGF (non-acronymic), the BDNF-inducible secreted neuronal protein and peptide precursor, for efficacy. In addition, the VGF-derived C-terminal peptide TLQP-62 (named by its 4 N-terminal amino acids and length) has antidepressant efficacy following icv or intra-hippocampal administration, in the forced swim test (FST). Similar to ketamine, the rapid antidepressant actions of TLQP-62 require BDNF expression, mTOR activation (rapamycin-sensitive), and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor activation (NBQX-sensitive) and are associated with GluR1 insertion. We review recent findings that identify a rapidly induced autoregulatory feedback loop, which likely plays a critical role in sustained efficacy of rapid-acting antidepressants, depression-like behavior, and cognition, and requires VGF, its C-terminal peptide TLQP-62, BDNF/TrkB signaling, the mTOR pathway, and AMPA receptor activation and insertion.

Targeting cytokines in reduction of depressive symptoms: A comprehensive review

Heterogeneity in response to conventional antidepressants is a well-recognized limitation of evidence-based pharmacological treatments of major depressive disorder (MDD). Abnormal activation of inflammatory pathways is postulated as one likely mechanism contributing to treatment resistance in MDD. In a subset of depressed patients, the balance between pro- and anti-inflammatory cytokines is thought to be altered, causing mood symptoms due to inflammation, as seen in co-morbid depression associated with inflammatory conditions (e.g. psoriasis, hepatitis C, inflammatory bowel disease, rheumatoid arthritis, ankylosing spondylitis). The objectives of the current narrative review are to critically evaluate the literature about the effects of cytokine blockers on clinical outcomes in MDD and in the reduction of depressive symptom severity in individuals using these medications primarily to treat inflammatory conditions. A small number of clinical trials assessing the effects of cytokine blockers for depression and depressive symptoms have been completed. These trials suggest that in individuals with immune dysfunction (e.g. elevated pro-inflammatory cytokine levels), cytokine blockers may allow for improved clinical outcomes in MDD that would not be achievable with current conventional antidepressants alone. Additional well-designed clinical trials to assess the clinical utility of anti-inflammatory medications for the treatment of depression and depressive symptoms are merited. Further, the use of anti-inflammatories show promise for disease modifying effects that may alter illness trajectory, rather than solely ameliorating current mood symptoms.

A randomized controlled dosing study of Iyengar yoga and coherent breathing for the treatment of major depressive disorder: Impact on suicidal ideation and safety findings

BACKGROUND

Yoga interventions offer promise for the treatment of major depressive disorder (MDD), yet their safety and potential impact on suicidal ideation (SI) have not been well documented. This study evaluated the safety of a randomized controlled dose-finding trial of Iyengar yoga plus coherent breathing for individuals with MDD, as well as the potential effects of the intervention on SI without intent.

METHODS

Participants with Beck Depression Inventory-II (BDI-II) scores ≥14 and a diagnosis of MDD (using DSM-IV criteria) were randomized to either a low dose group (LDG) or high dose group (HDG) and received a 12-week manualized intervention. The LDG included two 90-min yoga classes plus three 30-min homework sessions weekly. The HDG offered three 90-min classes plus four 30-min homework sessions weekly.

RESULTS

Thirty-two individuals with MDD were randomized, of which 30 completed the protocol. At screening, SI without intent was endorsed on the BDI-II by 9 participants; after completing the intervention, 8 out of 9 reported resolution of SI. There were 17 adverse events possibly-related and 15 definitely-related to the intervention. The most common protocol-related adverse event was musculoskeletal pain, which resolved over the course of the study.

CONCLUSIONS

The Iyengar yoga plus coherent breathing intervention was associated with the resolution of SI in 8 out of 9 participants, with mild side effects that were primarily musculoskeletal in nature. This preliminary evidence suggests that this intervention may reduce SI without intent and be safe for use in those with MDD.

Eicosapentaenoic and docosahexaenoic acids have different effects on peripheral phospholipase A2 gene expressions in acute depressed patients

INTRODUCTION

Omega-3 polyunsaturated fatty acids (PUFAs) have been proven critical in the development and management of major depressive disorder (MDD) by a number of epidemiological, clinical and preclinical studies, but the molecular mechanisms underlying this therapeutic action are yet to be understood. Although eicosapentaenoic acid (EPA) seems to be the active component of omega-3 PUFAs' antidepressant effects, the biological research about the difference of specific genetic regulations between EPA and docosahexaenoic acid (DHA), the two main components of omega-3 PUFAs, is still lacking in human subjects.

METHODS

We conducted a 12-week randomized-controlled trial comparing the effects of EPA and DHA on gene expressions of phospholipase A2 (cPLA2) and cyclooxygenase-2 (COX2), serotonin transporter (5HTT), and Tryptophan hydroxylase 2 (TPH-2) in 27 MDD patients. In addition, the erythrocyte PUFA compositions and the candidate gene expressions were also compared between these 27 MDD patients and 22 healthy controls.

RESULTS

EPA was associated with a significant decrease in HAM-D scores (CI: -13 to -21, p<0.001) and significant increases in erythrocyte levels of EPA (CI: +1.0% to +2.9%, p=0.001) and DHA (CI: +2.9% to +5.6%, p=0.007). DHA treatment was associated with a significant decrease in HAM-D scores (CI: -6 to -14, p<0.001) and a significant increase in DHA levels (CI: +0.2% to +2.3%, p=0.047), but not of EPA levels. The cPLA2 gene expression levels were significantly increased in patients received EPA (1.9 folds, p=0.038), but not DHA (1.08 folds, p=0.92). There was a tendency for both EPA and DHA groups to decrease COX-2 gene expressions. The gene expressions of COX-2, cPLA2, TPH-2 and 5-HTT did not differ between MDD cases and healthy controls.

CONCLUSIONS

EPA differentiates from DHA in clinical antidepressant efficacy and in upregulating cPLA2 gene regulations, which supports the clinical observation showing the superiority of EPA's antidepressant effects.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02615405.

