Interaction of FKBP5 with childhood adversity on risk for post-traumatic stress disorder

Environmental stressors and epigenetic control of the hypothalamic-pituitary-adrenal axis

In this review, we provide a brief summary of several key studies that broaden our understanding of stress and its epigenetic control of the function and behavior of the hypothalamic-pituitary-adrenal (HPA) axis. Clinical and animal studies suggest a link among exposure to stress, dysregulation of the HPA axis, and susceptibility to neuropsychiatric illnesses. Recent studies have supported the notion that exposure to glucocorticoids and stress in various forms, durations, and intensities during different periods of development leads to long-lasting maladaptive HPA axis response in the brain. They demonstrate that this maladaptive response is comprised of persistent epigenetic changes in the function of HPA axis-associated genes that govern homeostatic levels of glucocorticoids. Stressors and/or disruption of glucocorticoid dynamics also target genes such as brain-derived neurotrophic factor(BDNF) and tyrosine hydroxylase(TH) that are important for neuronal function and behavior. While a definitive role for epigenetic mechanisms remains unclear, these emerging studies implicate glucocorticoid signaling and its ability to alter the epigenetic landscape as one of the key mechanisms that alter the function of the HPA axis and its associated cascades. We also suggest some of the requisite studies and techniques that are important, such as additional candidate gene approaches, genome-wide epigenomic screens, and innovative functional and behavioral studies, in order to further explore and define the relationship between epigenetics and HPA axis biology. Additional studies examining stress-induced epigenetic changes of HPA axis genes, aided by innovative techniques and methodologies, are needed to advance our understanding of this relationship and lead to better preventive, diagnostic, and corrective measures.

Neurobehavioral Mechanisms of Traumatic Stress in Post-traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a debilitating psychiatric disorder that develops following trauma exposure. It is characterized by four symptom clusters: intrusion, avoidance, negative alteration in cognitions and mood, and alterations in arousal and reactivity. Several risk factors have been associated with PTSD, including trauma type and severity, gender and sexual orientation, race and ethnicity, cognitive reserve, pretrauma psychopathology, familial psychiatric history, and genetics. Great strides have been made in understanding the neurobiology of PTSD through animal models and human imaging studies. Most of the animal models have face validity, but they have limitations in the generalization to the human model of PTSD. Newer animal models, such as the "CBC" model, have better validity for PTSD, which takes into account the different components of its diagnostic criteria. To date, fear conditioning and fear extinction animal models have provided support for the hypothesis that PTSD is a dysregulation of the processes related to fear regulation and, especially, fear extinction. More research is needed to further understand these processes as they relate not only to PTSD but also to resilience. Further, this research could be instrumental in the development of novel effective treatments for PTSD.

Gene-environment interactions in common mental disorders: an update and strategy for a genome-wide search

A decade of research has demonstrated the explanatory potential of interplay between genetic variants and environmental factors in the development of common mental disorders. Initial findings have undergone tests of replicability and specificity. Some gene-environment interactions have been confirmed, some have not replicated and yet other turned out to be more specific than initially thought. Specific and complementary roles of genetic factors have been delineated: a common functional length polymorphism in the serotonin transporter gene (5-HTTLPR) moderated the effect of childhood maltreatment on chronic depression in adulthood, but did not substantially influence the effects of adult stressful life events on the onset of new depressive episodes; in contrast, a common functional polymorphism in the brain-derived neurotrophic factor gene (BDNF) moderated the effect of stressful life events in adulthood in triggering new depressive episodes, but did not influence the effects of childhood maltreatment. Molecular mechanisms underlying gene-environment interactions are being uncovered, including DNA methylation and other epigenetic modifications. New gene-environment interactions continue to be reported, still largely from hypothesis-driven research. Statistical and biological prioritization strategies are proposed to facilitate a systematic discovery of novel gene-environment interactions in genome-wide analyses.

Beyond risk, resilience, and dysregulation: Phenotypic plasticity and human development

We provide a theoretical and empirical basis for the claim that individual differences exist in developmental plasticity and that phenotypic plasticity should be a subject of study in its own right. To advance this argument, we begin by highlighting challenges that evolutionary thinking poses for a science of development and psychopathology, including for the diathesis–stress framework that has (fruitfully) guided so much empirical inquiry on developmental risk, resilience, and dysregulation. With this foundation laid, we raise a series of issues that the differential-susceptibility hypothesis calls attention to, while highlighting findings that have emerged over just the past several years and are pertinent to some of the questions posed. Even though it is clear that this new perspective on Person × Environment interaction is stimulating research and influencing how hypotheses are framed and data interpreted, a great many topics remain that need empirical attention. Our intention is to encourage students of development and psychopathology to treat phenotypic plasticity as an individual-difference construct while exploring unknowns in the differential-susceptibility equation.

Association among clinical response, hippocampal volume, and FKBP5 gene expression in individuals with posttraumatic stress disorder receiving cognitive behavioral therapy

BACKGROUND

Posttraumatic stress disorder (PTSD) is characterized by a reduced expression of FKBP5, a key modulator of the glucocorticoid receptor. Smaller hippocampal volume has also been documented in PTSD. We explored possible changes in FKBP5 gene expression and brain structure in patients with PTSD after cognitive behavioral therapy (CBT).

METHODS

We measured peripheral FKBP5 RNA and volumes of the hippocampus, amygdala, and medial orbitofrontal cortex in 39 patients with PTSD before and after CBT. The control subjects were 31 trauma-exposed individuals without PTSD who were also assessed twice. Gene expression changes were screened with a microarray toolkit, which was followed by quantitative polymerase chain reaction for FKBP5 RNA. Brain volumes were measured using FreeSurfer.

RESULTS

At baseline, patients with PTSD showed lower FKBP5 gene expression and smaller hippocampal and medial orbitofrontal cortex, but not amygdala, volumes relative to control subjects. At follow-up, we found significantly increased FKBP5 expression and increased hippocampal volume in patients with PTSD. At follow-up, patients did not differ from control subjects in hippocampal volume. Improvement in PTSD symptoms was predicted by increased FKBP5 expression and increased hippocampal volume, but the primary predictor was FKBP5 expression. The most significantly altered gene expression in patients with PTSD relative to control subjects was found for ribosomal protein S6 kinase, which did not change after CBT and did not correlate with hippocampal volume.

CONCLUSIONS

Clinical improvement in individuals with PTSD was associated with increased expression of FKBP5 and increased hippocampal volume, which were positively correlated.

The role of FKBP5 in mood disorders: action of FKBP5 on steroid hormone receptors leads to questions about its evolutionary importance

Research on the FKBP5 gene and FKBP51 protein has more than doubled since the discovery that polymorphisms in this gene could alter treatment outcomes and depressive behavior in humans. This coincided with other data suggesting that the stress hormone axis contributes to the development of numerous mental illnesses. As a result, FKBP51 now lies at the heart of the research of many stress related psychiatric disorders, which has led to advances in the understanding of this protein and its role in humans and in animal models. Specifically, FKBP5-/- mice and a naturally existing overexpression of FKBP5 in 3 genera of new world monkeys have helped understand the effects of FKBP5 in vivo. This review will highlight these finding as well as discuss the current evolutionary need for the FKBP5 gene.

