The serotonin transporter promoter variant (5-HTTLPR), stress, and depression meta-analysis revisited: evidence of genetic moderation

Prevalencia de depresión y factores asociados en hombres

El objetivo del presente estudio fue evaluar la prevalencia de depresión, detectar el riesgo suicida e identificar los factores sociodemográficos y personales asociados a este trastorno. La muestra no aleatorizada estuvo conformada por 1525 hombres colombianos con edades entre 18 y 83 años procedentes de 22 departamentos y de distintos niveles educativos. Para evaluar la depresión se usó el Cuestionario de Depresión para Hombres (Álvarez y Londoño, 2012); para evaluar la comorbilidad con ansiedad se usó la Escala de Ansiedad HADS (Zigmond y Snaith, 1983) y el IMAFE (Lara, 1991); y para recolectar información acerca de los factores personales y sociodemográficos se usó una ficha de registro. Se analizaron los datos para calcular la prevalencia de corte, el riesgo suicida, la comorbilidad a través del uso del paquete estadístico SPSS. Se concluye que la prevalencia real reportada y el riesgo suicida en la población estudiada son más altos que los detectados usando un instrumento no sensible al género.

Does preoperative depression and/or serotonin transporter gene polymorphism predict outcome after laparoscopic cholecystectomy?

OBJECTIVE

To determine whether preoperative psychological depression and/or serotonin transporter gene polymorphism are associated with poor outcomes after the common procedure of laparoscopic cholecystectomy.

DESIGN

Patients undergoing laparoscopic cholecystectomy were genotyped for the serotonin transporter gene 5-HTTLPR polymorphism and assessed for psychological morbidity before and 6 weeks after surgery. The main outcome was postoperative depression; secondary outcomes included fatigue, perceived pain, quality of life and subjective perception about return to usual.

RESULTS

Full genetic and psychological data were obtained from 273 out of 330 patients consented to the study (82% female). Significantly fewer people with preoperative depression (Beck Depression Inventory (BDI) score >5) had returned to employment (57% vs 86%, p<0.001) or made a full recovery (11% vs 44%, p<0.001) 6 weeks after surgery. Independent predictors for subjective return to usual after surgery included preoperative depression, body mass index and postoperative pain scores. Independent predictors of postoperative depression included preoperative antidepressant use and preoperative depression. SS genotype was associated with use of antidepressants preoperatively and higher anxiety levels after surgery. However, it was not associated with other salient postoperative psychosocial outcomes.

CONCLUSIONS

Depressive psychological morbidity preoperatively, pain and body mass index appear to be important factors in predicting recovery after this common surgical procedure. There may be a place to include preoperative brief psychological screening to enable targeted support. Our results suggest that the serotonin transporter gene is unlikely to be a useful clinical predictor of outcome in this group.

TRIAL REGISTRATION NUMBER

ISRCTN40219584.

Stressing over anxiety: A novel interaction of 5-HTTPLR genotype and anxiety-related phenotypes in older adults

Variation within the serotonin transporter gene-linked polymorphic region (5-HTTPLR) contributes to individual differences in trait neuroticism and increases risk for the development of psychopathology in the context of stressful life events. The underlying mechanisms may involve dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and the release of stress-related hormones. Yet, observed effects are small, possibly because they occur against the background of many other, mostly unknown, genetic and environmental variables. In this study, we removed much of the variance contributed by such background factors by including complex trait and behavioral measures in our analyses, to isolate the unique contributions of 5-HTTLPR genotype to cortisol baseline, reactivity, and recovery during the Trier Social Stress Test. We recruited 82 community-dwelling older adults (55 and older), an under-studied population, and measured salivary cortisol levels at baseline and following the TSST. As a comparison group we also recruited 88 younger adults (males only, 18-51 years old). Neuroticism, trait anxiety, perceived stress levels, and early childhood trauma experiences were measured using self-report questionnaires. An exploratory factor analysis revealed a latent anxiety trait. Cortisol baseline levels were significantly elevated in older adult S-allele carriers (but not in LL-homozygotes) who scored higher on the latent anxiety trait, relative to S-allele carriers. No such differences were found among younger adults, nor amongst measures obtained during the reactivity or recovery periods. These results highlight the utility of taking into account background variables that may otherwise obscure associations between genetic variables and endophenotypes.

Dopamine Receptor Gene DRD4 7-Repeat Allele X Maternal Sensitivity Interaction on Child Externalizing Behavior Problems: Independent Replication of Effects at 18 Months

The DRD4 VNTR has been associated with child behavior problems in interaction with maternal insensitivity in European and American cohorts of preschoolers, with the 7-repeat (7R) allele associated with greater problems. We sought to replicate and expand these findings by examining effects on reports of child behavior problems at 18 months. A 63 family sample with data for observed maternal sensitivity ratings, DRD4 VNTR genotype, and maternal report of child behavior problems at 18-months was used in this preliminary analysis. Maternal sensitivity was measured at 6-months of age using laboratory observational measures (free-play and a teaching task). Maternal report of toddler behavior was obtained at 18-months via the standard Child Behavior Checklist, and infant genotype on the DRD4 VNTR was obtained using PCR. Infants carrying the DRD4 7R allele showed greater effects of maternal insensitivity than non-carriers for behavioral problems at 18-months. We replicated previous findings of association of infant DRD4 x maternal sensitivity interactions with child Externalizing problems in the European-ancestry sample (N = 42) in a median split of maternal sensitivity (p = .00011, eta2 = .329) and in regression analyses controlling for maternal age, maternal depression, and child gender in European ancestry (B = -3.4, SE 1.33, p = .01) and the total sample (B = -2.2, SE 1.02, p = .02). Exploratory analyses also found evidence of DRD4 x maternal sensitivity interaction with the CBCL ADHD scale. These findings replicate in an independent cohort DRD4 x maternal insensitivity interaction effect on child externalizing behavior problems at 18 months, further supporting the role of the DRD4 genotype in differential sensitivity to parenting.

Association between reduced white matter integrity in the corpus callosum and serotonin transporter gene DNA methylation in medication-naive patients with major depressive disorder

Previous evidence suggests that the serotonin transporter gene (SLC6A4) is associated with the structure of brain regions that are critically involved in dysfunctional limbic-cortical network activity associated with major depressive disorder (MDD). Diffusion tensor imaging (DTI) and tract-based spatial statistics were used to investigate changes in white matter integrity in patients with MDD compared with healthy controls. A possible association between structural alterations in white matter tracts and DNA methylation of the SLC6A4 promoter region was also assessed. Thirty-five medication-naive patients with MDD (mean age: 40.34, male/female: 10/25) and age, gender and education level matched 49 healthy controls (mean age: 41.12, male/female: 15/34) underwent DTI. SLC6A4 DNA methylation was also measured at five CpG sites of the promoter region, and the cell type used was whole-blood DNA. Patients with MDD had significantly lower fractional anisotropy (FA) values for the genu of the corpus callosum and body of the corpus callosum than that in healthy controls (family-wise error corrected, P<0.01). Significant inverse correlations were observed between SLC6A4 DNA methylation and FA (CpG3, Pearson's correlation: r=-0.493, P=0.003) and axial diffusivity (CpG3, Pearson's correlation: r=-0.478, P=0.004) values of the body of the corpus callosum in patients with MDD. These results contribute to evidence indicating an association between epigenetic gene regulation and structural brain alterations in depression. Moreover, we believe this is the first report of a correlation between DNA methylation of the SLC6A4 promoter region and white matter integrity in patients with MDD.

