Mechanisms of antidepressant resistance

Characterization of "microbiome-metabolome-immunity" in depressed rats with divergent responses to Paroxetine

OBJECTIVES

Selective serotonin reuptake inhibitors (SSRIs) are the first-line anti-depressants. Unfortunately, about 30 % depressed patients do not effectively respond to SSRIs. It is still unclear that the gastrointestinal characteristics of responders and non-responders, and the differences.

METHODS

Herein, we characterized gut microbiome and metabolome of depressed rats with differential responses to Paroxetine (PX) by 16S rRNA sequencing and 1H NMR-based metabolomics, respectively. On top of this, we constructed both inter- and inner-layer networks, intuitively showing the correlations among behavioral indicators, immune factors, intestinal bacteria, and differential metabolites.

RESULTS

Consequently, we found that depressed rats differently responded to PX, which could be divided into PX responsive (PX-R) and non-responsive (PX-N) groups. Firstly, the depressive behaviors of PX-R rats and PX-N rats significantly differed. Meanwhile, inflammatory balance was also characterized for depressed rats with different responses to PX. Overall, PX-R rats and PX-N rats exhibited differential gut microbiome and metabolome, including intestinal structures, intestinal functions, metabolic profiles, metabolites, and metabolic pathways.

LIMITATIONS

Metabolites that identified by metabolomics based on 1H NMR are not comprehensive enough.

CONCLUSIONS

Taken together, our study demonstrated that gut microbiome and metabolome, as well as related functions, are of significance in differential responses of depressed rats to PX, which might be novel insights in uncovering the mechanisms of differences in efficacies of antidepressants.

Music prevents stress-induced depression and anxiety-like behavior in mice

Depression is the most prevalent psychiatric disorder worldwide and remains incurable; however, there is little research on its prevention. The leading cause of depression is stress, and music has been hypothesized to alleviate stress. To examine the potential beneficial effects of music on stress and depression, we subjected mice to chronic unpredictable mild stress (CUMS) during the day and music at night. Strikingly, our results indicated that music completely prevented CUMS-induced depression and anxiety-like behaviors in mice, as assessed by the open field, tail suspension, sucrose preference, novelty suppressed feeding, and elevated plus maze tests. We found that listening to music restored serum corticosterone levels in CUMS mice, which may contribute to the beneficial effects of music on the mouse brain, including the restoration of BDNF and Bcl-2 levels. Furthermore, listening to music prevented CUMS-induced oxidative stress in the serum, prefrontal cortex, and hippocampus of mice. Moreover, the CUMS-induced inflammatory responses in the prefrontal cortex and hippocampus of mice were prevented by listening to music. Taken together, we have demonstrated for the first time in mice experiments that listening to music prevents stress-induced depression and anxiety-like behaviors in mice. Music may restore hypothalamus-pituitary-adrenal axis homeostasis, preventing oxidative stress, inflammation, and neurotrophic factor deficits, which had led to the observed phenotypes in CUMS mice.

Precision medicine in complex diseases-Molecular subgrouping for improved prediction and treatment stratification

Complex diseases are caused by a combination of genetic, lifestyle, and environmental factors and comprise common noncommunicable diseases, including allergies, cardiovascular disease, and psychiatric and metabolic disorders. More than 25% of Europeans suffer from a complex disease, and together these diseases account for 70% of all deaths. The use of genomic, molecular, or imaging data to develop accurate diagnostic tools for treatment recommendations and preventive strategies, and for disease prognosis and prediction, is an important step toward precision medicine. However, for complex diseases, precision medicine is associated with several challenges. There is a significant heterogeneity between patients of a specific disease-both with regards to symptoms and underlying causal mechanisms-and the number of underlying genetic and nongenetic risk factors is often high. Here, we summarize precision medicine approaches for complex diseases and highlight the current breakthroughs as well as the challenges. We conclude that genomic-based precision medicine has been used mainly for patients with highly penetrant monogenic disease forms, such as cardiomyopathies. However, for most complex diseases-including psychiatric disorders and allergies-available polygenic risk scores are more probabilistic than deterministic and have not yet been validated for clinical utility. However, subclassifying patients of a specific disease into discrete homogenous subtypes based on molecular or phenotypic data is a promising strategy for improving diagnosis, prediction, treatment, prevention, and prognosis. The availability of high-throughput molecular technologies, together with large collections of health data and novel data-driven approaches, offers promise toward improved individual health through precision medicine.

Direct evidence for the involvement of intestinal reactive oxygen species in the progress of depression via the gut-brain axis

Depression is a serious global social problem. Various therapeutic drugs have been developed based on the monoamine hypothesis; however, treatment-resistant depression is a common clinical issue. Recently, the gut-brain axis, which is associated with the hypothesis that the intestinal environment affects the brain, has garnered significant interest, and several studies have attempted to treat brain disorders based on this axis. These attempts include fecal transplantation, probiotics and prebiotics. In this study, we focused on intestinal reactive oxygen species (ROS) because excessive ROS levels disturb the intestinal environment. To elucidate the impact of scavenging intestinal ROS on depression treatment via the gut-brain axis, a novel polymer-based antioxidant (siSMAPo^TN), which was distributed only in the intestine and did not diffuse into the whole body after oral administration, was used. siSMAPo^TN selectively scavenged intestinal ROS and protected the intestinal environment from damage caused by chronic restraint stress (CRS). In addition, siSMAPo^TN suppressed physiological and behavioral depression-related symptoms in the CRS mouse model.

Predictors of response and remission in patients with treatment-resistant depression: A post hoc pooled analysis of two acute trials of esketamine nasal spray

This exploratory post hoc analysis of two pooled 4-week, phase 3, double-blind, placebo- and active-controlled studies that compared esketamine nasal spray plus a newly initiated oral antidepressant (ESK+AD; n = 310) with a newly initiated oral AD plus placebo nasal spray (AD+PBO; n = 208) in patients with treatment-resistant depression (TRD) examined baseline patient demographic and psychiatric characteristics as potential predictors of response (≥50% reduction from baseline in Montgomery-Åsberg Depression Rating Scale [MADRS] total score) and remission (MADRS total score ≤12) at day 28. Overall, younger age, any employment, fewer failed ADs in the current depressive episode, and reduction in Clinical Global Impression-Severity (CGI-S) score at day 8 were significant positive predictors of response and remission at day 28. Treatment assignment was an important predictor of both response and remission. Patients treated with ESK+AD had 68% and 55% increased odds of achieving response and remission, respectively, versus those treated with AD+PBO. In the ESK+AD group, attainment of response and remission was more likely in patients who were employed, without significant anxiety at baseline, and who experienced a reduction in CGI-S score at day 8. Identification of predictors of response and remission may facilitate identification of those patients with TRD most likely to benefit from ESK+AD. Trial Registration: ClinicalTrials.gov: NCT02417064 (clinicaltrials.gov/ct2/show/NCT02417064) and NCT02418585 (clinicaltrials.gov/ct2/show/NCT02418585).

New insights from the last decade of research in psychiatric genetics: discoveries, challenges and clinical implications

Psychiatric genetics has made substantial progress in the last decade, providing new insights into the genetic etiology of psychiatric disorders, and paving the way for precision psychiatry, in which individual genetic profiles may be used to personalize risk assessment and inform clinical decision-making. Long recognized to be heritable, recent evidence shows that psychiatric disorders are influenced by thousands of genetic variants acting together. Most of these variants are commonly occurring, meaning that every individual has a genetic risk to each psychiatric disorder, from low to high. A series of large-scale genetic studies have discovered an increasing number of common and rare genetic variants robustly associated with major psychiatric disorders. The most convincing biological interpretation of the genetic findings implicates altered synaptic function in autism spectrum disorder and schizophrenia. However, the mechanistic understanding is still incomplete. In line with their extensive clinical and epidemiological overlap, psychiatric disorders appear to exist on genetic continua and share a large degree of genetic risk with one another. This provides further support to the notion that current psychiatric diagnoses do not represent distinct pathogenic entities, which may inform ongoing attempts to reconceptualize psychiatric nosology. Psychiatric disorders also share genetic influences with a range of behavioral and somatic traits and diseases, including brain structures, cognitive function, immunological phenotypes and cardiovascular disease, suggesting shared genetic etiology of potential clinical importance. Current polygenic risk score tools, which predict individual genetic susceptibility to illness, do not yet provide clinically actionable information. However, their precision is likely to improve in the coming years, and they may eventually become part of clinical practice, stressing the need to educate clinicians and patients about their potential use and misuse. This review discusses key recent insights from psychiatric genetics and their possible clinical applications, and suggests future directions.

