A continuum of genetic liability for minor and major depression

Prenatal antidepressant exposure and the risk of decreased gestational age and lower birthweight: A polygenic score approach to investigate confounding by indication

INTRODUCTION

Prenatal antidepressant exposure has been associated with lower gestational age and birthweight. Yet, unmeasured residual confounding may inflate this association. We explored if maternal genetic liability for major depression explains part of the association of antidepressant use in pregnancy with lower gestational age and birthweight.

MATERIAL AND METHODS

We employed the maternal polygenic score (PGS) for major depression as a measure of genetic liability. We used generalised linear models to estimate the differences in gestational age and birthweight at each PGS quintile between children whose mothers continued antidepressant use during pregnancy (continuation group), children whose mothers discontinued antidepressant use during pregnancy (discontinuation group) and unexposed children.

RESULTS

After adjusting for confounders, we found significant differences in birthweight between PGS quintiles in the continuation and unexposed group. Yet, this relationship was not linear. Furthermore, at the lowest and highest PGS quintiles, the continuation group had significantly reduced mean gestational ages (adjusted β ranges: 1.7-4.5 days, p < 0.001-0.008) and lower mean birthweights (adjusted β ranges: 58.6-165.4 g, p = 0.001-0.008) than the discontinuation and unexposed groups.

CONCLUSION

We confirmed that antidepressant use in pregnancy was associated with small reductions in gestational age and birthweight but found that genetic liability for depression was not linearly associated with this risk. The causality of the observed associations could not be established due to the observational nature of the study. Residual confounding linked to the underlying disease was likely still present.

Monozygotic twins discordant for depression: An extended network comparison of depressive symptoms, cognitive functions and daily activities

Monozygotic twins share the same genotype; however, they can be phenotypically discordant on various traits. Studying discordant monozygotic twins allows the investigation of differences in associations between symptoms and psychopathological risk factors, controlled for shared genetic liability. The network approach to psychopathology suggests that depressive symptoms, along with risk and protective factors (e.g., cognition, daily activities), form a complex system of mutually interacting components. We compared monozygotic twins discordant for lifetime depression on their respective extended networks of depressive symptoms, cognitive functions and daily activities (intellectual, physical, social), and evaluated if these networks differ in their associations between variables and in the role of each variable within the network. Regularized partial correlations investigated the networks' composition in 147 monozygotic twin pairs discordant for depression from the Danish Twin Registry. Affected twins had stronger overall associations within their network of depressive symptoms, cognitive functions and daily activities than their unaffected co-twins, while the importance of the network components' associations did not differ between the co-twins. In affected twins, decreased frequency in experiencing happiness had the strongest association with remaining variables (i.e., the most influence in activating other network elements). Also, variables from different groups were significantly associated (e.g., loneliness with delayed memory, pessimism with low social activities, verbal learning with intellectual activities). In unaffected twins, both mood symptoms and cognitive functions were important, but between-groups associations were quasi-absent. These results suggest that external events affecting the ability to feel happiness likely trigger the psychopathological process (depression network activation), independently from the genetic predisposition to depression.

Transcriptomic decoding of regional cortical vulnerability to major depressive disorder

Previous studies in small samples have identified inconsistent cortical abnormalities in major depressive disorder (MDD). Despite genetic influences on MDD and the brain, it is unclear how genetic risk for MDD is translated into spatially patterned cortical vulnerability. Here, we initially examined voxel-wise differences in cortical function and structure using the largest multi-modal MRI data from 1660 MDD patients and 1341 controls. Combined with the Allen Human Brain Atlas, we then adopted transcription-neuroimaging spatial correlation and the newly developed ensemble-based gene category enrichment analysis to identify gene categories with expression related to cortical changes in MDD. Results showed that patients had relatively circumscribed impairments in local functional properties and broadly distributed disruptions in global functional connectivity, consistently characterized by hyper-function in associative areas and hypo-function in primary regions. Moreover, the local functional alterations were correlated with genes enriched for biological functions related to MDD in general (e.g., endoplasmic reticulum stress, mitogen-activated protein kinase, histone acetylation, and DNA methylation); and the global functional connectivity changes were associated with not only MDD-general, but also brain-relevant genes (e.g., neuron, synapse, axon, glial cell, and neurotransmitters). Our findings may provide important insights into the transcriptomic signatures of regional cortical vulnerability to MDD.

Exploring the relationship between depression and delinquency: a sibling comparison design using the NLSY

Relative to the general population, adolescents with psychiatric disorders such as major depression disorder are incarcerated (and reincarcerated) at higher rates. Current research is mixed on whether this association is a cause, consequence, or the product of selection. For example, aggression can lead to more depressive symptoms, yet depression is associated with antisocial behaviors (e.g., delinquency). To better understand the relationship between depression and delinquent behavior, we used the discordant kinship model to examine data from sibling pairs in the National Longitudinal Surveys of Youth 1979, a nationally representative study. By explicitly modeling within- and between-family variance, we reduced the influence of genetic and shared-environmental confounds on our analysis. Our results suggest that the relationship between depression and delinquency is not causal, but rather a product of selection.

Altered intersubject functional variability of brain white-matter in major depressive disorder and its association with gene expression profiles

Major depressive disorder (MDD) is a clinically heterogeneous disorder. Its mechanism is still unknown. Although the altered intersubject variability in functional connectivity (IVFC) within gray-matter has been reported in MDD, the alterations to IVFC within white-matter (WM-IVFC) remain unknown. Based on the resting-state functional MRI data of discovery (145 MDD patients and 119 healthy controls [HCs]) and validation cohorts (54 MDD patients, and 78 HCs), we compared the WM-IVFC between the two groups. We further assessed the meta-analytic cognitive functions related to the alterations. The discriminant WM-IVFC values were used to classify MDD patients and predict clinical symptoms in patients. In combination with the Allen Human Brain Atlas, transcriptome-neuroimaging association analyses were further conducted to investigate gene expression profiles associated with WM-IVFC alterations in MDD, followed by a set of gene functional characteristic analyses. We found extensive WM-IVFC alterations in MDD compared to HCs, which were associated with multiple behavioral domains, including sensorimotor processes and higher-order functions. The discriminant WM-IVFC could not only effectively distinguish MDD patients from HCs with an area under curve ranging from 0.889 to 0.901 across three classifiers, but significantly predict depression severity (r = 0.575, p = 0.002) and suicide risk (r = 0.384, p = 0.040) in patients. Furthermore, the variability-related genes were enriched for synapse, neuronal system, and ion channel, and predominantly expressed in excitatory and inhibitory neurons. Our results obtained good reproducibility in the validation cohort. These findings revealed intersubject functional variability changes of brain WM in MDD and its linkage with gene expression profiles, providing potential implications for understanding the high clinical heterogeneity of MDD.

