A psychobiological perspective on genetic determinants of hypothalamus-pituitary-adrenal axis activity

Prenatal stress and child externalizing behavior: effects of maternal perceived stress and cortisol are moderated by child sex

BACKGROUND

Externalizing behavior problems are related to social maladjustment. Evidence indicates associations between prenatal stress and child behavioral outcomes. It remains unclear how psychological distress vs. biological correlates of stress (cortisol) differentially predict externalizing behavior, and how their effects might differ as a function of child sex.

METHOD

108 pregnant women from the community collected salivary cortisol and reported their perceived stress during each trimester of pregnancy. At child age 9 years (M = 9.01, SD = 0.55), 70 mothers and children reported on child behavior. Structural equation modelling was used to analyze how cortisol levels and perceived stress during pregnancy predicted current child externalizing behavior, considering the moderating effect of child sex.

RESULTS

Perceived stress predicted higher externalizing behavior in boys (β = 0.42, p = 0.009) and lower externalizing behavior in girls (β = - 0.56, p = 0.014). Cortisol predicted lower externalizing behavior in boys (β = - 0.81, p < .001) and was not related to girls' externalizing behavior (β = 0.37, p = 0.200).

DISCUSSION/CONCLUSION

Prenatal stress affected externalizing behavior differently in girls vs. boys. These response patters in turn differed for indicators of psychological vs. biological maternal stress, encouraging an integrated approach. Findings indicate that perceived stress and cortisol may affect child development via different trajectories.

The phenotypic associations and gene-environment underpinnings of socioeconomic status and diurnal cortisol secretion in adolescence

While converging evidence suggests that both environmental and genetic factors underlie variations in diurnal cortisol, the extent to which these sources of influence vary according to socioeconomic status (SES) has seldom been investigated, particularly in adolescence. To investigate whether a distinct genetic and environmental contribution to youth's diurnal cortisol secretion emerges according to family SES and whether the timing of these experiences matters. Participants were 592 twin pairs, who mostly came from middle-income and intact families and for whom SES was measured in childhood and adolescence. Diurnal cortisol was assessed at age 14 at awakening, 30 min later, in the afternoon and evening over four nonconsecutive days. SES-cortisol phenotypic associations were specific to the adolescence period. Specifically, higher awakening cortisol levels were detected in wealthier backgrounds, whereas higher cortisol awakening response (CAR) and diurnal changes were present at both ends of the SES continuum. Moreover, smaller genetic contributions emerged for awakening cortisol in youth from poorer compared to wealthier backgrounds. The results suggest that the relative contribution of inherited factors to awakening cortisol secretion may be enhanced or suppressed depending on the socio-family context, which may help to decipher the mechanisms underlying later adjustment.

Hypothalamic-pituitary-adrenal Axis Multilocus Genetic Variation, Childhood Parenting and Adolescent Anxiety Symptoms: Evidence of Cumulative Polygenic Plasticity

Research suggests that genetic variants that regulate the hypothalamic-pituitary-adrenal (HPA) axis function moderate the association between parenting and anxiety symptoms, but these studies have primarily focused on (i) individual genes with very small and unreliable effect and (ii) the role of mothers as opposed to fathers. Using a multilocus genetic profile score approach, the current study is the first to examine the moderation effect of HPA-axis multilocus genetic variants on the associations of both maternal and paternal parenting with adolescent anxiety symptoms. In a sample of Chinese Han adolescents (N = 772; 50.1% girls; M_age = 16.48 ± 1.40 years, range: 15-20 years), a theory-driven multilocus genetic profile score was computed by counting the numbers of alleles that were previously linked to heightened stress reactivity in six HPA-axis related genes. This HPA-axis related multilocus genetic profile score equivalently interacted with both maternal and paternal parenting in the prediction of adolescent anxiety symptoms. Consistent with cumulative polygenic plasticity hypothesis of differential susceptibility model, adolescents with more versus low alleles linked to heightened stress reactivity not only suffered more from poor maternal or paternal parenting quality, but also benefited more from high maternal or paternal parenting quality. However, none of the individual HPA-axis genes within this multilocus genetic profile score yielded a significant gene-by-environment (G × E) interaction when examined in isolation. The findings survived after internal replication analysis and a novel, valid influence statistic DFBETAS analysis, demonstrating the robustness of the results. The current study highlights the potential value of using a multilocus approach to understand G × E effects underlying anxiety symptoms and emphasizes the role of both mothers and fathers in such gene-parenting interactions, especially in Chinese families.

Childhood parenting and adolescent internalizing and externalizing symptoms: Moderation by multilocus hypothalamic-pituitary-adrenal axis-related genetic variation

Genetic variants that regulate hypothalamic-pituitary-adrenal (HPA) axis function have been demonstrated to moderate the association between parenting and mental health. However, extant research has focused primarily on (i) effects of individual genes or (ii) maternal as opposed to paternal parenting. Using a multilocus genetic profile score (MGPS) approach, the current study is the first to examine the moderation effect of multilocus HPA-axis related genetic variants on the association of both maternal and paternal parenting with adolescent internalizing and externalizing symptoms. In a sample of 772 Chinese Han adolescents (Mage = 16.48 ± 1.40 years; 50.1% girls), a theory-driven MGPS was calculated using six polymorphisms within HPA-axis related genes (CRHR1, NR3C1, NR3C2, FKBP5, COMT, and HT1RA). Results showed that the MGPS interacted with both maternal and paternal parenting in the association with adolescent internalizing symptoms, but not externalizing symptoms. Consistent with the differential susceptibility model, adolescents with high versus low MGPS exhibited not only more internalizing symptoms when exposed to low quality of parenting but also less internalizing symptoms when exposed to high quality of parenting. The current findings highlight the potential value of using a multilocus approach to understanding gene-by-environment interaction (G×E) effects underlying mental health. Within such G×E effects, not only maternal but also paternal parenting should be addressed.

Using the Ball-in-Bowl Metaphor to Outline an Integrative Framework for Understanding Dysregulated Emotion

Dysregulated emotion plays an important role for mental health problems. To elucidate the underlying mechanisms, researchers have focused on the domains of strategy-based emotion regulation, psychophysiological self-regulation, emotion evaluations, and resulting emotion dynamics. So far, these four domains have been looked at in relative isolation from each other, and their reciprocal influences and interactive effects have seldom been considered. This domain-specific focus constrains the progress the field is able to make. Here, we aim to pave the way towards more cross-domain, integrative research focused on understanding the raised reciprocal influences and interactive effects of strategy-based emotion-regulation, psychophysiological self-regulation, emotion evaluations, and emotion dynamics. To this aim, we first summarize for each of these domains the most influential theoretical models, the research questions they have stimulated, and their strengths and weaknesses for research and clinical practice. We then introduce the metaphor of a ball in a bowl that we use as a basis for outlining an integrative framework of dysregulated emotion. We illustrate how such a framework can inspire new research on the reciprocal influences and interactions between the different domains of dysregulated emotion and how it can help to theoretically explain a broader array of findings, such as the high levels of negative affect in clinical populations that have not been fully accounted for by deficits in strategy-based emotion regulation and the positive long-term consequences of accepting and tolerating emotions. Finally, we show how it can facilitate individualized emotion regulation interventions that are tailored to the specific regulatory impairments of the individual patient.