Understanding treatment-resistant depression using "omics" techniques: A systematic review

BACKGROUND

Treatment-resistant depression (TRD) results in huge healthcare costs and poor patient clinical outcomes. Most studies have adopted a "candidate mechanism" approach to investigate TRD pathogenesis, however this is made more challenging due to the complex and heterogeneous nature of this condition. High-throughput "omics" technologies can provide a more holistic view and further insight into the underlying mechanisms involved in TRD development, expanding knowledge beyond already-identified mechanisms. This systematic review assessed the information from studies that examined TRD using hypothesis-free omics techniques.

METHODS

PubMed, MEDLINE, Embase, APA PsycInfo, Scopus and Web of Science databases were searched on July 2022. 37 human studies met the eligibility criteria, totalling 17,518 TRD patients, 571,402 healthy controls and 62,279 non-TRD depressed patients (including antidepressant responders and untreated MDD patients).

RESULTS

Significant findings were reported that implicate the role in TRD of various molecules, including polymorphisms, genes, mRNAs and microRNAs. The pathways most commonly reported by the identified studies were involved in immune system and inflammation, neuroplasticity, calcium signalling and neurotransmitters.

LIMITATIONS

Small sample sizes, variability in defining TRD, and heterogeneity in study design and methodology.

CONCLUSIONS

These findings provide insight into TRD pathophysiology, proposing future research directions for novel drug targets and potential biomarkers for clinical staging and response to antidepressants (citalopram/escitalopram in particular) and electroconvulsive therapy (ECT). Further validation is warranted in large prospective studies using standardised TRD criteria. A multi-omics and systems biology strategy with a collaborative effort will likely deliver robust findings for translation into the clinic.

Antidepressant’s long-term effect on cognitive performance and cardiovascular system

Background: The nature of antidepressants and their adverse effects should be considered when treating severe depression in individuals with psychotic symptoms. Antidepressant prescription rates have risen steadily over the last 30 years, affecting people of all ages. Aim: The goal of this study was to see if depression and antidepressant usage were linked to long-term changes in cognitive function and cardiovascular health. Methodology: Meta-analysis was performed using PRISMA guidelines along with using the SPIDER search framework using related keywords on different search engines i.e. Google scholars, PubMed, Scopus, ISI, etc. Total (n=2256) papers were obtained and assessed for eligibility. Altogether 15 studies were included using databases and other methods. The Newcastle-Ottawa Scale examined the grades provided by the data after numerous screenings. Result: A distinct link was found between antidepressants with cognitive performance and the cardiovascular system. Dementia and hypertension were prevailing long-term effects caused by frequent use of antidepressants in chronic and mild depression.

Predictors of 4-week antidepressant outcome in patients with first-episode major depressive disorder: An ROC curve analysis

BACKGROUND

Pretreatment characteristics of patients, symptom and function could be associated with antidepressant treatment outcome, but its predictive ability is not adequate. Our study aimed to identify predictors of acute antidepressant efficacy in patients with first-episode Major Depressive Disorder (MDD).

METHODS

187 patients with first-episode MDD were included and assessed clinical symptoms, cognitive function and global functioning using the 17-item Hamilton Depression Inventory (HAMD-17), MATRICS Consensus Cognitive Battery (MCCB) and Global Assessment of Functioning (GAF). Participants received treatment with a SSRI (escitalopram or venlafaxine) for 4 weeks. Logistic regression was used to analyze the association between patients' characteristics, symptom profiles, cognitive performance, and global functioning and the antidepressant outcome at the end of 4 weeks, and ROC curve analysis was performed for predictive accuracy with area under the receiver operating curve (AUC).

RESULTS

Antidepressant improvement, response and remission rate at week 4 was 87.7%, 64.7% and 42.8%, respectively. The combination of pretreatment clinical profiles, speed of processing and global functioning showed moderate discrimination of acute improvement, response and remission with AUCs of 0.863, 0.812 and 0.734, respectively.

LIMITATIONS

The major limitation of the present study is the study did not combine pharmacogenomics from the perspective of antidepressant drug metabolism.

CONCLUSION

Aside from the baseline clinical symptoms, cognitive function and global functioning could be predictors of acute treatment outcome in first episode MDD using escitalopram or venlafaxine. This relatively simple application based on clinical symptoms and function seems to be cost-effective method to identify individuals who are more likely to respond to antidepressant treatment.

Antidepressant-like effects of a chlorogenic acid- and cynarine-enriched fraction from Dittrichia viscosa root extract

Dittrichia viscosa is a perennial Mediterranean plant used in traditional medicine for “calming purposes”, pointing at a possible antidepressant activity of the plant. We conducted chromatographic and bioassay-guided fractionation of D. viscosa root extract to isolate a specific fraction (fraction “K”) with antidepressant-like characteristics in vivo and strong antioxidant properties in vitro. A single dose of “K” reduced immobility time in the forced swim test with a mouse model possessing a depressive-like phenotype. Neurochemical profiling for 5-hydroxytryptamine (5-HT) and its primary metabolite, 5-hydroxyindoleacetic acid (5-HIAA), in prefrontal cortex and hippocampus of “K”-treated mice showed reduction in 5-HIAA, indicative of either serotonin uptake transporter or monoamine oxidase-A inhibition, as well as slight increases in 5-HT content. These neurochemical alterations, as well as the behavioral changes observed, were comparable to the effects of paroxetine. “K” also protected PC12 cells in a H₂O₂ cytotoxicity assay, thus demonstrating antioxidant properties, yet paroxetine augmented oxidative damage and cell death. Identification of the main compounds in “K” by high-performance liquid chromatography-tandem mass spectrometry (HPLC–MS/MS) indicated that chlorogenic acid and cynarine comprised 87% of the total components. D. viscosa root extract appears to produce antidepressant and cytoprotective effects and may serve as an attractive alternative to standard therapies for depression.

Extracellular vesicle-mediated delivery of circDYM alleviates CUS-induced depressive-like behaviours

Major depressive disorder (MDD) is the most prevalent psychiatric disorder worldwide and severely limits psychosocial function and quality of life, but no effective medication is currently available. Circular RNAs (circRNAs) have been revealed to participate in the MDD pathological process. Targeted delivery of circRNAs without blood-brain barrier (BBB) restriction for remission of MDD represents a promising approach for antidepressant therapy. In this study, RVG-circDYM-extracellular vesicles (RVG-circDYM-EVs) were engineered to target and preferentially transfer circDYM to the brain, and the effect on the pathological process in a chronic unpredictable stress (CUS) mouse model of depression was investigated. The results showed that RVG-circDYM-EVs were successfully purified by ultracentrifugation from overexpressed circDYM HEK 293T cells, and the characterization of RVG-circDYM-EVs was successfully demonstrated in terms of size, morphology and specific markers. Beyond demonstrating proof-of-concept for an RNA drug delivery technology, we observed that systemic administration of RVG-circDYM-EVs efficiently delivered circDYM to the brain, and alleviated CUS-induced depressive-like behaviours, and we discovered that RVG-circDYM-EVs notably inhibited microglial activation, BBB leakiness and peripheral immune cells infiltration, and attenuated astrocyte disfunction induced by CUS. CircDYM can bind mechanistically to the transcription factor TAF1 (TATA-box binding protein associated factor 1), resulting in the decreased expression of its downstream target genes with consequently suppressed neuroinflammation. Taken together, our findings suggest that extracellular vesicle-mediated delivery of circDYM is effective for MDD treatment and promising for clinical applications.