The dexamethasone corticotropin releasing hormone test in healthy and depressed women with and without childhood adversity

BACKGROUND

Alterations of the hypothalamic-pituitary-adrenal (HPA) axis are a prominent finding in patients with major depressive disorder (MDD). Inconsistencies regarding a hyper- or hypoactive HPA axis may be explained by the moderating effect of childhood adverse experiences (ACE) which are associated with both HPA axis dysfunction and MDD in adulthood. We aimed to systematically disentangle the effects of ACE and MDD on HPA axis by comparing healthy women with and without childhood adversity and women with MDD with and without ACE.

METHODS

The dexamethasone/corticotropin-releasing hormone (DEX/CRH) test was administered in 35 women with MDD and ACE as determined by a clinical interview (SCID, Early Trauma Inventory), 51 women with MDD without ACE, 21 women with ACE but no current or lifetime MDD and 37 healthy women without either MDD or ACE.

RESULTS

There were no group differences in age, smoking, body mass index, and intake of oral contraceptives. Free salivary cortisol responses were not significantly different between the four groups.

CONCLUSIONS

This study shows no evidence for a dysregulation of the HPA axis as measured by the DEX/CRH test in depressed women with and without childhood adversity as compared to mentally healthy women with or without early life stress. Our results do not support the assumption of distinct neuroendocrine endophenotypes in MDD with regard to ACE.

The effects of interleukin-6 neutralizing antibodies on symptoms of depressed mood and anhedonia in patients with rheumatoid arthritis and multicentric Castleman's disease

Cytokines, including interleukin-6 (IL-6), modulate neuronal plasticity and stress coping. Depressive symptoms and major depressive disorder (MDD) have been associated with changes in cytokines and their signaling. The current study examined the effect of IL-6 monoclonal antibody administration on depressive symptoms in patients with rheumatoid arthritis (RA) or multicentric Castleman's disease (MCD). The data were obtained from two phase 2, double-blind, placebo-controlled trials designed to test the efficacy of sirukumab in RA (N=176) or of siltuximab in MCD (N=65), and were analyzed post hoc to investigate the effects of these IL-6 antibodies on depressive symptoms. The SF-36 questionnaire items on depressed-mood and anhedonia were combined as the measure for depressive symptoms. The study participants were grouped by the presence/absence of prevalent depressed mood and anhedonia (PDMA, meaning either depressed mood or anhedonia was present at least 'most of the time' and the other at least 'some of the time' for four weeks) at baseline; 26.1% of the RA sample and 15.4% of the MCD sample met criteria for PDMA at baseline. Compared with placebo, sirukumab and siltuximab produced significantly greater improvements on depressive symptoms. To account for an effect on mood due to changes in RA or MCD, the analysis was (1) adjusted for symptom severities using DAS28-CRP for RA and MCDOS for MCD alone or together with bodily pain and physical functioning, and (2) performed within RA and MCD non-responders. Improvement in depressive symptoms remained significant in the treated group for both drugs. The significance over placebo was also observed in the siltuximab study. The improvement in depressive symptoms by sirukumab correlated positively with the baseline soluble IL-6 receptor levels. The data together suggest that the IL-6 antibodies improve depressive symptoms in patients with RA and MCD. Further studies are needed to elucidate to what extents the IL-6 antibodies improve depressive symptoms through improving primary disease dependent and independent mechanisms, especially in RA patients, and the brain mechanisms underlying depressive symptom improvements.

Challenges in comparing the acute cognitive outcomes of high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) vs. electroconvulsive therapy (ECT) in major depression: A systematic review

The present study aimed to systematically compare the cognitive outcomes of high-frequency repetitive transcranial magnetic stimulation (HF-rTMS) and electroconvulsive therapy (ECT) in head-to-head studies with major depression (MDD) patients. A systematic literature search identified six studies with 219 MDD patients that were too heterogeneous to reliably detect meaningful differences in acute cognitive outcomes after ECT vs. HF-rTMS. Cognitive effects of brain stimulation vary depending on the timeframe and methods of assessment, stimulation parameters, and maintenance treatment. Thus, acute and longer-term differences in cognitive outcomes both need to be investigated at precisely defined timeframes and with similar instruments assessing comparable functions.

Gray Matter Abnormalities in Non-comorbid Medication-naive Patients with Major Depressive Disorder or Social Anxiety Disorder

Background

An overlap of clinical symptoms between major depressive disorder (MDD) and social anxiety disorder (SAD) suggests that the two disorders exhibit similar brain mechanisms. However, few studies have directly compared the brain structures of the two disorders. The aim of this study was to assess the gray matter volume (GMV) and cortical thickness alterations between non-comorbid medication-naive MDD patients and SAD patients.

Methods

High-resolution T1-weighted images were acquired from 37 non-comorbid MDD patients, 24 non-comorbid SAD patients and 41 healthy controls (HCs). Voxel-based morphometry analysis of the GMV (corrected with a false discovery rate of p < 0.001) and vertex-based analysis of cortical thickness (corrected with a clusterwise probability of p < 0.001) were performed, and group differences were compared by ANOVA followed by post hoc tests.

Outcomes

Relative to the HCs, both the MDD patients and SAD patients showed the following results: GMV reductions in the bilateral orbital frontal cortex (OFC), putamen, and thalamus; cortical thickening in the bilateral medial prefrontal cortex, posterior dorsolateral prefrontal cortex, insular cortex, left temporal pole, and right superior parietal cortex; and cortical thinning in the left lateral OFC and bilateral rostral middle frontal cortex. In addition, MDD patients specifically showed a greater thickness in the left fusiform gyrus and right lateral occipital cortex and a thinner thickness in the bilateral lingual and left cuneus. SAD patients specifically showed a thinner cortical thickness in the right precentral cortex.

Interpretation

Our results indicate that MDD and SAD share common patterns of gray matter abnormalities in the orbitofrontal-striatal-thalamic circuit, salience network and dorsal attention network. These consistent structural differences in the two patient groups may contribute to the broad spectrum of emotional, cognitive and behavioral disturbances observed in MDD patients and SAD patients. In addition, we found disorder-specific involvement of the visual processing regions in MDD and the precentral cortex in SAD. These findings provide new evidence regarding the shared and specific neuropathological mechanisms that underlie MDD and SAD.

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MDD and SAD share common gray matter abnormalities in the orbitofrontal-striatal-thalamic circuit, salience and dorsal attention network.

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MDD patients show disorder-specific involvement of the visual processing regions.

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SAD patients show disorder-specific involvement of the precentral cortex.

