Polymorphisms in BDNF (Val66Met) and 5-HTTLPR, morning cortisol and subsequent depression in at-risk adolescents

Hypothalamic-pituitary-adrenal axis functioning in offspring of parents with a major affective disorder: a meta-analytic review

Because the offspring of parents with an affective disorder (OAD) are at high risk for developing mental disorders, and persons with an affective disorder (AD) show dysfunctional hypothalamic-pituitary-adrenal (HPA) axis activity, changes in HPA functioning in OAD might be an etiological risk factor that precedes the development of ADs. The primary aim of the meta-analysis was to quantitatively summarize the existing data on different indices of diurnal cortisol in the OAD. The secondary aim was to explore potential moderators of this relation. Following PRISMA guidelines, we included 26 studies (3052 offspring) on diurnal cortisol in our meta-analysis after an initial screening of 3408 articles. Intercept-only and meta-regression models were computed using the robust variance estimation method. Analyses examining mean cortisol levels at discrete timepoints, total cortisol output, and the cortisol rise in response to awakening (CAR) were conducted separately. The results demonstrated that the OAD had higher mean levels of cortisol at different timepoints throughout the day compared to controls (Hedge's g = 0.21). There was evidence of publication bias in studies examining CAR, such that effect sizes were positively biased. The present findings are consistent with a meta-analysis showing elevated cortisol in youth having an AD. Notable limitations across studies include the method of cortisol measurement and assessment of ADs. Altogether, these results highlight the fact that increased cortisol levels may act as a potential neuroendocrine antecedent and/or risk factor for the development of ADs among high risk youth.

[Movement as a Neuromodulator: How Physical Activity Influences the Physiology of Adolescent Depression]

Movement as a Neuromodulator: How Physical Activity Influences the Physiology of Adolescent Depression Abstract: In the context of adolescent depression, physical activity is becoming increasingly recognized for its positive effects on neuropathology. Current scientific findings indicate that physical training affects the biological effects of depression during adolescence. Yet the pathophysiology of adolescent depression is not yet fully understood. Besides psychosocial and genetic influences, various neurobiological factors are being discussed. One explanation model describes a dysfunction of the hypothalamus-pituitary-adrenal axis (HPA axis) with a sustained elevation in cortisol concentration. Recent studies highlight neuroimmunological processes and a reduced concentration of growth factors as causative factors. These changes appear to lead to a dysregulation of the excitation and inhibition balance of the cerebral cortex as well as to cerebral morphological alterations. Regular physical training can potentially counteract the dysregulation of the HPA axis and normalize cortisol levels. The release of proinflammatory cytokines is inhibited, and the expression of growth factors involved in adult neurogenesis is stimulated. One should ensure the synergistic interaction of biological and psychosocial factors when designing the exercise schedule (endurance or strength training, group or individual sports, frequency, duration, and intensity). Addressing these open questions is essential when integrating physical activity into the guidelines for treating depressive disorders in children and adolescents.

Integrating functional neuroimaging and serum proteins improves the diagnosis of major depressive disorder

BACKGROUND

The lack of effective objective diagnostic biomarkers for major depressive disorder (MDD) leads to high misdiagnosis. Compared with healthy controls (HC), abnormal brain functions and protein levels are often observed in MDD. However, it is unclear whether combining these changed multidimensional indicators could help improve the diagnosis of MDD.

METHODS

Sixty-three MDD and eighty-one HC subjects underwent resting-state fMRI scans, among whom 37 MDD and 45 HC provided blood samples. Amplitudes of low-frequency fluctuation (ALFF), regional homogeneity (ReHo), and serum levels of brain-derived neurotrophic factor (BDNF), cortisol, and multiple cytokines were measured and put into the linear discriminant analysis (LDA) to construct corresponding MDD diagnostic models. The area under the receiver operating characteristic curve (AUC) of 5-fold cross-validation was calculated to evaluate each model's performance.

RESULTS

Compared with HC, MDD patients' spontaneous brain activity, serum BDNF, cortisol, interleukin (IL)-4, IL-6, and IL-10 levels changed significantly. The combinations of unidimensional multi-indicator had better diagnostic performance than a single one. The model consisted of multidimensional multi-indicator further exhibited conspicuously superior diagnostic efficiency than those constructed with unidimensional multi-indicator, and its AUC, sensitivity, specificity, and accuracy of 5-fold cross-validation were 0.99, 92.0 %, 100.0 %, and 96.3 %, respectively.

LIMITATIONS

This cross-sectional study consists of relatively small samples and should be replicated in larger samples with follow-up data to optimize the diagnostic model.

CONCLUSIONS

MDD patients' neuroimaging features and serum protein levels significantly changed. The model revealed by LDA could diagnose MDD with high accuracy, which may serve as an ideal diagnostic biomarker for MDD.

Cortisol and development of depression in adolescence and young adulthood - a systematic review and meta-analysis

INTRODUCTION

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis has been implicated in the development of major depressive disorder (MDD) in adulthood. Less work has focused on the role of the HPA axis in depression in adolescence and young adulthood globally. The aim of this study was to conduct a systematic review and meta-analysis of worldwide research investigating the relationship between cortisol, a measure of HPA axis activity, and MDD in adolescence and young adulthood.

METHOD

We searched MEDLINE, PsycINFO, Cochrane Database of Systematic Reviews, Web of Science, Lilacs, African Journals Online, and Global Health for studies which examined the relationship between cortisol and MDD in global youth (10-24 years old).