Ameliorative effect of SIRT1 in postpartum depression mediated by upregulation of the glucocorticoid receptor

Recent evidence has confirmed the association of glucocorticoid receptor (GR) gene variants with the "stress" endocrine axis in postpartum depression (PPD). Sirtuin 1(SIRT1) is an NAD⁺-dependent histone deacetylase and transcriptional enhancer of GR. However, to date, the function of the SIRT1 gene in the regulation of GR expression in PPD remains to be fully determined. A hormone-stimulated pregnancy (HSP) and subsequent "postpartum" withdrawal of estrogen was employed to mimic the fluctuations in estradiol associated with pregnancy and postpartum. We confirmed that estradiol benzoate withdrawal (EW)-rats displayed depression- and anxiety-like behaviors. These behavioral dysfunctions are associated with attenuated expression of SIRT1 and GR in the hippocampus. To assess the role of SIRT1, as well as its regulatory target directly, a selective SIRT1 activator (SRT2104) was infused into the hippocampus of EW-rats. We found that pharmacological activation of hippocampal SIRT1 blocks the development of depression-related, but not anxiety-related, phenotypes of PPD. In addition, the activation of SIRT1 leads to an increase in hippocampal GR expression in EW-rats. We further confirmed that SIRT1 physically interacts with GR in a glucocorticoid-dependent manner. Taken together, our results suggest that neuropathology in PPD is caused, at least in part, by the inhibition of the SIRT1-GR signaling pathway. Elevating SIRT1 levels, either pharmacologically or through other means, could represent a therapeutic strategy for PPD.

[Anhedonia in depression: neurobiological and genetic aspects]

Anhedonia is indeed a pathogenetically important clinical phenotype and a promising endophenotype for depressive symptoms with a very high contribution of biological and genetic factors. Neurobiological mechanisms of anhedonia are impaired functioning of the reward system of the brain, which is confirmed by many neuroimaging, genetic and experimental studies. Anhedonia has a trans-diagnoctic character and should be understood as a complex phenomenon, and it is important to correctly evaluate it within the framework of a particular research paradigm. It seems optimal to form several complementary research strategies that evaluate the most important «facets» of anhedonia, regardless of the nosological form of the disease, within the framework of one study using various methods to search for adequate biomarkers of anhedonia severity (genetic, neuroimaging, biochemical). Given the high-quality organization of such comprehensive studies based on the correct methodology of evidence-based medicine, it is likely that significant biomarker systems will be available in the near future, which, if replicated in independent samples, can be used to personalize the diagnosis and treatment of depression.

Stress and Feline Health

In the health sciences, stress often is defined in terms of stressors; events that are perceived as threats to one's perception of control. From this perspective, a stressor is anything that activates the central threat response system (CTRS). Recent research shows that the CTRS can be sensitized to environmental events through epigenetic modulation of gene expression. When CTRS activation is chronic, health and welfare may be harmed. Environmental modification can mitigate the harmful effects of chronic CTRS activation by reducing the individual's perception of threat and increasing its perception of control, which improves health and welfare.

Inhibition of expression of glucocorticoids receptors may contribute to postpartum depression

Although postpartum depression (PPD) is the leading cause of disability worldwide, its molecular mechanisms are poorly understood. Recent evidence has suggested that impaired glucocorticoid receptor (GR), the signaling of key molecules of the HPA axis, plays a key role in the behavioral and neuroendorcrine alterations of major depression. However, the role of GR in postpartum period, which following with the abrupt withdrawal of placental corticotropin releasing hormone (CRH) and resulting in a re-equilibration of the maternal HPA axis in the days of post-delivery, is still not entirely clear. Previously, a hormone-simulated pregnancy (HSP), and the subsequent 'postpartum' withdrawal in estrogen has been employed to mimic the fluctuations in estradiol associated with pregnancy and postpartum. Using the HSP model, we investigated here the effect of 'postpartum' withdrawal in estrogen as well as depression- and anxiety-like behavior by intra-hippocampal infusion with GR inhibitor-RU486. Following the successful acquisition of PPD model by withdrawal in estrogen, reduced GR expression was observed in hippocampus. Further, HSP-rats suffered intra-hippocampal RU486 infusion presented depression- and anxiety-like behavior as postpartum depression. Together, these results suggest an important, though complex, role for GR in the behavioral regulation of postpartum depression.

Glucocorticoid receptor gene variants and lower expression of NR3C1 are associated with cocaine use

Animal and cross-sectional human studies suggest that chronic cocaine use is associated with altered responsivity of the hypothalamic-pituitary-adrenal axis to stress. Moreover, increased susceptibility to stress has been proposed as an important factor for development, maintenance and relapse of cocaine addiction. As the glucocorticoid receptor gene (NR3C1) mediates genomic effects of the stress hormone cortisol, we investigated NR3C1 expression and the association of NR3C1 genotypes with cocaine use, addiction and comorbid psychiatric symptoms in 126 chronic cocaine users and 98 stimulant-naïve healthy controls. A comprehensive psychiatric assessment was performed including severity of depressive symptoms and current psychological distress. Whole blood NR3C1 mRNA levels were determined and six NR3C1 polymorphisms (rs10482605, rs41423247, rs10052957, rs6189, rs56149945 and rs6198) were genotyped. Compared to controls, cocaine users showed significantly lower NR3C1 expression (P < 0.001), which was not affected by NR3C1 genotypes. In controls, rs41423247 [P < 0.01, false discovery rate (FDR)-corrected], haplotype 2 and haplotype 3 (both P < 0.05, FDR-corrected) were associated with altered NR3C1 gene expression. Haplotype 3 (including minor alleles of rs10052957 and rs41423247) was associated with an increased risk for cocaine addiction (odds ratio = 2.74, P < 0.05, uncorrected). Moreover, addicted cocaine users carrying haplotype 3 showed higher depression scores (P < 0.01, FDR-corrected) than noncarriers. Considering possible confounding effects of alcohol and/or depression, we conclude that chronic cocaine use is associated with lower NR3C1 gene expression suggesting possible direct effects of the drug on the biological adaptation of stress-related genes. Finally, we postulate that haplotype 3 of NR3C1 might serve as a potential risk factor for stimulant addiction and associated psychiatric symptoms.

Hair cortisol concentration in mothers and their children: roles of maternal sensitivity and child symptoms of attention-deficit/hyperactivity disorder

Associations between mothers' and children's cortisol secretion parameters are well established. According to the bio-behavioral synchrony model, these associations reflect influences of the mother-child relationship, the child's social adjustment, and might also reflect shared genetic dispositions. From the bio-behavioral synchrony model, we predicted a stronger mother-child hair cortisol concentration (HCC) link in mothers showing highly adequate (compared to those showing less adequate) parenting behaviors and in children showing low (compared to those showing high) ADHD symptoms. From a genetic perspective, no such moderator effects, or a stronger mother-child HCC link in children with high ADHD symptoms, can be expected. The study sample consisted of 111 4-5-year-old children (64 of whom screened positive for increased ADHD symptoms) and their mothers. ADHD symptoms were assessed by a clinical interview and parent and teacher questionnaires. Maternal sensitive/responsive parenting behavior was assessed by an at-home behavior observation procedure. In mothers and children, HCC in the most proximal 3-cm scalp hair segment was analyzed using luminescence immunoassay. Overall HCCs of mothers and their children correlated significantly. Maternal sensitivity/responsiveness and child ADHD symptoms proved to be significant moderator variables of this association: High maternal sensitivity/responsiveness and low ADHD symptoms of the child were associated with a stronger mother-child link in HCC. The findings are in line with the bio-behavioral synchrony model in the mother-child relationship, and are less compatible with a genetic perspective. The results might hint at environmental events influencing the development of stress axis functioning in subgroups of preschoolers with high ADHD symptoms.