Relative brain age is associated with socioeconomic status and anxiety/depression problems in youth

Brain age, a measure of biological aging in the brain, has been linked to psychiatric illness, principally in adult populations. Components of socioeconomic status (SES) associate with differences in brain structure and psychiatric risk across the lifespan. This study aimed to investigate the influence of SES on brain aging in childhood and adolescence, a period of rapid neurodevelopment and peak onset for many psychiatric disorders. We reanalyzed data from the Healthy Brain Network to examine the influence of SES components (occupational prestige, public assistance enrollment, parent education, and household income-to-needs ratio [INR]) on relative brain age (RBA). Analyses included 470 youth (5-17 years; 61.3% men), self-identifying as White (55%), African American (15%), Hispanic (9%), or multiracial (17.2%). Household income was 3.95 ± 2.33 (mean ± SD) times the federal poverty threshold. RBA quantified differences between chronological age and brain age using covariation patterns of morphological features and total volumes. We also examined associations between RBA and psychiatric symptoms (Child Behavior Checklist [CBCL]). Models covaried for sex, scan location, and parent psychiatric diagnoses. In a linear regression, lower RBA is associated with lower parent occupational prestige (p = .01), lower public assistance enrollment (p = .03), and more parent psychiatric diagnoses (p = .01), but not parent education or INR. Lower parent occupational prestige (p = .02) and lower RBA (p = .04) are associated with higher CBCL anxious/depressed scores. Our findings underscore the importance of including SES components in developmental brain research. Delayed brain aging may represent a potential biological pathway from SES to psychiatric risk. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Zuranolone and its role in treating major depressive disorder: a narrative review

Major Depressive Disorder (MDD) is a mood disorder classified as a persistent depressive mood and loss of interest lasting for more than two weeks and accompanied by a list of symptoms outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) diagnostic criteria. MDD affects approximately 264 million people worldwide and is the most prevailing form of neuropsychiatric disorder. Owing to the probable hypothesized pathophysiology of MDD being an outcome of abnormalities in the amino acid neurotransmitter system, including glutamate (the primary excitatory neurotransmitter) and γ-aminobutyric acid (GABA), SAGE-217 (Zuranolone) is being evaluated as a possible therapeutic treatment for MDD. Zuranolone is a synthetic, neuroactive steroid (NAS) and positive allosteric modulator (PMA) of GABAA receptors, regulating both synaptic and extra-synaptic release of GABA. It is administered as a once-daily oral dose for 2 weeks due to its low-moderate clearance. A change in total HAM-D score from baseline was the primary end-point of all the trials. A phase II trial conducted to evaluate the efficacy and safety of Zuranolone (30 mg, once-daily dose), described a significant reduction in total HAM-D score at day 14 and reported the drug to be well tolerated with headache, dizziness, nausea, and somnolence as the most common adverse events (AE). Additional phase III trials were also conducted to evaluate similar outcomes, the interim topline results of which have been released. Consequently, this article attempts to briefly analyze the pharmacology of Zuranolone, review the available clinical data and outcomes regarding its use, and evaluate its place as a prospective novel therapy in the effective management of MDD.

Cerebral blood flow changes and their genetic mechanisms in major depressive disorder: a combined neuroimaging and transcriptome study

BACKGROUND

Extensive research has shown abnormal cerebral blood flow (CBF) in patients with major depressive disorder (MDD) that is a heritable disease. The objective of this study was to investigate the genetic mechanisms of CBF abnormalities in MDD.

METHODS

To achieve a more thorough characterization of CBF changes in MDD, we performed a comprehensive neuroimaging meta-analysis of previous literature as well as examined group CBF differences in an independent sample of 133 MDD patients and 133 controls. In combination with the Allen Human Brain Atlas, transcriptome-neuroimaging spatial association analyses were conducted to identify genes whose expression correlated with CBF changes in MDD, followed by a set of gene functional feature analyses.

RESULTS

We found increased CBF in the reward circuitry and default-mode network and decreased CBF in the visual system in MDD patients. Moreover, these CBF changes were spatially associated with expression of 1532 genes, which were enriched for important molecular functions, biological processes, and cellular components of the cerebral cortex as well as several common mental disorders. Concurrently, these genes were specifically expressed in the brain tissue, in immune cells and neurons, and during nearly all developmental stages. Regarding behavioral relevance, these genes were associated with domains involving emotion and sensation. In addition, these genes could construct a protein-protein interaction network supported by 60 putative hub genes with functional significance.

CONCLUSIONS

Our findings suggest a cerebral perfusion redistribution in MDD, which may be a consequence of complex interactions of a wide range of genes with diverse functional features.

Association Between Single Nucleotide Polymorphisms Within lncRNA NONHSAT102891 and Depression Susceptibility in a Chinese Population

BACKGROUND

Depression is among the most common psychiatric disorders, and is a leading cause of the global disease burden. Its pathophysiological mechanism is unclear, which limits the development of therapeutic strategies. Long non-coding RNA (lncRNA) single nucleotide polymorphisms (SNPS) may be related. In this study, we aimed to determine the effects of the rs2242385, rs155979, rs3762983, and rs3762984 polymorphisms in the lncRNA NONHSAT102891 on depression susceptibility in a Chinese population.

METHODS

We conducted a case-control study in a cohort of 480 patients with depression and 329 healthy controls, and performed genotyping by gene sequencing ii.

RESULTS

The rs155979 GC genotype was significantly associated with increased risk of depression compared with healthy controls. Stratified analysis showed a 2.08-fold increased risk of suicide in patients with rs155979 GC or GG genotype. The rs2242385, rs3762983, and rs3762984 polymorphisms were not significantly associated with the risk of depression. Haploid analysis showed linkage disequilibrium between rs155979, rs3762983, and rs3762984, and the CCG haplotype reduced the risk of depression.

LIMITATIONS

The study sample was relatively small, and was restricted to patients from central and southern China. Further, only peripheral blood was used for DNA extraction.

CONCLUSION

The rs155979 polymorphism may be associated with the occurrence of depression in the Chinese population. However, further studies are needed to verify the reliability of our results in large populations and different ethnic groups.

Is subthreshold depression in adolescence clinically relevant?