Role of allelic variants of FK506-binding protein 51 (FKBP5) gene in the development of anxiety disorders

BACKGROUND

Anxiety disorders exhibit remarkably high rates of comorbidity with major depressive disorder (MDD). Mood and anxiety disorders are considered stress-related diseases. Genetic variations in the co-chaperone FK506-binding protein 51, FKBP5, which modulates the function of glucocorticoid receptors, have been associated with an increased risk for the development of posttraumatic stress disorder, but data regarding its role in MDD are controversial. The aims of this study were to clarify the role of the FKBP5 gene in depression and anxiety disorders through a case-control study and an association study with personality traits using the Temperament and Character Inventory (TCI) in healthy subjects.

METHODS

Six hundred fifty-seven MDD patients, with or without an anxiety disorder in comorbidity, and 462 healthy volunteers were enrolled in the study. Two hundred fifty-six controls agreed to fill out the TCI.

RESULTS

The results showed that the T allele of rs1360780 was more frequent among the patients affected by MDD with a comorbidity of anxiety disorders, compared to those without (P < .001). Among the controls, we found that the T allele more often exhibited personality traits associated with an increased vulnerability to anxiety.

CONCLUSIONS

These results support the hypothesis that allelic variants of FKBP5 are a risk factor for anxiety disorders. The identification of genetic variants involved in anxiety may have implications for the optimization of therapeutic interventions.

Genome-wide association study identifies new susceptibility loci for posttraumatic stress disorder

BACKGROUND

Genetic factors influence the risk for posttraumatic stress disorder (PTSD), a potentially chronic and disabling psychiatric disorder that can arise after exposure to trauma. Candidate gene association studies have identified few genetic variants that contribute to PTSD risk.

METHODS

We conducted genome-wide association analyses in 1578 European Americans (EAs), including 300 PTSD cases, and 2766 African Americans, including 444 PTSD cases, to find novel common risk alleles for PTSD. We used the Illumina Omni1-Quad microarray, which yielded approximately 870,000 single nucleotide polymorphisms (SNPs) suitable for analysis.

RESULTS

In EAs, we observed that one SNP on chromosome 7p12, rs406001, exceeded genome-wide significance (p = 3.97 × 10(-8)). A SNP that maps to the first intron of the Tolloid-Like 1 gene (TLL1) showed the second strongest evidence of association, although no SNPs at this locus reached genome-wide significance. We then tested six SNPs in an independent sample of nearly 2000 EAs and successfully replicated the association findings for two SNPs in the first intron of TLL1, rs6812849 and rs7691872, with p values of 6.3 × 10(-6) and 2.3 × 10(-4), respectively. In the combined sample, rs6812849 had a p value of 3.1×10(-9). No significant signals were observed in the African American part of the sample. Genome-wide association study analyses restricted to trauma-exposed individuals yielded very similar results.

CONCLUSIONS

This study identified TLL1 as a new susceptibility gene for PTSD.

Prevalence of bullying victimisation amongst first-episode psychosis patients and unaffected controls

BACKGROUND

Despite increasing evidence suggesting that childhood maltreatment is significantly associated with psychosis, the specific role of bullying in the onset of psychotic disorders is still unclear. This study aimed to examine whether bullying was more prevalent amongst individuals presenting to services for the first time with a psychotic disorder than in unaffected community controls.

METHODS

Data on exposure to bullying, psychotic symptoms, cannabis use and history of conduct disorder were collected cross-sectionally from 222 first-presentation psychosis cases and 215 geographically-matched controls. Bullying victimisation was assessed retrospectively as part of the Brief Life Events schedule. Logistic regression was used to examine associations between exposure to bullying and case-control status, while controlling for potential confounders.

RESULTS

Psychosis cases were approximately twice as likely to report bullying victimisation when compared to controls. No significant interactions between bullying and either gender or cannabis use were found. Controls reporting being a victim of bullying were approximately twice as likely to also report at least one psychosis-like symptom.

CONCLUSIONS

Our results extend previous research by suggesting that bullying victimisation may contribute to vulnerability to develop a psychotic disorder in some individuals.

Childhood maltreatment and psychopathology: A case for ecophenotypic variants as clinically and neurobiologically distinct subtypes

OBJECTIVE

Childhood maltreatment increases risk for psychopathology. For some highly prevalent disorders (major depression, substance abuse, anxiety disorders, and posttraumatic stress disorder) a substantial subset of individuals have a history of maltreatment and a substantial subset do not. The authors examined the evidence to assess whether those with a history of maltreatment represent a clinically and biologically distinct subtype.

METHOD

The authors reviewed the literature on maltreatment as a risk factor for these disorders and on the clinical differences between individuals with and without a history of maltreatment who share the same diagnoses. Neurobiological findings in maltreated individuals were reviewed and compared with findings reported for these disorders.

RESULTS

Maltreated individuals with depressive, anxiety, and substance use disorders have an earlier age at onset, greater symptom severity, more comorbidity, a greater risk for suicide, and poorer treatment response than nonmaltreated individuals with the same diagnoses. Imaging findings associated with these disorders, such as reduced hippocampal volume and amygdala hyperreactivity, are more consistently observed in maltreated individuals and may represent a maltreatment-related risk factor. Maltreated individuals also differ from others as a result of epigenetic modifications and genetic polymorphisms that interact with experience to increase risk for psychopathology.

CONCLUSIONS

Phenotypic expression of psychopathology may be strongly influenced by exposure to maltreatment, leading to a constellation of ecophenotypes. While these ecophenotypes fit within conventional diagnostic boundaries, they likely represent distinct subtypes. Recognition of this distinction may be essential in determining the biological bases of these disorders. Treatment guidelines and algorithms may be enhanced if maltreated and nonmaltreated individuals with the same diagnostic labels are differentiated.

Disorders and borders: psychiatric genetics and nosology

Over the past century, the definition and classification of psychiatric disorders has evolved through a combination of historical trends, clinical observations, and empirical research. The current nosology, instantiated in the DSM-5 and ICD-10, rests on descriptive criteria agreed upon by a consensus of experts. While the development of explicit criteria has enhanced the reliability of diagnosis, the validity of the current diagnostic categories has been the subject of debate and controversy. Genetic studies have long been regarded as a key resource for validating the boundaries among diagnostic categories. Genetic epidemiologic studies have documented the familiality and heritability of clinically defined psychiatric disorders and molecular genetic studies have begun to identify specific susceptibility variants. At the same time, there is growing evidence from family, twin and genomic studies that genetic influences on psychiatric disorders transcend clinical boundaries. Here I review this evidence for cross-disorder genetic effects and discuss the implications of these findings for psychiatric nosology. Psychiatric genetic research can inform a bottom-up reappraisal of psychopathology that may help the field move beyond a purely descriptive classification and toward an etiology-based nosology.

Gene-environment interaction of ApoE genotype and combat exposure on PTSD

Factors determining who develops PTSD following trauma are not well understood. The €4 allele of the apolipoprotein E (apoE) gene is associated with dementia and unfavorable outcome following brain insult. PTSD is also associated with dementia. Given evidence that psychological trauma adversely affects the brain, we hypothesized that the apoE genotype moderates effects of psychological trauma on PTSD pathogenesis. To investigate the moderation of the relationship between PTSD symptoms and combat exposure, we used 172 participants with combat trauma sustained during the Vietnam War. PTSD symptoms were the dependent variable and number of combat experiences, apoE genotype, and the combat experiences × apoE genotype interaction were predictors. We also examined the outcome of a diagnosis of PTSD (n = 39) versus no PTSD diagnosis (n = 131). The combat × apoE genotype interaction was significant for both PTSD symptoms (P = .014) and PTSD diagnosis (P = .009). ApoE genotype moderates the relationship between combat exposure and PTSD symptoms. Although the pathophysiology of PTSD is not well understood, the €4 allele is related to reduced resilience of the brain to insult. Our results are consistent with the €4 allele influencing the effects of psychological trauma on the brain, thereby affecting the risk of PTSD.