Bone density and depressive disorder: a meta-analysis

BACKGROUND

The aim of this study was to evaluate the evidence of low bone mineral density (BMD) in depression. Low BMD is a major risk factor for osteoporotic fractures and frailty.

METHODS

The searched database was Pubmed, Meta-analysis included human studies in men and women fulfilling the following criteria: (1) assessment of BMD in the lumbar spine, the femur or the total hip; (2) comparison of BMD between depressed individuals and the healthy control group; (3) measurement of BMD using dual-energy X-ray absorptiometry (DEXA); and (4) data on the mean, standard deviation, or standard error of BMD.

RESULTS

Twenty-one studies were identified, encompassing 1842 depressed and 17,401 nondepressed individuals. Significant negative composite weighted mean effect sizes were identified for the lumbar spine (d = -0.15, 95%CL -0.22 to -0.08), femur (d = -0.34, 95%CL -0.64 to -0.05), and total hip (d = -0.14, 95%CL -0.23 to -0.05) indicating low BMD in depression. Examining men and women shows low bone density in the lumbar spine and femur in women and low bone density in the hip in men. The differences between men and women with MDD and the comparison group tended to be higher when examined by expert interviewers. Low bone density was found in all age groups.

CONCLUSIONS

Bone mineral density is reduced in patients with depressive disorders. The studies provide little evidence for potential relevant mediating factors.

Nonsynonymous HTR2C polymorphism predicts cortisol response to psychosocial stress I: Effects in males and females

BACKGROUND

Genetic influences on stress reactivity may provide insight into depression risk mechanisms. The C-allele of rs6318, a putatively functional polymorphism located within the HTR2C gene, has been reported to predict greater cortisol and negative affective reactivity to lab-induced stress. However, the potential moderating effect of sex has not been examined despite X-linkage of HTR2C. We hypothesized that sex moderates the effect of rs6318 on cortisol and affective reactivity to lab-induced stress, with males showing stronger effects.

METHODS

Non-depressed young adults (N=112; 39 female) screened via clinical interview provided a DNA sample and completed either a negative evaluative Trier Social Stress Test, or a non-evaluative control protocol. Salivary cortisol and self-reported affect were assessed at four timepoints.

RESULTS

Contrary to hypotheses, C-carriers showed blunted rather than exaggerated cortisol responses to lab-induced stress in multilevel models (b=0.467, p<0.001), which persisted when covarying subclinical depressive symptoms. This effect was not moderated by sex (b=0.174, p=0.421), and remained significant when examining females (b=0.362, p=0.013) and males (b=0.537, p<0.001) separately. C-carriers also exhibited marginally greater reactivity in negative self-focused affect in response to stress than non-carriers when covarying subclinical depressive symptoms (b=-0.360, p=0.067), and exhibited higher levels of subclinical depressive symptoms than non-carriers (F=6.463, p=0.012).

CONCLUSIONS

Results support a role for the rs6318 C-allele in dysregulated stress responding, and suggest that the C-allele may contribute to risk for depression.

White matter integrity in major depressive disorder: Implications of childhood trauma, 5-HTTLPR and BDNF polymorphisms

This study examined the impact of childhood neglect, serotonin transporter (5-HTTLPR) and brain derived neurotrophic factor (BDNF) polymorphisms on white matter (WM) integrity in major depressive disorder (MDD) using diffusion tensor imaging (DTI). Fifty-five medication-free MDD patients and 18 controls underwent diffusion tensor imaging scanning, genotyping and completed the Childhood Trauma Questionnaire. Tract based spatial statistics (TBSS) findings revealed reduced fractional anisotropy (FA) in the MDD group in the anterior internal capsule. 5-HTTLPR-S'L' heterozygotes in the MDD group exhibited reduced FA in the internal capsule relative to S'S' and reduced FA in corona radiata compared to L'L'. Probabilistic tractography revealed higher FA in the uncinate fasciculus (UF) for BDNF val/val genotype relative to met-carriers, particularly in individuals with high depression severity. High depression severity and experiences of childhood physical or emotional neglect predicted higher FA in the UF and superior longitudinal fasciculus. Reductions in FA were identified for subgroups of MDD patients who were 5-HTTLPR heterozygotes and BDNF-met carriers. An association between emotional/physical neglect and FA was observed in subjects with high depressive symptoms. Our findings suggest that WM connectivity within frontal and limbic regions are affected by depression and influenced by experiences of neglect and genetic risk factors.

A Test-Replicate Approach to Candidate Gene Research on Addiction and Externalizing Disorders: A Collaboration Across Five Longitudinal Studies

This study presents results from a collaboration across five longitudinal studies seeking to test and replicate models of gene-environment interplay in the development of substance use and externalizing disorders (SUDs, EXT). We describe an overview of our conceptual models, plan for gene-environment interplay analyses, and present main effects results evaluating six candidate genes potentially relevant to SUDs and EXT (MAOA, 5-HTTLPR, COMT, DRD2, DAT1, and DRD4). All samples included rich longitudinal and phenotypic measurements from childhood/adolescence (ages 5-13) through early adulthood (ages 25-33); sample sizes ranged from 3487 in the test sample, to ~600-1000 in the replication samples. Phenotypes included lifetime symptom counts of SUDs (nicotine, alcohol and cannabis), adult antisocial behavior, and an aggregate externalizing disorder composite. Covariates included the first 10 ancestral principal components computed using all autosomal markers in subjects across the data sets, and age at the most recent assessment. Sex, ancestry, and exposure effects were thoroughly evaluated. After correcting for multiple testing, only one significant main effect was found in the test sample, but it was not replicated. Implications for subsequent gene-environment interplay analyses are discussed.

Paradise Lost: The Neurobiological and Clinical Consequences of Child Abuse and Neglect

In the past two decades, much evidence has accumulated unequivocally demonstrating that child abuse and neglect is associated with a marked increase in risk for major psychiatric disorders (major depression, bipolar disorder, post-traumatic stress disorder [PTSD], substance and alcohol abuse, and others) and medical disorders (cardiovascular disease, diabetes, irritable bowel syndrome, asthma, and others). Moreover, the course of psychiatric disorders in individuals exposed to childhood maltreatment is more severe. Recently, the biological substrates underlying this diathesis to medical and psychiatric morbidity have been studied. This Review summarizes many of the persistent biological alterations associated with childhood maltreatment including changes in neuroendocrine and neurotransmitter systems and pro-inflammatory cytokines in addition to specific alterations in brain areas associated with mood regulation. Finally, I discuss several candidate gene polymorphisms that interact with childhood maltreatment to modulate vulnerability to major depression and PTSD and epigenetic mechanisms thought to transduce environmental stressors into disease vulnerability.

The Interplay of Genetics, Behavior, and Pain with Depressive Symptoms in the Elderly

PURPOSE OF STUDY

About 25% of older adults suffer from depressive symptoms. Commonly studied candidate genes associated with depression include those that influence serotonin (SLC6A4), dopamine (COMT), or neuroplasticity (BDNF, NTRK3). However, the majority of candidate gene studies do not consider the interplay of genetics, demographic, clinical, and behavioral factors and how they jointly contribute to depressive symptoms among older adults. The purpose of this study was to gain a more comprehensive understanding of depressive symptoms among older adults.