An overlap of clinical symptoms between major depressive disorder (MDD) and social anxiety disorder (SAD) suggests similar brain mechanisms for the two disorders. However, few studies have directly compared the brain structures of the two disorders. The aim of this study was to assess gray matter volume and cortical thickness alterations between non-comorbid medication-naive MDD patients and SAD patients. We found that MDD and SAD shared a common pattern of gray matter abnormalities in the orbitofrontal-striatal-thalamic circuit, salience network and dorsal attention network. MDD patients showed disorder-specific involvement of the visual processing regions. SAD patients showed disorder-specific involvement of the precentral cortex.

Determination of a clinically important difference and definition of a responder threshold for the UCSD performance-based skills assessment (UPSA) in patients with major depressive disorder

BACKGROUND

This article reports an evaluation of the psychometric properties and clinically important difference (CID) threshold of the UCSD Performance-Based Skills Assessment (UPSA) in major depressive disorder (MDD), using data from a large-scale study of the effects of vortioxetine on cognitive functioning and functional capacity in MDD patients.

METHODS

Adults with moderate-to-severe recurrent MDD and self-reported cognitive dysfunction were randomized to 8 weeks of double-blind treatment with vortioxetine 10/20mg QD (flexible), duloxetine 60mg QD, or placebo. Pearson correlation coefficients were calculated between UPSA composite score and demographic/disease characteristics at baseline to examine construct validity. Two methods (distribution-based and anchor-based) were used to establish a CID threshold.

RESULTS

A total of 602 patients were randomized; 528 comprised the full analysis set. For the entire sample mean UPSA composite scores were 77.8 at baseline and 83.9 at week 8 (mean change, +6.1). As hypothesized, at baseline, the UPSA composite score correlated with cognitive functioning (Digit Symbol Substitution Test: r=0.36, P<0.001) and workplace productivity (Work Limitations Questionnaire: r=-0.17, P=0.008), but not depressive symptoms (Montgomery-Åsberg Depression Rating Scale: r=0.02, P=0.707) or subjective cognitive dysfunction (Perceived Deficits Questionnaire: r=-0.02, P=0.698).

LIMITATIONS

Two versions of the UPSA were used and no inclusion/exclusion criteria were based on the UPSA.

CONCLUSIONS

These results support the construct validity of UPSA for assessing functional capacity independent of mood symptoms. The estimated CID for changes in UPSA scores was quite consistent at +6.4 points and +6.7 based on distribution-based and anchor-based methods, respectively.

Electroretinographic anomalies in medicated and drug free patients with major depression: Tagging the developmental roots of major psychiatric disorders

The retina is tagged as an approachable part of the brain due to its common embryonic origin and appears as a promising site of investigation for psychiatric disorders. Retinal function is assessed best with the electroretinogram (ERG), which was obtained in a large sample of patients with major depressive disorder and matched controls. ERG cone and rod luminance response functions were recorded in non-dilated eyes in 100 major depressive disorder patients (MDD) and 100 controls, (mean age of 42.8 and 40.9y. o. respectively). Amongst MDD patients, 17 were drug free (mean age 41.2y. o). In medicated patients, at the cone level, a prolonged b-wave was observed (p≤0.01). In drug free patients a prolonged b-wave was discovered only when averaging the implicit time of the 3 highest b-wave amplitudes of the photopic hill. For the medicated patients, the mixed rods/cones a-wave was reduced (p=0.01) whereas a trend (p=0.06) was observed for the pure rod b-wave (reduced) and the mixed rods/cones (reduced and prolonged; p=0.05). In drug free patients, a similar pattern could be observed in terms of effect sizes. Overall, medicated and drug free MDD patients shared some deficits suggesting that some anomalies are present above and beyond the effect of medication. Of interest, the prolonged cone and reduced rod amplitude were reported by our group in schizophrenia patients, suggesting a common neurodevelopmental root of major psychiatric disorders.

Clinical utility of resting-state functional connectivity magnetic resonance imaging for mood and cognitive disorders

Although functional magnetic resonance imaging (fMRI) has long been used to assess task-related brain activity in neuropsychiatric disorders, it has not yet become a widely available clinical tool. Resting-state fMRI (rs-fMRI) has been the subject of recent attention in the fields of basic and clinical neuroimaging research. This method enables investigation of the functional organization of the brain and alterations of resting-state networks (RSNs) in patients with neuropsychiatric disorders. Rs-fMRI does not require participants to perform a demanding task, in contrast to task fMRI, which often requires participants to follow complex instructions. Rs-fMRI has a number of advantages over task fMRI for application with neuropsychiatric patients, for example, although applications of task fMR to participants for healthy are easy. However, it is difficult to apply these applications to patients with psychiatric and neurological disorders, because they may have difficulty in performing demanding cognitive task. Here, we review the basic methodology and analysis techniques relevant to clinical studies, and the clinical applications of the technique for examining neuropsychiatric disorders, focusing on mood disorders (major depressive disorder and bipolar disorder) and dementia (Alzheimer's disease and mild cognitive impairment).

High-dose antidepressants affect near-infrared spectroscopy signals: A retrospective study

BACKGROUND

Recent studies have highlighted the clinical usefulness of near-infrared spectroscopy (NIRS) in psychiatry. However, the potential effects of psychotropics on NIRS signals remain unknown.

METHODS

We conducted a systematic chart review of 40 depressed patients who underwent NIRS scans during a verbal fluency task to clarify the relationships between psychotropic dosage and NIRS signals. The dosage of psychotropic medications was calculated using defined daily dose (DDD). We investigated the associations between the DDD of psychotropic medications and oxygenated hemoglobin (oxy-Hb) in single channel levels.

LIMITATIONS

Retrospective study design and small sample size are the main limitations.

RESULTS

Multiple regression analysis revealed that one channel in the right temporoparietal region had a significant association with antidepressant DDD controlling for age, sex, depression severity, and the DDD of antipsychotics and benzodiazepines. Moreover, high doses of antidepressants had significant effects on NIRS signals compared with low doses, in group comparisons.

CONCLUSIONS

The dose-dependent impact of antidepressants on NIRS signals should be taken into account when interpreting NIRS data.