Translational reciprocity: bridging the gap between preclinical studies and clinical treatment of stress effects on the adolescent brain

The genetic, biological, and environmental backgrounds of an organism fundamentally influence the balance between risk and resilience to stress. Sex, age, and environment transact with responses to trauma in ways that can mitigate or exacerbate the likelihood that post-traumatic stress disorder will develop. Translational approaches to modeling affective disorders in animals will ultimately provide novel treatments and a better understanding of the neurobiological underpinnings behind these debilitating disorders. The extant literature on trauma/stress has focused predominately on limbic and cortical structures that innervate the hypothalamic-pituitary-adrenal axis and influence glucocorticoid-mediated negative feedback. It is through these neuroendocrine pathways that a self-perpetuating fear memory can propagate the long-term effects of early life trauma. Recent work incorporating translational approaches has provided novel pathways that can be influenced by early life stress, such as the glucocorticoid receptor chaperones, including FKBP51. Animal models of stress have differing effects on behavior and endocrine pathways; however, complete models replicating clinical characteristics of risk and resilience have not been rigorously studied. This review discusses a four-factor model that considers the importance of studying both risk and resilience in understanding the developmental response to trauma/stress. Consideration of the multifactorial nature of clinical populations in the design of preclinical models and the application of preclinical findings to clinical treatment approaches comprise the core of translational reciprocity, which is discussed in the context of the four-factor model.

Rethinking our public health genetics research paradigm

Since the sequencing of the human genome, tremendous resources have been dedicated to understanding how genetic determinants may drive the production of disease. Despite some successes, the promise of genetics research in these areas remains largely unrealized. The focus on isolating individual (or clusters of) genes that may be associated with narrowly defined phenotypes in large part explains this discrepancy. In particular, efforts to identify genotypes associated with narrow phenotypes force the field to use study designs that capitalize on homogeneous samples to minimize the potential for competing influences or confounders, which imposes important limitations on understanding the role of genes in human health. We argue that a population health genetics that incorporates genetics into large, multiwave, multilevel cohorts has the best potential to clarify how genes, in combination and with the environment, jointly influence population health.

Profiling of childhood adversity-associated DNA methylation changes in alcoholic patients and healthy controls

The increased vulnerability to alcohol dependence (AD) seen in individuals with childhood adversity (CA) may result in part from CA-induced epigenetic changes. To examine CA-associated DNA methylation changes in AD patients, we examined peripheral blood DNA methylation levels of 384 CpGs in promoter regions of 82 candidate genes in 279 African Americans [AAs; 88 with CA (70.5% with AD) and 191 without CA (38.2% with AD)] and 239 European Americans [EAs; 61 with CA (86.9% with AD) and 178 without CA (46.6% with AD)] using Illumina GoldenGate Methylation Array assays. The effect of CA on methylation of individual CpGs and overall methylation in promoter regions of genes was evaluated using a linear regression analysis (with consideration of sex, age, and ancestry proportion of subjects) and a principal components-based analysis, respectively. In EAs, hypermethylation of 10 CpGs in seven genes (ALDH1A1, CART, CHRNA5, HTR1B, OPRL1, PENK, and RGS19) were cross validated in AD patients and healthy controls who were exposed to CA. P values of two CpGs survived Bonferroni correction when all EA samples were analyzed together to increase statistical power [CHRNA5_cg17108064: P_adjust = 2.54×10⁻⁵; HTR1B_cg06031989: P_adjust = 8.98×10⁻⁵]. Moreover, overall methylation levels in the promoter regions of three genes (ALDH1A1, OPRL1 and RGS19) were elevated in both EA case and control subjects who were exposed to CA. However, in AAs, CA-associated DNA methylation changes in AD patients were not validated in healthy controls. Our findings suggest that CA could induce population-specific methylation alterations in the promoter regions of specific genes, thus leading to changes in gene transcription and an increased risk for AD and other disorders.

Pretrauma risk factors for posttraumatic stress disorder: a systematic review of the literature

As it has become clear that most individuals exposed to trauma do not develop PTSD, it has become increasingly important to examine pretrauma risk factors. However, PTSD research has overwhelmingly relied on retrospective accounts of trauma, which is beleaguered by problems of recall bias. To further our understanding of PTSD's etiology, a systematic review of 54 prospective, longitudinal studies of PTSD published between 1991 and 2013 were examined. Inclusion criteria required that all individuals were assessed both before and after an index trauma. Results revealed six categories of pretrauma predictor variables: 1) cognitive abilities; 2) coping and response styles; 3) personality factors; 4) psychopathology; 5) psychophysiological factors; and 6) social ecological factors. The results indicated that many variables, previously considered outcomes of trauma, are pretrauma risk factors. The review considered these findings in the context of the extant retrospective PTSD literature in order to identify points of overlap and discrepancy. Pretrauma predictor categories were also used to conceptualize variable risk for PTSD. Limitations and directions for future research are discussed.

Genetic association of FKBP5 and CRHR1 with cortisol response to acute psychosocial stress in healthy adults

RATIONALE

Chronic dysregulation of hypothalamus-pituitary-adrenal (HPA) axis activity is related to several neuropsychiatric disorders. Studies suggest that cortisol response to stress has a strong genetic etiology, and that FK506 binding protein 5 (FKBP5) and G-protein coupled type-I CRH receptor (CRHR1) are key proteins regulating response. Variations in the genes encoding these proteins, FKBP5 and CRHR1, have been associated with several neuropsychiatric disorders.

OBJECTIVES

We examined variation in these genes in relation to cortisol response to psychological stress in one of the largest Trier Social Stress Test (TSST) cohorts yet examined.

METHODS

A total of 368 healthy, young adults underwent the TSST. Salivary cortisol was measured at multiple time points before and after the stressor. Nine variants in FKBP5 and four in CRHR1 were assessed. Single marker analyses were conducted. Secondary analyses assessed haplotypes and interaction with stress-related variables.

RESULTS

The strongest association was for rs4713902 in FKBP5 with baseline cortisol (p dom = 0.0004). We also identified a male-specific effect of FKBP5 polymorphisms on peak response and response area under the curve (p = 0.0028 for rs3800374). In CRHR1, rs7209436, rs110402, and rs242924 were nominally associated with peak response (p rec = 0.0029-0.0047). We observed interactions between trait anxiety and rs7209436 and rs110402 in CRHR1 in association with baseline cortisol (p LRT = 0.0272 and p LRT = 0.0483, respectively).

CONCLUSIONS

We show association of variants in FKBP5 and CRHR1 with cortisol response to psychosocial stress. These variants were previously shown to be associated with neuropsychiatric disorders. These findings have implications for interindividual variation in HPA axis activity and potentially for the etiology of neuropsychiatric disorders.