DESIGN AND METHODS

In this descriptive study, demographic, behavioral, and clinical characteristics (age, gender, comorbidities, volunteering, physical activity, pain, and fear of falling) were obtained via interview of 114 residents in a continuing care retirement community. Peripheral whole blood was collected for DNA extraction. We examined common single nucleotide polymorphisms (SNPs) in the aforementioned genes using path analyses.

RESULTS

SNPs in the NTRK3 gene, pain, physical activity, and fear of falling were directly associated with depressive symptoms in older adults. Those who had polymorphisms in the NTRK3 gene, pain, fear of falling, and were less physically active were more likely to exhibit depressive symptoms. None of the SNPs in SLC6A4, COMT, or BDNF genes were significantly associated with depressive symptoms.

IMPLICATIONS

Our use of a path analysis to examine a biopsychosocial model of depressive symptoms provided the opportunity to describe a comprehensive clinical picture of older adults at risk for depressive symptoms. Thus, interventions could be implemented to identify older adults at risk for depressive symptoms.

Alcohol Dependence and Genetic Variability in the Serotonin Pathway among Currently and Formerly Alcohol-Dependent Males

BACKGROUND

Genes involved in the serotonin pathway may determine the susceptibility to alcohol dependence and its severity. The present study explored whether specific polymorphisms in the serotonin pathway could be associated with alcohol dependence or alcohol-related psychopathological symptoms.

METHODS

The cohort comprised 101 currently and 100 formerly alcohol-dependent males, as well as 97 male healthy blood donors. The following questionnaires were employed: the Alcohol Use Disorders Identification Test, the Zung Depression and Anxiety Scale, the Brief Social Phobia Scale, the Yale-Brown Obsessive Compulsive Scale and Obsessive Compulsive Drinking Scale, and the Buss-Durkee Hostility Inventory. Subjects were genotyped for bi- and triallelic SLC6A4 5-HTTLPR,HTR1A rs6295, and HTR1B rs13212041.

RESULTS

Statistical differences in bi- and triallelic SLC6A4 5-HTTLPR genotype distribution were observed between the 3 groups investigated (p = 0.008 and p = 0.023, respectively); however, no gene-dose effect was observed. The severity of the alcohol problems was higher in currently alcohol-dependent subjects with the 5-HTTLPR LL (p = 0.039) and L′L′ genotypes (p = 0.027). Formerly dependent subjects with the 5-HTTLPR S′S′ genotype showed more social anxiety, depressive, and anxiety traits (p = 0.009, p = 0.006, and p = 0.036, respectively). Healthy controls with the 5-HTTLPR SS genotype showed more traits of social anxiety (p = 0.020).

CONCLUSIONS

Our findings suggest that bi- and triallelic SLC6A4 5-HTTLPR has some effects on the severity of alcohol dependence. Triallelic 5-HTTLPR was associated with social anxiety, anxiety, and depressive traits in alcohol-dependent subjects.

In my end is my beginning: developmental trajectories of adverse childhood experiences to late-life suicide

OBJECTIVES

Converging evidence suggests that the sequelae of adverse childhood experiences (ACEs) including childhood abuse (e.g., sexual, physical, emotional/verbal abuse, neglect) and other ACE (e.g., family dysfunction, parental loss, parental psychopathology, substance abuse, incarceration, and domestic violence) have pronounced effects on suicidal behaviors (suicidal ideation, attempts, and death by suicide) in older age. There are fundamental changes in the developmental trajectory of biological, psychological and behavioral processes that result from ACE and that exert influence throughout the life span. Different moderators and mediators may affect the extent and nature of the relationship. However, the literature on the specific mechanisms whereby ACE affects suicidality in later life has not been well identified.

METHOD

We review and draw from extant multidisciplinary evidence to develop a heuristic framework through which to understand how ACE may lead to suicide in later life.

RESULTS

Proposed mechanisms span biological factors (neurological, gene-environment), psychiatric and health functioning, and psychosocial development (cognitive biases, coping resources, interpersonal deficits). Evidence suggests that ACEs affect each of these constructs, and it is likely in the interaction of these constructs with late-life stressors that suicidality in older adulthood emerges.

CONCLUSION

ACEs have persistent and multifaceted effects on suicidality in late life. This association is due to multi-varied pathways. It is believed that the explanatory framework developed herein--in which biological, psychological and behavioral factors are organized, and the role of late-life stressors is highlighted--will spark further scientific inquiry into this important area.

Meta-analysis of the serotonin transporter promoter variant (5-HTTLPR) in relation to adverse environment and antisocial behavior

Several studies have suggested an association between antisocial, aggressive, and delinquent behavior and the short variant of the serotonin transporter gene polymorphism (5-HTTLPR). Yet, genome wide and candidate gene studies in humans have not convincingly shown an association between these behaviors and 5-HTTLPR. Moreover, individual studies examining the effect of 5-HTTLPR in the presence or absence of adverse environmental factors revealed inconsistent results. We therefore performed a meta-analysis to test for the robustness of the potential interaction effect of the "long-short" variant of the 5-HTTLPR genotype and environmental adversities, on antisocial behavior. Eight studies, comprising of 12 reasonably independent samples, totaling 7,680 subjects with an effective sample size of 6,724, were included in the meta-analysis. Although our extensive meta-analysis resulted in a significant interaction effect between the 5-HTTLPR genotype and environmental adversities on antisocial behavior, the methodological constraints of the included studies hampered a confident interpretation of our results, and firm conclusions regarding the direction of effect. Future studies that aim to examine biosocial mechanisms that influence the etiology of antisocial behavior should make use of larger samples, extend to genome-wide genetic risk scores and properly control for covariate interaction terms, ensuring valid and well-powered research designs. © 2016 Wiley Periodicals, Inc.

5-HT2A Gene Variants Moderate the Association between PTSD and Reduced Default Mode Network Connectivity

The default mode network (DMN) has been used to study disruptions of functional connectivity in a wide variety of psychiatric and neurological conditions, including posttraumatic stress disorder (PTSD). Studies indicate that the serotonin system exerts a modulatory influence on DMN connectivity; however, no prior study has examined associations between serotonin receptor gene variants and DMN connectivity in either clinical or healthy samples. We examined serotonin receptor single nucleotide polymorphisms (SNPs), PTSD, and their interactions for association with DMN connectivity in 134 White non-Hispanic veterans. We began by analyzing candidate SNPs identified in prior meta-analyses of relevant psychiatric traits and found that rs7997012 (an HTR2A SNP), implicated previously in anti-depressant medication response in the Sequenced Treatment Alternatives for Depression study (STAR(*)D; McMahon et al., 2006), interacted with PTSD to predict reduced connectivity between the posterior cingulate cortex (PCC) and the right medial prefrontal cortex and right middle temporal gyrus (MTG). rs130058 (HTR1B) was associated with connectivity between the PCC and right angular gyrus. We then expanded our analysis to 99 HTR1B and HTR2A SNPs and found two HTR2A SNPs (rs977003 and rs7322347) that significantly moderated the association between PTSD severity and the PCC-right MTG component of the DMN after correcting for multiple testing. Finally, to obtain a more precise localization of the most significant SNP × PTSD interaction, we performed a whole cortex vertex-wise analysis of the rs977003 effect. This analysis revealed the locus of the pre-frontal effect to be in portions of the superior frontal gyrus, while the temporal lobe effect was centered in the middle and inferior temporal gyri. These findings point to the influence of HTR2A variants on DMN connectivity and advance knowledge of the role of 5-HT2A receptors in the neurobiology of PTSD.