Epigenetic Potential as a Mechanism of Phenotypic Plasticity in Vertebrate Range Expansions

SYNOPSIS

During range expansions, organisms are often exposed to multiple pressures, including novel enemies (i.e., predators, competitors and/or parasites) and unfamiliar or limited resources. Additionally, small propagule sizes at range edges can result in genetic founder effects and bottlenecks, which can affect phenotypic diversity and thus selection. Despite these obstacles, individuals in expanding populations often thrive at the periphery of a range, and this success may be mediated by phenotypic plasticity. Increasing evidence suggests that epigenetic mechanisms may underlie such plasticity because they allow for more rapid phenotypic responses to novel environments than are possible via the accumulation of genetic variation. Here, we review how molecular epigenetic mechanisms could facilitate plasticity in range-expanding organisms, emphasizing the roles of DNA methylation and other epigenetic marks in the physiological regulatory networks that drive whole-organism performance. We focus on the hypothalamic-pituitary-adrenal (HPA) axis, arguing that epigenetically-mediated plasticity in the regulation of glucocorticoids in particular might strongly impact range expansions. We hypothesize that novel environments release and/or select for epigenetic potential in HPA variation and hence organismal performance and ultimately fitness.

Memory performance is related to the cortisol awakening response in older people, but not to the diurnal cortisol slope

There are large individual differences in age-related cognitive decline. Hypothalamic-pituitary-adrenal axis (HPA-axis) functioning has been suggested as one of the mechanisms underlying these differences. This study aimed to investigate the relationships between the diurnal cortisol cycle, measured as the cortisol awakening response (CAR), and the diurnal cortisol slope (DCS) and the memory performance of healthy older people. To do so, we assessed the verbal, visual, and working memory performance of 64 participants (32 men) from 57 to 76 years old who also provided 14 saliva samples on two consecutive weekdays to determine their diurnal cortisol cycle. The CAR was linearly and negatively associated with verbal (significantly) and visual (marginally) memory domains, but not with working memory. Sex did not moderate these relationships. Furthermore, no associations were found between the DCS and any of the three memory domains assessed. Our results indicate that the two components of the diurnal cortisol cycle have different relationships with memory performance, with the CAR being more relevant than DCS in understanding the link from HPA-axis activity and regulation to different types of memory. These results suggest that the CAR is related to memory domains dependent on hippocampal functioning (i.e., declarative memory), but not to those that are more dependent on prefrontal cortex functioning (i.e., working memory).

Associations between the neuron-specific glucocorticoid receptor (NR3C1) Bcl-1 polymorphisms and suicide in cancer patients within the first year of diagnosis

Background

Cancer diagnosis is associated with an increased suicide risk, particularly within the first 1 year after diagnosis of cancer. Abnormal function of the hypothalamic–pituitary–adrenal axis has been implicated in the pathophysiology of depression and suicide. We examined genetic associations of the functional Bcl-1 polymorphism of (rs41423247) neuron-specific glucocorticoid receptor (NR3C1) gene, with death by suicide in cancer patients. Suicides occurring within a year of cancer diagnosis (‘early suicide’) were considered separately from those suicides during the second or subsequent year (‘late suicide’) after cancer diagnosis.

Methods

The subjects consisted of 343 cancer patients admitted to a general hospital in Seoul, South Korea from 1996 to 2009, of which 182 had died by suicide and 161 were alive on December 31, 2009. Genomic DNA was extracted from formalin-fixed paraffin-embedded tissue sample of patients with cancer. We conducted a case-control association analysis of Bcl-1 polymorphism of NR3C1 gene.

Results

Subjects carrying the GG genotype of Bcl-1 polymorphism were at increased risk of early suicide when compared to those carrying the CC genotype (OR 3.80, 95 % CI 1.02–14.16, p = .047). Similarly, those individuals carrying the GG genotype (recessive mode) had an increased risk of early suicide relative to the CC or CG genotype (OR 3.71, 95 % CI 1.03–13.43, p = .045). However, there were no differences in the genotype distributions of the NR3C1 Bcl-1 polymorphism between late suicide cases and controls.

Conclusions

Our findings suggest that the NR3C1 Bcl-1 polymorphisms may be involved in the susceptibility to suicide within the first year after cancer diagnosis among cancer patients in Korean population.

Personality traits modulate emotional and physiological responses to stress

An individual's susceptibility to psychological and physical disorders associated with chronic stress exposure, for example, cardiovascular and infectious disease, may also be predicted by their reactivity to acute stress. One factor associated with both stress resilience and health outcomes is personality. An understanding of how personality influences responses to acute stress may shed light upon individual differences in susceptibility to chronic stress-linked disease. This study examined the relationships between personality and acute responses to stress in 125 healthy adults, using hierarchical linear regression. We assessed personality traits using the Multidimensional Personality Questionnaire (MPQ-BF), and responses to acute stress (cortisol, heart rate, blood pressure, mood) using a standardized laboratory psychosocial stress task, the Trier Social Stress Test. Individuals with high Negative Emotionality exhibited greater emotional distress and lower blood pressure responses to the Trier Social Stress Test. Individuals with high agentic Positive Emotionality exhibited prolonged heart rate responses to stress, whereas those with high communal Positive Emotionality exhibited smaller cortisol and blood pressure responses. Separate personality traits differentially predicted emotional, cardiovascular, and cortisol responses to a psychosocial stressor in healthy volunteers. Future research investigating the association of personality with chronic stress-related disease may provide further clues to the relationship between acute stress reactivity and susceptibility to disease.

Cancer, coping, and cognition: a model for the role of stress reactivity in cancer-related cognitive decline

BACKGROUND

Cognitive decline and accompanying neurological changes associated with non-CNS cancer diagnosis and treatment have been increasingly identified in a subset of patients. Initially believed to be because of neurotoxic effects of chemotherapy exposure, observation of cognitive decline in patients not treated with chemotherapy, cancer-diagnosed individuals prior to treatment, and patients receiving alternative treatment modalities (surgery, endocrine therapy, and radiation) has led to the investigation of additional potential etiologies and moderating factors. Stressful experiences have long been posited as a contributor to these cognitive changes. Through reciprocal connectivity with peripheral systems, the brain maintains a dynamic circuitry to adapt to stress (allostasis). However, overuse of this system leads to dysregulation and contributes to pathophysiology (allostatic load). At this time, little research has been conducted to systematically examine the role of allostatic load in cancer-related cognitive dysfunction.

METHODS AND RESULTS

Here, we integrate theories of stress biology, neuropsychology, and coping and propose a model through which individuals with a high level of allostatic load at diagnosis may be particularly vulnerable to the neurocognitive effects of cancer.

CONCLUSIONS

Opportunities for future research to test and extend proposed mechanisms are discussed in addition to points of prevention and intervention based on individual variation in stress reactivity and coping skills.