Tryptophan Hydroxylase 2 Deficiency Modifies the Effects of Fluoxetine and Pargyline on the Behavior, 5-HT- and BDNF-Systems in the Brain of Zebrafish (Danio rerio)

The mechanisms of resistance to antidepressant drugs is a key and still unresolved problem of psychopharmacology. Serotonin (5-HT) and brain-derived neurotrophic factor (BDNF) play a key role in the therapeutic effect of many antidepressants. Tryptophan hydroxylase 2 (TPH2) is the rate-limiting enzyme in 5-HT synthesis in the brain. We used zebrafish (Danio rerio) as a promising model organism in order to elucidate the effect of TPH2 deficiency caused by p-chlorophenylalanine (pCPA) on the alterations in behavior and expression of 5-HT-related (Tph2, Slc6a4b, Mao, Htr1aa, Htr2aa) and BDNF-related (Creb, Bdnf, Ntrk2a, Ngfra) genes in the brain after prolonged treatment with two antidepressants, inhibitors of 5-HT reuptake (fluoxetine) and oxidation (pargyline). In one experiment, zebrafish were treated for 72 h with 0.2 mg/L fluoxetine, 2 mg/L pCPA, or the drugs combination. In another experiment, zebrafish were treated for 72 h with 0.5 mg/L pargyline, 2 mg/L pCPA, or the drugs combination. Behavior was studied in the novel tank diving test, mRNA levels were assayed by qPCR, 5-HT and its metabolite concentrations were measured by HPLC. The effects of interaction between pCPA and the drugs on zebrafish behavior were observed: pCPA attenuated “surface dwelling” induced by the drugs. Fluoxetine decreased mRNA levels of Tph2 and Htr2aa genes, while pargyline decreased mRNA levels of Slc6a4b and Htr1aa genes. Pargyline reduced Creb, Bdnf and Ntrk2a genes mRNA concentration only in the zebrafish treated with pCPA. The results show that the disruption of the TPH2 function can cause a refractory to antidepressant treatment.

Adult Neural Stem Cells as Promising Targets in Psychiatric Disorders

The development of new therapies for psychiatric disorders is of utmost importance, given the enormous toll these disorders pose to society nowadays. This should be based on the identification of neural substrates and mechanisms that underlie disease etiopathophysiology. Adult neural stem cells (NSCs) have been emerging as a promising platform to counteract brain damage. In this perspective article, we put forth a detailed view of how NSCs operate in the adult brain and influence brain homeostasis, having profound implications at both behavioral and functional levels. We appraise evidence suggesting that adult NSCs play important roles in regulating several forms of brain plasticity, particularly emotional and cognitive flexibility, and that NSC dynamics are altered upon brain pathology. Furthermore, we discuss the potential therapeutic value of utilizing adult endogenous NSCs as vessels for regeneration, highlighting their importance as targets for the treatment of multiple mental illnesses, such as affective disorders, schizophrenia, and addiction. Finally, we speculate on strategies to surpass current challenges in neuropsychiatric disease modeling and brain repair.

Feasibility and Efficacy of the Addition of Heart Rate Variability Biofeedback to a Remote Digital Health Intervention for Depression

A rise in the prevalence of depression underscores the need for accessible and effective interventions. The objectives of this study were to determine if the addition of a treatment component showing promise in treating depression, heart rate variability-biofeedback (HRV-B), to our original smartphone-based, 8-week digital intervention was feasible and whether patients in the HRV-B (“enhanced”) intervention were more likely to experience clinically significant improvements in depressive symptoms than patients in our original (“standard”) intervention. We used a quasi-experimental, non-equivalent (matched) groups design to compare changes in symptoms of depression in the enhanced group (n = 48) to historical outcome data from the standard group (n = 48). Patients in the enhanced group completed a total average of 3.86 h of HRV-B practice across 25.8 sessions, and were more likely to report a clinically significant improvement in depressive symptom score post-intervention than participants in the standard group, even after adjusting for differences in demographics and engagement between groups (adjusted OR 3.44, 95% CI [1.28–9.26], P = .015). Our findings suggest that adding HRV-B to an app-based, smartphone-delivered, remote intervention for depression is feasible and may enhance treatment outcomes.

PI3K/AKT pathway mediates the antidepressant- and anxiolytic-like roles of hydrogen sulfide in streptozotocin-induced diabetic rats via promoting hippocampal neurogenesis

We have previously demonstrated that hydrogen sulfide (H₂S), the third endogenous gasotransmitter, ameliorates the depression- and anxiety-like behaviors in diabetic rats, but the underlying mechanism remains unclear. The present was aimed to investigate whether the hippocampal phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) pathway mediates H₂S-ameliorated depression- and anxiety-like behaviors in diabetic rats by improving the hippocampal neurogenesis. The depression-like behaviors were examined by Tail suspension test (TST), the anxiety-like behaviors were examined by Elevated plus maze test (EPM), and the locomotor activity was detected by Open Field Test (OFT). The expressions of doublecortin (DCX), neuron-specific nuclear protein (NeuN), glial fibrillary acidic protein (GFAP), p-AKT, and AKT in the hippocampus were determined by Western blot analysis. Results showed that NaHS, a donor of exogenous H₂S, not only activated the hippocampal PI3K/AKT pathway, as evidenced by the increase of phosphorylated AKT, but also favorably reversed streptozotocin (STZ)-disturbed hippocampal neurogenesis, as evidenced by the increases in the expressions of DCX and NeuN as well as the decrease in the expression of GFAP in the hippocampus of STZ-induced diabetic rats. Furthermore, inhibited PI3K/AKT pathway by LY294002 significantly abolished H₂S-exerted the improvement of hippocampal neurogenesis and the antidepressant- and anxiolytic-like effects in the STZ-induced diabetic rats. Taken together, these results uncover that the activation of hippocampal PI3K/AKT pathway plays an important role to restore hippocampal neurogenesis and subsequently to mediate the antidepressant- and anxiolytic-like roles of H₂S in STZ-induced diabetic rats and enhance our understanding of the robustness of H₂S as a therapeutic strategy for treatment of depression in diabetes mellitus.

Involvement of Chaperone Sigma1R in the Anxiolytic Effect of Fabomotizole

Sigma-1 receptor (chaperone Sigma1R) is an intracellular protein with chaperone functions, which is expressed in various organs, including the brain. Sigma1R participates in the regulation of physiological mechanisms of anxiety (Su, T. P. et al., 2016) and reactions to emotional stress (Hayashi, T., 2015). In 2006, fabomotizole (ethoxy-2-[2-(morpholino)-ethylthio]benzimidazole dihydrochloride) was registered in Russia as an anxiolytic (Seredenin S. and Voronin M., 2009). The molecular targets of fabomotizole are Sigma1R, NRH: quinone reductase 2 (NQO2), and monoamine oxidase A (MAO-A) (Seredenin S. and Voronin M., 2009). The current study aimed to clarify the dependence of fabomotizole anxiolytic action on its interaction with Sigma1R and perform a docking analysis of fabomotizole interaction with Sigma1R. An elevated plus maze (EPM) test revealed that the anxiolytic-like effect of fabomotizole (2.5 mg/kg i.p.) administered to male BALB/c mice 30 min prior EPM exposition was blocked by Sigma1R antagonists BD-1047 (1.0 mg/kg i.p.) and NE-100 (1.0 mg/kg i.p.) pretreatment. Results of initial in silico study showed that fabomotizole locates in the active center of Sigma1R, reproducing the interactions with the site's amino acids common for established Sigma1R ligands, with the ΔGbind value closer to that of agonist (+)-pentazocine in the 6DK1 binding site.

Brain immune cells characterization in UCMS exposed P2X7 knock-out mouse

BACKGROUND

Several lines of evidence suggest that neuroinflammation might be a key neurobiological mechanism of depression. In particular, the P2X7 receptor (P2X7R), an ATP-gated ion channel involved in activation of the pro-inflammatory interleukin IL-1β, has been shown to be a potential new pharmacological target in depression. The aim of this study was to explore the impact of unpredictable chronic mild stress (UCMS) on behavioural changes, hippocampal neurogenesis, and cellular characterisation of brain immune cells, in P2X7R Knock-Out (KO) mice.

METHODS

P2X7R KO and wild-type (WT) mice were subjected to a 6-week UCMS protocol and received a conventional oral antidepressant (15 mg.kg^-1 fluoxetine) or water per os. The mice then underwent behavioural tests consisting of the tail suspension test (TST), the elevated plus maze (EPM) test, the open field test, the splash test and the nest building test (week 7). Doublecortin immunostaining (DCX) of brain slices was used to assess neurogenesis in the dentate gyrus. Iba1 and TMEM119 immunostaining was used to characterise brain immune cells, Iba1 as a macrophage marker (including microglial cells) and TMEM119 as a potential specific resident microglial cells marker.

RESULTS

After a 6-week UCMS exposure, P2X7R KO mice exhibited less deterioration of their coat state, spent a significantly smaller amount of time immobile in the TST and spent a larger amount of time in the open arms of the EPM. As expected, adult ventral hippocampal neurogenesis was significantly decreased by UCMS in WT mice, while P2X7R KO mice maintained ventral hippocampal neurogenesis at similar levels in both control and UCMS conditions. In stress-related brain regions, P2X7R KO mice also exhibited less recruitment of Iba1+/TMEM119+ and Iba1+/TMEM119- cells in the brain. The ratio between these two staining patterns revealed that brain immune cells were mostly composed of Iba1+/TMEM119+ cells (87 to 99%), and this ratio was affected neither by P2X7R genetic depletion nor by antidepressant treatment.