Early predictors of behavioural problems in pre-schoolers - a longitudinal study of constitutional and environmental main and interaction effects

Background

The early environment is important for child development and wellbeing. Gene-by-environment studies investigating the impact of the serotonin transporter gene-linked polymorphic region (5-HTTLPR) and the Brain Derived Neurotrophic Factor (BDNF) Val66Met polymorphisms by life events on mental health and behaviour problems have been inconclusive. Methodological differences regarding sample sizes, study population, definitions of adversities and measures of mental health problems obstacle their comparability. Furthermore, very few studies included children. The aim of this study was to examine the associations between a broad range of risk factors covering pregnancy and birth, genetic polymorphism, experience of multiple life events and psychosocial environment, and child behaviour at age 3, using a comparably large, representative, population-based sample.

Methods

A total of 1,106 children, and their mothers, were followed from pregnancy to age 3. Information on pregnancy and birth-related factors was retrieved from the Medical Birth Register. Questionnaires on depressive symptoms, child behaviour and child experiences of life events were filled in by the mothers. Child saliva samples were used for genotyping the 5-HTTLPR and BDNF Val66Met polymorphisms. Multiple logistic regression was used to investigate the association between psychological scales and genetic polymorphisms.

Results

Symptoms of postpartum depression increased the risk of both internalizing and externalizing problems. Experience of multiple life events was also a predictor of behavioural problems across the scales. No gene-by-environment or gene-by-gene-by-environment interactions were found. Children of immigrants had an increased risk of internalizing problems and parental unemployment was significantly associated with both internalizing and externalizing type of problems.

Conclusion

This study shows the importance of the psychosocial environment for psychosocial health in preschool children, and adds to the literature of null-findings of gene-by-environment effects of 5-HTTLPR and BDNF in children.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-016-0614-x) contains supplementary material, which is available to authorized users.

The Relationship between Personality Traits, the 5HTT Polymorphisms, and the Occurrence of Anxiety and Depressive Symptoms in Elite Athletes

The purpose of this study was to determine the relationship between personality, the serotonin transporter (5HTT) polymorphisms and the occurrence of anxiety and depressive symptoms in elite athletes. 133 healthy participants completed the NEO Five-Factor Inventory (NEO-FFI). The mood states were assessed using the Profile of Mood States (POMS) questionnaire. The athlete's mental skills were assessed through the Sport Performance Psychological Inventory (IPPS-48). The occurrence of psychiatric and personality disorders was assessed using the Clinical Interview for DSM-IV Disorders. A polymerase chain reaction was employed to identify genotypes at the 5HTTLPR polymorphism. The 5HTTLPR s/s genotype was associated with both neuroticism (p< 0.001) and tension/anxiety symptoms according to the POMS (p<0.02), cognitive anxiety and emotional arousal control according to the IPPS-48 (p<0.01). Significant correlations were proved between neuroticism and symptoms of anxiety and depression (p<0.05). Neuroticism mediates the association between the 5HTTLPR polymorphism and symptoms of cognitive anxiety and emotional arousal control (p<0.05). These results suggest a significant interaction between the 5HTTLPR polymorphism, neuroticism and sport related stress that predict adverse mental health outcomes in athletes. Identification of homogeneous groups of athletes having predispositions to anxiety and depressive symptoms may help to implement early prevention programs.

Traumatic brain injury and bipolar psychosis in the Genomic Psychiatry Cohort

Approximately three million individuals in the United States sustain traumatic brain injury (TBI) every year, with documented impact on a range of neurological and psychiatric disturbances including mania, depression, and psychosis. Identification of subsets of individuals that may demonstrate increased propensity for posttraumatic symptoms and who may share genetic vulnerabilities for gene-environment interactions can enhance efforts to understand, predict, and prevent these phenomena. A sample of 11,489 cases from the Genomic Psychiatry Cohort (GPC), a NIMH-managed data repository for the investigation of schizophrenia and bipolar disorder, was used for this study. Cases were excluded if TBI was deemed causal to their mental illness. A k-means clustering algorithm was used to probe differences between schizophrenia and bipolar disorder associated with variables including onset age, hallucinations, delusions, head injury, and TBI. Cases were separated into an optimum number of seven clusters, with two clusters including all cases with brain injury. Bipolar disorder with psychosis and TBI were significantly correlated in one cluster in which 72% of cases were male and 99.2% sustained head injury. This cluster also carried the longest average period of unconsciousness. This study demonstrates an association of TBI with psychosis in a subset of bipolar cases, suggesting that traumatic stressors may have the ability to impact gene expression in a vulnerable population, and/or there is a heightened occurrence of TBI in individuals with underlying psychosis. Further studies should more closely examine the interplay between genetic variation in bipolar disorder and susceptibility to psychosis following TBI. © 2015 Wiley Periodicals, Inc.

Triangulating meta-analyses: the example of the serotonin transporter gene, stressful life events and major depression

Background

Meta-analysis is intended as a tool for the objective synthesis of evidence across a literature, in order to obtain the best evidence as to whether or not an association or effect is robust. However, as the use of meta-analysis has proliferated it has become increasingly clear that the results of a meta-analysis can be critically sensitive to methodological and analytical choices, so that different meta-analyses on the same topic can arrive at quite different conclusions.

Results

We demonstrate the variability in results of different meta-analyses on the same topic, using the example of the literature on the putative moderating effect of 5-HTTLPR genotype on the association between stressful life events and major depression. We also extend on previous work by including a P-curve analysis of studies from this literature, drawn from a previous meta-analysis, in an attempt to resolve the discrepant conclusions arrived at by previous meta-analyses.

Conclusions

We highlight the divergent conclusions that can be reached when different methodological and analytical choices are taken, and argue that triangulating evidence using multiple evidence synthesis methods is preferable where possible, and that every effort should be made for meta-analyses to be as unbiased as possible (e.g., conducted by methodologists or as part of an adversarial collaboration between authors from opposing camps).

Electronic supplementary material

The online version of this article (doi:10.1186/s40359-016-0129-0) contains supplementary material, which is available to authorized users.

Face and emotion expression processing and the serotonin transporter polymorphism 5-HTTLPR/rs22531

Face cognition, including face identity and facial expression processing, is a crucial component of socio-emotional abilities, characterizing humans as highest developed social beings. However, for these trait domains molecular genetic studies investigating gene-behavior associations based on well-founded phenotype definitions are still rare. We examined the relationship between 5-HTTLPR/rs25531 polymorphisms - related to serotonin-reuptake - and the ability to perceive and recognize faces and emotional expressions in human faces. For this aim we conducted structural equation modeling on data from 230 young adults, obtained by using a comprehensive, multivariate task battery with maximal effort tasks. By additionally modeling fluid intelligence and immediate and delayed memory factors, we aimed to address the discriminant relationships of the 5-HTTLPR/rs25531 polymorphisms with socio-emotional abilities. We found a robust association between the 5-HTTLPR/rs25531 polymorphism and facial emotion perception. Carriers of two long (L) alleles outperformed carriers of one or two S alleles. Weaker associations were present for face identity perception and memory for emotional facial expressions. There was no association between the 5-HTTLPR/rs25531 polymorphism and non-social abilities, demonstrating discriminant validity of the relationships. We discuss the implications and possible neural mechanisms underlying these novel findings.