Glucocorticoid actions on synapses, circuits, and behavior: implications for the energetics of stress

Environmental stimuli that signal real or potential threats to homeostasis lead to glucocorticoid secretion by the hypothalamic-pituitary-adrenocortical (HPA) axis. Glucocorticoids promote energy redistribution and are critical for survival and adaptation. This adaptation requires the integration of multiple systems and engages key limbic-neuroendocrine circuits. Consequently, glucocorticoids have profound effects on synaptic physiology, circuit regulation of stress responsiveness, and, ultimately, behavior. While glucocorticoids initiate adaptive processes that generate energy for coping, prolonged or inappropriate glucocorticoid secretion becomes deleterious. Inappropriate processing of stressful information may lead to energetic drive that does not match environmental demand, resulting in risk factors for pathology. Thus, dysregulation of the HPA axis may promote stress-related illnesses (e.g. depression, PTSD). This review summarizes the latest developments in central glucocorticoid actions on synaptic, neuroendocrine, and behavioral regulation. Additionally, these findings will be discussed in terms of the energetic integration of stress and the importance of context-specific regulation of glucocorticoids.

Sex-specific prediction of hypothalamic-pituitary-adrenal axis activity by pituitary volume during adolescence: a longitudinal study from 12 to 17 years of age

OBJECTIVE

To investigate the longitudinal relationship between pituitary gland volume (PGV) and parameters of hypothalamic-pituitary-adrenal axis (HPAA) functioning during adolescence.

METHODS

Participants were 49 adolescents (19 girls and 30 boys) selected from a larger longitudinal, population-based study of adolescent development. Assessments were conducted at three time points (S1, S2 and S3). MRI sessions were at S1 (age: M=12.62, SD=0.45 years) and S3 (M=16.48, SD=0.53 years) and multiple assessments of salivary cortisol were undertaken at S2 (M=15.51, SD=0.35 years). PGV was measured via previously validated manual tracing methods, and the cortisol awakening response (CAR) and diurnal slope (DSL) were used as indices of HPAA functioning.

RESULTS

A significant sex-linked interaction was found for PGV at S1 predicting both CAR (p=0.025) and DSL (p=0.009) at S2. Specifically, PGV at S1 significantly predicted CAR (p=0.033) and DSL (p=0.010) in boys only, with no significant results found for girls. Neither CAR nor DSL at S2 predicted growth of PGV from S1 to S3.

CONCLUSIONS

PGV in early adolescence predicted HPAA functioning in mid-adolescent boys but not in girls. The results suggest a significant influence of sex-specific development on the relationship between PGV and HPAA activity and reactivity. The findings have potential implications for understanding and interpreting sex-linked and stress related clinical disorders that emerge during mid-to-late adolescence.

Maternal influence on child HPA axis: a prospective study of cortisol levels in hair

OBJECTIVE

To investigate cortisol concentrations in hair as biomarker of prolonged stress in young children and their mothers and the relation to perinatal and sociodemographic factors.

METHODS

Prospective cohort study of 100 All Babies In Southeast Sweden study participants with repeated measures at 1, 3, 5, and 8 years and their mothers during pregnancy. Prolonged stress levels were assessed through cortisol in hair. A questionnaire covered perinatal and sociodemographic factors during the child's first year of life.

RESULTS

Maternal hair cortisol during the second and third trimester and child hair cortisol at year 1 and 3 correlated. Child cortisol in hair levels decreased over time and correlated to each succeeding age, between years 1 and 3 (r = 0.30, P = .002), 3 and 5 (r = 0.39, P < .001), and 5 and 8 (r = 0.44, P < .001). Repeated measures gave a significant linear association over time (P < .001). There was an association between high levels of hair cortisol and birth weight (β = .224, P = .020), nonappropriate size for gestational age (β = .231, P = .017), and living in an apartment compared with a house (β = .200, P = .049). In addition, we found high levels of cortisol in hair related to other factors associated with psychosocial stress exposure.

CONCLUSIONS

Correlation between hair cortisol levels in mothers and their children suggests a heritable trait or maternal calibration of the child's hypothalamic-pituitary-adrenocortical axis. Cortisol output gradually stabilizes and seems to have a stable trait. Cortisol concentration in hair has the potential to become a biomarker of prolonged stress, especially applicable as a noninvasive method when studying how stress influences children's health.

Cortisol levels in children of parents with a substance use disorder

BACKGROUND

Children of parents with a substance use disorder (CPSUDs) are at increased risk for the development of substance use disorders later in life, and therefore may manifest vulnerability markers for these disorders at a higher level than children from the general population. Our aim was to examine hypothalamic-pituitary-adrenal (HPA) axis activity as a potential vulnerability marker in CPSUDs as compared to healthy controls. We further examined whether having experienced more adverse life events (ALEs) accounted for differences in cortisol levels between CPSUDs and controls.

METHODS

83 CPSUDs were matched to 83 controls on the basis of age, sex and socioeconomic status. Salivary cortisol was assessed at four time points during a normal day and at six time points during a psychosocial stress procedure, during which perceived stress was also measured. We implemented piecewise multilevel growth curve modeling to examine group differences in diurnal and stress-evoked cortisol levels.

RESULTS

Diurnal cortisol levels of CPSUDs did not differ from those of controls. Only stress-evoked cortisol levels at onset of the experiment were explained by group status, such that CPSUDs exhibited lower cortisol levels at onset of the stress procedure. CPSUDs reported experiencing significantly more ALEs, yet number of ALEs was not related to cortisol levels. CPSUDs furthermore reported less perceived stress than controls at onset of the procedure.

CONCLUSIONS

HPA axis dysregulation may be a vulnerability marker for substance use disorders, as CPSUDs show blunted activation in anticipation of stress. These blunted cortisol levels were not the result of having experienced more stressful experiences during their lifetimes, thus might reflect an inborn vulnerability to substance use disorders.

A review on the relationship between testosterone and life-course persistent antisocial behavior

Life-course persistent antisocial behavior is 10 to 14 times more prevalent in males and it has been suggested that testosterone levels could account for this gender bias. Preliminary studies with measures of fetal testosterone find inconsistent associations with antisocial behavior, especially studies that use the 2D:4D ratio as a proxy for fetal testosterone. However, circulating testosterone consistently shows positive associations with antisocial behaviors throughout childhood, adolescence, and adulthood, particularly in males. It is suggested that high fetal/circulating testosterone interactively influence the maturation and functionality of mesolimbic dopaminergic circuitry, right orbitofrontal cortex, and cortico-subcortical connectivity, resulting in a strong reward motivation, low social sensitivity, and dampened regulation of strong motivational/emotional processes. The link between these testosterone induced endophenotypes and actual display of antisocial behavior is strongly modulated by different social (e.g., social rejection, low SES) and genetic (e.g., MAOA, 5HTT) risk factors that can disturb socio-, psycho-, and biological development and interact with testosterone in shaping behavior. When these additional risk factors are present, the testosterone induced endophenotypes may increase the risk for a chronic antisocial lifestyle. However, behavioral endophenotypes induced by testosterone can also predispose towards socially adaptive traits such as a strong achievement motivation, leadership, fair bargaining behaviors, and social assertiveness. These adaptive traits are more likely to emerge when the high testosterone individual has positive social experiences that promote prosocial behaviors such as strong and secure attachments with his caregivers, affiliation with prosocial peers, and sufficient socioeconomic resources. A theoretical model is presented, various hypotheses are examined, and future venues for research are discussed.