The link between long noncoding RNAs and depression

The major depressive disorder (MDD) is a relatively common mental disorder from which that hundreds of million people have suffered, leading to displeasing life quality, which is characterized by health damage and even suicidal thoughts. The complicated development and functioning of MDD is still under exploration. Long noncoding RNA (lncRNAs) are highly expressed in the brain, could affect neural stem cell maintenance, neurogenesis and gliogenesis, brain patterning, synaptic and stress responses, and neural plasticity. The dysregulation of certain lncRNAs induces in neurodevelopmental, neurodegenerative and neuroimmunological disorders, primary brain tumors, and psychiatric diseases. Although advances have been made, no fully satisfactory treatments for major depression are available, further investigation is requested. And recently data showed that the expression level of the majority of lncRNAs demonstrated a clear tendency of upregulation, and the certain dysregulated miRNAs and lncRNAs in the MDD have been proved to have a co-synergism mechanism, that is why we speculate lncRNA might get the capability to regulate MDD. Few identified lncRNAs have been deeply studied in detailed experiments up until now, little predictions of their function have been raised, and further researches is calling for discover their signal pathway and related regulatory networks.

Cognitive and neural consequences of memory suppression in major depressive disorder

Negative biases in cognition have been documented consistently in major depressive disorder (MDD), including difficulties in the ability to control the processing of negative material. Although negative information-processing biases have been studied using both behavioral and neuroimaging paradigms, relatively little research has been conducted examining the difficulties of depressed persons with inhibiting the retrieval of negative information from long-term memory. In this study, we used the think/no-think paradigm and functional magnetic resonance imaging to assess the cognitive and neural consequences of memory suppression in individuals diagnosed with depression and in healthy controls. The participants showed typical behavioral forgetting effects, but contrary to our hypotheses, there were no differences between the depressed and nondepressed participants or between neutral and negative memories. Relative to controls, depressed individuals exhibited greater activity in right middle frontal gyrus during memory suppression, regardless of the valence of the suppressed stimuli, and differential activity in the amygdala and hippocampus during memory suppression involving negatively valenced stimuli. These findings indicate that depressed individuals are characterized by neural anomalies during the suppression of long-term memories, increasing our understanding of the brain bases of negative cognitive biases in MDD.

Incremental decreases in quality-adjusted life years (QALY) associated with higher levels of depressive symptoms for U.S. Adults aged 65 years and older

Background

Quality-adjusted life years (QALY) is a single value index that quantifies the overall burden of disease. It reflects all aspects of heath, including nonfatal illness and mortality outcomes by weighting life-years lived with health-related quality of life (HRQOL) scores. This study examine the burden of disease due to increasing levels of depressive symptoms by examining the association between the 9-item Patient Health Questionnaire (PHQ-9) scores and QALY for U.S. adults aged 65 years and older.

Methods

We ascertained respondents’ HRQOL scores and mortality status from the 2005–2006, 2007–2008, and 2009–2010 cohorts of the National Health and Nutrition Examination Survey (NHANES) with mortality follow-up data through December 31, 2011. This analysis included respondents aged 65 years and older (n = 3,680). We estimated the mean QALY throughout the remaining lifetime according to participants’ depression severity categories: none or minimal (PHQ-9 score 0–4), mild (5–9), moderate (10–14), and moderately severs and severe (15 or higher). We estimated QALY loss due to major depressive disorder (PHQ-9 score 10 or higher) and to mild depression (5–9).

Results

The QALY for persons with none/minimal, mild, moderate, and moderately severe/severe depression were 14.0, 7.8, 4.7, and 3.3 years, respectively. Compared to persons without major depressive disorder, persons with major depressive disorder had 8.3 fewer QALY (12.7 vs. 4.4), or a 65% loss. Compared to persons who reported “none” or minimal depressive symptoms, persons who reported mild depressive symptoms had 6.2 fewer QALY (14.0 vs. 7.8), or a 44% loss. The same patterns were noted in demographic and socioeconomic subgroups and according to number of comorbidities.

Conclusions

This study not only confirmed the significant burden of disease for major depressive disorder among the U.S. elderly, but also showed an incremental decrease in QALY with an increasing severity of depressive symptoms as well as significant QALY loss due to mild depression. Specifically, individuals with higher (or more impaired) PHQ-9 scores had significantly fewer QALYs and our findings of fewer years of QALY for persons with major depressive disorder and mild depression were not only statistically significant but also clinically important.

Early cortical biomarkers of longitudinal transcutaneous vagus nerve stimulation treatment success in depression

Transcutaneous vagus nerve stimulation (tVNS), a non-invasive method of brain stimulation through the auricular branch of the vagus nerve, has shown promising results in treating major depressive disorder (MDD) in several pilot studies. However, the neural mechanism by which the effect on depression might be achieved has not been fully investigated, with only a few neuroimaging studies demonstrating tVNS-induced changes in the brains of healthy volunteers. Identifying specific neural pathways, which are influenced by tVNS compared with sham in depressed individuals, as well as determining neurobiomarkers of tVNS treatment success are needed to advance the application of tVNS for MDD. In order to address these questions, we measured fMRI brain activity of thirty-eight depressed patients assigned to undergo tVNS (n = 17) or sham (n = 21) treatment for 4 weeks, during the first stimulation session. The results showed significant fMRI signal increases in the left anterior insula, revealed by a direct comparison of tVNS and sham stimulation. Importantly, the insula activation level during the first stimulation session in the tVNS group was significantly associated with the clinical improvement at the end of the four-week treatment, as indicated by the Hamilton Depression Rating Scale (HAM-D) score. Our findings suggest that anterior insula fMRI activity could serve as a potential cortical biomarker and an early predictor of tVNS longitudinal treatment success.

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Transcutaneous vagus nerve stimulation (tVNS) was used to treat depression (75).

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Significant fMRI activation in the left anterior insula was observed during tVNS (81).

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Insula activation during the first treatment was associated with clinical improvement (85).