Take your mind off it: Coping style, serotonin transporter linked polymorphic region genotype (5-HTTLPR), and children's internalizing and externalizing problems

Individuals with the short variant of the serotonin transporter linked polymorphic region gene are more susceptible than individuals homozygous for the long allele to the effects of stressful life events on risk for internalizing and externalizing problems. We tested whether individual differences in coping style explained this increased risk for problem behavior among youth who were at both genetic and environmental risk. Participants included 279 children, ages 8-11, from the Children's Experiences and Development Study. Caregivers and teachers reported on children's internalizing and externalizing symptoms, and caregivers and children on children's exposure to harsh parenting and parental warmth in middle childhood, and traumatic events. Children reported how frequently they used various coping strategies. Results revealed that short/short homozygotes had higher levels of internalizing problems compared with long allele carriers and that short allele carriers had higher levels of externalizing problems compared with long/long homozygotes under conditions of high cumulative risk. Moreover, among children who were homozygous for the short allele, those who had more cumulative risk indicators less frequently used distraction coping strategies, which partly explained why they had higher levels of internalizing problems. Coping strategies did not significantly mediate Gene × Environment effects on externalizing symptoms.

[Eco-epidemiology: towards epidemiology of complexity]

In order to solve public health problems posed by the epidemiology of risk factors centered on the individual and neglecting the causal processes linking the risk factors with the health outcomes, Mervyn Susser proposed a multilevel epidemiology called eco-epidemiology, addressing the interdependence of individuals and their connection with molecular, individual, societal, environmental levels of organization participating in the causal disease processes. The aim of this epidemiology is to integrate more than a level of organization in design, analysis and interpretation of health problems. After presenting the main criticisms of risk-factor epidemiology focused on the individual, we will try to show how eco-epidemiology and its development could help to understand the need for a broader and integrative epidemiology, in which studies designed to identify risk factors would be balanced by studies designed to answer other questions equally vital to public health.

The Unexpected Effects of Beneficial and Adverse Social Experiences during Adolescence on Anxiety and Aggression and Their Modulation by Genotype

Anxiety and aggression are part of the behavioral repertoire of humans and animals. However, in their exaggerated form both can become maladaptive and result in psychiatric disorders. On the one hand, genetic predisposition has been shown to play a crucial modulatory role in anxiety and aggression. On the other hand, social experiences have been implicated in the modulation of these traits. However, so far, mainly experiences in early life phases have been considered crucial for shaping anxiety-like and aggressive behavior, while the phase of adolescence has largely been neglected. Therefore, the aim of the present study was to elucidate how levels of anxiety-like and aggressive behavior are shaped by social experiences during adolescence and serotonin transporter (5-HTT) genotype. For this purpose, male mice of a 5-HTT knockout mouse model including all three genotypes (wildtype, heterozygous and homozygous 5-HTT knockout mice) were either exposed to an adverse social situation or a beneficial social environment during adolescence. This was accomplished in a custom-made cage system where mice experiencing the adverse environment were repeatedly introduced to the territory of a dominant opponent but had the possibility to escape to a refuge cage. Mice encountering beneficial social conditions had free access to a female mating partner. Afterwards, anxiety-like and aggressive behavior was assessed in a battery of tests. Surprisingly, unfavorable conditions during adolescence led to a decrease in anxiety-like behavior and an increase in exploratory locomotion. Additionally, aggressive behavior was augmented in animals that experienced social adversity. Concerning genotype, homozygous 5-HTT knockout mice were more anxious and less aggressive than heterozygous 5-HTT knockout and wildtype mice. In summary, adolescence is clearly an important phase in which anxiety-like and aggressive behavior can be shaped. Furthermore, it seems that having to cope with challenge during adolescence instead of experiencing throughout beneficial social conditions leads to reduced levels of anxiety-like behavior.

DNA methylation at stress-related genes is associated with exposure to early life institutionalization

OBJECTIVES

Differences in DNA methylation have been associated with early life adversity, suggesting that alterations in methylation function as one pathway through which adverse early environments are biologically embedded. This study examined associations between exposure to institutional care, quantified as the proportion of time in institutional care at specified follow-up assessment ages, and DNA methylation status in two stress-related genes: FKBP5 and SLC6A4.

MATERIALS AND METHODS

We analyzed data from the Bucharest Early Intervention Project, which is a prospective study in which children reared in institutional settings were randomly assigned (mean age 22 months) to either newly created foster care or care as usual (to remain in their current placement) and prospectively followed. A group of children from the same geographic area, with no history of institutionalized caregiving, were also recruited. DNA methylation status was determined in DNA extracted from buccal epithelial cells of children at age 12.

RESULTS

An inverse association was identified such that more time spent in institutional care was associated with lower DNA methylation at specific CpG sites within both genes.

DISCUSSION

These results suggest a lasting impact of early severe social deprivation on methylation patterns in these genes, and contribute to a growing literature linking early adversity and epigenetic variation in children. Am J Phys Anthropol 161:84-93, 2016.. © 2016 Wiley Periodicals, Inc.

Perinatal reduction of functional serotonin transporters results in developmental delay

While there is strong evidence from rodent and human studies that a reduction in serotonin transporter (5-HTT) function in early-life can increase the risk for several neuropsychiatric disorders in adulthood, the effects of reduced 5-HTT function on behavior across developmental stages are underinvestigated. To elucidate how perinatal pharmacological and lifelong genetic inactivation of the 5-HTT affects behavior across development, we conducted a battery of behavioral tests in rats perinatally exposed to fluoxetine or vehicle and in 5-HTT(-/-) versus 5-HTT(+/+) rats. We measured motor-related behavior, olfactory function, grooming behavior, sensorimotor gating, object directed behavior and novel object recognition in the first three postnatal weeks and if possible the tests were repeated in adolescence and adulthood. We also measured developmental milestones such as eye opening, reflex development and body weight. We observed that both pharmacological and genetic inactivation of 5-HTT resulted in a developmental delay. Except for hypo-locomotion, most of the observed early-life effects were normalized later in life. In adolescence and adulthood we observed object directed behavior and decreased novel object recognition in the 5-HTT(-/-) rats, which might be related to the lifelong inactivation of 5-HTT. Together, these data provide an important contribution to the understanding of the effects of perinatal and lifelong 5-HTT inactivation on behavior across developmental stages.

Adult attachment representation moderates psychotherapy treatment efficacy in clinically depressed inpatients

BACKGROUND

We explored in a sample of clinically depressed patients the influence of attachment security and unresolved trauma on psychotherapeutic outcome as well as changes in attachment representation through psychotherapeutic intervention.

METHODS

The sample consisted of 85 women (aged 19-52), 43 clinically depressed patients from a psychosomatic inpatient unit, and 42 healthy control subjects matched for age and education. Average length of hospitalization in the patient group was eight weeks. Attachment representations were assessed with the Adult Attachment Interview at the time of admission (baseline) and at discharge. Depressive symptoms were measured using the PHQ-9 at T1 and T2.