Comorbidity of partial and subthreshold ptsd among men and women with eating disorders in the national comorbidity survey-replication study

OBJECTIVE

The comorbidity of posttraumatic stress disorder (PTSD) and eating disorders (EDs) is high among women but has been understudied in men. Little is known about the association between partial or subthreshold PTSD and EDs among women or men.

METHOD

This study included PTSD and ED data from male (n = 2,382) and female (n = 3,310) National Comorbidity Survey-Replication study participants.

RESULTS

The vast majority of women and men with anorexia nervosa, bulimia nervosa (BN), and binge eating disorder (BED) reported a history of interpersonal trauma. Rates of PTSD were significantly higher among women and men with BN and BED. Subthreshold PTSD was more prevalent than threshold PTSD among women with BN and women and men with BED.

DISCUSSION

Interpersonal forms of trauma, PTSD, and subthreshold/partial PTSD, were prevalent among men and women with EDs. Findings highlight the importance of assessing for trauma and PTSD in ED patients.

Acute and chronic stress induced changes in sensitivity of peripheral inflammatory pathways to the signals of multiple stress systems --2011 Curt Richter Award Winner

Exposure to psychosocial stress has been associated with increasing rates of morbidity in humans and in animal models, but the underlying mechanisms are not completely understood. Major stress responsive systems, such as the hypothalamus-pituitary adrenal (HPA) axis and the autonomic nervous system (ANS) are under investigation as underlying pathways, but although acute stress reliably activates these systems, findings of long-term alternations in baseline activity are inconsistent at present. Emerging evidence suggests that stress-related changes in the sensitivity of target systems toward glucocorticoid (GC) regulation, i.e. development of GC resistance, might help explain inflammatory disinhibition and development of disease related to inflammation. More recent findings further show that the autonomic nervous system might play an important role in the regulatory control of the inflammatory cascade. The major argument put forward in this manuscript is that target tissues for stress system modulation, such as the inflammatory cascade, vary in their ability to respond to stress system signaling, and that assessing alterations in this stress signal sensitivity which can be caused by stress or disease processes, might be necessary to understand and explain stress effects on health. This review focuses on the inflammatory system in particular, because anti-inflammatory effects of most stress systems have been documented, but the general assumption might have to be generalized to other target systems. The main conclusion to be made is that reduction in glucocorticoid sensitivity of target tissues is the most consistent finding at present, and that assessing such changes in glucocorticoid sensitivity might be necessary to understand many stress-related changes in physiology.

Interaction of the BcII glucocorticoid receptor polymorphism and childhood abuse in Bulimia Nervosa (BN): relationship to BN and to associated trait manifestations

We recently documented a gene-environment interaction suggesting that individuals with Bulimia Nervosa (BN) differed from normal eaters as to the combined presence of the low-function allele of the glucocorticoid receptor polymorphism, BcII, and childhood abuse. The present study examined the extent to which any such interaction effect may have been attributable to behavioral impulsivity, sensation seeking, affective instability or depression. We had 174 bulimic and 130 nonbulimic women provide blood for genetic assays, and measured psychopathological traits and childhood abuse using structured interviews and self-report questionnaires. As expected, we observed a significant BcII × abuse interaction indicating genetic and environmental susceptibilities to co-occur significantly more often in bulimic than in nonbulimic individuals. The BcII × abuse interaction was attenuated when levels of depression were accounted for, but was surprisingly unaffected by controls for motoric impulsivity, sensation seeking or affective instability. Our findings suggest that stress-induced alterations in glucocorticoid sensitivity contribute to BN and depressive disturbances--without being associated with the behavioral/affective dysregulation seen in many BN sufferers. We discuss theoretical and clinical implications of these observations.

Association of hypothalamic-pituitary-adrenal axis-related polymorphisms with stress in asthmatic children on inhaled corticosteroids

OBJECTIVE

Long-term treatment of asthmatic children with low and moderate doses of inhaled corticosteroids (ICS) may result in mild adrenal suppression. Various associations have been shown between adrenal reactivity and single nucleotide polymorphisms (SNPs) related to the hypothalamic-pituitary-adrenal (HPA) axis. We aimed to investigate the genetic contribution of four HPA axis-related SNPs to the individual stress response when on ICS.

METHODS

The low dose Synacthen test was performed in 62 asthmatic children (43 males, median age 7.9 years) before and after 3 months of treatment with inhaled fluticasone (200 μg/day) or budesonide (400 μg/day). The SNPs determined were: rs1876828 and rs242941 in the corticotropin-releasing hormone receptor 1 (CRHR1) gene, T(-2C) in the promoter region of the melanocortin receptor 2 (MC2R) gene and BclI restriction fragment length polymorphsism in the glucocorticoid receptor (GR) gene.

RESULTS

Homozygotes for the variant rs242941 (TT) demonstrated a delayed cortisol response after treatment with ICS compared to heterozygotes (GT) (p = 0.033) and those with the wild-type (GG) genotype (p = 0.018). Homozygotes for the variant rs1876828 (AA) manifested lower baseline cortisol levels before treatment (p = 0.009) compared to the GG genotype and delayed cortisol response after treatment compared to the GA genotype (p = 0.05). BclI heterozygotes for the G allele (GC) demonstrated higher basal cortisol levels before and after treatment with ICS compared to homozygotes (CC) (p = 0.024, p = 0.018). Three SNP interactions were associated with serum cortisol levels.

CONCLUSION

There is evidence of a contribution of HPA axis-related genetic variation to the stress response of asthmatic children on ICS. The clinical importance of this finding needs further elucidation.

Sensitivity to stress among the offspring of parents with bipolar disorder: a study of daytime cortisol levels

BACKGROUND

It is well known that the hypothalamic-pituitary-adrenal (HPA) axis is compromised in major depression and bipolar disorder. There is increasing evidence that subtle HPA abnormalities, such as elevated cortisol levels, precede the development of an affective disorder. Interpersonal stress is also associated with the development of affective disorders. The present study sought to determine whether interpersonal chronic and episodic stress moderated the relationship between cortisol levels in the natural environment and risk status, defined as having a parent with bipolar disorder.

METHOD

Sixty-two offspring of parents with bipolar disorder (OBD) and 60 offspring with no family history of affective disorders (OFH-), aged 19.48 years (s.d.=3.38, range 14-28), completed interviews assessing mental disorders and chronic and episodic stress, and provided saliva samples over 3 days.

RESULTS

Regression analyses revealed that the OBD who experienced high interpersonal chronic stress displayed a larger cortisol rise following awakening than the OBD reporting low interpersonal chronic stress. The same relationship was also found for levels of non-interpersonal chronic stress. The OBD who reported experiencing severe interpersonal episodic stress exhibited higher levels of daytime cortisol than the OBD reporting interpersonal episodic stress of mild severity. Importantly, none of the above relationships were detected in the OFH-. Each of the interactions between family history of affective disorders and stress remained after controlling for age, gender and offspring lifetime affective disorders and current non-affective disorders.