BACKGROUND

Subthreshold depression is highly prevalent in adolescence, but compared to major depressive disorder, the clinical impact is under-researched. The aim of this review was to compare subthreshold depression and major depressive disorder in adolescents by reviewing available literature on epidemiology, risk factors, illness trajectories, brain anatomy and function, genetics, and treatment response.

METHODS

We conducted a scoping review of papers on subthreshold depression and major depressive disorder in adolescence published in English. Studies in adults were included when research in adolescence was not available.

RESULTS

We found that individuals with subthreshold depression were similar to individuals with major depressive disorder in several regards, including female/male ratio, onset, functional impairment, comorbidity, health care utilization, suicidal ideation, genetic predisposition, brain alterations, and treatment response. Further, subthreshold depression was about two times more common than major depressive disorder.

LIMITATIONS

The definition of subthreshold depression is highly variable across studies. Adolescent-specific data are limited in the areas of neurobiology and treatment.

CONCLUSIONS

The findings of the current review support the idea that subthreshold depression is of clinical importance and provide evidence for a spectrum, versus categorical model, for depressive symptomatology. Given the frequency of subthreshold depression escalating to major depressive disorder, a greater recognition and awareness of the significance of subthreshold depression in research, clinical practice and policy-making may facilitate the development and application of early prevention and intervention.

cAMP-PKA cascade: An outdated topic for depression?

Depression is a common neuropsychiatric disorder characterized by persistent depressed mood and causes serious socioeconomic burden worldwide. Hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, deficiency of monoamine transmitters, neuroinflammation and abnormalities of the gut flora are strongly associated with the onset of depression. The cyclic AMP (cAMP)/protein kinase A (PKA) cascade, a major cross-species cellular signaling pathway, is supposed as important player and regulator of depression onset by controlling synaptic plasticity, cytokinesis, transcriptional regulation and HPA axis. In the central nervous system, the cAMP-PKA cascade can dynamically shape neural circuits by enhancing synaptic plasticity, and affect K⁺ channels by phosphorylating Kir4.1, thereby regulating neuronal excitation. The reduction of cAMP-PKA cascade affects neuronal excitation as well as synaptic plasticity, ultimately leading to pathological outcome of depression, while activation of cAMP-PKA cascade would provide a rapid antidepressant effect. In this review, we proposed to reconsider the function of cAMP-PKA cascade, especially in the rapid antidepressant effect. Local activation or indirect activation of PKA through adjusting anchor proteins would provide new idea for acute treatment of depression.

Characterizing Heterogeneity in Neuroimaging, Cognition, Clinical Symptoms, and Genetics Among Patients With Late-Life Depression

Importance

Late-life depression (LLD) is characterized by considerable heterogeneity in clinical manifestation. Unraveling such heterogeneity might aid in elucidating etiological mechanisms and support precision and individualized medicine.

Objective

To cross-sectionally and longitudinally delineate disease-related heterogeneity in LLD associated with neuroanatomy, cognitive functioning, clinical symptoms, and genetic profiles.

Design, Setting, and Participants

The Imaging-Based Coordinate System for Aging and Neurodegenerative Diseases (iSTAGING) study is an international multicenter consortium investigating brain aging in pooled and harmonized data from 13 studies with more than 35 000 participants, including a subset of individuals with major depressive disorder. Multimodal data from a multicenter sample (N = 996), including neuroimaging, neurocognitive assessments, and genetics, were analyzed in this study. A semisupervised clustering method (heterogeneity through discriminative analysis) was applied to regional gray matter (GM) brain volumes to derive dimensional representations. Data were collected from July 2017 to July 2020 and analyzed from July 2020 to December 2021.

Main Outcomes and Measures

Two dimensions were identified to delineate LLD-associated heterogeneity in voxelwise GM maps, white matter (WM) fractional anisotropy, neurocognitive functioning, clinical phenotype, and genetics.

Results

A total of 501 participants with LLD (mean [SD] age, 67.39 [5.56] years; 332 women) and 495 healthy control individuals (mean [SD] age, 66.53 [5.16] years; 333 women) were included. Patients in dimension 1 demonstrated relatively preserved brain anatomy without WM disruptions relative to healthy control individuals. In contrast, patients in dimension 2 showed widespread brain atrophy and WM integrity disruptions, along with cognitive impairment and higher depression severity. Moreover, 1 de novo independent genetic variant (rs13120336; chromosome: 4, 186387714; minor allele, G) was significantly associated with dimension 1 (odds ratio, 2.35; SE, 0.15; P = 3.14 ×108) but not with dimension 2. The 2 dimensions demonstrated significant single-nucleotide variant-based heritability of 18% to 27% within the general population (N = 12 518 in UK Biobank). In a subset of individuals having longitudinal measurements, those in dimension 2 experienced a more rapid longitudinal change in GM and brain age (Cohen f2 = 0.03; P = .02) and were more likely to progress to Alzheimer disease (Cohen f2 = 0.03; P = .03) compared with those in dimension 1 (N = 1431 participants and 7224 scans from the Alzheimer's Disease Neuroimaging Initiative [ADNI], Baltimore Longitudinal Study of Aging [BLSA], and Biomarkers for Older Controls at Risk for Dementia [BIOCARD] data sets).

Conclusions and Relevance

This study characterized heterogeneity in LLD into 2 dimensions with distinct neuroanatomical, cognitive, clinical, and genetic profiles. This dimensional approach provides a potential mechanism for investigating the heterogeneity of LLD and the relevance of the latent dimensions to possible disease mechanisms, clinical outcomes, and responses to interventions.

Gender analysis of the frequency and course of depressive disorders and relationship with personality traits in general population: A prospective cohort study

BACKGROUND

We aimed to determine the prevalence and course of subthreshold depressive symptomatology (sDS) and probable major depressive episode (MDE) and to examine their association with personality traits among men and women.

METHODS

A community-based sample aged 35 years or older was examined in two waves (median follow-up of 6.9 years). The Patient Health Questionnaire-9 (PHQ-9) was used to assess sDS and MDE. The 10-item version of the Big Five Inventory was used to assess personality traits. Prevalence was assessed at baseline (n = 5,557) and incidence and persistence-recurrence rates were computed at follow up (n = 3,102). Logistic regression models were adjusted to explore the association of personality traits with prevalence and course of depressive disorders.

RESULTS

The prevalence of sDS and MDE was 14.04% (95% CI = 17.04-19.08) and 8.54 (95% CI=7.82-9.31), the incidence was 14.30 per 1,000 person-years (95% CI=12.49-16.31) and 4.34 per 1,000 person-years (95% CI=3.46-5.36), and the persistence-recurrence was 35.04 per 1,000 person-years (95% CI=29.00-41.96) and 28.8 per 1,000 person-years (95% CI=20.49-38.14). The gender gap was higher for MDE. Personality traits were differentially associated with the prevalence and course of depressive disorders between men and women.