RESULTS

Twenty-six studies were included in the systematic review and 14 were eligible for the meta-analysis, but only one study included young adults in their sample. Results from the meta-analysis demonstrated that elevated morning, but not evening, cortisol levels was prospectively associated with later MDD development in adolescence and young adulthood. However, morning cortisol levels did not significantly differ between healthy controls and individuals with MDD in cross-sectional studies. Afternoon cortisol and cortisol stress response also did not differ between adolescents with MDD and healthy controls. Qualitative synthesis of the three studies examining nocturnal cortisol showed higher nocturnal cortisol was both longitudinally and cross-sectionally associated with MDD in adolescence.

CONCLUSION

Our findings suggest elevated morning cortisol precedes depression in adolescence. Despite this, we did not find any differences in other cortisol measures in association with MDD in cross-sectional studies. Taken together, these findings suggest that elevated morning and nocturnal cortisol are risk factors for depression in adolescence rather than a biomarker of existing MDD. This supports a role for the hyperactivity of the HPA axis in the development of MDD in adolescence. Most of the studies were from high-income-countries (HICs) and thus further work would need to be conducted in low- and middle-income countries (LMICs) to understand if our findings are generalisable also to these populations.

The Mediating and Moderating Roles of Life Skills and Cortisol in the Relationship Between Sleep Quality and Depressive Symptoms Among Chinese Adolescents With Childhood Household Dysfunction

BACKGROUND

Various studies show that sleep quality, life skills, and cortisol are associated with depressive symptoms, separately. However, the relationships between sleep quality, life skills, cortisol, and depressive symptoms remain unclear. Thus, this study aims to examine the mediating or moderating roles of life skills and cortisol in the relationship between sleep quality and depressive symptoms.

METHODS

A retrospective cross-sectional study was performed among 212 adolescents with childhood household dysfunction (CHD) from August to October 2020 in China. We used the Pittsburgh Sleep Quality Index, the Secondary School Student Life Skills Rating Scale, and the Center for Epidemiologic Studies Depression Scale to measure sleep quality, life skills, and depressive symptoms, respectively. Additionally, 65 participants provided blood samples to assess their blood cortisol levels. Analyses included correlations, regressions, and structural equation models. Bootstrapping was performed to examine the mediation effect. Multiple regression analysis was performed to examine the moderation effect.

RESULTS

The results showed that sleep quality and life skills were significantly associated with depressive symptoms (p < 0.01). Life skills mediated the relationship between sleep quality and depressive symptoms. Cortisol moderated the relationship between sleep quality and depressive symptoms.

CONCLUSION

Our findings support potential mediating and moderating roles of life skills and cortisol in the relationship between sleep quality and depressive symptoms, which suggests improving sleep quality, life skills are of great significance in the prevention and intervention of depression in adolescents with CHD, and disseminating knowledge about the high risk of developing increased depressive symptoms among adolescents with CHD with higher cortisol levels is indicated.

In(s) and out(s) of adolescent depression - Trajectories of development and recovery

While the role of biological markers in understanding major depressive disorder (MDD) in adults have been studied extensively, less has been done to identify the biomarkers of MDD development and recovery in adolescence. With the majority of mental health disorders starting in adolescence, identifying biomarkers of transition and recovery from MDD early in life is critical for developing effective prevention strategies. Considering most of the child and adolescent populations come from low-and-middle-income countries (LMICs), it is vital to focus on adolescent populations in these settings. With most studies coming from high-income countries (HICs), evidence suggests that elevated morning cortisol levels including cortisol awakening response (CAR), increased peripheral inflammation and brain abnormalities such as cortico-limbic dysregulation or blunted activity in reward related regions in response to positive information are associated with MDD and being at-risk for MDD development in adolescence. We also find that some of the biological mechanisms of recovery from MDD, mainly normalisation in the cortico-limbic dysregulation, are reported following psychological therapy, suggesting shared pathways leading to MDD vulnerability and recovery. Although, only a few studies include adolescent populations. Understanding molecular mechanisms through which psychological interventions are effective, as well as molecular markers of transition to depression in individuals at-risk, are important to inform effective prevention and intervention strategies.

Peripheral Markers of Depression

Major Depressive Disorder (MDD) is a leading cause of disability worldwide, creating a high medical and socioeconomic burden. There is a growing interest in the biological underpinnings of depression, which are reflected by altered levels of biological markers. Among others, enhanced inflammation has been reported in MDD, as reflected by increased concentrations of inflammatory markers-C-reactive protein, interleukin-6, tumor necrosis factor-α and soluble interleukin-2 receptor. Oxidative and nitrosative stress also plays a role in the pathophysiology of MDD. Notably, increased levels of lipid peroxidation markers are characteristic of MDD. Dysregulation of the stress axis, along with increased cortisol levels, have also been reported in MDD. Alterations in growth factors, with a significant decrease in brain-derived neurotrophic factor and an increase in fibroblast growth factor-2 and insulin-like growth factor-1 concentrations have also been found in MDD. Finally, kynurenine metabolites, increased glutamate and decreased total cholesterol also hold promise as reliable biomarkers for MDD. Research in the field of MDD biomarkers is hindered by insufficient understanding of MDD etiopathogenesis, substantial heterogeneity of the disorder, common co-morbidities and low specificity of biomarkers. The construction of biomarker panels and their evaluation with use of new technologies may have the potential to overcome the above mentioned obstacles.

Brain-derived neurotrophic factor Val66Met polymorphism affects cortical thickness of rostral anterior cingulate in patients with major depressive disorder

OBJECTIVE

The neuro-anatomical substrates of major depressive disorder (MDD) remain poorly understood. Brain-derived neurotrophic factor (BDNF) gene polymorphism (Val66Met/rs6265) is associated with neuro-plasticity and development. In the present study, we explore the influence of BDNF gene polymorphism on cortical thickness in nonelderly, first episode, drug-naive patients with MDD.