RESULTS

Insecure attachment representations were overrepresented in depressed patients. Treatment effects were moderated by baseline attachment representation: patients with higher attachment security scores at admission benefited more from the inpatient treatment and were less depressed at time of discharge than less secure patients (η(2)=.07). Generally, attachment security increased (η(2)=.19) and depressive symptoms decreased (η(2)=.23) after inpatient psychotherapy treatment in the patient group. No significant effects for unresolved symptoms were found.

LIMITATIONS

The study is not a randomized controlled study, but used a quasi-experimental matched control group design with female subjects only.

CONCLUSIONS

Our results suggest that attachment representations play a major role in both the development and treatment of clinical depression. Baseline attachment security may influence psychotherapeutic outcome, perhaps through relational factors such as therapeutic working alliance. Inpatient psychotherapy may also need to address psychological issues associated with depression such as attachment insecurity.

Financial difficulties but not other types of recent negative life events show strong interactions with 5-HTTLPR genotype in the development of depressive symptoms

Several studies indicate that 5-HTTLPR mediates the effect of childhood adversity in the development of depression, while results are contradictory for recent negative life events. For childhood adversity the interaction with genotype is strongest for sexual abuse, but not for other types of childhood maltreatment; however, possible interactions with specific recent life events have not been investigated separately. The aim of our study was to investigate the effect of four distinct types of recent life events in the development of depressive symptoms in a large community sample. Interaction between different types of recent life events measured by the List of Threatening Experiences and the 5-HTTLPR genotype on current depression measured by the depression subscale and additional items of the Brief Symptom Inventory was investigated in 2588 subjects in Manchester and Budapest. Only a nominal interaction was found between life events overall and 5-HTTLPR on depression, which failed to survive correction for multiple testing. However, subcategorising life events into four categories showed a robust interaction between financial difficulties and the 5-HTTLPR genotype, and a weaker interaction in the case of illness/injury. No interaction effect for the other two life event categories was present. We investigated a general non-representative sample in a cross-sectional approach. Depressive symptoms and life event evaluations were self-reported. The 5-HTTLPR polymorphism showed a differential interaction pattern with different types of recent life events, with the strongest interaction effects of financial difficulties on depressive symptoms. This specificity of interaction with only particular types of life events may help to explain previous contradictory findings.

Association study of polymorphism in the serotonin transporter gene promoter, methylation profiles, and expression in patients with major depressive disorder

The serotonin transporter (5HTT) may be associated with the pathogenesis of major depressive disorder (MDD). The 5HTT-linked polymorphic region (5HTTLPR) genotype may determine how levels of 5HTT mRNA are influenced by promoter methylation. We examined the association of 5HTT gene methylation, which influences gene expression, and the 5HTTLPR genotype before antidepressant treatment and expression before and after treatment. The aims of this study were (1) to investigate the association between 5HTT methylation or expression in leukocytes and depression and (2) to investigate a possible effect of 5HTT methylation, expression, and genotype on clinical symptoms in MDD. The 5HTTLPR genotype was significantly associated with mean methylation levels in patients only (patients: r = 0.40, p = 0.035, controls: p = 0.96). The mean methylation level was significantly increased in patients compared with controls (patients: 5.30 ± 0.24, controls: 4.70 ± 0.19, unpaired t-test, p = 0.04). 5HTT expression using real-time PCR and Taqman probes was increased in unmedicated patients compared with controls and then decreased 8 weeks after antidepressant treatment. The mean 5HTT expression level was not associated with the 5HTTLPR genotype in patients or controls. Increased depressive symptoms were related to decreased levels of methylation. Copyright © 2016 John Wiley & Sons, Ltd.

Stressful life events moderate the relationship between genes and biased attention to emotional faces in youth

Attention bias to emotion may be an intermediate trait for stress-reactive psychopathology associated with biologically plausible candidate genes, yet the precise direction of effects within the youth literature remains unclear. The present study investigated whether stressful life events (SLEs) moderate the link between genetic risk (5-HTTLPR and COMT) and attention bias to emotion among youth (n= 467). Analyses revealed a differential effect of gene. Among youth who had experienced more recent SLEs, those homozygous for the low expressing allele of 5-HTTLPR (S/S) demonstrated preferential attention toward negative emotional expressions, whereas youth homozygous for the high expressing COMT genotype (Val/Val) showed attentional avoidance of positive facial expressions. No interaction between 5-HTTLPR and COMT was found. These findings highlight the importance of investigating stress as a moderator within the intermediate trait literature and suggest that biologically plausible candidate genes may have a differential effect in the pathway to psychological disorders.

Developmental psychopathology in an era of molecular genetics and neuroimaging: A developmental neurogenetics approach

The emerging field of neurogenetics seeks to model the complex pathways from gene to brain to behavior. This field has focused on imaging genetics techniques that examine how variability in common genetic polymorphisms predict differences in brain structure and function. These studies are informed by other complimentary techniques (e.g., animal models and multimodal imaging) and have recently begun to incorporate the environment through examination of Imaging Gene × Environment interactions. Though neurogenetics has the potential to inform our understanding of the development of psychopathology, there has been little integration between principles of neurogenetics and developmental psychopathology. The paper describes a neurogenetics and Imaging Gene × Environment approach and how these approaches have been usefully applied to the study of psychopathology. Six tenets of developmental psychopathology (the structure of phenotypes, the importance of exploring mechanisms, the conditional nature of risk, the complexity of multilevel pathways, the role of development, and the importance of who is studied) are identified, and how these principles can further neurogenetics applications to understanding the development of psychopathology is discussed. A major issue of this piece is how neurogenetics and current imaging and molecular genetics approaches can be incorporated into developmental psychopathology perspectives with a goal of providing models for better understanding pathways from among genes, environments, the brain, and behavior.

Early life adversity and serotonin transporter gene variation interact to affect DNA methylation of the corticotropin-releasing factor gene promoter region in the adult rat brain

The interaction between childhood maltreatment and the serotonin transporter (5-HTT) gene linked polymorphic region has been associated with increased risk to develop major depression. This Gene × Environment interaction has furthermore been linked with increased levels of anxiety and glucocorticoid release upon exposure to stress. Both endophenotypes are regulated by the neuropeptide corticotropin-releasing factor (CRF) or hormone, which is expressed by the paraventricular nucleus of the hypothalamus, the bed nucleus of the stria terminalis, and the central amygdala (CeA). Therefore, we hypothesized that altered regulation of the expression of CRF in these areas represents a major neurobiological mechanism underlying the interaction of early life stress and 5-HTT gene variation. The programming of gene transcription by Gene × Environment interactions has been proposed to involve epigenetic mechanisms such as DNA methylation. In this study, we report that early life stress and 5-HTT genotype interact to affect DNA methylation of the Crf gene promoter in the CeA of adult male rats. Furthermore, we found that DNA methylation of a specific site in the Crf promoter significantly correlated with CRF mRNA levels in the CeA. Moreover, CeA CRF mRNA levels correlated with stress coping behavior in a learned helplessness paradigm. Together, our findings warrant further investigation of the link of Crf promoter methylation and CRF expression in the CeA with behavioral changes that are relevant for psychopathology.