Predicting PTSD: pre-existing vulnerabilities in glucocorticoid-signaling and implications for preventive interventions

Posttraumatic stress disorder (PTSD) is an anxiety disorder that may develop in response to a traumatic event. Approximately 10% of trauma-exposed individuals subsequently develop PTSD. It is hypothesized that the development of PTSD is associated with biological vulnerability factors, which are already present prior to the onset of symptoms. In this review we present an overview of currently identified vulnerability factors in the glucocorticoid (GC) signaling pathway for the development of PTSD. In addition, the implications of the identified vulnerability factors for potential preventive intervention strategies, including glucocorticoid receptor (GR) agonists and oxytocin, are discussed. Summarized, the findings of these studies indicate that individuals vulnerable for development of PTSD have dysregulations on various levels of the GC-signaling cascade: i.e. low levels of circulating levels of cortisol shortly after trauma, high GR number in peripheral blood mononuclear cells (PBMCs), high GILZ mRNA expression and low FKBP5 expression in PBMCs prior to trauma, and high sensitivity of T-cells for regulation by GCs prior to trauma. Furthermore, single nucleotide polymorphisms in the GR and FKBP5 genes have been found to be associated with increased risk for PTSD. Collectively, the identified vulnerability factors tentatively suggest that the development of PTSD may be preceded by a high sensitivity of various cells for regulation by GCs. The identification of these vulnerability factors may ultimately aid selective targeting of preventive interventions towards individuals at risk for PTSD. In addition, the identification of these vulnerability factors may eventually result in new preventive pharmacological strategies for PTSD.

The association of a novel haplotype in the dopamine transporter with preschool age posttraumatic stress disorder

OBJECTIVE

Significant evidence supports a genetic contribution to the development of posttraumatic stress disorder (PTSD). Three previous studies have demonstrated an association between PTSD and the nine repeat allele of the 3' untranslated region (3'UTR) variable number tandem repeat (VNTR) in the dopamine transporter (DAT, rs28363170). Recently a novel, functionally significant C/T single-nucleotide polymorphism (SNP) in the 3'UTR (rs27072) with putative interactions with the 3'VNTR, has been identified. To provide enhanced support for the role of DAT and striatal dopamine regulation in the development of PTSD, this study examined the impact of a haplotype defined by the C allele of rs27072 and the nine repeat allele of the 3'VNTR on PTSD diagnosis in young trauma-exposed children.

METHODS

DAT haplotypes were determined in 150 trauma-exposed 3-6 year-old children. PTSD was assessed with a semistructured interview. After excluding double heterozygotes, analysis was performed on 143 total subjects. Haplotype was examined in relation to categorical and continuous measures of PTSD, controlling for trauma type and race. Additional analysis within the two largest race categories was performed, as other means of controlling for ethnic stratification were not available.

RESULTS

The number of haplotypes (0, 1, or 2) defined by the presence of the nine repeat allele of rs28363170 (VNTR in the 3'UTR) and the C allele of rs27072 (SNP in the 3'UTR) was significantly associated with both the diagnosis of PTSD and total PTSD symptoms. Specifically, children with one or two copies of the haplotype had significantly more PTSD symptoms and were more likely to be diagnosed with PTSD than were children without this haplotype.

CONCLUSIONS

These findings extend previous findings associating genetic variation in the DAT with PTSD. The association of a haplotype in DAT with PTSD provides incremental traction for a model of genetic vulnerability to PTSD, a specific underlying mechanism implicating striatal dopamine regulation, and insight into potential future personalized interventions.

Polymorphisms in the glucocorticoid receptor co-chaperone FKBP5 predict persistent musculoskeletal pain after traumatic stress exposure

Individual vulnerability factors influencing the function of the hypothalamic-pituitary-adrenal axis may contribute to the risk of the development of persistent musculoskeletal pain after traumatic stress exposure. The objective of the study was to evaluate the association between polymorphisms in the gene encoding FK506 binding protein 51, FKBP5, a glucocorticoid receptor co-chaperone, and musculoskeletal pain severity 6 weeks after 2 common trauma exposures. The study included data from 2 prospective emergency department-based cohorts: a discovery cohort (n=949) of European Americans experiencing motor vehicle collision and a replication cohort of adult European American women experiencing sexual assault (n=53). DNA was collected from trauma survivors at the time of initial assessment. Overall pain and neck pain 6 weeks after trauma exposure were assessed using a 0-10 numeric rating scale. After adjustment for multiple comparisons, 6 FKBP5 polymorphisms showed significant association (minimum P<0.0001) with both overall and neck pain in the discovery cohort. The association of rs3800373, rs9380526, rs9394314, rs2817032, and rs2817040 with neck pain and/or overall pain 6 weeks after trauma was replicated in the sexual assault cohort, showing the same direction of the effect in each case. The results of this study indicate that genetic variants in FKBP5 influence the severity of musculoskeletal pain symptoms experienced during the weeks after motor vehicle collision and sexual assault. These results suggest that glucocorticoid pathways influence the development of persistent posttraumatic pain, and that such pathways may be a target of pharmacologic interventions aimed at improving recovery after trauma.

FKBP5 and attention bias for threat: associations with hippocampal function and shape

IMPORTANCE

The FKBP5 gene product regulates glucocorticoid receptor (GR) sensitivity and hypothalamic-pituitary-adrenal axis functioning and has been associated with many stress-related psychiatric disorders. The study of intermediate phenotypes, such as emotion-processing biases and their neural substrates, provides a way to clarify the mechanisms by which FKBP5 dysregulation mediates risk for psychiatric disorders.

OBJECTIVE

To examine whether allelic variations for a putatively functional single-nucleotide polymorphism associated with FKBP5 gene regulation (rs1360780) would relate differentially to attention bias for threat. this was measured through behavioral response on a dot probe task and hippocampal activation during task performance. Morphologic substrates of differential hippocampal response were also measured.

DESIGN

Cross-sectional study conducted from 2010 to 2012 examining associations between genotype, behavioral response, and neural response (using functional magnetic resonance imaging [fMRI]) on the dot probe; voxel-based morphometry and global and local shape analyses were used to measure structural differences in hippocampi between genotype groups.

SETTING

Participants were recruited from primary care clinics of a publicly funded hospital in Atlanta, Georgia.

PARTICIPANTS

An African American cohort of adults (N = 103) was separated into 2 groups by genotype: one genotype group included carriers of the rs1360780 T allele, which has been associated with increased risk for posttraumatic stress disorder and affective disorders; the other group did not carry this allele. Behavioral data included both sexes (N = 103); the MRI cohort (n = 36) included only women.

MAIN OUTCOME MEASURES

Behavioral and fMRI (blood oxygen level-dependent) response, voxel-based morphometry, and shape analyses.

RESULTS

Carriers of the rs1360780 T allele showed an attention bias toward threat compared with individuals without this allele (F1,90 = 5.19, P = .02). Carriers of this allele demonstrated corresponding increases in hippocampal activation and differences in morphology; global and local shape analyses revealed alterations in hippocampal shape for TT/TC compared with CC genotype groups.

CONCLUSION

Genetic variants of FKBP5 may be associated with risk for stress-related psychiatric disorders via differential effects on hippocampal structure and function, resulting in altered attention response to perceived threat.

Gene × environment interactions in the prediction of response to antidepressant treatment

Major depressive disorder (MDD) is responsible for an increasing individual and global health burden. Extensive research on the genetic disposition to develop MDD and to predict the response to antidepressant treatment has yet failed to identify strong genetic effects. The concept of gene × environment interaction takes into account that environmental factors have been identified as important components in the development of MDD and combines both, genetic predisposition and environmental exposure, to elucidate complex traits such as MDD. Here, we review the current research on gene × environment interactions with regard to the development of MDD as well as response to antidepressant treatment. We hypothesize that gene × environment interactions delineate specific biological subtypes of depression and that individuals with such pathophysiological distinct types of depression will likely respond to different treatments. The elucidation of gene × environment interactions may thus not only help to understand the pathophysiology of MDD but could also provide markers for a personalized antidepressant therapy.

FKBP5 as a possible moderator of the psychosis-inducing effects of childhood trauma

BACKGROUND

FK506 binding protein 5 (FKBP5) has repeatedly been shown to be a critical determinant of post-traumatic stress disorder (PTSD) and depression following childhood trauma.