Identification of SLC25A37 as a major depressive disorder risk gene

Major depressive disorder (MDD) is one of the most prevalent and disabling mental disorders, but the genetic etiology remains largely unknown. We performed a meta-analysis (14,543 MDD cases and 14,856 controls) through combining the GWAS data from the Major Depressive Disorder Working Group of the Psychiatric GWAS Consortium and the CONVERGE consortium and identified seven SNPs (four of them located in the downstream of SCL25A37) that showed suggestive associations (P < 5.0 × 10^-7) with MDD. Systematic integration (Sherlock integrative analysis) of brain eQTL and GWAS meta-analysis identified SCL25A37 as a novel MDD risk gene (P = 2.22 × 10^-6). A cis SNP (rs6983724, ∼28 kb downstream of SCL25A37) showed significant association with SCL25A37 expression (P = 1.19 × 10^-9) and suggestive association with MDD (P = 1.65 × 10^-7). We validated the significant association between rs6983724 and SCL25A37 expression in independent expression datasets. Finally, we found that SCL25A37 is significantly down-regulated in hippocampus and blood of MDD patients (P = 3.49 × 10^-3 and P = 2.66 × 10^-13, respectively). Our findings implicate that the SCL25A37 is a MDD susceptibility gene whose expression may influence MDD risk. The consistent down-regulation of SCL25A37 in MDD patients in three independent samples suggest that SCL25A37 may be used as a potential biomarker for MDD diagnosis. Further functional characterization of SCL25A37 may provide a potential target for future therapeutics and diagnostics.

Ablation of Type III Adenylyl Cyclase in Mice Causes Reduced Neuronal Activity, Altered Sleep Pattern, and Depression-like Phenotypes

BACKGROUND

Although major depressive disorder (MDD) has low heritability, a genome-wide association study in humans has recently implicated type 3 adenylyl cyclase (AC3; ADCY3) in MDD. Moreover, the expression level of AC3 in blood has been considered as a MDD biomarker in humans. Nevertheless, there is a lack of supporting evidence from animal studies.

METHODS

We employed multiple approaches to experimentally evaluate if AC3 is a contributing factor for major depression using mouse models lacking the Adcy3 gene.

RESULTS

We found that conventional AC3 knockout (KO) mice exhibited phenotypes associated with MDD in behavioral assays. Electroencephalography/electromyography recordings indicated that AC3 KO mice have altered sleep patterns characterized by increased percentage of rapid eye movement sleep. AC3 KO mice also exhibit neuronal atrophy. Furthermore, synaptic activity at cornu ammonis 3-cornu ammonis 1 synapses was significantly lower in AC3 KO mice, and they also exhibited attenuated long-term potentiation as well as deficits in spatial navigation. To confirm that these defects are not secondary responses to anosmia or developmental defects, we generated a conditional AC3 floxed mouse strain. This enabled us to inactivate AC3 function selectively in the forebrain and to inducibly ablate it in adult mice. Both AC3 forebrain-specific and AC3 inducible knockout mice exhibited prodepression phenotypes without anosmia.

CONCLUSIONS

This study demonstrates that loss of AC3 in mice leads to decreased neuronal activity, altered sleep pattern, and depression-like behaviors, providing strong evidence supporting AC3 as a contributing factor for MDD.

Assessment of abnormal brain structures and networks in major depressive disorder using morphometric and connectome analyses

BACKGROUND

It is hypothesized that the phenomenology of major depressive disorder (MDD) is subserved by disturbances in the structure and function of brain circuits; however, findings of structural abnormalities using MRI have been inconsistent. Generalized q-sampling imaging (GQI) methodology provides an opportunity to assess the functional integrity of white matter tracts in implicated circuits.

METHODS

The study population was comprised of 16 outpatients with MDD (mean age 44.81±2.2 years) and 30 age- and gender-matched healthy controls (mean age 45.03±1.88 years). We excluded participants with any other primary mental disorder, substance use disorder, or any neurological illnesses. We used T1-weighted 3D MRI with voxel-based morphometry (VBM) and vertex-wise shape analysis, and GQI with voxel-based statistical analysis (VBA), graph theoretical analysis (GTA) and network-based statistical (NBS) analysis to evaluate brain structure and connectivity abnormalities in MDD compared to healthy controls correlates with clinical measures of depressive symptom severity, Hamilton Depression Rating Scale 17-item (HAMD) and Hospital Anxiety and Depression Scale (HADS).

RESULTS

Using VBM and vertex-wise shape analyses, we found significant volumetric decreases in the hippocampus and amygdala among subjects with MDD (p<0.001). Using GQI, we found decreases in diffusion anisotropy in the superior longitudinal fasciculus and increases in diffusion probability distribution in the frontal lobe among subjects with MDD (p<0.01). In GTA and NBS analyses, we found several disruptions in connectivity among subjects with MDD, particularly in the frontal lobes (p<0.05). In addition, structural alterations were correlated with depressive symptom severity (p<0.01).

LIMITATIONS

Small sample size; the cross-sectional design did not allow us to observe treatment effects in the MDD participants.

CONCLUSIONS

Our results provide further evidence indicating that MDD may be conceptualized as a brain disorder with abnormal circuit structure and connectivity.

Cortisol/DHEA ratio and hippocampal volume: A pilot study in major depression and healthy controls

Structural imaging studies investigating the relationship between hippocampal volume (HCV) and peripheral measures of glucocorticoids (GCs) have produced conflicting results in both normal populations and in individuals with MDD, raising the possibility of other modulating factors. In preclinical studies, dehydroepiandrosterone (DHEA) and its sulfate ester (DHEAS; together abbreviated, DHEA(S)) have been shown to antagonize the actions of GCs on the central nervous system. Therefore, considering the relationship of HCV to both of these hormones simultaneously may be important, although it has rarely been done in human populations. Using high-resolution magnetic resonance imaging (MRI), the present pilot study examined the relationship between morning serum cortisol, DHEA(S), and HCV in nineteen normal controls and eighteen unmedicated subjects with Major Depressive Disorder (MDD). Serum cortisol and DHEA(S) were not significantly correlated with HCV across all subjects (cortisol: r=-0.165, p=0.33; DHEA: r=0.164, p=0.35; DHEAS: r=0.211, p=0.22, respectively). However, the ratios of cortisol/DHEA(S) were significantly negatively correlated with HCV in combined group (Cortisol/DHEA: r=-0.461, p=0.005; Cortisol/DHEAS: r=-0.363, p=0.03). Significant or near-significant correlations were found between some hormonal measurements and HCV in the MDDs alone (DHEA: r=0.482, p=0.059; DHEAS: r=0.507, p=0.045; cort/DHEA: r=-0.589, p=0.02; cort/DHEAS: r=-0.424p=0.10), but not in the controls alone (DHEA: r=0.070, p=0.79; DHEAS: r=0.077, p=0.77; cort/DHEA: r=-0.427, p=0.09; cort/DHEAS: r=-0.331, p=0.19). However, Group (MDDs vs controls) did not have a significant effect on the relationship between cortisol, DHEA(S), and their ratios with HCV (p>0.475 in all analyses). Although the exact relationship between serum and central steroid concentrations as well as their effects on the human hippocampus remains not known, these preliminary results suggest that the ratio of cortisol to DHEA(S), compared to serum cortisol alone, may convey additional information about "net steroid activity" with relation to HCV.