DISCUSSION

Behavioural patterns, neurogenesis levels and density of brain immune cells in P2X7R KO mice after exposure to UCMS significantly differed from control conditions. Brain immune cells were mostly increased in brain regions known to be sensitive to UCMS exposure in WT but not in P2X7R KO mice. Considering Iba1+/TMEM119- staining might characterize peripheral immune cells, the ratio between Iba1+/TMEM119+ cells and IBA1+/TMEM119- cells, suggests that the rate of peripheral immune cells recruitment may not be modified neither by P2X7R gene expression nor by antidepressant treatment.

Effects of dietary intake of heat-inactivated Lactobacillus gasseri CP2305 on stress-induced behavioral and molecular changes in a subchronic and mild social defeat stress mouse model

The intestinal ecosystem is involved in the pathogenesis of mood disorders such as depression. Intestinal microbes can affect the central nervous system through the gut-brain axis, which raises the possibility of using probiotics for preventing depression. In this study, we examined the effect of heat-inactivated Lactobacillus gasseri CP2305 (CP2305) in a subchronic and mild social defeat stress (sCSDS) mouse model. sCSDS suppressed food intake. However, dietary CP2305 intake rescued it, suggesting that CP2305 improved the decreased appetite in sCSDS mice. sCSDS did not alter the gene expression of brain-derived neurotrophic factor, nerve growth factor, and neurotrophin-3 in the hippocampus. However, dietary CP2305 provided following sCSDS increased the gene expression of these neurotrophins in the hippocampus. These findings suggest that CP2305 supplementation would aid in preventing psychosocial stress-induced disorders.

Treatment-resistant depression: Neurobiological correlates and the effect of sleep deprivation with sleep phase advance for the augmentation of pharmacotherapy

OBJECTIVES

To assess the neurobiology of treatment-resistant depression (TRD), and factors connected with improvement after total sleep deprivation (TSD) with sleep phase advance (SPA), for the augmentation of pharmacotherapy.

METHODS

The study comprised 43 patients with TRD, (15 male, 28 female), aged 48 ± 13 years, with the illness duration 12 ± 9 years, and the depressive episode 8 ± 7 months. TRD was defined as a lack of significant improvement despite at least two antidepressant treatments and the augmentation with mood-stabilisers. Clinical improvement (response) was a reduction of ≥50% of points in the Hamilton Depression Rating Scale (HDRS), and the remission criterion was ≤7 points in HDRS, lasting until the 14th day after TSD + SPA.

RESULTS

TRD severity was associated with greater activity of the hypothalamic-pituitary-adrenal axis, the pro-inflammatory status of the immune system and lower reactivity of the hypothalamic-pituitary-thyroid axis. The response was achieved by 18 of 42 subjects, and connected with the later onset and shorter duration of the disease. In responders, there was a decrease in cortisol and interferon-gamma. In all subjects, a decrease in thyroid hormones was observed.

CONCLUSIONS

TRD can improve after augmentation of pharmacotherapy by TSD + SPA and some biological changes may be compatible with a decrease in allostatic load.

The relationship of tryptophan hydroxylase-2 methylation to early-life stress and its impact on short-term antidepressant treatment response

INTRODUCTION

The gene tryptophan hydroxylase 2 (TPH2) encodes the associated rate-limiting enzyme in the biosynthesis 5-HT (serotonin). Early life stress and adult variability in TPH2 can correspond with diminished response to antidepressants for patients with major depressive disorder (MDD). DNA methylation is an epigenetic mechanism mediating gene expression, often tempered by environmental factors. Here, we investigate the influence of TPH2 methylation combined with stress on response to antidepressants within the first two weeks of treatment initiation.

METHODS

291 Han Chinese patients with major depressive disorder and 100 healthy controls comprised the study population. The Life Events Scale (LES) and the Childhood Trauma Questionnaire (CTQ) rated recent and early-life stress. The primary outcome equaled a reduction by ≥ 50% from the Hamilton Depression Rating Scale-17 (HAMD-17) after 2 weeks of treatment. The Illumina HiSeq platform assessed methylation status in 38 CpG sites located upstream and downstream of 11 TPH2 polymorphism sites.

RESULTS

In 291 patients and 100 healthy controls, 3 CpG sites predict antidepressant treatment response per sex (TPH2-7-142, p=0.012; TPH2-1-43, p=0.033; TPH2-5-203, p=0.036). High-level CTQ scores relate significantly to DNA hypomethylation at CpG-site TPH2-8-237 in males (false discovery rate [FDR]-corrected p=0.038). Additionally, the interaction of hypermethylation in two CpG sites and elevated early-life stress may reduce antidepressant response (TPH2-5-203, FDR corrected p=0.010; TPH2-10-60, FDR corrected p=0.001).

CONCLUSIONS

Our study suggests that TPH2 methylation and its interaction with early-life stress may impair antidepressant response, suggesting that pharmaco-epigenetic studies could identify epigenetic biomarkers for antidepressant response.

Can precision medicine advance psychiatry?

Precision medicine is a new approach that considers differences in genes, environment, and lifestyle in an attempt to tailor treatments for individual patients. Psychiatry, as a discipline, has historically relied on clinical judgement and phenomenology-based diagnostic guidelines and has yet to take full advantage. This editorial provides an insight into the expanding role of precision medicine in psychiatry, both in research and clinical practice. It discusses the application of genetics and subgroup stratification in increasing response rates to therapeutic interventions, mainly focusing on major depressive disorder and schizophrenia. It presents an overview of machine learning techniques and how they are being integrated with traditional research methods within the field. In the context of these developments, while emphasizing the considerable potential for moving toward precision psychiatry, we also acknowledge the inherent challenges.

Targeting Inflammatory-Mitochondrial Response in Major Depression: Current Evidence and Further Challenges

The prevalence of psychiatric disorders has increased in recent years. Among existing mental disorders, major depressive disorder (MDD) has emerged as one of the leading causes of disability worldwide, affecting individuals throughout their lives. Currently, MDD affects 15% of adults in the Americas. Over the past 50 years, pharmacotherapy, psychotherapy, and brain stimulation have been used to treat MDD. The most common approach is still pharmacotherapy; however, studies show that about 40% of patients are refractory to existing treatments. Although the monoamine hypothesis has been widely accepted as a molecular mechanism to explain the etiology of depression, its relationship with other biochemical phenomena remains only partially understood. This is the case of the link between MDD and inflammation, mitochondrial dysfunction, and oxidative stress. Studies have found that depressive patients usually exhibit altered inflammatory markers, mitochondrial membrane depolarization, oxidized mitochondrial DNA, and thus high levels of both central and peripheral reactive oxygen species (ROS). The effect of antidepressants on these events remains unclear. Nevertheless, the effects of ROS on the brain are well known, including lipid peroxidation of neuronal membranes, accumulation of peroxidation products in neurons, protein and DNA damage, reduced antioxidant defenses, apoptosis induction, and neuroinflammation. Antioxidants such as ascorbic acid, tocopherols, and coenzyme Q have shown promise in some depressive patients, but without consensus on their efficacy. Hence, this paper provides a review of MDD and its association with inflammation, mitochondrial dysfunction, and oxidative stress and is aimed at thoroughly discussing the putative links between these events, which may contribute to the design and development of new therapeutic approaches for patients.

Xiaoyao Pills Prevent Lipopolysaccharide-Induced Depression by Inhibiting Inflammation and Protecting Nerves

Lipopolysaccharides are pro-inflammation mediators that can induce inflammation in the serum, hippocampus, and cortex of animals. And lipopolysaccharide-induced neuroinflammatory state resulted in significant depression-like behaviors, including reduced locomotor activity in the open field test, reduced saccharin preference, added immobility time in tail suspension test and forced swimming test, decreased comb time in the splash test, and increased latency to food in the novelty suppressed feeding test time, and reduced the levels of neurotrophic factors and synaptic proteins, and decreased Nissl bodies. Treatment with Xiaoyao Pills ameliorated the depression-like behavior, decreased the levels of inflammatory indicators, increased those of neurotrophic factors and synaptic proteins, and restored Nissl bodies. Our study suggests that lipopolysaccharides induce inflammation and nerve injury, thereby leading to depression. Xiaoyao Pills could be considered a potential therapeutic candidate for inflammation-induced depression.