LIMITATIONS

Because this study used questionnaires to assess depressive disorders and personality traits, information bias could not be ruled out.

CONCLUSIONS

The gender gap was higher for the prevalence and course of the probable MDE. There were more personality traits related with the course of the sDS and they had a major role in the course of the probable MDE in women.

Structural connectivity associated with familial risk for mental illness: A meta‐analysis of diffusion tensor imaging studies in relatives of patients with severe mental disorders

Schizophrenia (SCZ), bipolar disorder (BD), and major depressive disorder (MDD) are heritable conditions with overlapping genetic liability. Transdiagnostic and disorder‐specific brain changes associated with familial risk for developing these disorders remain poorly understood. We carried out a meta‐analysis of diffusion tensor imaging (DTI) studies to investigate white matter microstructure abnormalities in relatives that might correspond to shared and discrete biomarkers of familial risk for psychotic or mood disorders. A systematic search of PubMed and Embase was performed to identify DTI studies in relatives of SCZ, BD, and MDD patients. Seed‐based d Mapping software was used to investigate global differences in fractional anisotropy (FA) between overall and disorder‐specific relatives and healthy controls (HC). Our search identified 25 studies that met full inclusion criteria. A total of 1,144 relatives and 1,238 HC were included in the meta‐analysis. The overall relatives exhibited decreased FA in the genu and splenium of corpus callosum (CC) compared with HC. This finding was found highly replicable in jack‐knife analysis and subgroup analyses. In disorder‐specific analysis, compared to HC, relatives of SCZ patients exhibited the same changes while those of BD showed reduced FA in the left inferior longitudinal fasciculus (ILF). The present study showed decreased FA in the genu and splenium of CC in relatives of SCZ, BD, and MDD patients, which might represent a shared familial vulnerability marker of severe mental illness. The white matter abnormalities in the left ILF might represent a specific familial risk for bipolar disorder.

Familial risk for depressive and anxiety disorders: associations with genetic, clinical, and psychosocial vulnerabilities

BACKGROUND

In research and clinical practice, familial risk for depression and anxiety is often constructed as a simple Yes/No dichotomous family history (FH) indicator. However, this measure may not fully capture the liability to these conditions. This study investigated whether a continuous familial loading score (FLS), incorporating family- and disorder-specific characteristics (e.g. family size, prevalence of depression/anxiety), (i) is associated with a polygenic risk score (PRS) for major depression and with clinical/psychosocial vulnerabilities and (ii) still captures variation in clinical/psychosocial vulnerabilities after information on FH has been taken into account.

METHODS

Data came from 1425 participants with lifetime depression and/or anxiety from the Netherlands Study of Depression and Anxiety. The Family Tree Inventory was used to determine FLS/FH indicators for depression and/or anxiety.

RESULTS

Persons with higher FLS had higher PRS for major depression, more severe depression and anxiety symptoms, higher disease burden, younger age of onset, and more neuroticism, rumination, and childhood trauma. Among these variables, FH was not associated with PRS, severity of symptoms, and neuroticism. After regression out the effect of FH from the FLS, the resulting residualized measure of FLS was still associated with severity of symptoms of depression and anxiety, rumination, and childhood trauma.

CONCLUSIONS

Familial risk for depression and anxiety deserves clinical attention due to its associated genetic vulnerability and more unfavorable disease profile, and seems to be better captured by a continuous score that incorporates family- and disorder-specific characteristics than by a dichotomous FH measure.

Exploring the genetic heterogeneity in major depression across diagnostic criteria

Major depressive disorder (MDD) is defined differently across genetic research studies and this may be a key source of heterogeneity. While previous literature highlights differences between minimal and strict phenotypes, the components contributing to this heterogeneity have not been identified. Using the cardinal symptoms (depressed mood/anhedonia) as a baseline, we build MDD phenotypes using five components-(1) five or more symptoms, (2) episode duration, (3) functional impairment, (4) episode persistence, and (5) episode recurrence-to determine the contributors to such heterogeneity. Thirty-two depression phenotypes which systematically incorporate different combinations of MDD components were created using the mental health questionnaire data within the UK Biobank. SNP-based heritabilities and genetic correlations with three previously defined major depression phenotypes were calculated (Psychiatric Genomics Consortium (PGC) defined depression, 23andMe self-reported depression and broad depression) and differences between estimates analysed. All phenotypes were heritable (h2SNP range: 0.102-0.162) and showed substantial genetic correlations with other major depression phenotypes (Rg range: 0.651-0.895 (PGC); 0.652-0.837 (23andMe); 0.699-0.900 (broad depression)). The strongest effect on SNP-based heritability was from the requirement for five or more symptoms (1.4% average increase) and for a long episode duration (2.7% average decrease). No significant differences were noted between genetic correlations. While there is some variation, the two cardinal symptoms largely reflect the genetic aetiology of phenotypes incorporating more MDD components. These components may index severity, however, their impact on heterogeneity in genetic results is likely to be limited.

Associations of FKBP5 polymorphisms and methylation and parenting style with depressive symptoms among Chinese adolescents

BACKGROUND

Genetic factors may interplay with environmental stressors to contribute to risks of depressive symptoms. This study aimed to investigate the association of FKBP5 polymorphisms and DNA methylation with depressive symptoms among Chinese adolescents, considering the role of parenting style.

METHODS

This study used a nested case-control study design based on a cohort study, and the case (n = 120) and control groups (n = 118) were matched with age. Depressive symptoms, parenting style, and other demographics were measured. Fourteen potential polymorphisms and one promoter region in the FKBP5 gene were selected for genotyping and methylation analysis.

RESULTS

In the adjusted models, a significant association between FKBP5 rs7757037 and depressive symptoms was found in the codominant model (AG vs. GG; adjusted odds ratio [AOR] = 2.56, 95% CI = 1.13-5.78) and dominant model (AA+AG vs. GG; AOR = 2.38, 95% CI = 1.11-5.120); rs2817032 and rs2817035 polymorphisms were associated with depressive symptoms in the codominant model and dominant model. Significant interactions between rs7757037 and the father's parenting style were found in the codominant model (P = 0.043) and dominant model (P = 0.043), but the gene-environment interactions were not significant after correcting for multiple testing. Moreover, the significant main effects of FKBP5 methylation status on depressive symptoms were not observed, and there was no significant interaction between FKBP5 methylation status and parenting style on depressive symptoms.