Selective amotivation deficits following chronic psychosocial stress in mice

Amotivation is a major symptom of several psychiatric disorders. However, which specific motivations are most affected in various illnesses is not well understood. In major depressive disorder (MDD), anecdotal evidence suggests the motivation to explore may be especially affected, but direct evidence from either patients or animal models is lacking. To investigate the potential for, and nature of, exploratory drive deficits in MDD, we subjected mice to a chronic social defeat (CSD) manipulation that gives rise to a MDD-like behavioural ensemble, and performed a behavioural battery to examine bodyweight homeostasis, ambulation, anxiety, exploratory behaviour motivated by either novelty or fear, and short-term memory. Consistent with previous reports, we found a disruption of bodyweight homeostasis and reduced ambulation following CSD treatment, but we found no evidence for anxiogenic effects or impairments in short-term memory. Surprisingly, we also observed profoundly delayed and diminished exploration of novel, safe space following CSD, while exploration motivated by fear remained intact. These results extend our knowledge of the behavioural phenotypes in mice resulting from CSD by homing in on specific motivational drives. In MDD patients, reduced exploration could compound disease symptomatology by preventing engagement in what could be rewarding exploration experiences, and targeting deficits in the motivation to explore may represent a novel avenue for treatment.

The interaction of combined effects of the BDNF and PRKCG genes and negative life events in major depressive disorder

Major depressive disorder (MDD) is a mental disorder that results from complex interplay between multiple and partially overlapping sets of susceptibility genes and environmental factors. The brain derived neurotrophic factor (BDNF) and Protein kinase C gamma type (PRKCG) are logical candidate genes in MDD. Among diverse environmental factors, negative life events have been suggested to exert a crucial impact on brain development. In the present study, we hypothesized that interactions between genetic variants in BDNF and PRKCG and negative life events may play an important role in the development of MDD. We recruited a total of 406 patients with MDD and 391 age- and gender-matched control subjects. Gene-environment interactions were analyzed using generalized multifactor dimensionality reduction (GMDR). Under a dominant model, we observed a significant three-way interaction among BDNF rs6265, PRKCG rs3745406, and negative life events. The gene-environment combination of PRKCG rs3745406 C allele, BDNF rs6265 G allele and high level of negative life events (C-G-HN) was significantly associated with MDD (OR, 5.97; 95% CI, 2.71-13.15). To our knowledge, this is the first report of evidence that the BDNF-PRKCG interaction may modify the relationship between negative life events and MDD in the Chinese population.

Resting-state functional network connectivity in prefrontal regions differs between unmedicated patients with bipolar and major depressive disorders

BACKGROUND

Differentiating bipolar disorder (BD) from major depressive disorder (MDD) often poses a major clinical challenge, and optimal clinical care can be hindered by misdiagnoses. This study investigated the differences between BD and MDD in resting-state functional network connectivity (FNC) using a data-driven image analysis method.

METHODS

In this study, fMRI data were collected from unmedicated subjects including 13 BD, 40 MDD and 33 healthy controls (HC). The FNC was calculated between functional brain networks derived from fMRI using group independent component analysis (ICA). Group comparisons were performed on connectivity strengths and other graph measures of FNC matrices.

RESULTS

Statistical tests showed that, compared to MDD, the FNC in BD was characterized by more closely connected and more efficient topological structures as assessed by graph theory. The differences were found at both the whole-brain-level and the functional-network-level in prefrontal networks located in the dorsolateral/ventrolateral prefrontal cortex (DLPFC, VLPFC) and anterior cingulate cortex (ACC). Furthermore, interconnected structures in these networks in both patient groups were negatively associated with symptom severity on depression rating scales.

LIMITATIONS

As patients were unmedicated, the sample sizes were relatively small, although they were comparable to those in previous fMRI studies comparing BD and MDD.

CONCLUSIONS

Our results suggest that the differences in FNC of the PFC reflect distinct pathophysiological mechanisms in BD and MDD. Such findings ultimately may elucidate the neural pathways in which distinct functional changes can give rise to the clinical differences observed between these syndromes.

Subgenual anterior cingulate cortex and hippocampal volumes in depressed youth: The role of comorbidity and age

OBJECTIVES

Many studies have reported that adults with recurrent major depressive disorder (MDD) have smaller hippocampal volumes than control participants. The data are more variable in youth with MDD, where findings have been inconsistent and the effects of factors such as age and co-morbidity have not been systematically examined. This study therefore assessed hippocampus and subgenual anterior cingulate (sgACC) morphometry in 168 youth, aged 12-25, with or without MDD and comorbid anxiety.

METHODS

Structural magnetic resonance imaging (MRI) scans and clinical assessments were obtained from 80 participants with MDD (36 with comorbid anxiety disorder) and 88 age-matched control participants.

RESULTS

Participants with MDD had smaller right hippocampi than controls (p=.013). Older depressed participants (20.1-25 years) had smaller hippocampal volumes than younger ones (<20.1 years; p=.05); this age effect was not apparent in controls (p=.46). Depression scores, indexed by the HAMD17, correlated with hippocampal volumes in older depressed youth. Depressed participants with comorbid anxiety had smaller sgACC, but not hippocampal, volumes than those without anxiety (p=.042).

LIMITATIONS

Longitudinal, versus cross-sectional, studies can most optimally assess the influence of depression on neurodevelopmental profiles. Though our participants were largely treatment-naïve or in their first week of pharmacotherapy, a handful had extensive treatment histories; thus, treatment history may have influenced brain morphometry.