Computational Analysis of Therapeutic Neuroadaptation to Chronic Antidepressant in a Model of the Monoaminergic Neurotransmitter and Stress Hormone Systems

The clinical practice of selective serotonin reuptake inhibitor (SSRI) augmentation relies heavily on trial-and-error. Unfortunately, the drug combinations prescribed today fail to provide relief for many depressed patients. In order to identify potentially more effective treatments, we developed a computational model of the monoaminergic neurotransmitter and stress-steroid systems that neuroadapts to chronic administration of combinations of antidepressant drugs and hormones by adjusting the strengths of its transmitter-system components (TSCs). We used the model to screen 60 chronically administered drug/hormone pairs and triples, and identified as potentially therapeutic those combinations that raised the monoamines (serotonin, norepinephrine, and dopamine) but lowered cortisol following neuroadaptation in the model. We also evaluated the contributions of individual and pairs of TSCs to therapeutic neuroadaptation with chronic SSRI using sensitivity, correlation, and linear temporal-logic analyses. All three approaches revealed that therapeutic neuroadaptation to chronic SSRI is an overdetermined process that depends on multiple TSCs, providing a potential explanation for the clinical finding that no single antidepressant regimen alleviates depressive symptoms in all patients.

Grey Matter changes in treatment-resistant depression during electroconvulsive therapy

INTRODUCTION

20-30% of depressed patients experience Treatment Resistant Depression (TRD). Electroconvulsive Therapy (ECT) remains the treatment of choice for TRD. However, the exact mechanism of ECT remains unclear. We aim to assess grey matter changes in patients with TRD undergoing bilateral ECT treatment at different points during and after treatment.

METHODS

Patients are recruited at the University Hospital of Toulouse. Eligibility criteria include a diagnosis of TRD and an age between 50 and 70 years old. Patients received clinical assessments (Hamilton Depression Rating Scale) and structural scans (MRI) at three points: baseline (within 48 h before the first ECT); V2 (after the first ECT considered effective); and V3 (within 1 week of completing ECT).

RESULTS

At baseline, controls had significantly higher cortical thickness than patients in the fusiform gyrus, the inferior, middle and superior temporal gyrus, the parahippocampal gyrus and the transverse temporal gyrus (respectively: t(35)=2.7, p = 0.02; t(35)=2.89, p = 0.017; t(35)=3.1, p = 0.015; t(35)=3.6, p = 0.009; t(35)=2.37, p = 0.031; t(35)=2.46, p = 0.03). This difference was no longer significant after ECT. We showed an increase in cortical thickness in superior temporal gyrus between (i) baseline and V3 (t(62)=-3.43 p = 0.009) and (ii) V2 and V3 (t(62)=-3.42 p = 0.009). We showed an increase in hippocampal volume between (i) baseline and V3 (t(62)=-5.23 p < 0.001) and (ii) V2 and V3 (t(62)=-5.3 p < 0.001).

CONCLUSION

We highlight that there are grey matter changes during ECT treatment in a population with TRD compared to a healthy control population. These changes seem to occur after several rounds of ECT.

Plasminogen Activator Inhibitor-1 (PAI-1) deficiency predisposes to depression and resistance to treatments

Major depressive disorder (MDD) is one of the most frequent psychiatric illnesses, leading to reduced quality of life, ability to work and sociability, thus ranking among the major causes of disability and morbidity worldwide. To date, genetic and environmental determinants of MDD remain mostly unknown. Here, we investigated whether and how the Plasminogen Activator Inhibitor-1 (PAI-1) may contribute to MDD. We first examined the phenotype of PAI-1 knockout (PAI-1−/−) and wild-type (PAI-1+/+) male mice with a range of behavioral tests assessing depressive-like behaviors (n = 276). We next investigated the mechanisms relating PAI-1 to MDD using molecular, biochemical and pharmacological analyzes. We demonstrate here that PAI-1 plays a key role in depression by a mechanism independent of the tissue-type Plasminogen Activator (tPA) – Brain-Derived Neurotrophic Factor (BDNF) axis, but associated with impaired metabolisms of serotonin and dopamine. Our data also reveal that PAI-1 interferes with therapeutic responses to selective serotonin reuptake inhibitors (escitalopram, fluoxetine). We thus highlight a new genetic preclinical model of depression, with the lack of PAI-1 as a factor of predisposition to MDD. Altogether, these original data reveal that PAI-1 should be now considered as a key player of MDD and as a potential target for the development of new drugs to cure depressive patients resistant to current treatments.

Psilocybin for depression: Considerations for clinical trial design

Background and aims

Given the enormous global burden of depressive illness, there is an urgent need to develop novel and more effective treatments for major depressive disorder (MDD). Recent findings have suggested that psychedelic drugs may have a role in the treatment of depressive symptoms, and a number of groups are in the process of developing protocols to study this question systematically. Given the subjective quality of both the psychedelic experience and depressive symptomatology, great care must be taken when designing a protocol to study the clinical efficacy of psychedelic drugs. This study will discuss many factors to consider when designing a clinical trial of psilocybin for MDD.

Methods

We provide a thorough review of pertinent research into antidepressant clinical trial methodology and review practical considerations that are relevant to the study of psychedelic-assisted treatment for depression.

Results

We discuss participant selection (including diagnostic accuracy, exclusion criteria, characteristics of the depressive episode, and the use of concurrent medications), study interventions (including dosing regimens, placebo selection, non-pharmacological components of treatment, and the importance of blinding), trial duration, outcome measures, and safety considerations.

Conclusions

Careful and transparent study design and data analysis will maximize the likelihood of generating meaningful, reproducible results, and identifying a treatment-specific effect. Meeting the highest standards for contemporary trial design may also broaden the acceptance of psychedelic research in the scientific community at large.

Long-Term Outcomes of a Therapist-Supported, Smartphone-Based Intervention for Elevated Symptoms of Depression and Anxiety: Quasiexperimental, Pre-Postintervention Study

Background

Depression is one of the most common mental health disorders and severely impacts one’s physical, psychological, and social functioning. To address access barriers to care, we developed Ascend—a smartphone-delivered, therapist-supported, 8-week intervention based on several evidence-based psychological treatments for depression and anxiety. A previous feasibility study with 102 adults with elevated depression reported that Ascend is associated with a postintervention reduction in depression symptoms.

Objective

We aimed to examine whether Ascend is associated with a reduction in symptoms of anxiety, and importantly, whether reductions in symptoms of depression and anxiety are maintained up to 12-months postintervention.

Methods

We assessed whether the previously reported, end-of-treatment improvements seen in the 102 adults with elevated symptoms of depression extended up to 12 months posttreatment for depression symptoms (measured by the Patient Health Questionnaire-9 [PHQ-9]) and up to 6 months posttreatment for anxiety symptoms (added to the intervention later and measured using the Generalized Anxiety Disorder-7 [GAD-7] scale). We used linear mixed effects models with Tukey contrasts to compare time points and reported intention-to-treat statistics with a sensitivity analysis.

Results

The intervention was associated with reductions in symptoms of depression that were maintained 12 months after the program (6.67-point reduction in PHQ-9 score, 95% CI 5.59-7.75; P<.001; Hedges g=1.14, 95% CI 0.78-1.49). A total of 60% of the participants with PHQ-9 scores above the cutoff for major depression at baseline (PHQ≥10) reported clinically significant improvement at the 12-month follow-up (at least 50% reduction in PHQ-9 score and postprogram score <10). Participants also reported reductions in symptoms of anxiety that were maintained for at least 6 months after the program (4.26-point reduction in GAD-7 score, 95% CI 3.14-5.38; P<.001; Hedges g=0.91, 95% CI 0.54-1.28).

Conclusions

There is limited evidence on whether outcomes associated with smartphone-based interventions for common mental health problems are maintained posttreatment. Participants who enrolled in Ascend experienced clinically significant reductions in symptoms of depression and anxiety that were maintained for up to 1 year and 6 months after the intervention, respectively. Future randomized trials are warranted to test Ascend as a scalable solution to the treatment of depression and anxiety.

Treating psychiatric symptoms and disorders with non-psychotropic medications

A few drugs prescribed in internal medicine, ie, non-psychotropic drugs, can be used to treat certain neuropsychiatric disorders. For most of these situations, the level of evidence remains low. But when sufficient data becomes available, these molecules are then included in official guidelines for the treatment of neuropsychiatric disorders. In this article we review interesting drugs which may be relevant from an evidence-based medicine point of view, and could become part of psychiatric practice in the future.