CONCLUSIONS

A biological sensitivity to stress may underlie the susceptibility to affective disorders among the OBD.

Contributions of the glucocorticoid receptor polymorphism (Bcl1) and childhood abuse to risk of bulimia nervosa

This study evaluated the hypothesis that traumatic stress can increase risk of bulimia nervosa (BN) in individuals who are genetically disposed towards lower modulation of physiological stress reactions. We explored the extent to which childhood abuse (physical or sexual), variants of a main glucocorticoid receptor (GR) polymorphism (Bcl1), or their interaction, differentiated women with and without BN. Women seeking treatment for BN (N=129) and non-eating-disordered comparison women (N=98) provided blood samples for assays of the Bcl1 polymorphism, and completed structured interviews assessing eating symptoms, psychiatric symptoms and childhood abuse. Compared to normal-eaters, bulimic women were significantly more likely to carry the low-function Bcl1 C allele (CC or CG genotypes), to report a history of childhood abuse and, more importantly, to be positive for both factors. We interpret our findings as indicating that traumatic stress, when impacting individuals disposed to lower GR modulation, can be etiological for BN.

Stress and abdominal fat: preliminary evidence of moderation by the cortisol awakening response in Hispanic peripubertal girls

Stress and the cortisol awakening response (CAR) have been independently linked to increases in abdominal fat depots. This cross-sectional study examined the CAR as a moderator of the association between stress, visceral adipose tissue (VAT), and subcutaneous abdominal adipose tissue (SAT) in a sample (N = 23) of female peripubertal Hispanic girls aged from 8 to 11. The study included: (i) monitored salivary cortisol collection, (ii) VAT and SAT obtained by multislice magnetic resonance imaging, and (iii) a stressful life events checklist with four domain-specific subscales: peer, family, personal, and school. Regression analysis indicated an interaction of school-related life events and CAR on VAT and SAT, with greater numbers of school-related events being related to greater VAT and SAT for girls with high CAR, but no association with VAT or SAT for girls with low CAR. Similar to job stress in adults, school-related stress in children may contribute to central adiposity, especially for girls with high CAR.

Gene-environment interactions: early life stress and risk for depressive and anxiety disorders

RATIONALE

Prior reviews have examined how stress, broadly defined, interacts with genetic diathesis in the pathogenesis of internalizing (i.e., depressive and anxiety) disorders. Recent findings have suggested a unique role for early life stress (ELS) in the development of internalizing disorders, contributing to the rapid proliferation of research in this area.

OBJECTIVE

This paper critically reviews studies in humans examining gene-environment interaction (GxE) effects of ELS on the risk for depression and anxiety, primarily from a candidate gene perspective. Major methodological challenges that are unique to such studies are considered.

RESULTS

The majority of published studies have focused on candidates that regulate the serotonin system, especially the serotonin transporter. More recent work has addressed interactions of ELS with candidates from the hypothalamic-pituitary-adrenal axis and neurotrophin system. Available studies vary greatly with respect to definitions of ELS, examination of gene-gene interactions, consideration of gender effects, and attention to analytic limitations.

CONCLUSIONS

Overall, there is support for GxE effects of ELS on the risk for depressive and anxiety outcomes. Future studies of ELS in this context will require careful attention to methodologic considerations. Such studies would benefit from more systematic assessment of positive environmental factors (e.g., social support) and greater utilization of developmentally sensitive paradigms.

The Adaptive Calibration Model of stress responsivity

This paper presents the Adaptive Calibration Model (ACM), an evolutionary-developmental theory of individual differences in the functioning of the stress response system. The stress response system has three main biological functions: (1) to coordinate the organism's allostatic response to physical and psychosocial challenges; (2) to encode and filter information about the organism's social and physical environment, mediating the organism's openness to environmental inputs; and (3) to regulate the organism's physiology and behavior in a broad range of fitness-relevant areas including defensive behaviors, competitive risk-taking, learning, attachment, affiliation and reproductive functioning. The information encoded by the system during development feeds back on the long-term calibration of the system itself, resulting in adaptive patterns of responsivity and individual differences in behavior. Drawing on evolutionary life history theory, we build a model of the development of stress responsivity across life stages, describe four prototypical responsivity patterns, and discuss the emergence and meaning of sex differences. The ACM extends the theory of biological sensitivity to context (BSC) and provides an integrative framework for future research in the field.

FKBP5 and resistant attachment predict cortisol reactivity in infants: gene-environment interaction

Quality of the parent-infant attachment relationship influences physiological stress regulation. Genetic factors also contribute to the stress regulatory HPA-axis. Quality of attachment as an index of the rearing environment (measured with the Strange Situation Procedure, SSP), and HPA-axis related SNPs (BclI, rs41423247; TthIIII, rs10052957; GR-9β, rs6198; N363S, rs6195; ER22/23EK, rs6189 and 6190; and FKBP5, rs1360780) were hypothesized to be related to cortisol reactivity in the stressful SSP. In this large population based sample, FKBP5 rs1360780, but not GR haplotype, was related to cortisol reactivity. Moreover, we found a significant interaction effect for insecure-resistant attachment and FKBP5 rs1360780, indicating a double-risk for heightened cortisol reactivity levels in infants with one or two T-alleles of the FKBP5 SNP and an insecure-resistant attachment relationship with their mother. Findings are discussed from the perspective of gene-environment interaction.

Genetic and environmental influences on cortisol regulation across days and contexts in middle-aged men

Cortisol is an indicator of hypothalamic-pituitary-adrenal axis responsivity to stress, but few twin studies have examined the heritability of cortisol concentrations in adults across the diurnal cycle and in different contexts. Saliva samples were provided by 783 middle-aged male twins on one laboratory and two home days as part of the Vietnam Era Twin Study of Aging. Significant cortisol heritability estimates were found for laboratory measures only: awakening (.56); 30 min after awakening (.48); 1000 h (.42); mean output across the day (.43); and mean cortisol awakening response (.64). Twin correlations at home were low. In the laboratory, they were unchanged for fraternal twins, but increased for identical twins. Greater measurement error at home did not appear to account for home-laboratory differences. The results suggest that genetic factors influence cortisol responses to specific environmental stressors. Thus, cortisol levels are correlated in identical twins only when they undergo similar experiences.

Cortisol function among early school-aged homeless children

Homelessness represents a context of extreme poverty and risk for child development. This study compared the relative influence of two classes of risk in the context of homelessness. Levels of socioeconomic resource-related risk and negative lifetime events were examined with respect to morning cortisol levels and cortisol response to a set of cognitive tasks. Participants were 66 children between the ages of 4 and 7 years staying in an emergency shelter for families. Adversities largely reflecting family level negative life events predicted higher levels of morning cortisol and differences in initial level and change over the course of the session of cognitive tasks. In contrast, a socioeconomic cumulative risk score was not associated with morning or session-related differences in cortisol.