AIMS

To examine the role of FKBP5-trauma interactions in the partly stress-related psychosis phenotype.

METHOD

In 401 general population twins, four functional polymorphisms were examined in models of psychosis and cortisol, and followed up in models of psychosis in three samples at different familial liability (175 controls, 200 unaffected siblings and 195 patients with a psychotic disorder).

RESULTS

The most consistent finding was an interaction between childhood trauma and rs9296158/rs4713916 on psychotic symptoms and cortisol in the twin sample, combined with a directionally similar interaction in siblings (rs4713916) and patients (rs9296158), A-allele carriers at both polymorphisms being most vulnerable to trauma.

CONCLUSIONS

Trauma may increase the risk of psychosis through enduring changes in the cortisol feedback loop, similar to that for PTSD, suggesting comparable biological mechanisms for psychosis across diagnostic boundaries.

FKBP5 and emotional neglect interact to predict individual differences in amygdala reactivity

Individual variation in physiological responsiveness to stress mediates risk for mental illness and is influenced by both experiential and genetic factors. Common polymorphisms in the human gene for FK506 binding protein 5 (FKBP5), which is involved in transcriptional regulation of the hypothalamic-pituitary-adrenal (HPA) axis, have been shown to interact with childhood abuse and trauma to predict stress-related psychopathology. In the current study, we examined if such gene-environment interaction effects may be related to variability in the threat-related reactivity of the amygdala, which plays a critical role in mediating physiological and behavioral adaptations to stress including modulation of the HPA axis. To this end, 139 healthy Caucasian youth completed a blood oxygen level-dependent functional magnetic resonance imaging probe of amygdala reactivity and self-report assessments of emotional neglect (EN) and other forms of maltreatment. These individuals were genotyped for 6 FKBP5 polymorphisms (rs7748266, rs1360780, rs9296158, rs3800373, rs9470080 and rs9394309) previously associated with psychopathology and/or HPA axis function. Interactions between each SNP and EN emerged such that risk alleles predicted relatively increased dorsal amygdala reactivity in the context of higher EN, even after correcting for multiple testing. Two different haplotype analyses confirmed this relationship as haplotypes with risk alleles also exhibited increased amygdala reactivity in the context of higher EN. Our results suggest that increased threat-related amygdala reactivity may represent a mechanism linking psychopathology to interactions between common genetic variants affecting HPA axis function and childhood trauma.

Genetic variation in FKBP5 associated with the extent of stress hormone dysregulation in major depression

The FK506 binding protein 51 or FKBP5 has been implicated in the regulation of glucocorticoid receptor (GR) sensitivity, and genetic variants in this gene have been associated with mood and anxiety disorders. GR resistance and associated stress hormone dysregulation are among the most robust biological findings in major depression, the extent of which may be moderated by FKBP5 polymorphisms. FKBP5 mRNA expression in peripheral blood cells (baseline and following in vivo GR stimulation with 1.5 mg dexamethasone p.o.) was analyzed together with plasma cortisol, ACTH, dexamethasone levels and the FKBP5 polymorphism rs1360780 in 68 depressed patients and 87 healthy controls. We observed a significant (P = 0.02) interaction between disease status and FKBP5 risk allele carrier status (minor allele T) on GR-stimulated FKBP5 mRNA expression. Patients carrying the risk T allele, but not the CC genotype, showed a reduced induction of FKBP5 mRNA. This FKBP5 polymorphism by disease status interaction was paralleled by the extent of plasma cortisol and ACTH suppression following dexamethasone administration, with a reduced suppression only observed in depressed patients carrying the T allele. Only depressed patients carrying the FKBP5 rs1360780 risk allele showed significant GR resistance compared with healthy controls, as measured by dexamethasone-induced FKBP5 mRNA induction in peripheral blood cells and suppression of plasma cortisol and ACTH concentrations. This finding suggests that endocrine alterations in depressed patients are determined by genetic variants and may allow identification of specific subgroups.

Adcyap1r1 genotype, posttraumatic stress disorder, and depression among women exposed to childhood maltreatment

BACKGROUND

A growing literature indicates that genetic variation, in combination with adverse early life experiences, shapes risk for later mental illness. Recent work also suggests that molecular variation at the ADCYAP1R1 locus is associated with posttraumatic stress disorder (PTSD) in women. We sought to test whether childhood maltreatment (CM) interacts with ADCYAP1R1 genotype to predict PTSD in women.

METHODS

Data were obtained from 495 adult female participants from the Detroit Neighborhood Health Study. Genotyping of rs2267735, an ADCYAP1R1 variant, was conducted via TaqMan assay. PTSD, depression, and CM exposure were assessed via structured interviews. Main and interacting effects of ADCYAP1R1 and CM levels on past month PTSD and posttraumatic stress (PTS) severity were examined using logistic regression and a general linear model, respectively. As a secondary analysis, we also assessed main and interacting effects of ADCYAP1R1 and CM variation on risk of past-month depression diagnosis and symptom severity.

RESULTS

No significant main effects were observed for ADCYAP1R1 genotype on either PTSD/PTS severity. In contrast, a significant ADCYAP1R1 × CM interaction was observed for both past month PTSD and PTS severity, with carriers of the "C" allele showing enhanced risk for these outcomes among women exposed to CM. No significant main or interaction effects were observed for past month depression/depression severity.

CONCLUSIONS

Genetic variation at the ADCYAP1R1 locus interacts with CM to shape risk of later PTSD, but not depression, among women. The molecular mechanisms contributing to this interaction require further investigation.

Gene-environment interactions in major depressive disorder

Family, twin, and epidemiologic studies have suggested that both genes and environment are important risk factors for the development of major depressive disorder (MDD). In the absence of consistent and strong main genetic effects, numerous studies have supported gene-environment interactions in this disorder. While the impact of negative environmental factors, such as early life stress, traumatic experiences, and negative life events have been established as risk factors, they are not sufficient to predict MDD. This article will review evidence suggesting that genetic variants moderate the effects of adversities on the development of MDD, with a focus on the importance of careful characterization of the stressful life events as well as systemic and molecular mechanisms that potentially mediate these gene-environment interactions.

A complex interplay between personality domains, marital status and a variant in CHRNA5 on the risks of cocaine, nicotine dependences and cocaine-induced paranoia

Background

Personality correlates highly with both cocaine and nicotine dependencies (CD, ND), and their co-morbid psychopathologies. However, little is known about the nature of these relationships. This study examined if environment (marriage) or genetics (a single SNP, CHRNA5*rs16969968) would moderate the correlation of personality with CD, ND and cocaine-induced paranoia (CIP) in African and European Americans (AAs, EAs).

Methods

1432 EAs and 1513 AAs were examined using logistic regression. Personality was assessed by NEO-PI-R, while CD, ND and CIP were diagnosed according to DSM-IV. ND and CD were examined as binary traits and for the analysis of CIP, subjects were divided into 3 groups: (A) Controls with no CIP; (B) CD cases without CIP; and (C) CD cases with CIP. Multiple testing was Bonferroni-corrected.

Results

For CD and ND in the EA population, marital status proved to be a significant moderator in their relationship with openness only (OR = 1.90, 95%CI = 1.36–2.64, p = 1.54e-04 and OR = 2.12, 95%CI = 1.52–2.90, p = 4.65e-06 respectively). For CIP, marriage was observed to moderate its correlation with openness and neuroticism (OR = 1.39, 95%CI = 1.18–1.63, p = 7.64e-04 and OR = 1.26, 95%CI = 1.12–1.42, p = 1.27e-03 respectively). The correlations moderated by rs16969968 were those of conscientiousness and CD (OR = 1.62, 95%CI: 1.23–2.12, p = 8.94e-04) as well as CIP (OR = 1.21, 95%CI: 1.11–1.32, p = 4.93e-04 when comparing group A versus group C). No significant interactions were observed in AA population. The Bonferroni-corrected significance threshold was set to be 1.67e-03.