Plasma-Based Strategies for Therapeutic Modulation of Brain Aging

Age is the primary risk factor for the vast majority of disorders, including neurodegenerative diseases impacting brain function. Whether the consequences of aging at the biological level can be reversed, or age-related changes prevented, to change the trajectory of such disorders is thus of extreme interest and value. Studies using young plasma, the acellular component of blood, have demonstrated that aging is malleable, with the ability to restore functions in old animals. Fascinatingly, this functional improvement is even observed in the brain, despite the blood-brain barrier, indicating that peripheral sources can effectively impact central sites leading to clinically relevant changes such as enhancement of cognitive function. A plasma-based approach is also attractive as aging is inherently complex, with an array of mechanisms dysregulated in diverse cells and organs throughout the body leading to disturbed function. Plasma, containing a natural mixture of components, has the ability to act multimodally, modulating diverse mechanisms that can converge to change the trajectory of age-related diseases. Here we review the evidence that plasma modulates aging processes in the brain and consider the therapeutic applications that derive from these observations. Plasma and plasma-derived therapeutics are an attractive translation of this concept, requiring critical consideration of benefits, risks, and ethics. Ultimately, knowledge derived from this science will drive a comprehensive molecular understanding to deliver optimized therapeutics. The potential of highly differentiated, multimodal therapeutics for treatment of age-related brain disorders provides an exciting new clinical approach to address the complex etiology of aging.

Melanin-concentrating hormone does not modulate serotonin release in primary cultures of fetal raphe nucleus neurons

Melanin-concentrating hormone (MCH) is a neuropeptide present in neurons located in the hypothalamus that densely innervate serotonergic cells in the dorsal raphe nucleus (DRN). MCH administration into the DRN induces a depressive-like effect through a serotonergic mechanism. To further understand the interaction between MCH and serotonin, we used primary cultured serotonergic neurons to evaluate the effect of MCH on serotonergic release and metabolism by HPLC-ED measurement of serotonin (5-HT) and 5-hydroxyindolacetic acid (5-HIAA) levels. We confirmed the presence of serotonergic neurons in the E14 rat rhombencephalon by immunohistochemistry and showed for the first time evidence of MCHergic fibers reaching the area. Cultures obtained from rhombencephalic tissue presented 2.2 ± 0.7% of serotonergic and 48.9 ± 5.4% of GABAergic neurons. Despite the low concentration of serotonergic neurons, we were able to measure basal cellular and extracellular levels of 5-HT and 5-HIAA without the addition of any serotonergic-enhancer drug. As expected, 5-HT release was calcium-dependent and induced by depolarization. 5-HT extracellular levels were significantly increased by incubation with serotonin reuptake inhibitors (citalopram and nortriptyline) and a monoamine-oxidase inhibitor (clorgyline), and were not significantly modified by a 5-HT1A autoreceptor agonist (8-OHDPAT). Even though serotonergic cells responded as expected to these pharmacological treatments, MCH did not induce significant modifications of 5-HT and 5-HIAA extracellular levels in the cultures. Despite this unexpected result, we consider that assessment of 5-HT and 5-HIAA levels in primary serotonergic cultures may be an adequate approach to study the effect of other drugs and modulators on serotonin release, uptake and turnover.

A systematic meta-review of predictors of antidepressant treatment outcome in major depressive disorder

INTRODUCTION

The heterogeneity of symptoms and complex etiology of depression pose a significant challenge to the personalization of treatment. Meanwhile, the current application of generic treatment approaches to patients with vastly differing biological and clinical profiles is far from optimal. Here, we conduct a meta-review to identify predictors of response to antidepressant therapy in order to select robust input features for machine learning models of treatment response. These machine learning models will allow us to learn associations between patient features and treatment response which have predictive value at the individual patient level; this learning can be optimized by selecting high-quality input features for the model. While current research is difficult to directly apply to the clinic, machine learning models built using knowledge gleaned from current research may become useful clinical tools.

METHODS

The EMBASE and MEDLINE/PubMed online databases were searched from January 1996 to August 2017, using a combination of MeSH terms and keywords to identify relevant literature reviews. We identified a total of 1909 articles, wherein 199 articles met our inclusion criteria.

RESULTS

An array of genetic, immune, endocrine, neuroimaging, sociodemographic, and symptom-based predictors of treatment response were extracted, varying widely in clinical utility.

LIMITATIONS

Due to heterogeneous sample sizes, effect sizes, publication biases, and methodological disparities across reviews, we could not accurately assess the strength and directionality of every predictor.

CONCLUSION

Notwithstanding our cautious interpretation of the results, we have identified a multitude of predictors that can be used to formulate a priori hypotheses regarding the input features for a computational model. We highlight the importance of large-scale research initiatives and clinically accessible biomarkers, as well as the need for replication studies of current findings. In addition, we provide recommendations for future improvement and standardization of research efforts in this field.

Intrinsic Brain Network Biomarkers of Antidepressant Response: a Review

PURPOSE OF REVIEW

Poor treatment response is a hallmark of major depressive disorder. To tackle this problem, recent neuroimaging studies have sought to characterize antidepressant response in terms of pretreatment differences in intrinsic functional brain networks. Our aim is to review recent studies that predict antidepressant response using intrinsic network connectivity. We discuss current methodological limitations and directions for future antidepressant biomarker studies.

RECENT FINDINGS

Functional connectivity stemming from the subgenual and rostral anterior cingulate has shown particular consistency in predicting antidepressant response. Differences in this connectivity may prove fruitful in differentiating treatment responders to many antidepressant interventions. Future biomarker studies should integrate biological MDD subtypes to address the disorder's inherent clinical heterogeneity. These clinical and scientific advancements have the potential to address this population marked by limited treatment response. Methodological considerations, including patient selection, response criteria, and model overfitting, will require future investigation to ensure that biomarkers generalize for prospective prediction of treatment response.

Diminished responses to monoaminergic antidepressants but not ketamine in a mouse model for neuropsychiatric lupus

BACKGROUND

A significant proportion of patients suffering from major depression fail to remit following treatment and develop treatment-resistant depression. Developing novel treatments requires animal models with good predictive validity. MRL/lpr mice, an established model of systemic lupus erythematosus, show depression-like behavior.

AIMS

We evaluated responses to classical antidepressants, and associated immunological and biochemical changes in MRL/lpr mice.

METHODS AND RESULTS

MRL/lpr mice showed increased immobility in the forced swim test, decreased wheel running and sucrose preference when compared with the controls, MRL/MpJ mice. In MRL/lpr mice, acute fluoxetine (30 mg/kg, intraperitoneally (i.p.)), imipramine (10 mg/kg, i.p.) or duloxetine (10 mg/kg, i.p.) did not decrease the immobility time in the Forced Swim Test. Interestingly, acute administration of combinations of olanzapine (0.03 mg/kg, subcutaneously)+fluoxetine (30 mg/kg, i.p.) or bupropion (10 mg/kg, i.p.)+fluoxetine (30 mg/kg, i.p.) retained efficacy. A single dose of ketamine but not three weeks of imipramine (10 mg/kg, i.p.) or escitalopram (5 mg/kg, i.p.) treatment in MRL/lpr mice restored sucrose preference. Further, we evaluated inflammatory, immune-mediated and neuronal mechanisms. In MRL/lpr mice, there was an increase in autoantibodies' titers, [3H]PK11195 binding and immune complex deposition. There was a significant infiltration of the brain by macrophages, neutrophils and T-lymphocytes. p11 mRNA expression was decreased in the prefrontal cortex. Further, there was an increase in the 5-HT_2aR expression, plasma corticosterone and indoleamine 2,3-dioxygenase activity.

CONCLUSION

In summary, the MRL/lpr mice could be a useful model for Treatment Resistant Depression associated with immune dysfunction with potential to expedite antidepressant drug discovery.