Gene expression of hepatic glucocorticoid receptor NR3C1 and correlation with plasmatic corticosterone in Italian chickens

This study examined breed-specific stress-related hormonal and gene expression profiles in three Italian chicken breeds (Valdarnese Bianca, Bionda Piemontese, Robusta Maculata) reared in controlled conditions. Glucocorticoids work through the glucocorticoid receptor (GR), which modulates target genes transcription. We investigated breed-specific changes in corticosterone (ELISA) and GR expression. GR mRNA levels were analyzed using one-tube, two-temperature real-time PCR for absolute quantification of the gene expression by the standard curve method. Our results show high expression of GR in hepatic tissue. Significant effect of the breed was recorded for plasma corticosterone concentration: Valdarnese Bianca 3.35 ng/mL, Bionda Piemontese 1.73 ng/mL, Robusta Maculata 2.02 ng/mL. Breed specific gene expression has been recorded with a GR ranging from 1.12E+04 (Robusta Maculata) to 1.00E+05 (Bionda Piemontese) mRNA copy number/100 ng total RNA. Negative correlation was found between gene expression and blood corticosterone level.

The role of the alpha 2A-adrenoceptor in mouse stress-coping behaviour

Acute stress is known to impair memory functions in both men and laboratory rodents. In human the alpha 2A-adrenoceptor system is known to play a critical role in regulating acute neuropsychological stress responses and, ultimately, stress-coping behaviour. In search for neurobiological and central nervous mechanisms behind these behaviours we investigated if the alpha 2A-adrenoceptor is involved in these mechanisms in mice. Phenotypical differences between the A/J and C57BL/6J (B6) mouse inbred strains were evaluated in previous studies. These data showed significant strain differences in various motivational systems (anxiety, exploration, locomotion, memory etc.). From the literature it is known that chromosome 19 contains the gene for the adrenergic alpha 2A receptor that is thought to be involved in emotional behaviours, among others anxiety-related avoidance behaviour and arousal. We investigated if this pathway could possibly be involved in avoidance/arousal susceptibility by applying an agonist (dexmedetomidine) and an antagonist (atipamezole) of the alpha 2A-adrenoceptor to male mice from a consomic strain (C57BL/6J-Chr 19(A)/NaJ, abbreviated to CSS19=anxious), and the corresponding donor (A/J=anxious) and host (B6=non-anxious) strains. The mice were tested in the modified hole board (mHB) test which allows for the assessment of a variety of behavioural patterns by use of only one test. In addition, a forced swimming test (FST) was conducted to test for stress-coping behaviour. Results of the behavioural testing in the mHB-test showed significant strains differences and strain-specific treatment effects for parameters describing anxiety-related endophenotypes. The FST revealed effects of dexmedetomidine and atipamezole on stress-coping behaviour. In conclusion, the involvement of the alpha 2A-adrenoceptor, located on mouse chromosome 19, on anxiety-related behaviour remains unclear and will possibly not play a main role in the development of anxiety-related behaviour in mice. However, we could show involvement of this receptor in stress-coping behaviour in mice.

Depression gets old fast: do stress and depression accelerate cell aging?

Depression has been likened to a state of "accelerated aging," and depressed individuals have a higher incidence of various diseases of aging, such as cardiovascular and cerebrovascular diseases, metabolic syndrome, and dementia. Chronic exposure to certain interlinked biochemical pathways that mediate stress-related depression may contribute to "accelerated aging," cell damage, and certain comorbid medical illnesses. Biochemical mediators explored in this theoretical review include the hypothalamic-pituitary-adrenal axis (e.g., hyper- or hypoactivation of glucocorticoid receptors), neurosteroids, such as dehydroepiandrosterone and allopregnanolone, brain-derived neurotrophic factor, excitotoxicity, oxidative and inflammatory stress, and disturbances of the telomere/telomerase maintenance system. A better appreciation of the role of these mediators in depressive illness could lead to refined models of depression, to a re-conceptualization of depression as a whole body disease rather than just a "mental illness," and to the rational development of new classes of medications to treat depression and its related medical comorbidities.

Human models in acute and chronic stress: assessing determinants of individual hypothalamus-pituitary-adrenal axis activity and reactivity

Stress is one of the most significant health problems in modern societies and the 21st century. This explains a pressing need for investigations into the biological pathways linking stress and health. Besides the locus coeruleus-noradrenaline/autonomic (sympathetic) nervous system ( Chrousos and Gold 1992 ), the hypothalamus-pituitary-adrenal (HPA) axis is the major physiological stress response system in the body. Since alterations in HPA axis regulation under basal conditions and in response to acute stress appear to be a close correlate or even a determining factor of the onset of different diseases or disease progression ( Holsboer 1989 ; Chrousos and Gold 1992 ; Tsigos and Chrousos 1994, 2002 ; Stratakis and Chrousos 1995 ; McEwen 1998 ; Heim et al. 2000a ; Raison and Miller 2003 ), the characterization of an individual's HPA axis activity as well as reactivity pattern to psychosocial stress appears to be of major interest. It is obvious that such a research agenda substantially depends on the availability of appropriate measures. However, since the HPA axis is a highly adaptive system which is characterized by marked inter- and intraindividual variability ( Mason 1968 ; Hellhammer et al. 2009 ), the development of such markers of HPA axis regulation in humans was-and still is-a rather challenging task. In this brief review, we focus on findings on two HPA axis measures, namely the cortisol-awakening response (CAR) to assess HPA axis basal activity and the Trier social stress test (TSST) to investigate HPA axis stress reactivity.

Glucocorticoid receptor gene and depression in patients with coronary heart disease: the Heart and Soul Study-2009 Curt Richter Award Winner

Alterations of glucocorticoid receptor sensitivity have been associated with depression. Thus, variation in the glucocorticoid receptor gene that determines glucocorticoid sensitivity may influence risk for depression. In a cross-sectional genetic association study of 526 white outpatients with chronic coronary heart disease, we examined whether haplotypes of the glucocorticoid receptor gene (NR3C1) are associated with depression. Participants were genotyped for four common glucocorticoid receptor gene polymorphisms (ER22/23EK, BclI C/G, N363S, and 9beta A/G) and haplotype analyses were conducted. Depression was assessed by an interview (Computerized Diagnostic Interview Schedule). Of the 526 participants, 355 (67.5%) were non-carriers, 153 (29.1%) had one copy, and 17 (3.2%) had 2 copies of the haplotype 3 allele, which includes the minor allele of the 9beta A/G polymorphism and which has been associated with reduced glucocorticoid sensitivity. The prevalence of depression ranged from 24.4% in the non-carriers to 34.4% in heterozygotes to 52.9% in participants homozygous for the haplotype 3 allele (p<0.01). In logistic regression analyses, carriers of one haplotype 3 allele had an odds ratio of 1.64 (95% CI 1.1-2.5, p=0.02) for depression, while the odds ratio of homozygous haplotype 3 carriers was 3.52 (95% CI 1.3-9.4, p=0.01). These associations persisted after adjusting for potentially confounding variables. A common GR haplotype was associated with depression in a gene-dosage dependent manner and might be a vulnerability factor for depression.

Developmental influences on medically unexplained symptoms

BACKGROUND

Medically unexplained (or 'functional') symptoms (MUS) are physical symptoms that prompt the sufferer to seek healthcare but remain unexplained after an appropriate medical evaluation. Examples of MUS also occur in veterinary medicine. For example, domestic cats suffer a syndrome comparable to interstitial cystitis, a chronic pelvic pain syndrome of humans.