METHODS

Two hundred and sixteen participants (105 MDD patients and 111 healthy controls) were divided into subgroups based on the BDNF genotype. High-resolution MRI was obtained in all participants. A relationship of BDNF Val66Met gene polymorphism and cortical thickness was investigated.

RESULTS

The significant main effect of diagnosis was identified in the left rostal anterior cingulate (rACC), right inferior temporal and right lateral orbitofrontal (lOFC). The main effect of the genotype was observed in the left posterior cingulate cortex. The diagnosis-by-genotype interaction effect was found located in the left rACC. MDD patients who were Met-carriers exhibited thinner cortical thickness in the left rACC than healthy controls Met-carriers. Neither the symptom severity nor the illness duration was correlated significantly with cortical thickness.

CONCLUSION

Our findings suggested that the BDNF gene polymorphism was associated with cortical thickness alterations of the left rACC in MDD patients, and genotype that carries Met may serve as a vulnerability factor in MDD regarding the cortical thickness loss in the left rACC. This finding can be considered as a supportive evidence for the neurotrophic factor hypothesis of depression.

Prospective biomarkers of major depressive disorder: a systematic review and meta-analysis

Leading biological hypotheses propose that biological changes may underlie major depressive disorder onset and relapse/recurrence. Here, we investigate if there is prospective evidence for biomarkers derived from leading theories. We focus on neuroimaging, gastrointestinal factors, immunology, neurotrophic factors, neurotransmitters, hormones, and oxidative stress. Searches were performed in Pubmed, Embase and PsychInfo for articles published up to 06/2019. References and citations of included articles were screened to identify additional articles. Inclusion criteria were having an MDD diagnosis as outcome, a biomarker as predictor, and prospective design search terms were formulated accordingly. PRISMA guidelines were applied. Meta-analyses were performed using a random effect model when three or more comparable studies were identified, using a random effect model. Our search resulted in 67,464 articles, of which 75 prospective articles were identified on: Neuroimaging (N = 24), Gastrointestinal factors (N = 1), Immunology (N = 8), Neurotrophic (N = 2), Neurotransmitters (N = 1), Hormones (N = 39), Oxidative stress (N = 1). Meta-analyses on brain volumes and immunology markers were not significant. Only cortisol (N = 19, OR = 1.294, p = 0.024) showed a predictive effect on onset/relapse/recurrence of MDD, but not on time until MDD onset/relapse/recurrence. However, this effect disappeared when studies including participants with a baseline clinical diagnosis were removed from the analyses. Other studies were too heterogeneous to compare. Thus, there is a lack of evidence for leading biological theories for onset and maintenance of depression. Only cortisol was identified as potential predictor for MDD, but results are influenced by the disease state. High-quality (prospective) studies on MDD are needed to disentangle the etiology and maintenance of MDD.

At-risk studies and clinical antecedents of psychosis, bipolar disorder and depression: a scoping review in the context of clinical staging

Identifying young people at risk of developing serious mental illness and identifying predictors of onset of illness has been a focus of psychiatric prediction research, particularly in the field of psychosis. Work in this area has facilitated the adoption of the clinical staging model of early clinical phenotypes, ranging from at-risk mental states to chronic and severe mental illness. It has been a topic of debate if these staging models should be conceptualised as disorder-specific or transdiagnostic. In order to inform this debate and facilitate cross-diagnostic discourse, the present scoping review provides a broad overview of the body of literature of (a) longitudinal at-risk approaches and (b) identified antecedents of (homotypic) illness progression across three major mental disorders [psychosis, bipolar disorder (BD) and depression], and places these in the context of clinical staging. Stage 0 at-risk conceptualisations (i.e. familial high-risk approaches) were identified in all three disorders. However, formalised stage 1b conceptualisations (i.e. ultra-high-risk approaches) were only present in psychosis and marginally in BD. The presence of non-specific and overlapping antecedents in the three disorders may support a general staging model, at least in the early stages of severe psychotic or mood disorders.

The relationship between labor pain management, cortisol level and risk of postpartum depression development: a prospective nonrandomized observational monocentric trial

Postpartum depression (PPD) is the main psychological status disorder and women suffering from postpartum depression often need long-term psychological and socio-economic rehabilitation. The study is dedicated to the evaluation of the role of labor pain management using epidural analgesia in natural delivery on stress level in labor and frequency of postnatal depression.

Materials and methods

210 women were investigated and divided into two groups. In the first group for labor pain management in natural delivery, patient-controlled epidural analgesia was used (bolus - 10.0 - 0.08% ropivacaine hydrochloride, lockout - 30 min, limit - 120 ml/6 h) with a background of continuous-flow infusion of local anesthetic 0.08% ropivacaine hydrocluoride solution. Patients in the second group had no pain relief in delivery. The stress level was evaluated using blood plasma cortisol level in the early stages of labor, 6 hours and 3 days after delivery. The assessment of depression development was carried out step-by-step: Before the delivery, 6 hours after, 3 days and 6 weeks after the delivery.

Results

The baby blues frequency 6 hours after the delivery in the group where the pain relief was conducted was 29.91%, with cortisol level below and equal to 2310.91 nmol/l. In the group with no pain relief 6 hours after delivery, baby blues was found in 15.53% of puerperas (p < 0.05) and the cortisol level was 2673.82 nmol/l (p < 0.05). Six weeks after the birth, postpartum depression was diagnosed in 4.67% of women who received epidural analgesia during delivery, in comparison to 6.79% with no pain relief during delivery. However, the difference was not statistically significant (p < 0.05).