Significant Decrease in Hippocampus and Amygdala Mean Diffusivity in Treatment-Resistant Depression Patients Who Respond to Electroconvulsive Therapy

Introduction: The hippocampus plays a key role in depressive disorder, and the amygdala is involved in depressive disorder through the key role that it plays in emotional regulation. Electroconvulsive therapy (ECT) may alter the microstructure of these two regions. Since mean diffusivity (MD), is known to be an indirect marker of microstructural integrity and can be derived from diffusion tensor imaging (DTI) scans, we aim to test the hypothesis that treatment-resistant depression (TRD) patients undergoing bilateral (BL) ECT exhibit a decrease of MD in their hippocampus and amygdala. Methods: Patients, between 50 and 70 years of age, diagnosed with TRD were recruited from the University Hospital of Toulouse and assessed clinically (Hamilton Depression Rating Scale, HAM-D) and by DTI scans at three time points: baseline, V2 (during treatment), and V3 within 1 week of completing ECT. Results: We included 15 patients, who were all responders. The left and right hippocampi and the left amygdala showed a significant decrease in MD at V3, compared to baseline [respectively: β = -2.78, t = -1.97, p = 0.04; β = -2.56, t = -2, p = 0.04; β = -2.5, t = -2.3, p = 0.04, false discovery rate (FDR) corrected]. MD did not decrease in the right amygdala. Only the left amygdala was significantly associated with a reduction in HAM-D (ρ = 0.55, p = 0.049, FDR corrected). Conclusion: MD is an indirect microstructural integrity marker, which decreases in the hippocampus and the left amygdala, during BL ECT in TRD populations. This could be interpreted as a normalization of microstructural integrity in these structures.

Treating psychiatric symptoms and disorders with non-psychotropic medications

A few drugs prescribed in internal medicine, ie, non-psychotropic drugs, can be used to treat certain neuropsychiatric disorders. For most of these situations, the level of evidence remains low. But when sufficient data becomes available, these molecules are then included in official guidelines for the treatment of neuropsychiatric disorders. In this article we review interesting drugs which may be relevant from an evidence-based medicine point of view, and could become part of psychiatric practice in the future.
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Barriers to complete recovery of major depression: cross-sectional, multi-centre study on clinical practice. RECORD study

INTRODUCTION

To identify barriers to complete recovery in patients suffering from major depressive disorder.

METHODS

A total of 461 psychiatrists participated in a cross-sectional, non-randomised, qualitative and multi-centre study based on a survey. The study questionnaire included 42 ítems related to management, prevalence, patient profile, impact of residual symptoms, barriers to full recovery, and strategies to increase complete recovery.

RESULTS

Complete recovery was defined by 86% of participants as complete remission of symptoms plus functional recovery. A total of 83.4% of participants considered that sick leave usually lasted more than 4 months. Seventy-five percent stated that residual symptoms were the main reason for prolongation of sick leave, and 62% that between 26%-50% of patients complained of residual symptoms. Poor compliance with treatment was the most important barrier to complete recovery, followed by a lack of patient cooperation, late beginning of treatment, partial response to antidepressants, and low doses of antidepressant medication. In the case of partial response, 71.8% of participants chose to increase the dose of current treatment, and in the case of lack of response, 72.7% would switch to another antidepressant, and 22.8% would use the combination of two antidepressants, in which case 85.2% would choose agents with complementary mechanisms of action. Forty-nine percent of participants would recommend standard cognitive-behavioural psychotherapy for patients without complete response.

CONCLUSIONS

Some 50% of patients did not achieve complete remission, frequently related to persistence of residual symptoms. Achievement of complete recovery should be an essential objective.

Inhibitor of Striatal-Enriched Protein Tyrosine Phosphatase, 8-(Trifluoromethyl)-1,2,3,4,5-Benzopentathiepin-6-Amine hydrochloride (TC-2153), Produces Antidepressant-Like Effect and Decreases Functional Activity and Protein Level of 5-HT2A Receptor in the Brain

The serotoninergic 5-HT_2A receptor is involved in the mechanism of depression and antidepressant drugs action. Earlier we showed that striatal-enriched protein tyrosine phosphatase (STEP) inhibitor - 8-(trifluoromethyl)-1,2,3,4,5-benzopentathiepin-6-amine hydrochloride (TC-2153) affects both the brain serotoninergic system and the brain-derived neurotropic factor that are known to be involved in the psychopathology of depression. In the present study we investigated the effects of chronic TC-2153 administration on behavior in the standard battery of tests as well as the effects of acute and chronic TC-2153 treatment on the brain 5-HT_2A receptors in mice. We obtained a prominent antidepressant-like effect of chronic TC-2153 treatment in the forced swim test without any adverse side effects on locomotor activity, anxiety, exploration, motor skill and obsessive-compulsive-like behavior. Moreover, both acute and chronic TC-2153 administration inhibited the functional activity of 5-HT_2A receptors estimated by the number of 2,5-dimethoxy-4-iodoamphetamine (DOI, agonist of 5-HT_2A receptors)-induced head-twitches. TC-2153 treatment also attenuated the DOI-induced c-fos expression in cortical and hippocampal neurons and reduced the 5-HT_2A receptor protein level in the hippocampus and frontal cortex, but not in the striatum. Taken together, our combined data demonstrate that the antidepressant effect of STEP inhibitor TC-2153 could be mediated by its inhibitory properties towards the 5-HT_2A receptor-mediated signaling.

Depression and adult neurogenesis: Positive effects of the antidepressant fluoxetine and of physical exercise

Of wide interest for health is the relation existing between depression, a very common psychological illness, accompanied by anxiety and reduced ability to concentrate, and adult neurogenesis. We will focus on two neurogenic stimuli, fluoxetine and physical exercise, both endowed with the ability to activate adult neurogenesis in the dentate gyrus of the hippocampus, known to be required for learning and memory, and both able to counteract depression. Fluoxetine belongs to the class of selective serotonin reuptake inhibitor (SSRI) antidepressants, which represent the most used pharmacological therapy; physical exercise has also been shown to effectively counteract depression symptoms in rodents as well as in humans. While there is evidence that the antidepressant effect of fluoxetine requires its pro-neurogenic action, exerted by promoting proliferation, differentiation and survival of progenitor cells of the hippocampus, on the other hand fluoxetine exerts also neurogenesis-independent antidepressant effects by influencing the plasticity of the new neurons generated. Similarly, the antidepressant action of running also correlates with an increase of hippocampal neurogenesis and plasticity, although the gene pathways involved are only partially coincident with those of fluoxetine, such as those involved in serotonin metabolism and synapse formation. We further discuss how extra-neurogenic actions are also suggested by the fact that, unlike running, fluoxetine is unable to stimulate neurogenesis during aging, but still displays antidepressant effects. Moreover, in specific conditions, fluoxetine or running activate not only progenitor but also stem cells, which normally are not stimulated; this fact reveals how stem cells have a long-term, hidden ability to self-renew and, more generally, that neurogenesis is subject to complex controls that may play a role in depression, such as the type of neurogenic stimulus or the state of the local niche. Finally, we discuss how fluoxetine or running are effective in counteracting depression originated from stress or neurodegenerative diseases.

Transcriptomic and epigenomic biomarkers of antidepressant response

BACKGROUND

Antidepressant treatment is associated with a high rate of poor response, and thus, biomarker development is warranted.

METHODS

We aimed to synthesize studies investigating gene expression, small RNAs, and epigenomic biomarkers of antidepressant response. We conducted a narrative review of the literature.

RESULTS

Firstly, we detailed the challenges involved, in terms of biological tissues, relevant study time frames, and mandatory statistical tools. Secondly we synthesized results obtained in gene expression studies, focusing mainly on genome-wide studies, particularly small non-coding RNA, including micro-RNA and other small RNA species. In addition, we reviewed the potential biomarkers of antidepressant response arising from studies investigating DNA methylation variation and histone modifications.

LIMITATIONS

We did not conduct a meta-analysis due to the heterogeneity of the study.

CONCLUSION

Although promising, the field of gene expression and epigenomic biomarkers of antidepressant response is still in its infancy, and needs further development to define useful biomarkers in clinical practice.

Nanomedicine applications in women's health: state of the art

State-of-the-art applications of nanomedicine have the potential to revolutionize the diagnosis, prevention, and treatment of a range of conditions and diseases affecting women’s health. In this review, we provide a synopsis of potential applications of nanomedicine in some of the most dominant fields of women’s health: mental health, sexual health, reproductive medicine, oncology, menopause-related conditions and dementia. We explore published studies arising from in vitro and in vivo experiments, and clinical trials where available, to reveal novel and highly promising therapeutic applications of nanomedicine in these fields. For the first time, we summarize the growing body of evidence relating to the use of nanomaterials as experimental tools for the detection, prevention, and treatment of significant diseases and conditions across the life course of a cisgender woman, from puberty to menopause; revealing the far-reaching and desirable theoretical impact of nanomedicine across different medical disciplines. We also present an overview of potential concerns regarding the therapeutic applications of nanomedicine and the factors currently restricting the growth of applied nanomedicine.