METHOD

Review of current evidence suggests the hypothesis that developmental factors may play a role in some cases of MUS. Maternal perception of a threatening environment may be transmitted to the fetus when hormones cross the placenta and affect fetal physiology, effectively 'programming' the fetal stress response system and associated behaviors toward enhanced vigilance. After birth, intense stress responses in the individual may result in similar vulnerability, which may be unmasked by subsequent stressors.

RESULTS

Epigenetic modulation of gene expression (EMGEX) appears to play a central role in creation of this 'survival phenotype'. The recent development of techniques to identify the presence of EMGEX provides new tools to investigate these questions, and drugs and other interventions that may reverse EMGEX are also under active investigation.

CONCLUSION

Viewing MUS from the perspective of underlying developmental influences involving EMGEX that affect function of a variety of organs based on familial (genetic and environmental) predispositions rather than from the traditional viewpoint of isolated organ-originating diseases has at least two important implications: it provides a parsimonious explanation for findings heretofore difficult to reconcile, and it opens whole new areas of investigation into causes and treatments for this class of disorders.

Genetics of PTSD: Fear Conditioning as a Model for Future Research

In the last decade, the number of publications in psychiatric genetics has nearly tripled but little attention has been paid to the role of genetic factors in the etiology of posttraumatic stress disorder (PTSD). The present review summarizes the current state of genetic research on PTSD. First, we outline information regarding genetic influences provided by family investigations and by twin studies. Second, we propose the fear-conditioning model of PTSD as a framework for the nomination of candidate genes that may be related to the disorder. Third, we review lines of evidence from three neurobiological systems involved in fear conditioning, and we summarize published investigations of genetic variants studied in association with PTSD in these three systems. Finally, we review gene-by-environment interaction research, a promising novel approach to genetic research in PTSD.

An angiotensin-1 converting enzyme polymorphism is associated with allostatic load mediated by C-reactive protein, interleukin-6 and cortisol

Allostatic load (AL) is a theoretical framework that describes the cumulative physiologic effects of adaptation to change or stress throughout the lifespan. AL is operationalized by a composite index of multiple biomarkers. Accordingly, genes, behavior and environment contribute to AL. To determine if individual differences in AL may be influenced by inherent genetic variation, we calculated an allostatic load index (ALI) for 182 Caucasian subjects derived from a population-based study of chronic fatigue syndrome. Nearly 65% of the subjects in this study sample reported fatiguing illness. ALI was calculated based on 11 measures representing metabolic, cardiovascular, inflammatory, hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS) activities. Subjects were dichotomized into high (ALI > or = 3) or low (ALI < 3) AL groups, and the association between high AL and 129 polymorphisms in 32 genes related to the HPA axis, neurotransmission, inflammation, cardiovascular and metabolic functions were evaluated. Polymorphisms in angiotensin-1 converting enzyme (ACE), corticotropin-releasing hormone receptor 1 (CRHR1), and serotonin receptors (HTR3A and HTR4) were associated with AL (p=0.0007-0.0486), but only one polymorphism, rs4968591, in ACE remained significant after correction for multiple comparisons. The T allele of ACE rs4968591 was more common in subjects with high AL (67.5%) than in subjects with low AL (49.3%) (p=0.0007), and this effect appeared independent of age, sex, body mass index and fatigue status. Additionally, high interleukin-6 (IL-6; p(trend)=0.04), and C-reactive protein (CRP; p(trend)=0.01) levels, as well as low urinary cortisol levels in females (p=0.03) were associated with the T allele, which may result in allele-specific binding of the transcription factor, E2F1. Our results suggest a role for ACE in the bidirectional communication between the central nervous and immune systems in response to stress. Further studies will be needed (a) to replicate the association between AL and ACE polymorphisms in population studies designed to differentiate the effects of sex, age and racial/ethnic background, (b) to evaluate the effect of allele-specific binding of E2F1 at rs4968591, and (c) to examine the role of ACE in the co-regulation of CRP, IL-6 and cortisol.

Salivary cortisol as a biomarker in stress research

Salivary cortisol is frequently used as a biomarker of psychological stress. However, psychobiological mechanisms, which trigger the hypothalamus-pituitary-adrenal axis (HPAA) can only indirectly be assessed by salivary cortisol measures. The different instances that control HPAA reactivity (hippocampus, hypothalamus, pituitary, adrenals) and their respective modulators, receptors, or binding proteins, may all affect salivary cortisol measures. Thus, a linear relationship with measures of plasma ACTH and cortisol in blood or urine does not necessarily exist. This is particularly true under response conditions. The present paper addresses several psychological and biological variables, which may account for such dissociations, and aims to help researchers to rate the validity and psychobiological significance of salivary cortisol as an HPAA biomarker of stress in their experiments.

Why do we respond so differently? Reviewing determinants of human salivary cortisol responses to challenge

Stress and stress-related health impairments are major problems in human life and elucidating the biological pathways linking stress and disease is of substantial importance. However, the identification of mechanisms underlying a dysregulation of major components of the stress response system is, particularly in humans, a very challenging task. Salivary cortisol responses to diverse acute challenge paradigms show large intra- and interindividual variability. In order to uncover mechanisms mediating stress-related disorders and to potentially develop new therapeutic strategies, an extensive phenotyping of HPA axis stress responses is essential. Such a research agenda depends on substantial knowledge of moderating and intervening variables that affect cortisol responses to different stressors and stimuli. The aim of this report is, therefore, to provide a comprehensive summary of important determinants of, in particular, human salivary cortisol responses to different kinds of laboratory stimuli including acute psychosocial stress as well as pharmacological provocation procedures. This overview demonstrates the role of age and gender, endogenous and exogenous sex steroid levels, pregnancy, lactation and breast-feeding, smoking, coffee and alcohol consumption as well as dietary energy supply in salivary cortisol responses to acute stress. Furthermore, it briefly summarizes current knowledge of the role of genetic factors and methodological issues in terms of habituation to repeated psychosocial stress exposures and time of testing as well as psychological factors, that have been shown to be associated with salivary cortisol responses like early life experiences, social factors, psychological interventions, personality as well as acute subjective-psychological stress responses and finally states of chronic stress and psychopathology.

Unipolar depression and hippocampal volume: impact of DNA sequence variants of the glucocorticoid receptor gene

Glucocorticoid receptor (GR) plays a major role in regulation of the hypothalamic-pituitary-adrenocortical (HPA) system; HPA dysregulation represents the most consistent biological pattern of depression. Multiple functional polymorphisms are known for the GR gene, which might influence the development of unipolar depression. Previous studies reported associations to some variants in this gene but not consistently so. We investigated seven genetic polymorphisms in the GR gene (NR3C1) located in the putative promoter, exon 2 and intron 2 region. Study populations were 322 German inpatients with recurrent unipolar depression, and 298 German controls recruited from the general population. The relationships between intermediate phenotypes (hippocampal and amygdala volumes) and NR3C1 DNA sequence variants were additionally explored in a subpopulation of patients. We found association between the diagnosis of depression and DNA sequence variants in intron 2 as well as in the 5' region of the NR3C1 gene but not for the previously studied exon 2 and putative promoter variants (global test after control of multiple testing, P = 0.02). In patients, diagnosis-related alleles were also associated to hippocampal volume reduction and amygdala volume variation. Unipolar depression is associated with DNA variants of the NR3C1 gene in our population. Neurobiological underpinnings of depression as volumetric reductions of the hippocampus may also be mediated by variants in this gene.