Conclusions

The use of epidural analgesia leads to a significant reduction of pain syndrome and stress response during natural delivery, increases the risk of baby blues in the early postnatal period, but slightly influences the frequency of postpartum depression.

Classroom social experiences in early elementary school relate to diurnal cortisol levels

Social stress has been linked to altered hypothalamic-pituitary-adrenocorticol (HPA) axis activation. During elementary school, children can become exposed to negative peer relations, such as poor appraisal among classroom peers, which is considered a social stressor. However, little is known about the association between classroom peer appraisal and the physiological stress system in children. The goal of this study was to examine the association of peer acceptance and peer non-acceptance with diurnal cortisol concentrations in 222 children from 20 mainstream elementary schools (Mage=6.97years, SD=0.99, 55% boys) in the Netherlands. Saliva samples were collected at awakening, 30min post-awakening, at noon and at 8 pm during a weekend day. From these assessments, the Cortisol Awakening Response (CAR), diurnal cortisol concentration (AUC_g) and diurnal cortisol slope were calculated. Peer nominations of peer acceptance (being liked), and peer non-acceptance (being disliked) were collected across a one year interval. Associations were controlled for peer victimization, age, sex and SES and children's levels of emotional problems and behavioural problems. Results showed that low peer acceptance was associated with heightened diurnal cortisol concentration (i.e., heightened AUG_g), lower cortisol reductions across the day (i.e., less decreasing cortisol slope) and heightened cortisol awakening response (i.e., heightened CAR). Peer non-acceptance and the interaction between peer acceptance and peer non-acceptance (known as peer rejection) were not associated with AUCg, cortisol slope or the CAR. The findings emphasize the association between poor appraisal among classroom peers and children's heightened HPA-axis activation. This underscores the importance of the physiological stress system in studying the consequences of negative peer relations in children.

Brain-derived neurotrophic factor (BDNF) Val66Met polymorphism interacts with gender to influence cortisol responses to mental stress

Brain-derived neurotrophic factor (BDNF) Val66Met polymorphism has been associated with cortisol responses to stress with gender differences reported, although the findings are not entirely consistent. To evaluate the role of Val66Met genotype and gender on cortisol responses to stress, we conducted a 45-min mental stress protocol including four tasks and four rest periods. Blood cortisol was collected for assay immediately before and after each task and rest period. A significant two-way interaction of Val66Met genotype×gender (P=0.022) was observed on the total area under the curve (AUC), a total cortisol response over time, such that the Val/Val genotype was associated with a larger cortisol response to stress as compared to the Met group in women but not in men. Further contrast analyses between the Val/Val and Met group for each stress task showed a similar increased cortisol pattern among women Val/Val genotype but not among men. The present findings indicate the gender differences in the effect of Val66Met genotype on the cortisol responses to stress protocol, and extend the evidence for the importance of gender and the role of Val66Met in the modulation of stress reactivity and subsequent depression prevalence. Further studies and the underlying mechanism need to be investigated, which may provide an insight for prevention, intervention, and treatment strategies that target those at high risk.

Integrated transcriptome and methylome analysis in youth at high risk for bipolar disorder: a preliminary analysis

First-degree relatives of patients with bipolar disorder (BD), particularly their offspring, have a higher risk of developing BD and other mental illnesses than the general population. However, the biological mechanisms underlying this increased risk are still unknown, particularly because most of the studies so far have been conducted in chronically ill adults and not in unaffected youth at high risk. In this preliminary study we analyzed genome-wide expression and methylation levels in peripheral blood mononuclear cells from children and adolescents from three matched groups: BD patients, unaffected offspring of bipolar parents (high risk) and controls (low risk). By integrating gene expression and DNA methylation and comparing the lists of differentially expressed genes and differentially methylated probes between groups, we were able to identify 43 risk genes that discriminate patients and high-risk youth from controls. Pathway analysis showed an enrichment of the glucocorticoid receptor (GR) pathway with the genes MED1, HSPA1L, GTF2A1 and TAF15, which might underlie the previously reported role of stress response in the risk for BD in vulnerable populations. Cell-based assays indicate a GR hyporesponsiveness in cells from adult BD patients compared to controls and suggest that these GR-related genes can be modulated by DNA methylation, which poses the theoretical possibility of manipulating their expression as a means to counteract the familial risk presented by those subjects. Although preliminary, our results suggest the utility of peripheral measures in the identification of biomarkers of risk in high-risk populations and further emphasize the potential role of stress and DNA methylation in the risk for BD in youth.

Altered stress patterns and increased risk for postpartum depression among low-income pregnant women

Postpartum depression (PPD) has been associated with a number of negative maternal and infant health outcomes. Despite these adverse health effects, few studies have prospectively examined patterns of pre- and postnatal stress that may increase a woman's risk for PPD. The current study examined whether the timing of altered salivary cortisol patterns and perceived stress levels during pregnancy and at 3 months postpartum was associated with PPD symptoms among 100 low-income mothers. Higher levels of PPD were found among women with a lower cortisol awakening response (first and second trimester), lower average daily cortisol (second trimester), a flatter diurnal cortisol pattern (second and third trimester and at 3 months postpartum), and a less abrupt drop in both cortisol and perceived stress from the third trimester to 3 months postpartum. These results support the need for early screening and regulation of stress levels to promote depression prevention efforts in at-risk populations.

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

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

Physical exercise counteracts genetic susceptibility to depression

BACKGROUND/AIMS

Depression is a highly prevalent disorder in elderly individuals. A genetic variant (rs6265) of the brain-derived neurotrophic factor (BDNF) impacting on emotion processing is known to increase the risk for depression. We aim to investigate whether intensive endurance sports might attenuate this genetic susceptibility in a cohort of elderly marathon athletes.