Genetic moderation of interpersonal psychotherapy efficacy for low-income mothers with major depressive disorder: implications for differential susceptibility

Genetic moderation of interpersonal psychotherapy (IPT) efficacy for economically disadvantaged women with major depressive disorder was examined. Specifically, we investigated whether genotypic variation in corticotropin releasing hormone receptor 1 (CRHR1) and the linked polymorphic region of the serotonin transporter gene (5-HTTLPR) moderated effects of IPT on depressive symptoms over time. We also tested genotype moderation of IPT mechanisms on social adjustment and perceived stress. Non-treatment-seeking urban women at or below the poverty level with infants were recruited from the community (N = 126; M age = 25.33 years, SD = 4.99; 54.0% African American, 22.2% Caucasian, and 23.8% Hispanic/biracial) and randomized to individual IPT or Enhanced Community Standard groups. The results revealed that changes in depressive symptoms over time depended on both intervention group and genotypes (5-HTTLPR and CRHR1). Moreover, multiple-group path analysis indicated that IPT improved depressive symptoms, increased social adjustment, and decreased perceived stress at posttreatment among women with the 0 copies of the CRHR1 TAT haplotype only. Finally, improved social adjustment at postintervention significantly mediated the effect of IPT on reduced depressive symptoms at 8 months postintervention for women with 0 copies of the TAT haplotype only. Post hoc analyses of 5-HTTLPR were indicative of differential susceptibility, albeit among African American women only.

Serotonin transporter linked polymorphic region (5-HTTLPR) genotype moderates the longitudinal impact of early caregiving on externalizing behavior

We examined caregiver report of externalizing behavior from 12 to 54 months of age in 102 children randomized to care as usual in institutions or to newly created high-quality foster care. At baseline no differences by group or genotype in externalizing were found. However, changes in externalizing from baseline to 42 months of age were moderated by the serotonin transporter linked polymorphic region genotype and intervention group, where the slope for short-short (S/S) individuals differed as a function of intervention group. The slope for individuals carrying the long allele did not significantly differ between groups. At 54 months of age, S/S children in the foster care group had the lowest levels of externalizing behavior, while children with the S/S genotype in the care as usual group demonstrated the highest rates of externalizing behavior. No intervention group differences were found in externalizing behavior among children who carried the long allele. These findings, within a randomized controlled trial of foster care compared to continued care as usual, indicate that the serotonin transporter linked polymorphic region genotype moderates the relation between early caregiving environments to predict externalizing behavior in children exposed to early institutional care in a manner most consistent with differential susceptibility.

Cross-species evidence for the role of interleukin-33 in depression risk

Extensive evidence highlights the role of inflammatory processes in major depressive disorder (MDD). However, most studies have examined a consistent set of inflammatory cytokines and there is evidence that other immune-derived products may play a role in MDD. In this article, we present data from 3 complimentary studies that support the role of a novel cytokine, interleukin-33 (IL-33), in depression risk. First, we show that a 2-SNP haplotype in the IL-33 gene (rs11792633 and rs7044343) moderated the link between women's history of childhood abuse and their history of recurrent MDD (rMDD), such that the link between childhood abuse and rMDD was stronger among women with fewer copies of the protective IL-33 CT haplotype. Second, linking these findings to differences in circulating cytokine levels, we show in a separate sample that those with a history of rMDD had higher peripheral levels of IL-33 and IL-1β compared with women with a single MDD episode or no history of MDD. Third, providing initial evidence of brain regions underlying these effects using archival rat brain tissue, we show that an acute stressor increased IL-33 expression in the paraventricular nucleus of the hypothalamus and, to a lesser extent, the prefrontal cortex, key brain regions underlying stress response and emotion regulation. These findings provide converging support for the potential role of IL-33 in risk for recurrent MDD. (PsycINFO Database Record

Relationship of 5-HTTLPR Polymorphism with Various Factors of Pain Processing: Subjective Experience, Motor Responsiveness and Catastrophizing

Although serotonin is known to play an important role in pain processing, the relationship between the polymorphism in 5-HTTLPR and pain processing is not well understood. To examine the relationship more comprehensively, various factors of pain processing having putative associations with 5-HT functioning were studied, namely the subjective pain experience (pain threshold, rating of experimental pain), catastrophizing about pain (Pain Catastrophizing Scale = PCS) and motor responsiveness (facial expression of pain). In 60 female and 67 male participants, heat pain stimuli were applied by a contact thermode to assess pain thresholds, supra-threshold ratings and a composite score of pain-relevant facial responses. Participants also completed the PCS and were grouped based on their 5-HTTLPR genotype (bi-allelic evaluation) into a group with s-allele carriers (ss, sl) and a second group without (ll). S-allele carriers proved to have lower pain thresholds and higher PCS scores. These two positive findings were unrelated to each other. No other difference between genotype groups became significant. In all analyses, “age” and “gender” were controlled for. In s-allele carriers the subjective pain experience and the tendency to catastrophize about pain was enhanced, suggesting that the s-allele might be a risk factor for the development and maintenance of pain. This risk factor seems to act via two independent routes, namely via the sensory processes of subjective pain experiences and via the booster effects of pain catastrophizing.

GENOME-WIDE ASSOCIATION STUDY (GWAS) AND GENOME-WIDE BY ENVIRONMENT INTERACTION STUDY (GWEIS) OF DEPRESSIVE SYMPTOMS IN AFRICAN AMERICAN AND HISPANIC/LATINA WOMEN

BACKGROUND

Genome-wide association studies (GWAS) have made little progress in identifying variants linked to depression. We hypothesized that examining depressive symptoms and considering gene-environment interaction (GxE) might improve efficiency for gene discovery. We therefore conducted a GWAS and genome-wide by environment interaction study (GWEIS) of depressive symptoms.

METHODS

Using data from the SHARe cohort of the Women's Health Initiative, comprising African Americans (n = 7,179) and Hispanics/Latinas (n = 3,138), we examined genetic main effects and GxE with stressful life events and social support. We also conducted a heritability analysis using genome-wide complex trait analysis (GCTA). Replication was attempted in four independent cohorts.

RESULTS

No SNPs achieved genome-wide significance for main effects in either discovery sample. The top signals in African Americans were rs73531535 (located 20 kb from GPR139, P = 5.75 × 10(-8) ) and rs75407252 (intronic to CACNA2D3, P = 6.99 × 10(-7) ). In Hispanics/Latinas, the top signals were rs2532087 (located 27 kb from CD38, P = 2.44 × 10(-7) ) and rs4542757 (intronic to DCC, P = 7.31 × 10(-7) ). In the GEWIS with stressful life events, one interaction signal was genome-wide significant in African Americans (rs4652467; P = 4.10 × 10(-10) ; located 14 kb from CEP350). This interaction was not observed in a smaller replication cohort. Although heritability estimates for depressive symptoms and stressful life events were each less than 10%, they were strongly genetically correlated (rG = 0.95), suggesting that common variation underlying self-reported depressive symptoms and stressful life event exposure, though modest on their own, were highly overlapping in this sample.

CONCLUSIONS

Our results underscore the need for larger samples, more GEWIS, and greater investigation into genetic and environmental determinants of depressive symptoms in minorities.

Depression as a risk factor for Alzheimer's disease: Genes, steroids, cytokines and neurogenesis - What do we need to know?