CONCLUSIONS

Further studies are required to confirm the effect of FKBP5 polymorphisms and methylation as well as their interactions with parenting styles in larger samples.

The role of the intestinal microbiota in the pathogenesis of host depression and mechanism of TPs relieving depression

Depression is a prevalent neuropsychiatric disease with a high recurrence rate, affecting over 350 million people worldwide. Intestinal flora disorders and gut-brain-axis (GBA) dysfunction may cause mental disorders. Alterations in the intestinal flora composition could increase the permeability of the gut barrier, activate systemic inflammation and immune responses, regulate the release and efficacy of monoamine neurotransmitters, alter the activity and function of the hypothalamic-pituitary-adrenal (HPA) axis, and modify the abundance of the brain-derived neurotrophic factor (BDNF); all of these showed a close correlation with the occurrence of depression. In addition, the disturbance of the intestinal flora is related to circadian rhythm disorders, which aggravate the symptoms of depression. Tea polyphenols (TPs) have been found to have antidepressant effects. Therefore, the close reciprocity between the intestinal flora and circadian rhythm provides a new opportunity for TPs to regulate depression relying on the intestinal flora. In this review, we discussed the relationship between intestinal flora dysbiosis and the pathogenesis of depression and the mechanism of TPs relieving depression via the GBA.

Transcriptional-regulatory convergence across functional MDD risk variants identified by massively parallel reporter assays

Family and population studies indicate clear heritability of major depressive disorder (MDD), though its underlying biology remains unclear. The majority of single-nucleotide polymorphism (SNP) linkage blocks associated with MDD by genome-wide association studies (GWASes) are believed to alter transcriptional regulators (e.g., enhancers, promoters) based on enrichment of marks correlated with these functions. A key to understanding MDD pathophysiology will be elucidation of which SNPs are functional and how such functional variants biologically converge to elicit the disease. Furthermore, retinoids can elicit MDD in patients and promote depressive-like behaviors in rodent models, acting via a regulatory system of retinoid receptor transcription factors (TFs). We therefore sought to simultaneously identify functional genetic variants and assess retinoid pathway regulation of MDD risk loci. Using Massively Parallel Reporter Assays (MPRAs), we functionally screened over 1000 SNPs prioritized from 39 neuropsychiatric trait/disease GWAS loci, selecting SNPs based on overlap with predicted regulatory features-including expression quantitative trait loci (eQTL) and histone marks-from human brains and cell cultures. We identified >100 SNPs with allelic effects on expression in a retinoid-responsive model system. Functional SNPs were enriched for binding sequences of retinoic acid-receptive transcription factors (TFs), with additional allelic differences unmasked by treatment with all-trans retinoic acid (ATRA). Finally, motifs overrepresented across functional SNPs corresponded to TFs highly specific to serotonergic neurons, suggesting an in vivo site of action. Our application of MPRAs to screen MDD-associated SNPs suggests a shared transcriptional-regulatory program across loci, a component of which is unmasked by retinoids.

Association of FKBP5 gene variants with depression susceptibility: A comprehensive meta-analysis

BACKGROUND

This comprehensive meta-analysis aimed to combine data from different studies and to estimate the association between FKBP5 polymorphisms and depression.

METHODS

We performed a meta-analysis of observational studies. An electronic search was conducted on four databases for articles published before July 1, 2020.

RESULTS

A total of 5125 patients with depression and 8399 controls from 16 independent studies were included in the analysis. The results showed that FKBP5 rs1360780 was associated with the risk of depression in the codominant model (CT vs. CC; OR = 1.10, 95% CI = 1.00-1.20, P = .04); rs4713916 polymorphism was associated with depression in the codominant model (AG vs. GG; OR = 1.19, 95% CI = 1.05-1.34, P = .008) and recessive model (AA vs. AG + GG; OR = 0.74, 95% CI = 0.56-0.99, P = .04); a significant association between rs3800373 and depression was found in the codominant genetic model (AC vs. AA; OR = 1.18, 95% CI = 1.05-1.34, P = .007) and dominant model (CC + AC vs. AA; OR = 1.15, 95% CI = 1.03-1.30, P = .02); there was no significant association of FKBP5 rs9470080 or rs9296158 with depression in any genetic model (P > .05). No publication bias was observed in our analysis. Moreover, sensitivity analyses demonstrated the Zobel's study significantly affected the heterogeneity for rs4713916 and rs3800373.

CONCLUSIONS

FKBP5 rs1360780 was associated with an increased risk of depression in the codominant model. We also found that rs4713916 and rs3800373 were involved in depression, rs4713916 was positively associated with depression in the codominant model and recessive model, and rs3800373 was related to an elevated risk of depression in the codominant model and dominant model.

Integrative analysis of genome-wide association studies identifies novel loci associated with neuropsychiatric disorders

Neuropsychiatric disorders, such as autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), schizophrenia (SCZ), bipolar disorder (BIP), and major depressive disorder (MDD) share common clinical presentations, suggesting etiologic overlap. A substantial proportion of SNP-based heritability for neuropsychiatric disorders is attributable to genetic components, and genome-wide association studies (GWASs) focusing on individual diseases have identified multiple genetic loci shared between these diseases. Here, we aimed at identifying novel genetic loci associated with individual neuropsychiatric diseases and genetic loci shared by neuropsychiatric diseases. We performed multi-trait joint analyses and meta-analysis across five neuropsychiatric disorders based on their summary statistics from the Psychiatric Genomics Consortium (PGC), and further carried out a replication study of ADHD among 2726 cases and 16299 controls in an independent pediatric cohort. In the multi-trait joint analyses, we found five novel genome-wide significant loci for ADHD, one novel locus for BIP, and ten novel loci for MDD. We further achieved modest replication in our independent pediatric dataset. We conducted fine-mapping and functional annotation through an integrative multi-omics approach and identified causal variants and potential target genes at each novel locus. Gene expression profile and gene-set enrichment analysis further suggested early developmental stage expression pattern and postsynaptic membrane compartment enrichment of candidate genes at the genome-wide significant loci of these neuropsychiatric disorders. Therefore, through a multi-omics approach, we identified novel genetic loci associated with the five neuropsychiatric disorders which may help to better understand the underlying molecular mechanism of neuropsychiatric diseases.

Confirming diagnostic categories within a depression continuum: Testing extra-linearity of risk factors and a latent class analysis

BACKGROUND

Dimensions are recommended as replacements for diagnostic categories of depression, but clinicians continue to use categories. Categories are appropriate if major, underlying changes in symptom structure occur above a clinical cut-off on a depression continuum.