METHODS

Fifty-five athletes and 58 controls were included. rs6265 of the BDNF gene was genotyped by the TaqMan method. Depressive symptoms were assessed by standardized self-rating tests (BDI = Beck Depression Inventory, GDS = Geriatric Depression Scale).

RESULTS

In multivariable analysis of BDI and GDS scores, the interaction between group (athletes vs. controls) and genotypes ([C];[C] vs. [C];[T] + [T];[T]) was found to be statistically significant (BDI: p = 0.027, GDS: p = 0.013). Among [C];[C] carriers, merely controls had an increased relative risk of 3.537 (95% CI = 1.276-9.802) of achieving a subclinical depression score ≥10 on the BDI. There was no such effect in carriers of the [T] allele. In a multivariable binary logistic regression, genetic information, group (athletes/controls), but no information on rs6265 allele carrier status presented as a significant predictor of BDI scores ≥10.

CONCLUSION

Physical exercise positively affects BDNF effects on mood. Since 66Met BDNF secretion is impaired, this effect seems to be much stronger in [C];[C] homozygous individuals expressing the 66Val variant. This confirms that genetic susceptibility to depressive symptoms can indeed be influenced by endurance sports in elderly people.

Corticosterone exposure augments sensitivity to the behavioral and neuroplastic effects of fluoxetine in C57BL/6 mice

Both genetic background and pre-existing stress play critical roles in the effects of antidepressant drugs. The current studies showed this principal by demonstrating that exposure to the stress hormone corticosterone (CORT) allowed behavioral and neurogenic effects to emerge following chronic treatment with fluoxetine of C57BL/6 mice, a strain ordinarily resistant to these effects. Adult male mice were implanted subcutaneously with 21-day slow-release CORT pellets (10 mg) or placebo and then co-treated with 5 mg/kg fluoxetine (b.i.d., i.p.) or saline for 14 days. Animals were then assessed for approach behavior in the novelty-induced hypophagia (NIH) test, hippocampal cell proliferation, corticosteroid receptor expression, and CORT plasma levels. Co-treatment of CORT with fluoxetine significantly reduced approach behavior in the novel environment of the NIH test and increased hippocampal cell proliferation whereas fluoxetine given alone was ineffective. CORT given alone did not alter approach behavior in the novel environment and caused a smaller increase of cell proliferation. The CORT effect was blocked by adrenalectomy and was likely due to increased adrenal feedback. Cell proliferation in CORT-treated animals was associated with reduced mineralocorticoid, but not glucocorticoid, receptor mRNA expression. Although the pellets were advertised to release CORT for 21 days, plasma CORT levels were increased at 1 day after implantation but were not sustained when measured at 7 days or longer intervals. Nevertheless, the transient CORT increase was sufficient to induce long-lasting behavioral and molecular changes when followed by fluoxetine treatment. These studies warrant further investigation into the role of glucocorticoids and environmental stress as adjunctive facilitators of the response to antidepressants, especially for treatment-resistant patients.

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C57BL/6J mice are not responsive to behavioral and neurogenic effects of chronic fluoxetine.

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CORT reduced anxiogenic behavior, increased hippocampal neurogenesis in response to fluoxetine.

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CORT pellets are not effective in sustaining elevated plasma CORT levels.

The Involvement of Genes in Adolescent Depression: A Systematic Review

Numerous studies have reported on the roles of genetic factors in the development of depression in adolescents and young adults. However, there are few systematic reviews that update our understanding of adolescent depression with the biological findings identifying the roles of gene expression and/or polymorphism(s). This review systematically summarized the findings that clearly identified the contribution of a gene to the risk of depression in adolescents between the ages of 10 and 19 years old and young adults between the ages of 20 and 25 years old. Data were obtained through searching PubMed, Embase, and Web of Science. A total of 47 studies on early adolescence and three studies on young adults were included in the current review. Most articles studied genes in the serotonergic system (n = 26), dopaminergic system (n = 3), and the Brain-derived neurotropic factor (BDNF) gene (n = 12). 92.3% of studies (24/26) identified positive associations of 5-HTTLPR polymorphism with depressive illness or depressive symptoms. 83.3% of studies (10/12) found positive association between BDNF Val66Met genotype and adolescent depressive symptoms. More studies should be conducted on the 18 genes reported in a few studies to clarify their roles in the risk for adolescent depression.

Genes, environments and depressions in young people

Among the common mental illnesses in childhood and adolescence, the unipolar depressions are the most concerning. These mental illnesses are aetiologically and clinically heterogeneous and little is known about their pathophysiology. This selected review considers the contribution of genetic and environmental factors in the emergence of these illnesses in the second decade of life.

Prenatal and Postpartum Evening Salivary Cortisol Levels in Association with Peripartum Depressive Symptoms

BACKGROUND

The biology of peripartum depression remains unclear, with altered stress and the Hypothalamus-Pituitary-Adrenal axis response having been implicated in its pathophysiology.

METHODS

The current study was undertaken as a part of the BASIC project (Biology, Affect, Stress, Imaging, Cognition), a population-based longitudinal study of psychological wellbeing during pregnancy and the postpartum period in Uppsala County, Sweden, in order to assess the association between evening salivary cortisol levels and depressive symptoms in the peripartum period. Three hundred and sixty-five pregnant women from the BASIC cohort were recruited at pregnancy week 18 and instructed to complete a Swedish validated version of the Edinburgh Postnatal Depression Scale at the 36th week of pregnancy as well as the sixth week after delivery. At both times, they were also asked to provide evening salivary samples for cortisol analysis. A comprehensive review of the relevant literature is also provided.