Conclusion

The role of personality in CD and CIP may be interceded by both environment and genetics, while in ND by environment only.

Considering trauma exposure in the context of genetics studies of posttraumatic stress disorder: a systematic review

BACKGROUND

Posttraumatic stress disorder (PTSD) is a debilitating anxiety disorder. Surveys of the general population suggest that while 50-85% of Americans will experience a traumatic event in their lifetime, only 2-50% will develop PTSD. Why some individuals develop PTSD following trauma exposure while others remain resilient is a central question in the field of trauma research. For more than half a century, the role of genetic influences on PTSD has been considered as a potential vulnerability factor. However, despite the exponential growth of molecular genetic studies over the past decade, limited progress has been made in identifying true genetic variants for PTSD.

METHODS

In an attempt to aid future genome wide association studies (GWAS), this paper presents a systematic review of 28 genetic association studies of PTSD. Inclusion criteria required that 1) all participants were exposed to Criterion A traumatic events, 2) polymorphisms of relevant genes were genotyped and assessed in relation to participants' PTSD status, 3) quantitative methods were used, and 4) articles were published in English and in peer-reviewed journals. In the examination of these 28 studies, particular attention was given to variables related to trauma exposure (e.g. number of traumas, type of trauma).

RESULTS

Results indicated that most articles did not report on the GxE interaction in the context of PTSD or present data on the main effects of E despite having data available. Furthermore, some studies that did consider the GxE interaction had significant findings, underscoring the importance of examining how genotypes can modify the effect of trauma on PTSD. Additionally, results indicated that only a small number of genes continue to be studied and that there were marked differences in methodologies across studies, which subsequently limited robust conclusions.

CONCLUSIONS

As trauma exposure is a necessary condition for the PTSD diagnosis, this paper identifies gaps in the current literature as well as provides recommendations for how future GWAS studies can most effectively incorporate trauma exposure data in both the design and analysis phases of studies.

Glucocorticoid sensitizers Bag1 and Ppid are regulated by adolescent stress in a sex-dependent manner

Early life stress precipitates dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and this effect is most pronounced in females. The mechanisms that mediate female sensitivity to stress-induced HPA axis dysregulation are unknown. The purpose of this study was to determine whether sex moderates the effects of chronic adolescent stress on glucocorticoid receptor (GR) translocation and moderators of the GR system. Female adolescent rats with a history of chronic stress exposure demonstrated a delayed resolution of the plasma corticosterone response to an acute stressor and this delay was accompanied by attenuated GR translocation compared to control adolescent females. The chronic stress-induced phenotype in females was similar to the baseline phenotype in male adolescent rats. Conversely, the expression patterns of GR moderators/co-chaperones became more sexually dimorphic following chronic stress, suggesting divergent function of the GR system between male and female adolescent rats. Gene expression of Ppid, a positive regulator of the GR, was predicted by plasma estradiol and 34% lower in control adolescent females than males, indicating that sex steroids may play a role in the sexually dimorphic response. After chronic adolescent stress, females displayed elevated hippocampal expression of Bag1 and Ppid genes that was not observed in males. Overall, the GR output to an acute stressor, illustrated by transcription of Nr3c1 (encoding the GR), Bag1, Fkbp5, Ppid, and Src1, was significantly upregulated and differed in a sex-specific and chronic stress-dependent manner. This study provides new evidence for sex differences during development and adaptation of the glucocorticoid receptor chaperone system.

Childhood trauma as a cause of psychosis: linking genes, psychology, and biology

Recent studies have provided robust evidence for an association between childhood trauma (CT) and psychosis. Meta-analyses have quantified the association, pointing to odds ratios in the order of around 3, and prospective studies have shown that reverse causation is unlikely to explain the association. However, more work is needed to address the possibility of a gene-environment correlation, that is, whether genetic risk for psychosis predicts exposure to CT. Nevertheless, multiple studies have convincingly shown that the association between CT and psychosis remains strong and significant when controlling for genetic risk, in agreement with a possible causal association. In addition, several studies have shown plausible psychological and neurobiological mechanisms linking adverse experiences to psychosis, including induction of social defeat and reduced self-value, sensitization of the mesolimbic dopamine system, changes in the stress and immune system, and concomitant changes in stress-related brain structures, such as the hippocampus and the amygdala, findings that should be integrated, however, in more complex models of vulnerability. It is currently unclear whether genetic vulnerability plays a role in conferring the mental consequences of adversity, and which genes are likely to be involved. The current, limited evidence points to genes that are not specifically involved in psychosis but more generally in regulating mood (serotonin transporter gene), neuroplasticity (brain-derived neurotrophic factor), and the stress-response system (FKBP5), in line with a general effect of CT on a range of mental disorders, rather than suggesting specificity for psychosis.

Exploring epigenetic regulation of fear memory and biomarkers associated with post-traumatic stress disorder

This review examines recent work on epigenetic mechanisms underlying animal models of fear learning as well as its translational implications in disorders of fear regulation, such as Post-traumatic Stress Disorder (PTSD). Specifically, we will examine work outlining roles of differential histone acetylation and DNA-methylation associated with consolidation, reconsolidation, and extinction in Pavlovian fear paradigms. We then focus on the numerous studies examining the epigenetic modifications of the Brain-derived neurotrophin factor (BDNF) pathway and the extension of these findings from animal models to recent work in human clinical populations. We will also review recently published data on FKBP5 regulation of glucocorticoid receptor function, and how this is modulated in animal models of PTSD and in human clinical populations via epigenetic mechanisms. As glucocorticoid regulation of memory consolidation is well established in fear models, we examine how these recent data contribute to our broader understanding of fear memory formation. The combined recent progress in epigenetic modulation of memory with the advances in fear neurobiology suggest that this area may be critical to progress in our understanding of fear-related disorders with implications for new approaches to treatment and prevention.

Interindividual Variability in Stress Susceptibility: A Role for Epigenetic Mechanisms in PTSD

Post-traumatic stress disorder (PTSD) is a psychiatric condition characterized by intrusive and persistent memories of a psychologically traumatic event that leads to significant functional and social impairment in affected individuals. The molecular bases underlying persistent outcomes of a transient traumatic event have remained elusive for many years, but recent studies in rodents have implicated epigenetic modifications of chromatin structure and DNA methylation as fundamental mechanisms for the induction and stabilization of fear memory. In addition to mediating adaptations to traumatic events that ultimately cause PTSD, epigenetic mechanisms are also involved in establishing individual differences in PTSD risk and resilience by mediating long-lasting effects of genes and early environment on adult function and behavior. In this review, we discuss the current evidence for epigenetic regulation of PTSD in human studies and in animal models and comment on ways in which these models can be expanded. In addition, we identify key outstanding questions in the study of epigenetic mechanisms of PTSD in the context of rapidly evolving technologies that are constantly updating and adjusting our understanding of epigenetic modifications and their functional roles. Finally, we discuss the potential application of epigenetic approaches in identifying markers of risk and resilience that can be utilized to promote early intervention and develop therapeutic strategies to combat PTSD after symptom onset.