CONCLUSIONS

Age effects were apparent when hippocampal volumes of older and younger participants with MDD were compared; such differences were not apparent in healthy participants. Comorbid anxiety was associated with decreased sgACC volumes suggesting delayed or altered neurodevelopment in a key emotion regulation region.

Deep transcranial magnetic stimulation (DTMS) in the treatment of major depression: An exploratory systematic review and meta-analysis

BACKGROUND

Deep transcranial magnetic stimulation (DTMS) is a relatively new, non-invasive method of stimulating larger and, presumably, deeper brain regions. The current study investigated if DTMS delivered with H-coils has acute antidepressant effects in major depression using a systematic literature review and a quantitative meta-analysis.

METHODS

Seventeen studies on 'DTMS or H-coil' and 'depression' were identified on Medline, PsycInfo, and Google Scholar (until November 2014). Data from nine open-label studies were meta-analysed using a random-effects model with inverse-variance weights. The outcome measures were the standardised paired mean difference (Cohen's d) in depression scores on Hamilton Depression Rating Scale (HDRS), response, remission, and dropout rates after acute DTMS treatment compared to baseline.

RESULTS

There was a large antidepressant effect after 20 acute, high-frequency DTMS sessions compared to baseline according to HDRS change scores (overall mean weighted d=2.04, 95% confidence interval: 1.53-2.55; nine studies; 150 patients). Overall weighted response, remission, and dropout rates were 60%, 29%, and 18% respectively. HDRS change scores and response rates tended to be higher in four studies with 68 patients on concurrent antidepressants compared to two studies with 26 patients who received DTMS as a monotherapy.

LIMITATIONS

These results are based on data from a low number of open-label studies.

CONCLUSION

High-frequency DTMS appears to have acute antidepressant effects after 20 sessions in mostly unipolar and treatment-resistant patients. Concurrent treatment with antidepressants might enhance the efficacy of DTMS.

DHEAS and cortisol/DHEAS-ratio in recurrent depression: State, or trait predicting 10-year recurrence?

BACKGROUND

Major depressive disorder (MDD) has been associated with low dehydroepiandrosterone-sulphate (DHEAS), - particularly relative to high cortisol - although conflicting findings exist. Moreover, it is unclear whether low DHEAS is only present during the depressive state, or manifests as a trait that may reflect vulnerability for recurrence. Therefore, we longitudinally tested whether low DHEAS and high cortisol/DHEAS-ratio in recurrent MDD (I) reflects a trait, and/or (II) varies with depressive state. In addition, we tested associations with (III) previous MDD-episodes, (IV) prospective recurrence, and (V) effects of cognitive therapy.

METHODS

At study-entry, we cross-sectionally compared morning and evening salivary DHEAS and molar cortisol/DHEAS-ratio of 187 remitted recurrent MDD-patients with 72 matched controls. Subsequently, patients participated in an 8-week randomized controlled cognitive therapy trial. We repeated salivary measures after 3 months and 2 years. We measured clinical symptoms during a 10-year follow-up.

RESULTS

Remitted patients showed steeper diurnal DHEAS-decline (p<.005) and a flatter diurnal profile of cortisol/DHEAS-ratio (p<.001) than controls. We found no state-effect in DHEAS or cortisol/DHEAS-ratio throughout follow-up and no association with number of previous episodes. Higher morning cortisol/DHEAS-ratio predicted shorter time till recurrence over the 10-year follow-up in interaction with the effects of cognitive therapy (p<.05). Finally, cognitive therapy did not influence DHEAS or cortisol/DHEAS-ratio.

CONCLUSIONS

Diurnal profiles of DHEAS and cortisol/DHEAS-ratio remain equally altered in between depressive episodes, and may predict future recurrence. This suggests they represent an endophenotypic vulnerability trait rather than a state-effect, which provides a new road to understand recurrent depression and its prevention.

TRIAL REGISTRATION

www.isrctn.com/ISRCTN68246470.

Prescription patterns of Chinese herbal products for patients with sleep disorder and major depressive disorder in Taiwan

ETHNOPHARMACOLOGICAL RELEVANCE

Chinese herbal products (CHPs) are commonly prescribed for sleep disorder and major depressive disorder (MDD). The aim of this study was to investigate the prescription patterns of CHPs and Western medicine for patients with these disorders in Taiwan, and analyze the frequency of using single herbs (SHs) and herbal formulas (HFs).

MATERIALS AND METHODS

In this retrospective population-based study secondary data analysis was performed using data from Taiwan's Longitudinal Health Insurance Database (LHID) between January 2007 and December 2011. In total, 1000,000 beneficiaries from the LHID were randomly selected from the 2010 registry for beneficiaries of the National Health Insurance Research Database. Patients with sleep disorder and MDD according to the International Classification of Diseases, Ninth Revision, Clinical Modification codes 307.40 and 311, respectively.

RESULTS

Among a total of 11,030 patients with sleep disorder, 9619 used Western medicine, 1334 used CHPs, and 77 used both, Among a total of 11,571 patients with MDD, 11,389 used Western medicine, 131 used CHPs, and 51 used both. Regardless of disorder type, women were predominant The majority of the patients were aged 22-44 years, had a monthly income of NT$17,281-NT$22,800, and lived in an area with Level 1 and Level 2 urbanization. Of the patients with sleep disorder, 1411 had used CHPs and visited a clinic 5298 times on average. Of the patients with MDD, 182 had used CHPs and visited a clinic 755 times on average. The three most commonly used SHs and HFs were Ziziphi Spinosae Semen, Polygoni Multiflori Caulis, and Polygalae Radix, and Jia-Wei-Xiao-Yao-San, Suan-Zao-Ren-Tang, and Chai-Hu-Chia-Lung-Ku-Mu-Li-Tang, respectively.

CONCLUSION

Chinese herbal products including SHs and HFs are prescribed for patients with sleep disorder and MDD. However, the efficacy and safety of CHPs for sleep disorder and MDD need to be further evaluated.