RESULTS

Women with postpartum EPDS score ≥ 10 had higher salivary evening cortisol at six weeks postpartum compared to healthy controls (median cortisol 1.19 vs 0.89 nmol/L). A logistic regression model showed a positive association between cortisol levels and depressive symptoms postpartum (OR = 4.1; 95% CI 1.7-9.7). This association remained significant even after controlling for history of depression, use of tobacco, partner support, breastfeeding, stressful life events, and sleep problems, as possible confounders (aOR = 4.5; 95% CI 1.5-14.1). Additionally, women with postpartum depressive symptoms had higher postpartum cortisol levels compared to both women with depressive symptoms antenatally and controls (p = 0.019 and p = 0.004, respectively).

CONCLUSIONS

Women with depressive symptoms postpartum had higher postpartum cortisol levels, indicating an altered response of the HPA-axis in postpartum depression.

[Depression comorbid to ischemic heart disease: a psychometric and molecular-genetic study]

OBJECTIVE

To compare psychometric and molecular-genetic characteristics of depression caused by ischemic heart disease (IHD) and depression in patients with IHD caused by other psychogenic factors.

MATERIAL AND METHODS

One hundred and thirty-five patients with depression comorbid to ischemic heart disease (IHD) were examined. Depression was associated with IHD in 71 patients (group 1). In 64 patients, depression was caused by other psychogenic factors (group 2). The HAMD-21 scale was used to measure depressive symptoms.

RESULTS AND CONCLUSION

The comparative analysis of the core symptoms of depression demonstrated that group 1 had a peculiar psychometric profile with marked apathy, which was not accompanied by marked hypothymia, guilt feelings or anxiety, compared to group 2. The molecular-genetic correlate of this profile was found. It included a combination of an allele S (5-HTTLPR) of the serotonin transporter gene, an allele G (A-1438G) of the serotonin receptor type 2A gene and the genotype ValVal (Val66Met) of the brain-derived neurotrophic factor gene.

Biomarkers of intergenerational risk for depression: a review of mechanisms in longitudinal high-risk (LHR) studies

BACKGROUND

Longitudinal research is critical for understanding the biological mechanisms underlying the development of depression. Researchers recruit high-risk cohorts to understand how risk is transmitted from one generation to the next. Biological measurements have been incorporated into these longitudinal high-risk (LHR) studies in order to illuminate mechanistic pathways.

METHODS

To frame our review, we first present heritability estimates along the gene-by-environment continuum as a foundation. We then offer a Biomarkers of Intergenerational Risk for Depression (BIRD) model to describe the multiple hits individuals at risk receive and to allow for greater focus on the interactive effects of markers. BIRD allows for the known multifinality of pathways towards depression and considers the context (i.e., environment) in which these mechanisms emerge. Next, we review the extant LHR cohort studies that have assessed central nervous system (electroencephalography (EEG), neuroimaging), endocrine (hypothalamic-pituitary-adrenal axis (HPA)/cortisol), autonomic (startle, heart rate), genetic, sleep, and birth characteristics.

RESULTS

Results to date, in conjunction with the proposed model, point towards several pathways of discovery in understanding mechanisms, providing clear direction for future research examining potential endophenotypes.

LIMITATIONS

Our review is based on relatively narrow inclusion and exclusion criteria. As such, many interesting studies were excluded, but this weakness is offset by strengths such as the increased reliability of findings.

CONCLUSIONS

Blanket prevention programs are inefficient and plagued by low effect sizes due to low rates of actual conversion to disorder. The inclusion of biomarkers of risk may lead to enhanced program efficiency by targeting those at greatest risk.

Mental health and support among young key populations: an ecological approach to understanding and intervention

INTRODUCTION

The patterning of the HIV epidemic within young key populations (YKPs) highlights disproportionate burden by mental disorders in these populations. The mental wellbeing of YKPs is closely associated with biological predispositions and psychosocial factors related to YKPs' sexual and gender identities and socio-economic status. The purpose of this paper is to highlight sources of risk and resilience, as well as identify treatment and supports for mental health disorders (MHDs) among YKPs.

DISCUSSION

This paper utilizes Bronfenbrenner's Bioecological Systems Theory and the Social Stress Model to explore the risk and protective factors for MHDs across YKPs' ecological systems, and identify current gaps in treatment and support for MHDs among these youth. We emphasize the fluidity and intersections across these categorizations which reinforce the vulnerability of these populations, the lack of concrete data to inform mental health interventions among YKPs, and the need to ground YKP interventions and programmes with human rights principles stipulated in the convention on the rights of a child.

CONCLUSIONS

We put forth recommendations for future research and strategies to address the mental wellbeing of YKPs, including the need for integrated interventions that address the multiplicity of risk factors inherent in the multiple group membership, rather than single-focus interventions whilst addressing the unique needs or challenges of YKPs.

A Review of Biomarkers in Mood and Psychotic Disorders: A Dissection of Clinical vs. Preclinical Correlates

Despite significant research efforts aimed at understanding the neurobiological underpinnings of mood (depression, bipolar disorder) and psychotic disorders, the diagnosis and evaluation of treatment of these disorders are still based solely on relatively subjective assessment of symptoms as well as psychometric evaluations. Therefore, biological markers aimed at improving the current classification of psychotic and mood-related disorders, and that will enable patients to be stratified on a biological basis into more homogeneous clinically distinct subgroups, are urgently needed. The attainment of this goal can be facilitated by identifying biomarkers that accurately reflect pathophysiologic processes in these disorders. This review postulates that the field of psychotic and mood disorder research has advanced sufficiently to develop biochemical hypotheses of the etiopathology of the particular illness and to target the same for more effective disease modifying therapy. This implies that a "one-size fits all" paradigm in the treatment of psychotic and mood disorders is not a viable approach, but that a customized regime based on individual biological abnormalities would pave the way forward to more effective treatment. In reviewing the clinical and preclinical literature, this paper discusses the most highly regarded pathophysiologic processes in mood and psychotic disorders, thereby providing a scaffold for the selection of suitable biomarkers for future studies in this field, to develope biomarker panels, as well as to improve diagnosis and to customize treatment regimens for better therapeutic outcomes.