METHODS

Cross-sectional surveys of Chinese undergraduates (n = 39,446) 2014-2018 measured self-reported depressive symptoms, associated psychopathology and etiological risk factors using standardised instruments. We created a continuum using PHQ-9 scores and tested linear and extra-linear contrasts in associated psychopathology, and etiology. We carried out latent class analyses (LCA).

RESULTS

Most symptoms showed linear increase, but depressed mood, anhedonia, and suicidal ideation showed marked increase at the severe end of the continuum. There was extra-linear increase in associated psychotic symptoms, other psychopathology, age, low family income, chronic pain and physical illness, childhood physical and sexual abuse, and neglect. Four LCs corresponding to Melancholic, Severe melancholic, Non-melancholic, and Mild depression were confirmed, but only above a clinical cut-off along the continuum. Etiological risk factors did not differentiate between classes but showed overall dramatic increase in impact above threshold of clinical severity.

LIMITATIONS

Only one self-report instrument was used (PHQ-9) to measure depression and diagnoses were not validated by clinical interviews.

CONCLUSIONS

Categories are necessary to describe the dramatic changes in underlying structure and symptom associations above a clinical threshold of severity. These result from extra-linear impact of etiological risk factors at the severe end of the depression continuum. Although the study confirmed melancholic and non-melancholic subtypes, further investigation should investigate etiological factors that determine this subdivision.

Animal Models of Depression: What Can They Teach Us about the Human Disease?

Depression is apparently the most common psychiatric disease among the mood disorders affecting about 10% of the adult population. The etiology and pathogenesis of depression are still poorly understood. Hence, as for most human diseases, animal models can help us understand the pathogenesis of depression and, more importantly, may facilitate the search for therapy. In this review we first describe the more common tests used for the evaluation of depressive-like symptoms in rodents. Then we describe different models of depression and discuss their strengths and weaknesses. These models can be divided into several categories: genetic models, models induced by mental acute and chronic stressful situations caused by environmental manipulations (i.e., learned helplessness in rats/mice), models induced by changes in brain neuro-transmitters or by specific brain injuries and models induced by pharmacological tools. In spite of the fact that none of the models completely resembles human depression, most animal models are relevant since they mimic many of the features observed in the human situation and may serve as a powerful tool for the study of the etiology, pathogenesis and treatment of depression, especially since only few patients respond to acute treatment. Relevance increases by the fact that human depression also has different facets and many possible etiologies and therapies.

Genetic Architecture of Depression: Where Do We Stand Now?

The research of depression genetics has been occupied by historical candidate genes which were tested by candidate gene association studies. However, these studies were mostly not replicable. Thus, genetics of depression have remained elusive for a long time. As research moves from candidate gene association studies to GWAS, the hypothesis-free non-candidate gene association studies in genome-wide level, this trend will likely change. Despite the fact that the earlier GWAS of depression were not successful, the recent GWAS suggest robust findings for depression genetics. These altogether will catalyze a new wave of multidisciplinary research to pin down the neurobiology of depression.

Implicit bias of encoded variables: frameworks for addressing structured bias in EHR-GWAS data

The 'discovery' stage of genome-wide association studies required amassing large, homogeneous cohorts. In order to attain clinically useful insights, we must now consider the presentation of disease within our clinics and, by extension, within our medical records. Large-scale use of electronic health record (EHR) data can help to understand phenotypes in a scalable manner, incorporating lifelong and whole-phenome context. However, extending analyses to incorporate EHR and biobank-based analyses will require careful consideration of phenotype definition. Judgements and clinical decisions that occur 'outside' the system inevitably contain some degree of bias and become encoded in EHR data. Any algorithmic approach to phenotypic characterization that assumes non-biased variables will generate compounded biased conclusions. Here, we discuss and illustrate potential biases inherent within EHR analyses, how these may be compounded across time and suggest frameworks for large-scale phenotypic analysis to minimize and uncover encoded bias.

Identification of antisense lncRNAs targeting GSK3β as a regulator in major depressive disorder

Aim: To identify lncRNAs targeting GSK3β in MDD. Materials & methods: The levels of GSK3β and its three targeting lncRNAs (gsk3β antisense AS1, AS2 and AS3) were detected in 52 patients with major depressive disorder (MDD) before and after 8 weeks of escitalopram treatment. The functional study was evaluated using the silence of lncR-gsk3βAS2/3. The correlation between lncRNA-gsk3β and 89 MDD patients was analyzed. Human neuron progenitor cells were used to investigate the functional role of lncRNA-gsk3β in MDD. Results: All three lncRNAs were downregulated in MDD patients but upregulated after treatment. Inhibition of gsk3βAS2/3 reduced GSK3β expression and its phosphorylation levels in the neuron progenitor cells. Conclusion: Our findings suggest that lncRNA-gsk3βAS3 regulates GSK3β activity in MDD and has potential as a novel therapeutic target.

Features of minor depressive disorder subtypes in conditions of COVID-19 pandemic

BACKGROUND

The continuous research on minor depressive disorder is one of the pressing issues in the context of the COVID-19 pandemic. We studied the features of minor depressive disorder subtypes in conditions of the COVID-19 pandemic.

MATERIALS AND METHODS

Sixty-two patients were observed with the administration of clinical follow-up research method.

RESULTS

The following major subtypes of minor depressive disorder were identified: Asthenic, hysterical, hypochondriacal, apathetic, and minor depressive disorder with obsessive-compulsive symptoms.

CONCLUSIONS

The COVID-19 pandemic lead to an increase in the development of the minor depressive disorder with a predominance of asthenic and obsessive-phobic symptoms. Therapy of minor depressive disorder requires the involvement of a wide range of specialists, preferably with the inclusion of community-based treatment.

Genetic Liability for Depression, Social Factors and Their Interaction Effect in Depressive Symptoms and Depression Over Time in Older Adults

OBJECTIVES

The objectives of this study were to investigate the effect of genetic and social factors on depressive symptoms and depression over time and to test whether social factors moderate the relationship between depressive symptoms and its underlying genetics in later life.

METHODS

The study included 2,279 participants with a mean follow-up of 15 years from the Longitudinal Aging Study Amsterdam with genotyping data. The personal genetic loading for depression was estimated for each participant by calculating a polygenic risk scores (PRS-D), based on 23,032 single nucleotide polymorphisms associated with major depression in a large genome-wide association study. Partner status, network size, received and given emotional support were assessed via questionnaires and depressive symptoms were assessed using the CES-D Scale. A CES-D Scale of 16 and higher was considered as clinically relevant depression.