Chronic administration of fluoxetine and pro-inflammatory cytokine change in a rat model of depression

This study evaluated the chronic effects of fluoxetine, a commonly prescribed SSRI antidepressant, on the peripheral and central levels of inflammatory cytokines including IL-1β, IL-6, TNF-α and IL-17 over a 4-interval in a rat model of chronic mild stress (CMS) which resembles the human experience of depression. Twenty-four Sprague-Dawley rats were randomly assigned to CMS+vehicle (n = 9), CMS+fluoxetine (n = 9) and the control (n = 6) groups. Sucrose preference and forced swim tests were performed to assess behavioral change. Blood samples were collected on day 0, 60, 90 and 120 for measurement of cytokine levels in plasma. On day 120, the brain was harvested and central level of cytokines was tested using Luminex. Four months of fluoxetine treatment resulted in changes in the sucrose preference and immobility time measurements, commensurate with antidepressant effects. The CMS+vehicle group exhibited elevated plasma levels of IL-1β, IL-17, and TNF-α on day 60 or 120. Rats treated with fluoxetine demonstrated lower IL-1β in plasma and brain after 90 and 120-day treatment respectively (p<0.05). There was a trend of reduction of IL-6 and TNF-α concentration. This study revealed the potential therapeutic effects of fluoxetine by reducing central and peripheral levels of IL-1β in the alleviation of depressive symptoms.

Social Isolation in Early versus Late Adolescent Mice Is Associated with Persistent Behavioral Deficits That Can Be Improved by Neurosteroid-Based Treatment

Early trauma and stress exposure during a critical period of life may increase the risk of major depressive disorder (MDD) and post-traumatic stress disorder (PTSD) in adulthood. The first-choice treatment for MDD and PTSD are selective serotonin reuptake inhibitor (SSRI) antidepressants. Unfortunately, half of MDD and PTSD patients show resistance to the therapeutic effects of these drugs and more efficient treatments are essential. Both MDD and PTSD patients present reduced levels of allopregnanolone (Allo), a potent endogenous positive allosteric modulator of GABA action at GABA_A receptors which are normalized by SSRIs in treatment responders. Thus, Allo analogs or drugs that stimulate its levels may offer an alternative in treating SSRIs-non-responders. We tested several drugs on the aggressive behavior of early and late adolescent socially-isolated (SI) mice, a model of PTSD. Isolation in early adolescence (PND 21) induced more severe aggression than mice isolated at PND 45. A single non-sedating administration of S-fluoxetine (S-FLX; 0.375–1.5 mg/kg), or of the Allo analogs ganaxolone (GNX; 10 mg/kg), BR351 (1–5 mg/kg), or BR297 (0.3125–2.5 mg/kg), or of the endocannabinoid, N-palmitoylethanolamine (PEA; 5–20 mg/kg) all decreased aggression more effectively in late than early adolescent SI mice. Importantly, the number of drug non-responders was higher in early than late SI mice for all the drugs tested. The non-responder rate was more elevated (12–64%) after S-FLX treatment, while 100% of mice responded to a single administration of PEA at the dose range of 15–20 mg/kg. Moreover, GNX, BR351, and BR297’s antiaggressive effect persisted longer than S-FLX in both late and early SI mice. All drugs tested failed to alter locomotor activity of SI mice. Our results show that drugs that mimic Allo’s action or that induce Allo biosynthesis may be valuable for the treatment of “SSRIs non-responder” patients.

Neurosteroid biosynthesis down-regulation and changes in GABAA receptor subunit composition: a biomarker axis in stress-induced cognitive and emotional impairment

By rapidly modulating neuronal excitability, neurosteroids regulate physiological processes, such as responses to stress and development. Excessive stress affects their biosynthesis and causes an imbalance in cognition and emotions. The progesterone derivative, allopregnanolone (Allo) enhances extrasynaptic and postsynaptic inhibition by directly binding at GABA_A receptors, and thus, positively and allosterically modulates the function of GABA. Allo levels are decreased in stress-induced psychiatric disorders, including depression and post-traumatic stress disorder (PTSD), and elevating Allo levels may be a valid therapeutic approach to counteract behavioural dysfunction. While benzodiazepines are inefficient, selective serotonin reuptake inhibitors (SSRIs) represent the first choice treatment for depression and PTSD. Their mechanisms to improve behaviour in preclinical studies include neurosteroidogenic effects at low non-serotonergic doses. Unfortunately, half of PTSD and depressed patients are resistant to current prescribed 'high' dosage of these drugs that engage serotonergic mechanisms. Unveiling novel biomarkers to develop more efficient treatment strategies is in high demand. Stress-induced down-regulation of neurosteroid biosynthesis and changes in GABA_A receptor subunit expression offer a putative biomarker axis to develop new PTSD treatments. The advantage of stimulating Allo biosynthesis relies on the variety of neurosteroidogenic receptors to be targeted, including TSPO and endocannabinoid receptors. Furthermore, stress favours a GABA_A receptor subunit composition with higher sensitivity for Allo. The use of synthetic analogues of Allo is a valuable alternative. Pregnenolone or drugs that stimulate its levels increase Allo but also sulphated steroids, including pregnanolone sulphate which, by inhibiting NMDA tonic neurotransmission, provides neuroprotection and cognitive benefits. In this review, we describe current knowledge on the effects of stress on neurosteroid biosynthesis and GABA_A receptor neurotransmission and summarize available pharmacological strategies that by enhancing neurosteroidogenesis are relevant for the treatment of SSRI-resistant patients. Linked Articles This article is part of a themed section on Pharmacology of Cognition: a Panacea for Neuropsychiatric Disease? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.19/issuetoc.

Clinical improvements following bilateral anterior capsulotomy in treatment-resistant depression

BACKGROUND

The purpose of this study was to evaluate a programme of lesion surgery carried out on patients with treatment-resistant depression (TRD).

METHOD

This was a retrospective study looking at clinical and psychometric data from 45 patients with TRD who had undergone bilateral stereotactic anterior capsulotomy surgery over a period of 15 years, with the approval of the Mental Health Act Commission (37 with unipolar depression and eight with bipolar disorder). The Beck Depression Inventory (BDI) before and after surgery was used as the primary outcome measure. The Montgomery-Asberg Depression Rating Scale was administered and cognitive aspects of executive and memory functions were also examined. We carried out a paired-samples t test on the outcome measures to determine any statistically significant change in the group as a consequence of surgery.

RESULTS

Patients improved on the clinical measure of depression after surgery by -21.20 points on the BDI with a 52% change. There were no significant cognitive changes post-surgery. Six patients were followed up in 2013 by phone interview and reported a generally positive experience. No major surgical complications occurred.

CONCLUSIONS

With the limitations of an uncontrolled, observational study, our data suggest that capsulotomy can be an effective treatment for otherwise TRD. Performance on neuropsychological tests did not deteriorate.

Gene expression and proliferation biomarkers for antidepressant treatment resistance

The neurotrophic hypothesis of depression suggests an association between effects on neuroplasticity and clinical response to antidepressant drug therapy. We studied individual variability in antidepressant drug effects on cell proliferation in lymphoblastoid cell lines (LCLs) from n=25 therapy-resistant patients versus n=25 first-line therapy responders from the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) study. Furthermore, the variability in gene expression of genes associated with cell proliferation was analyzed for tentative candidate genes for prediction of individual LCL donor's treatment response. Cell proliferation was quantified by EdU (5-ethynyl-2'-deoxyuridine) assays after 21-day incubation of LCLs with fluoxetine (0.5 ng μl-1) and citalopram (0.3 ng μl-1) as developed and described earlier. Gene expression of a panel of candidate genes derived from genome-wide expression analyses of antidepressant effects on cell proliferation of LCLs from the Munich Antidepressant Response Signature (MARS) study was analyzed by real-time PCR. Significant differences in in vitro cell proliferation effects were detected between the group of LCLs from first-line therapy responders and LCLs from treatment-resistant patients. Gene expression analysis of the candidate gene panel revealed and confirmed influence of the candidate genes ABCB1, FZD7 and WNT2B on antidepressant drug resistance. The potential of these genes as tentative biomarkers for antidepressant drug resistance was confirmed. In vitro cell proliferation testing may serve as functional biomarker for individual neuroplasticity effects of antidepressants.