The longitudinal association of the diurnal cortisol rhythm with internalizing and externalizing problems in pre-schoolers. The Generation R Study

BACKGROUND

Studies investigating the association between diurnal cortisol rhythm and behavioural problems in young children have yielded inconsistent results. We tested the hypothesis that variations in diurnal cortisol rhythm in pre-schoolers are already related to problem behaviour early in life with a cross-sectional and longitudinal design.

METHODS

This study was embedded in Generation R, a population-based cohort from foetal life onwards. Parents collected saliva samples from their infant at 5 moments during 1 day. In 322 infants aged 12-20 months, we determined the diurnal cortisol rhythm by calculating the area under the curve (AUC), the cortisol awakening response (CAR), and the diurnal slope. Problem behaviour was assessed at ages 1.5 and 3 years with the Child Behavior Checklist/1.5-5 years.

RESULTS

No cross-sectional associations between the cortisol composite measures and problem behaviour were found at 1.5 years. However, cortisol predicted change in internalizing problems as assessed from 1.5 to 3 years, but not change in externalizing problems. Children with higher AUC levels, flatter slopes and a more positive CAR at baseline were more likely to score higher on the Internalizing Problems scale (β per nmol/L AUC: 0.08, 95% CI: 0.00; 0.17, p=0.04; β per nmol/L/h slope: 0.57, 95% CI: 0.17; 0.98, p=0.006; β per nmol/L CAR: 0.04, 95% CI: 0.01; 0.08, p=0.02) at follow-up.

CONCLUSIONS

Variations in diurnal cortisol rhythm are associated with change in internalizing problems in pre-schoolers. The results suggest that variations in diurnal cortisol patterns early in life precede internalizing problems.

A functional polymorphism in the HTR2C gene associated with stress responses: a validation study

Previously we have shown that a functional nonsynonymous single nucleotide polymorphism (SNP), rs6318 on the HTR2C gene located on the X-chromosome, is associated with hypothalamic-pituitary-adrenal axis response to a laboratory stress recall task. The present paper reports a validation of the cortisol response to stress in a second, independent sample. The study population consisted of 60 adult participants (73.3% males). Consistent with our prior findings, compared to Cys23 G allele carriers, persons homozygous for the Ser23C allele had a significantly greater average cortisol response (p=0.007) and area under the curve (p=0.021) over the course of an emotional stress recall protocol. Also parallel to our prior report, the change in cortisol from baseline to the average during the stress protocol was roughly twice as large among Ser23C homozygotes than among persons with Cys23 G. These findings validate our initial observation of association between rs6318 and cortisol response to an acute stressor, and extend the results to include females.

Immunological and neurotrophic markers of risk status and illness development in high-risk youth: understanding the neurobiological underpinnings of bipolar disorder

Bipolar disorder is a highly heritable illness that onsets in adolescence and young adulthood. We examined gene expression (mRNA) and protein levels of candidate immune and neurotrophic markers in well-characterized offspring of bipolar parents in order to identify reliable indicators of illness risk status and the early clinical stages of illness development. We measured mRNA expression and protein levels in candidate immune (TNF-α, IL-1β, IL-10, IFN-δ) and neurotrophic (brain-derived neurotrophic factor (BDNF)) markers from plasma. High-risk offspring were identified from families in which one parent had confirmed bipolar disorder. Control offspring were identified from families in which neither parent met lifetime criteria for a major psychiatric disorder. All parental Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) diagnoses were based on Schedule for Affective Disorders - Lifetime Version (SADS-L) interviews and blind consensus review. As part of an ongoing study, all offspring were prospectively assessed using KSADS-PL format interviews and diagnoses confirmed on blind consensus review. High-risk offspring had significantly increased IL-6 (p = 0.050) and BDNF (p = 0.006) protein levels compared to controls. Those high-risk offspring in earlier compared to later clinical stages of illness development had higher IL-6 (p = 0.050) and BDNF (p = 0.045) protein levels. After adjustments, only differences in BDNF protein levels remained significant. There was a moderating effect of the BDNF genotype on both gene expression and protein levels in high-risk compared to control offspring. The BDNF genotype also moderated the association between clinical stage and gene expression levels in high-risk offspring. These findings provide support for detectable differences in candidate immune and neurotrophic markers in individuals at high risk of developing bipolar disorder and for detectable changes over the clinical stages of illness development. These associations appear to be moderated by genetic variants.

Salivary cortisol and depression in public sector employees: cross-sectional and short term follow-up findings

INTRODUCTION

Increased cortisol levels have been suggested to play a role in the development of depression. An association has been shown in some studies but not consistently. The timing of an association is uncertain, and long-term follow-up studies may miss associations in narrower time windows. In the present study, we examined the association of several cortisol measures and depression in a repeated cross-sectional and short-term follow-up design. Depression was assessed by both self-reported symptoms of depression and clinical interviews.