RESULTS

Higher PRS-D was associated with more depressive symptoms whereas having a partner and having a larger network size were independently associated with less depressive symptoms. After extra adjustment for education, cognitive function and functional limitations, giving more emotional support was also associated with less depressive symptoms. No evidence for gene-environment interaction between PRS-D and social factors was found. Similar results were found for clinically relevant depression.

CONCLUSION

Genetic and social factors are independently associated with depressive symptoms over time in older adults. Strategies that boost social functioning should be encouraged in the general population of older adults regardless of the genetic liability for depression.

Minimal phenotyping yields genome-wide association signals of low specificity for major depression

Minimal phenotyping refers to the reliance on the use of a small number of self-reported items for disease case identification, increasingly used in genome-wide association studies (GWAS). Here we report differences in genetic architecture between depression defined by minimal phenotyping and strictly defined major depressive disorder (MDD): the former has a lower genotype-derived heritability that cannot be explained by inclusion of milder cases and a higher proportion of the genome contributing to this shared genetic liability with other conditions than for strictly defined MDD. GWAS based on minimal phenotyping definitions preferentially identifies loci that are not specific to MDD, and, although it generates highly predictive polygenic risk scores, the predictive power can be explained entirely by large sample sizes rather than by specificity for MDD. Our results show that reliance on results from minimal phenotyping may bias views of the genetic architecture of MDD and impede the ability to identify pathways specific to MDD.

Seeking for potential pathogenic genes of major depressive disorder in the Gene Expression Omnibus database

INTRODUCTION

Major depressive disorder (MDD) is one of the most common mental disorders worldwide. The aim of this study was to identify potential pathological genes in MDD.

METHODS

We searched and downloaded gene expression data from the Gene Expression Omnibus database to identify differentially expressed genes (DEGs) in MDD. Then, Kyoto Encyclopedia of Genes and Genomes pathway, Gene Ontology analysis, and protein-protein interaction (PPI) network were applied to investigate the biological function of identified DEGs. The quantitative real-time polymerase chain reaction and a published dataset were used to validate the result of bioinformatics analysis.

RESULTS

A total of 514 DEGs were identified in MDD. In the PPI network, some hub genes with high degrees were identified, such as EEF2, RPL26L1, RPLP0, PRPF8, LSM3, DHX9, RSRC1, and AP2B1. The result of in vitro validation of RPL26L1, RSRC1, TOMM20L, RPLPO, PRPF8, AP2B1, STIP1, and C5orf45 was consistent with the bioinformatics analysis. Electronic validation of C5orf45, STIP1, PRPF8, AP2B1, and SLC35E1 was consistent with the bioinformatics analysis.

DISCUSSION

The deregulated genes could be used as potential pathological factors of MDD. In addition, EEF2, RPL26L1, RPLP0, PRPF8, LSM3, DHX9, RSRC1, and AP2B1 might be therapeutic targets for MDD.

Neuroinflammation, Gut-Brain Axis and Depression

Psychiatric diseases are the manifestations that result from the individual's genetic structure, physiology, immunology and ways of coping with environmental stressors. The current psychiatric diagnostic systems do not include any systematic characterization in regard to neurobiological processes that reveal the clinical picture in individuals who got psychiatric diagnosis. It is obvious that further research in different areas is needed to understand the psychopathology. The problems in the functions of immune system and the correlation of neuroinflammatory processes with psychiatric disorders have been one of the main research topics of psychiatry in recent years and have contributed to our understanding of psychopathology. Recent advances in the fields of immunology and genetics as well as rapidly increasing knowledge on the effects of immunological processes on brain functions have drawn attention to the correlations between psychiatric disorders and immune system dysfunctions. There are still unfilled gaps in the biology, pathophysiology, and treatment of major depressive disorder, which is quite prevalent among the psychiatric disorders, can lead to significant disability, and frequently has a recurrent course. It appears that low-grade chronic neuroinflammation plays a key role in forming a basis for the interaction between psychological stress, impaired gut microbiota and major depressive disorder. In this review, the role of neuroinflammation in the etiopathogenesis of depression and the mechanism of action of the gut-brain axis that leads to this are discussed in the light of current studies.

Unraveling the genetic architecture of major depressive disorder: merits and pitfalls of the approaches used in genome-wide association studies

To identify genetic risk loci for major depressive disorder (MDD), two broad study design approaches have been applied: (1) to maximize sample size by combining data from different phenotype assessment modalities (e.g. clinical interview, self-report questionnaires) and (2) to reduce phenotypic heterogeneity through selecting more homogenous MDD subtypes. The value of these strategies has been debated. In this review, we summarize the most recent findings of large genomic studies that applied these approaches, and we highlight the merits and pitfalls of both approaches with particular attention to methodological and psychometric issues. We also discuss the results of analyses that investigated the heterogeneity of MDD. We conclude that both study designs are essential for further research. So far, increasing sample size has led to the identification of a relatively high number of genomic loci linked to depression. However, part of the identified variants may be related to a phenotype common to internalizing disorders and related traits. As such, samples containing detailed clinical information are needed to dissect depression heterogeneity and enable the potential identification of variants specific to a more restricted MDD phenotype. A balanced portfolio reconciling both study design approaches is the optimal approach to progress further in unraveling the genetic architecture of depression.

Disease-discordant twin structural MRI studies on affective disorders

Magnetic resonance imaging (MRI) studies have identified neural structures implicated in the pathophysiology of mood disorders, especially bipolar disorder (BD) and major depressive disorder (MDD). However, the role of genetic and environmental influences on such brain deficits is still unclear. In this context, the present review summarizes the current evidence from structural MRI and Diffusion Tensor Imaging (DTI) studies on twin samples concordant or discordant for BD or MDD, with the aim of clarifying the role of genetic and environmental risk factors on brain alterations. Although the results showed a complex interplay between gene and environment in affective disorders, the evidence seem to underline that both genetic and environmental risk factors have an impact on brain areas and vulnerability to MDD and BD. However, the precise mechanism of action and the interaction between these factors still needs to be unveiled. Therefore, future larger studies on concordant or discordant twins should be encouraged, because this population provides a unique opportunity to probe separately genetic and environmental markers of disease vulnerability.