Postpartum depression: psychoneuroimmunological underpinnings and treatment

Postpartum depression (PPD) is common, occurring in 10%-15% of women. Due to concerns about teratogenicity of medications in the suckling infant, the treatment of PPD has often been restricted to psychotherapy. We review here the biological underpinnings to PPD, suggesting a powerful role for the tryptophan catabolites, indoleamine 2,3-dixoygenase, serotonin, and autoimmunity in mediating the consequences of immuno-inflammation and oxidative and nitrosative stress. It is suggested that the increased inflammatory potential, the decreases in endogenous anti-inflammatory compounds together with decreased omega-3 poly-unsaturated fatty acids, in the postnatal period cause an inflammatory environment. The latter may result in the utilization of peripheral inflammatory products, especially kynurenine, in driving the central processes producing postnatal depression. The pharmacological treatment of PPD is placed in this context, and recommendations for more refined and safer treatments are made, including the better utilization of the antidepressant, and the anti-inflammatory and antioxidant effects of melatonin.

Epigenetic Biomarkers as Predictors and Correlates of Symptom Improvement Following Psychotherapy in Combat Veterans with PTSD

Epigenetic alterations offer promise as diagnostic or prognostic markers, but it is not known whether these measures associate with, or predict, clinical state. These questions were addressed in a pilot study with combat veterans with PTSD to determine whether cytosine methylation in promoter regions of the glucocorticoid related NR3C1 and FKBP51 genes would predict or associate with treatment outcome. Veterans with PTSD received prolonged exposure (PE) psychotherapy, yielding responders (n = 8), defined by no longer meeting diagnostic criteria for PTSD, and non-responders (n = 8). Blood samples were obtained at pre-treatment, after 12 weeks of psychotherapy (post-treatment), and after a 3-month follow-up. Methylation was examined in DNA extracted from lymphocytes. Measures reflecting glucocorticoid receptor (GR) activity were also obtained (i.e., plasma and 24 h-urinary cortisol, plasma ACTH, lymphocyte lysozyme IC50-DEX, and plasma neuropeptide-Y). Methylation of the GR gene (NR3C1) exon 1F promoter assessed at pre-treatment predicted treatment outcome, but was not significantly altered in responders or non-responders at post-treatment or follow-up. In contrast, methylation of the FKBP5 gene (FKBP51) exon 1 promoter region did not predict treatment response, but decreased in association with recovery. In a subset, a corresponding group difference in FKBP5 gene expression was observed, with responders showing higher gene expression at post-treatment than non-responders. Endocrine markers were also associated with the epigenetic markers. These preliminary observations require replication and validation. However, the results support research indicating that some glucocorticoid related genes are subject to environmental regulation throughout life. Moreover, psychotherapy constitutes a form of "environmental regulation" that may alter epigenetic state. Finally, the results further suggest that different genes may be associated with prognosis and symptom state, respectively.

Allele-specific FKBP5 DNA demethylation mediates gene-childhood trauma interactions

Although the fact that genetic predisposition and environmental exposures interact to shape development and function of the human brain and, ultimately, the risk of psychiatric disorders has drawn wide interest, the corresponding molecular mechanisms have not yet been elucidated. We found that a functional polymorphism altering chromatin interaction between the transcription start site and long-range enhancers in the FK506 binding protein 5 (FKBP5) gene, an important regulator of the stress hormone system, increased the risk of developing stress-related psychiatric disorders in adulthood by allele-specific, childhood trauma-dependent DNA demethylation in functional glucocorticoid response elements of FKBP5. This demethylation was linked to increased stress-dependent gene transcription followed by a long-term dysregulation of the stress hormone system and a global effect on the function of immune cells and brain areas associated with stress regulation. This identification of molecular mechanisms of genotype-directed long-term environmental reactivity will be useful for designing more effective treatment strategies for stress-related disorders.

A consideration of select pre-trauma factors as key vulnerabilities in PTSD

Posttraumatic stress disorder (PTSD) is a pathological response to a traumatic event. A number of risk and vulnerability factors predicting PTSD development have been identified in the literature. Many of these variables are specific factors occurring during and after exposure to a traumatic event or are not measured prospectively to assess temporal sequence. Recent research, however, has begun to focus on pre-trauma individual differences that could contribute to risk for developing PTSD. The present review proposes that a number of biological and cognitive vulnerability factors place individuals at risk for PTSD development prior to the actual experience of trauma. Accordingly, this review provides a summary of evidence for a select number of these factors as pre-trauma vulnerabilities to PTSD. Included is a discussion of biological factors, including molecular genetic studies of systems regulating serotonin, catecholamines, and glucocorticoids as well as aspects of the neuroendocrine system. Specific cognitive factors are also considered, including intelligence, neuropsychological functioning and cognitive biases such as negative attributional style and appraisals. For each factor, the present review summarizes evidence to date regarding PTSD vulnerability and highlights directions for future research in this area.

The role of limbic system irritability in linking history of childhood maltreatment and psychiatric outcomes in low-income, high-risk women: moderation by FK506 binding protein 5 haplotype

Childhood maltreatment is associated with lasting changes in neuroendocrine regulation, alterations in brain structure and function, and symptoms of "limbic irritability." Limbic irritability symptoms include somatic, sensory, and behavioral phenomena and may stem from increased excitatory neurotransmission following maltreatment. We tested the hypotheses that child maltreatment is indirectly associated with depressive and dissociative symptomatology via indicators of limbic irritability and that variation within the FK506 binding protein 5 gene (FKBP5), a gene involved in glucorticoid receptor functioning, moderates these effects. The sample consisted of high-risk, low-income women (N = 236) living in an inner-city environment. Child maltreatment, limbic irritability, and symptoms of depression and dissociation were measured cross-sectionally using self-report assessments. Haplotype analyses were conducted across four FKBP5 single nucleotide polymorphisms: rs3800373, rs9296158, rs1360870, and rs9470080. Path analysis using bootstrapping procedures was performed to test hypotheses regarding indirect and conditional indirect effects. We found significant indirect effects of maltreatment on depression (β = 0.088, p < .01) and dissociation (β = 0.105, p < .01) via limbic irritability. In addition, variation within FKBP5 moderated these significant indirect effects. For individuals with one to two copies of the CATT haplotype, the indirect effects of maltreatment on depression (β = 0.137, p < .01) and dissociation (β = 0.132, p < .01) via limbic irritability were significant, whereas the indirect paths were not significant for individuals with no copies of this haplotype (depression: β = 0.037, p > .05; dissociation: β = 0.002, p > .05). These results add to the growing evidence that child maltreatment may lead to symptoms of internalizing psychopathology through its impact on the limbic system. In addition, this study revealed a potential role of FKBP5 gene variants in contributing to risk for limbic system dysfunction.

Resilience and measured gene–environment interactions

The past decade has witnessed an exponential growth in studies that have attempted to identify the genetic polymporphisms that moderate the influence of environmental risks on mental disorders. What tends to be neglected in these Gene × Environment (G × E) interaction studies has been a focus on resilience, which refers to a dynamic pattern of positive adaptation despite the experience of a significant trauma or adversity. In this article, we argue that one step toward advancing the field of developmental psychopathology would be for G × E research to consider resilience instead of focusing almost exclusively on mental disorders. After providing an up-to-date summary on the expanding definitions and models of resilience, and the available evidence regarding measured G × E studies of childhood maltreatment, we discuss why resilience would be a worthwhile phenotype for studies of measured G × E. First, although G × E hypotheses require that there be an environmental risk (e-risk) involved in a causal process that leads to psychopathology, e-risks are typically not included in the diagnostic criteria for most psychiatric disorders. In contrast, resilience by definition includes an e-risk. Second, G × E hypotheses require that there is evidence of variability in response to an environmental stressor, and resilience often represents the positive end on this continuum of adaptation. Third, both resilience and G × E are best understood from a developmental perspective. Fourth, although resilient outcomes are not public health concerns, the types of adversities (e.g., childhood maltreatment, poverty, or exposure to natural disasters) that are often investigated in studies of resilience certainly are. Understanding how some individuals, perhaps because of their genetic makeup, are able to withstand such adversities can inform prevention and intervention efforts to improve mental health.