Prefrontal cortical GABA abnormalities are associated with reduced hippocampal volume in major depressive disorder

Hippocampal volume reduction has been related to treatment-resistant depression (TRD) and is hypothesized to reflect impaired amino-acid neurotransmission. To better understand the role of amino acid neurotransmission in hippocampal volume deficits, and subsequent resistance to treatment, this study investigated the relationship between hippocampal volumes and GABA levels in the anterior cingulate cortex (ACC), previously associated with TRD. Thirty-three medication-free major depressive disorder (MDD; 14 TRD and 19 non-TRD) and 26 healthy controls (HC) subjects were studied. Participants underwent high-resolution magnetic resonance imaging (MRI) to estimate hippocampal volume and proton MR spectroscopy ((1)H MRS) to measure ACC GABA levels. MDD patients, with known ACC GABA levels, were divided into two groups: MDD Low GABA and MDD High GABA. We found a significant reduction in hippocampal volume in the MDD Low GABA group compared to MDD High GABA (p<0.001) and HC (p=0.01). The relationship between hippocampal volume and cortical GABA was population (i.e. MDD group) and region specific (i.e. prefrontal cortex). Comparing TRD, non-TRD and HC groups, there was a main effect of group on hippocampal volume (p=0.04), which post hoc analysis revealed as smaller hippocampal volume in TRD subjects than in non-TRD (p=0.05) and HC groups (p=0.03). No hippocampal volume differences between non-TRD and HC groups. The data provides insight into the role of prefrontal neurochemical deficits in the limbic structural abnormalities observed in MDD. In addition, it replicates the relationship between TRD and smaller hippocampal volumes.

Edivoxetine compared to placebo as adjunctive therapy to selective serotonin reuptake inhibitors in the prevention of symptom re-emergence in major depressive disorder

OBJECTIVE

When patients with major depressive disorder (MDD) are partial responders to antidepressant therapy, adjunctive treatment with an agent that has a different mode of action may provide additional benefit. We investigated the efficacy of edivoxetine, a highly selective norepinephrine reuptake inhibitor (NRI), as adjunctive treatment to selective serotonin reuptake inhibitors (SSRIs) in the prevention of re-emergence of depressive symptoms in patients with MDD (ClinicalTrials.gov identifier: NCT01299272).

METHODS

Adult outpatients with MDD who were partial responders to SSRI treatment (N = 1249) entered an open-label 8 week flexibly dosed (12-18 mg/day) adjunctive edivoxetine period. Patients who achieved remission (Montgomery-Åsberg Depression Rating Scale total score ≤10 at week 8) entered a 12 week open-label fixed-dose (12 mg or 18 mg/day) stabilization period, and those still in remission at each of weeks 18, 19, and 20 were randomized to continue treatment at the same dose of edivoxetine or switch to placebo for a 24 week double-blind withdrawal period. All patients remained on SSRI therapy throughout the study. The primary outcome was time to re-emergence of depressive symptoms during double-blind withdrawal.

RESULTS

Two hundred and ninety-four patients were randomized to continue adjunctive edivoxetine and 292 were switched to adjunctive placebo. Comparing adjunctive edivoxetine with adjunctive placebo, differences were not significant for time to re-emergence of symptoms (Kaplan-Meier log-rank p = 0.485), rates of symptom re-emergence (9.9% vs 8.2%, p = 0.565) or rates of sustained remission (75.4% vs 76.7%, p = 0.771). Treatment-emergent adverse events were consistent with the noradrenergic mechanism of action.

CONCLUSIONS

Edivoxetine failed to demonstrate superiority vs placebo as adjunctive treatment in the prevention of symptom re-emergence during maintenance treatment in SSRI partial responders with MDD. While no selective NRIs are approved for adjunctive treatment to SSRIs in MDD, the use of NRIs in this population is nonetheless accepted practice, but our data do not support the efficacy of this approach.

Structural abnormality of the corticospinal tract in major depressive disorder

BACKGROUND

Scientists are beginning to document abnormalities in white matter connectivity in major depressive disorder (MDD). Recent developments in diffusion-weighted image analyses, including tractography clustering methods, may yield improved characterization of these white matter abnormalities in MDD. In this study, we acquired diffusion-weighted imaging data from MDD participants and matched healthy controls. We analyzed these data using two tractography clustering methods: automated fiber quantification (AFQ) and the maximum density path (MDP) procedure. We used AFQ to compare fractional anisotropy (FA; an index of water diffusion) in these two groups across major white matter tracts. Subsequently, we used the MDP procedure to compare FA differences in fiber paths related to the abnormalities in major fiber tracts that were identified using AFQ.

RESULTS

FA was higher in the bilateral corticospinal tracts (CSTs) in MDD (p's < 0.002). Secondary analyses using the MDP procedure detected primarily increases in FA in the CST-related fiber paths of the bilateral posterior limbs of the internal capsule, right superior corona radiata, and the left external capsule.

CONCLUSIONS

This is the first study to implicate the CST and several related fiber pathways in MDD. These findings suggest important new hypotheses regarding the role of CST abnormalities in MDD, including in relation to explicating CST-related abnormalities to depressive symptoms and RDoC domains and constructs.

Impact of variation in the BDNF gene on social stress sensitivity and the buffering impact of positive emotions: replication and extension of a gene-environment interaction

A previous study reported that social stress sensitivity is moderated by the brain-derived-neurotrophic-factor(Val66Met) (BDNF rs6265) genotype. Additionally, positive emotions partially neutralize this moderating effect. The current study aimed to: (i) replicate in a new independent sample of subjects with residual depressive symptoms the moderating effect of BDNF(Val66Met) genotype on social stress sensitivity, (ii) replicate the neutralizing impact of positive emotions, (iii) extend these analyses to other variations in the BDNF gene in the new independent sample and the original sample of non-depressed individuals. Previous findings were replicated in an experience sampling method (ESM) study. Negative Affect (NA) responses to social stress were stronger in "Val/Met" carriers of BDNF(Val66Met) compared to "Val/Val" carriers. Positive emotions neutralized the moderating effect of BDNF(Val66Met) genotype on social stress sensitivity in a dose-response fashion. Finally, two of four additional BDNF SNPs (rs11030101, rs2049046) showed similar moderating effects on social stress-sensitivity across both samples. The neutralizing effect of positive emotions on the moderating effects of these two additional SNPs was found in one sample. In conclusion, ESM has important advantages in gene-environment (GxE) research and may attribute to more consistent findings in future GxE research. This study shows how the impact of BDNF genetic variation on depressive symptoms may be explained by its impact on subtle daily life responses to social stress. Further, it shows that the generation of positive affect (PA) can buffer social stress sensitivity and partially undo the genetic susceptibility.