Association Between Period 3 Gene Polymorphisms and Adverse Effects of Antidepressants for Major Depressive Disorder

Aims: Circadian rhythm genes including Period 3 (Per3) are associated with major depressive disorder (MDD) and have an effect on the patient's response to selective serotonin reuptake inhibitor (SSRI) antidepressants. The aim of this study was to identify possible associations between three single nucleotide polymorphisms (SNPs) of Per3 (rs10746473, rs228697, and rs228729), the MDD symptoms, and adverse effects of SSRIs. Materials and Methods: A total of 600 MDD patients who had been treated with SSRIs were enrolled. The 17-item Hamilton Rating Scale for Depression (HAMD₁₇) was used to evaluate symptoms and treatment efficacy. In addition, the Treatment Emergent Symptom Scale/UKU Consumer Satisfaction Rating Scale (TESS/UKU) was used to assess adverse effects. The Per3 locus was genotyped by PCR and DNA sequencing. Results: The Per3 rs228697 CC genotype was associated with a higher sleep factor score when compared with the CG genotype (F = 4.027, p = 0.046). In addition, the rs228729 TC genotype was associated with a greater risk of suffering from excitement/agitation (p = 0.002, OR [odds ratio] = 4.049), akathisia (p = 0.014, OR = 4.905) and weight loss (p = 0.041, OR = 2.287) when compared with the CC genotype. Finally, the rs10746473 AA genotype patients were more likely to suffer from dizziness (p = 0.042, OR = 0.362) and the GA genotype patients from tachycardia (p = 0.015, OR = 0.340) when compared with those with GG genotype. Conclusion: The Per3 gene variants in patients can predict adverse effects of SSRIs and drug compliance.

A model of human endogenous retrovirus (HERV) activation in mental health and illness

Despite strong evidence for the heritability of major depressive disorder (MDD), efforts to identify causal genes have been disappointing. Furthermore, although there is strong support for life stress as a major predictor of MDD, there are also considerable individual differences in susceptibility and resilience that remain poorly understood. Efforts to identify specific gene-by-environment risk factors produced results that were initially encouraging, but that were not supported by later large-scale studies. Here I propose a novel mechanism that could address the "missing heritability" of MDD, the role of environmental risk factors, and individual differences in susceptibility and resilience. This mechanism focuses on a class of transposable elements, Human Endogenous Retroviruses (HERVs), which make up approximately 8% of the human genome as the result of ancient retroviral infections that entered mammalian germ lines throughout the course of evolution. My primary hypothesis is that exposure to either exogenous viruses or traumatic experiences can activate HERVs in the brain to cause depressive (and possibly other psychiatric) symptoms. My secondary hypothesis is that individual differences in vulnerability or resilience result from the balance of activated HERVs with pathogenic versus protective functions in the brain. Future research can test these hypotheses by analysis of postmortem human brain tissue from donors with known viral or trauma histories; animal studies manipulating HERV expression; cell culture studies examining regulatory mechanisms of HERV expression; and from brain imaging studies of individuals with known HERV-expression. Such research may reveal novel functions of HERVs in neural tissue and may lead to a new generation of psychiatric interventions designed to target aberrant HERV activation.

The genetic and environmental etiology of child maltreatment in a parent-based extended family design

Child maltreatment has been associated with various cumulative risk factors. However, little is known about the extent to which genetic and environmental factors contribute to individual differences between parents in perpetrating child maltreatment. To estimate the relative contribution of genetic and environmental factors to perpetrating maltreatment we used a parent-based extended family design. Child-reported perpetrated maltreatment was available for 556 parents (283 women) from 63 families. To explore reporter effects (i.e., child perspective on maltreatment), child reports were compared to multi-informant reports. Based on polygenic model analyses, most of the variance related to the perpetration of physical abuse and emotional neglect was explained by common environmental factors (physical abuse: c2 = 59%, SE = 12%, p = .006; emotional neglect: c2 = 47%, SE = 8%, p &lt; .001) whereas genetic factors did not significantly contribute to the model. For perpetrated emotional abuse, in contrast, genetic factors did significantly contribute to perpetrated emotional abuse (h2 = 33%, SE = 8%, p &lt; .001), whereas common environment factors did not. Multi-informant reports led to similar estimates of genetic and common environmental effects on all measures except for emotional abuse, where a multi-informant approach yielded higher estimates of the common environmental effects. Overall, estimates of unique environment, including measurement error, were lower using multi-informant reports. In conclusion, our findings suggest that genetic pathways play a significant role in perpetrating emotional abuse, while physical abuse and emotional neglect are transmitted primarily through common environmental factors. These findings imply that interventions may need to target different mechanisms dependings on maltreatment type.

Reward Processing in Depression: A Conceptual and Meta-Analytic Review Across fMRI and EEG Studies

OBJECTIVE

A role for aberrant reward processing in the pathogenesis of depression has long been proposed. However, no review has yet examined its role in depression by integrating conceptual and quantitative findings across functional MRI (fMRI) and EEG methodologies. The authors quantified these effects, with an emphasis on development.

METHOD

A total of 38 fMRI and 12 EEG studies were entered into fMRI and EEG meta-analyses. fMRI studies primarily examined reward anticipation and reward feedback. These were analyzed using the activation likelihood estimation method. EEG studies involved mainly the feedback-related negativity (FRN) event-related potential, and these studies were analyzed using random-effects meta-analysis of the association between FRN and depression.

RESULTS

Analysis of fMRI studies revealed significantly reduced striatal activation in depressed compared with healthy individuals during reward feedback. When region-of-interest analyses were included, reduced activation was also observed in reward anticipation, an effect that was stronger in individuals under age 18. FRN was also significantly reduced in depression, with pronounced effects in individuals under age 18. In longitudinal studies, reduced striatal activation in fMRI and blunted FRN in EEG were found to precede the onset of depression in adolescents.

CONCLUSIONS

Taken together, the findings show consistent neural aberrations during reward processing in depression, namely, reduced striatal signal during feedback and blunted FRN. These aberrations may underlie the pathogenesis of depression and have important implications for development of new treatments.

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

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

Recognizing Depression from the Microbiota⁻Gut⁻Brain Axis

Major depression is one of the leading causes of disability, morbidity, and mortality worldwide. The brain⁻gut axis functions are disturbed, revealed by a dysfunction of the brain, immune system, endocrine system, and gut. Traditional depression treatments all target the brain, with different drugs and/or psychotherapy. Unfortunately, most of the patients have never received any treatment. Studies indicate that gut microbiota could be a direct cause for the disorder. Abnormal microbiota and the microbiota⁻gut⁻brain dysfunction may cause mental disorders, while correcting these disturbance could alleviate depression. Nowadays, the gut microbiota modulation has become a hot topic in treatment research of mental disorders. Depression is closely related with the health condition of the brain⁻gut axis, and maintaining/restoring the normal condition of gut microbiota helps in the prevention/therapy of mental disorders.