Depression (MDD) is prodromal to, and a component of, Alzheimer's disease (AD): it may also be a trigger for incipient AD. MDD is not a unitary disorder, so there may be particular subtypes of early life MDD that pose independent high risks for later AD, though the identification of these subtypes is problematical. There may either be a common pathological event underlying both MDD and AD, or MDD may sensitize the brain to a second event ('hit') that precipitates AD. MDD may also accelerate brain ageing, including altered DNA methylation, increased cortisol but decreasing DHEA and thus the risk for AD. So far, genes predicting AD (e.g. APOEε4) are not risk factors for MDD, and those implicated in MDD (e.g. SLC6A4) are not risks for AD, so a common genetic predisposition looks unlikely. There is as yet no strong indication that an epigenetic event occurs during some forms of MDD that predisposes to later AD, though the evidence is limited. Glucocorticoids (GCs) are disturbed in some cases of MDD and in AD. GCs have marked degenerative actions on the hippocampus, a site of early β-amyloid deposition, and rare genetic variants of GC-regulating enzymes (e.g. 11β-HSD) predispose to AD. GCs also inhibit hippocampal neurogenesis and plasticity, and thus episodic memory, a core symptom of AD. Disordered GCs in MDD may inhibit neurogenesis, but the contribution of diminished neurogenesis to the onset or progression of AD is still debated. GCs and cytokines also reduce BDNF, implicated in both MDD and AD and hippocampal neurogenesis, reinforcing the notion that those cases of MDD with disordered GCs may be a risk for AD. Cytokines, including IL1β, IL6 and TNFα, are increased in the blood in some cases of MDD. They also reduce hippocampal neurogenesis, and increased cytokines are a known risk for later AD. Inflammatory changes occur in both MDD and AD (e.g. raised CRP, TNFα). Both cytokines and GCs can have pro-inflammatory actions in the brain. Inflammation (e.g. microglial activation) may be a common link, but this has not been systematically investigated. We lack substantial, rigorous and comprehensive follow-up studies to better identify possible subtypes of MDD that may represent a major predictor for later AD. This would enable specific interventions during critical episodes of these subtypes of MDD that should reduce this substantial risk.

Role of Sirtuins in Linking Metabolic Syndrome with Depression

Depression is now widely regarded as a common disabling disorder that affects negatively the social functioning all over the world. Depression is associated with diverse phenomenon in brain such as neuroinflammation, synaptic dysfunction, and cognitive deficit. Recent studies reported that depression occurs by various metabolic changes, leading to metabolic syndrome. Sirtuins (SIRTs) are NAD⁺-dependent class III histone deacetylases, known to regulate diverse biological mechanism such as longevity, genomic stability, and inflammation. The modulation of sirtuin activity has been highlighted as a promising approach to reduce neurodegenerative processes. In this review, we summarize the recent discoveries regarding the potential relationship between SIRTs and depression caused by metabolic disorders (Mets). Ultimately, we suggest the possibility that SIRTs will be novel targets to alleviate neuropathogenesis induced by depression.

5-HTTLPR, victimization and ecological executive function of adolescents

Executive function (EF) plays an important role in guiding peer relationship, school performance and behavior control. Children exposed to traumatic environments have been reported to perform poorer in EF tasks. We explored if the relationship between victimization and EF was dependent on the functional variation 5-HTTLPR in a non-clinical sample of adolescents. Data on demographics, victimization and daily life EF were collected from school students (Han Chinese, n=2125). All those reporting executive dysfunction (n=169), and classmate controls (n=208), were genotyped for the 5-HTTLPR. It was shown that the number of victimizations associated positively with executive dysfunction (ED). This association was particularly strong in those homozygous for the short allele of 5-HTTLPR, whilst a statistical 5-HTTLPR×victimization interaction on ED was found. Our findings suggest that adolescents with a genotype conferring a low 5-HTT activity are more vulnerable to a childhood adversity-associated ED in their daily life.

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

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

Epigenetic regulation of G protein coupled receptor signaling and its implications in psychiatric disorders

G protein-coupled receptors (GPCRs) act as a relay center through which extracellular signals, in the form of neurotransmitters or therapeutics, are converted into an intracellular response, which ultimately shapes the overall response at the tissue and behavioral level. Remarkably in similar ways, epigenetic mechanisms also modulate the expression pattern of a large number of genes in response to the dynamic environment inside and outside of the body, and consequently overall response. Emerging evidences from the pharmacogenomics and preclinical studies clearly suggest that these two distinct mechanisms criss-cross each other in several neurological disorders. At one hand such cross-talks between two distinct mechanisms make disease etiology more challenging to understand, while on the other hand if dealt appropriately, such situations might provide an opportunity to find novel druggable target and strategy for the treatment of complex diseases. In this review article, we have summarized and highlighted the main findings that tie epigenetic mechanisms to GPCR mediated signaling in the pathophysiology of central nervous system (CNS) disorders, including depression, addiction and pain.

Stressful Life Events and Risk of Depression 25 Years Later: Race and Gender Differences

BACKGROUND

Although stressful life events (SLEs) predict subsequent risk of developing a major depressive episode (MDE), limited information exists on whether or not race and gender alters the predictive role of SLE on risk of MDE over a long-term period. The current study explored race and gender differences in the long-term predictive role of SLE at baseline (1986) on subsequent risk of MDE 25 years later (2011) in a nationally representative cohort in the United States.

METHODS

Using a life course epidemiological approach, this longitudinal study borrowed data from the Americans' Changing Lives (ACL) Study 1986-2011. Main predictor of interest was baseline SLE over the last 3 years measured at 1986. Main outcome was risk of MDE [Composite International Diagnostic Interview (CIDI)] 25 years later (2011). Covariates included demographics, socioeconomics, depressive symptoms [Center for Epidemiological Studies-Depression Scale (CES-D)], chronic medical conditions, and health behaviors measured at baseline (1986). Gender and race were the focal moderators. We employed logistic regressions in the pooled sample, and specific to race and gender, to test whether or not SLE × race and SLE × gender interactions are significant.

RESULTS

In the pooled sample, baseline SLE (1986) predicted risk of MDE 25 years later (2011). We also found a gender by SLE interaction, suggesting a stronger predictive role of SLE for subsequent clinical depression for men compared to women. Race did not modify the predictive role of SLE on subsequent risk of MDE 25 years later.

CONCLUSION

How SLE predicts MDE 25 years later differs for men and women, with a stronger predictive role for men compared to women. More research is needed to better understand the complex links between gender, sex, stress, and depression.

Serotonin transporter promoter polymorphism is associated with executive function impairments in patients with obsessive compulsive disorder

OBJECTIVE

In the present study, we investigate the association between the 5-HTTLPR polymorphism and executive functions in a sample of patients with obsessive compulsive disorder (OCD).

METHOD

A total of 98 unmedicated patients diagnosed with OCD according to DSM-IV criteria and 80 healthy controls were included in this study. The genotype frequencies of 5-HTTLPR polymorphism were compared in OCD and healthy control groups. The four subgroups of OCD and healthy control participants, determined according to having LaLa genotype (high expressing) or S- and/or Lg alleles (low expressing), were also compared using neuropsychological tests of executive functions.

RESULTS

The frequency of SLa genotype of 5-HTTLPR polymorphism was found to be higher in patients with OCD compared with healthy controls. The mean scores of conceptual level responses of the Wisconsin Card Sorting Test (WCST) were significantly lower in the OCD-high-expressing subgroup compared with the low-expressing control group. The mean scores of the number of moves of the Tower of London were found to be significantly higher in the OCD-high-expressing subgroup, compared with the high-expressing subgroup of healthy controls.

CONCLUSION

Our findings suggest that the high-expressing variant may be associated with lower performance on some abstraction and planning measures in OCD patients.