Linkage analysis followed by association show NRG1 associated with cannabis dependence in African Americans

BACKGROUND

A genetic contribution to cannabis dependence (CaD) has been established but susceptibility genes for CaD remain largely unknown.

METHODS

We employed a multistage design to identify genetic variants underlying CaD. We first performed a genome-wide linkage scan for CaD in 384 African American (AA) and 354 European American families ascertained for genetic studies of cocaine and opioid dependence. We then conducted association analysis under the linkage peak, first using data from a genome-wide association study from the Study of Addiction: Genetics and Environment, followed by replication studies of prioritized single nucleotide polymorphisms (SNPs) in independent samples.

RESULTS

We identified the strongest linkage evidence with CaD (logarithm of odds = 2.9) on chromosome 8p21.1 in AAs. In the association analysis of the Study of Addiction: Genetics and Environment sample under the linkage peak, we identified one SNP (rs17664708) associated with CaD in both AAs (odds ratio [OR] = 2.93, p = .0022) and European Americans (OR = 1.38, p = .02). This SNP, located at NRG1, a susceptibility gene for schizophrenia, was prioritized for further study. We replicated the association of rs17664708 with CaD in an independent AAs sample (OR = 2.81, p = .0068). The joint analysis of the two AA samples demonstrated highly significant association between rs17664708 and CaD with adjustment for either global (p = .00044) or local ancestry (p = .00075).

CONCLUSIONS

Our study shows that NRG1 is probably a susceptibility gene for CaD, based on convergent evidence of linkage and replicated associations in two independent AA samples.

Early interventions for PTSD: a review

The high prevalence of trauma exposure and subsequent negative consequences for both survivors and society as a whole emphasize the need for secondary prevention of posttraumatic stress disorder. However, clinicians and relief workers remain limited in their ability to intervene effectively in the aftermath of trauma and alleviate traumatic stress reactions that can lead to chronic PTSD. The scientific literature on early intervention for PTSD is reviewed, including early studies on psychological debriefing, pharmacological, and psychosocial interventions aimed at preventing chronic PTSD. Studies on fear extinction and memory consolidation are discussed in relation to PTSD prevention and the potential importance of immediate versus delayed intervention approaches and genetic predictors are briefly reviewed. Preliminary results from a modified prolonged exposure intervention applied within hours of trauma exposure in an emergency room setting are discussed, along with considerations related to intervention reach and overall population impact. Suggestions for future research are included. Prevention of PTSD, although currently not yet a reality, remains an exciting and hopeful possibility with current research approaches translating work from the laboratory to the clinic.

Serotonin transporter 5-HTTLPR genotype moderates the effects of childhood adversity on posttraumatic stress disorder risk: a replication study

We reported that the 5-HTTLPR polymorphism in the promoter region of the serotonin transporter gene (SLC6A4) moderates the effect of childhood adversity on posttraumatic stress disorder (PTSD) risk [Xie et al. (2009); Arch Gen Psychiatry 66 (11): 1201-1209]. In the present study, we considered 5,178 subjects (a group with generally high substance dependence comorbidity, as for our previous study) using similar methodology to replicate our previous results. We used logistic regression analyses to explore the interaction effect of 5-HTTLPR genotype and childhood adversity on PTSD risk. We found that, as reported in our previous study, in individuals with childhood adversity, the presence of one or two copies of the S allele of 5-HTTLPR increased the risk to develop PTSD. This gene-environment interaction effect was present in European Americans (EAs), but not in African Americans (AAs; EAs, OR = 1.49, 95% CI = 1.07-2.08, P = 0.019; AAs, OR = 0.90, 95% CI = 0.60-1.35, P = 0.62). The statistical power to detect this interaction effect was increased when data were combined with those from our previous study [Xie et al. (2009); Arch Gen Psychiatry 66 (11): 1201-1209]. The findings reported here replicate those from our previous work, adding to a growing body of research demonstrating that the 5-HTTLPR genotype moderates risk for anxiety and depression phenotypes in the context of stress and adverse events.

Consumer perspectives on genetic testing for psychiatric disorders: the attitudes of veterans with posttraumatic stress disorder and their families

The perspectives of patients with posttraumatic stress disorder (PTSD) on genetic research have not yet been investigated in the genetics research literature. To provide a basis for research on attitudes toward genetic research in PTSD, we surveyed the U.S. Military Afghanistan/Iraq-era veterans with PTSD and their social support companions to investigate the attitudes and knowledge about genetics and genetic testing. One hundred forty-six veterans (76 with PTSD and 70 without PTSD) participated in this study. Each veteran participant had a corresponding companion (primarily spouses, but also relatives and friends) who they identified as a primary member of their social support network. Participants and companions completed self-report measures on knowledge of genetics and attitudes toward genetic testing for PTSD. Results indicated that, relative to veterans without PTSD, veterans with PTSD had similar levels of genetic knowledge, but less-favorable attitudes toward genetic testing. Differences persisted after controlling for age and genetics knowledge. No differences between companions of those with and without PTSD were observed. Results suggest that the perspective of those with PTSD regarding genetic testing is in need of further investigation, especially if potentially beneficial genetic testing for PTSD is to be utilized in the target population.

Genetics of pediatric anxiety disorders

This article reviews the familiality, linkage, candidate gene, and genomewide association studies of obsessive-compulsive disorder, panic disorder, posttraumatic stress disorder, and other anxiety disorders (ie, generalized anxiety disorder, separation anxiety disorder, social phobia, and specific phobia). Studies involving children and adolescents are highlighted. Clinical and research implications are discussed.

BDNF Val66Met genotype modulates the effect of childhood adversity on subgenual anterior cingulate cortex volume in healthy subjects

According to the neurotrophic hypothesis of depression, stress can lead to brain atrophy by modifying brain-derived neurotrophic factor (BDNF) levels. Given that BDNF secretion is affected by a common polymorphism (rs6265, Val66Met), which also is associated with depression, we investigated whether this polymorphism modifies the effect of childhood adversity (CA) on local gray matter (GM) volume in depression-relevant brain regions, using data from two large cohorts of healthy subjects. We included 568 healthy volunteers (aged 18-50 years, 63% female) in our study, for whom complete data were available, with magnetic resonance imaging data at 1.5 Tesla (N=275) or 3 Tesla (N=293). We used a whole brain optimized voxel-based morphometry (VBM) approach assessing genotype-dependent GM differences, with focus on the amygdala, hippocampus and medial prefrontal cortex (PFC; including anterior cingulate cortex (ACC) and orbitomedial PFC). CA was assessed using a validated questionnaire. In both cohorts, we found that BDNF methionine (Met)-allele carriers with a history of CA had significantly less GM in subgenual ACC (P<0.05) compared with Met-allele carriers without CA and Val/Val homozygotes with CA. No differences were found in hippocampus, amygdala and orbitomedial PFC. On the basis of our findings, we conclude that BDNF Met-allele carriers are particularly sensitive to CA. Given the key role of the subgenual ACC in emotion regulation, this finding provides an important mechanistic link between stress and BDNF on one hand and mood impairments on the other hand.