METHOD

In 2007, 10,036 public sector employees received a questionnaire along with salivary cortisol test tubes for home administration. Morning (30min after awakening) and evening (2000h) salivary samples were collected. Questionnaires and valid saliva samples were returned from 3536 employees. Approximately 3.6 months later a subsample of the participants collected three morning saliva samples (at awakening, 20min and 40min after awakening) plus an evening sample (2000h); participants with high baseline scores of self-reported depressive symptoms, burnout and perceived stress were invited to a standardized interview (SCAN) to detect clinical depression; and the symptom questionnaire was repeated for subsample participants. The study was repeated in 2009 with questionnaires and salivary test tubes (n=2408). In four cross-sectional and two short-term follow-up analyses odds ratios of depressive symptoms and of clinical depression were estimated by logistic regression for morning, evening, mean and the difference between morning and evening cortisol (slope). For the subsample, awakening response (CAR) and area under the curve (AUC) cortisol measures were calculated. We adjusted for sex, age, income, education, family history of depression, physical activity and alcohol consumption.

RESULTS

None except one of the measures of salivary cortisol were associated with self-reported depressive symptoms or clinical depression, neither in the four cross-sectional analyses nor in the two short term follow-up analyses. E.g. in 2007, the adjusted odds ratios (OR) of depressive symptoms by a one unit increase in morning and evening cortisol (ln(nmol/litre saliva)) were 1.01 (95% CI: 0.88-1.17) and 1.05 (0.93-1.18), respectively. The one exception was significant at p=0.04 and was considered as due to chance.

CONCLUSION

In this large study, salivary cortisol was not associated with self-reported symptoms of depression or with clinical depression.

A two-year follow-up study of salivary cortisol concentration and the risk of depression

Stress is a suspected cause of depression. High cortisol concentration, a biomarker of an activated stress response, has been found in depressed patients. The aim of this study was to determine if a high level of salivary cortisol is a risk factor of depression. In 2007, we enrolled 4467 public employees. Morning and evening salivary cortisol concentration were measured for each participant. Participants reporting high levels of depressive, burnout, or stress symptoms, assessed by questionnaires were assigned to a psychiatric interview. In this interview 98 participants were diagnosed with depression and subsequently excluded. Two years later in 2009, 2920 participants who had provided at least one valid saliva cortisol measurement at baseline participated at follow up. The psychiatric interviews were repeated and 62 cases of newly onset depression were diagnosed. Odds ratios of depression were estimated for every 1.0nmol/l increase in morning, evening, and daily mean cortisol concentration, as well as for the difference between morning and evening cortisol concentration. The risk of depression decreased by increasing daily mean cortisol concentration and by increasing difference between morning and evening concentrations, while morning and evening cortisol concentrations were not significantly associated with depression. The adjusted odds ratios for 1.0nmol/l increase in morning, evening, and daily mean cortisol concentration were 0.69 (95% CI: 0.45, 1.05), 0.87 (95% CI: 0.59, 1.28), and 0.53 (95% CI: 0.32, 0.90), respectively. The adjusted odds ratio for 1.0nmol/l increase in difference between morning and evening concentration were 0.64 (95% CI: 0.45, 0.90). This study did not support the hypothesis that high salivary cortisol concentration is a risk factor of depression, but indicate that low mean salivary cortisol concentration and a small difference between morning and evening cortisol concentration may be risk factors of depression.

Conflict monitoring and adaptation in individuals at familial risk for developing bipolar disorder

OBJECTIVE

To examine conflict monitoring and conflict-driven adaptation in individuals at familial risk for developing bipolar disorder.

METHODS

We recruited 24 adolescents who had a parent with bipolar disorder and 23 adolescents with healthy parents. Participants completed an arrow version of the Eriksen Flanker Task that included trials with three levels of conflict: neutral, congruent, and incongruent flanks. Differences in performance were explored based upon the level of conflict in the current and previous trials.

RESULTS

Individuals at risk for developing bipolar disorder performed more slowly than youth with healthy parents in all trials. Analyses evaluating sequential effects revealed that at-risk subjects responded more slowly than youth of healthy parents for all trial types when preceded by an incongruent trial, for incongruent trials preceded by congruent trials, and for neutral and congruent trials when preceded by neutral trials. In contrast to the comparison group, at-risk adolescents failed to display a response time advantage for incongruent trials preceded by an incongruent trial. When removing subjects with attention-deficit hyperactivity disorder (ADHD), differences between groups in response time fell below significant level, but a difference in sequence modulation remained significant. Subjects at risk for bipolar disorder also displayed greater intra-subject response time variability for incongruent and congruent trials compared with the comparison adolescents. No differences in response accuracy were observed between groups.

CONCLUSIONS

Adolescents at risk for developing bipolar disorder displayed specific deficits in cognitive flexibility, which might be useful as a potential marker related to the development of bipolar disorder.

The cortisol awakening response predicts major depression: predictive stability over a 4-year follow-up and effect of depression history

BACKGROUND

The cortisol awakening response (CAR) has been shown to predict major depressive episodes (MDEs) over a 1-year period. It is unknown whether this effect: (a) is stable over longer periods of time; (b) is independent of prospective stressful life events; and (c) differentially predicts first onsets or recurrences of MDEs.

METHOD

A total of 270 older adolescents (mean age 17.06 years at cortisol measurement) from the larger prospective Northwestern-UCLA Youth Emotion Project completed baseline diagnostic and life stress interviews, questionnaires, and a 3-day cortisol sampling protocol measuring the CAR and diurnal rhythm, as well as up to four annual follow-up interviews of diagnoses and life stress.

RESULTS

Non-proportional person-month survival analyses revealed that higher levels of the baseline CAR significantly predict MDEs for 2.5 years following cortisol measurement. However, the strength of prediction of depressive episodes significantly decays over time, with the CAR no longer significantly predicting MDEs after 2.5 years. Elevations in the CAR did not significantly increase vulnerability to prospective major stressful life events. They did, however, predict MDE recurrences more strongly than first onsets.

CONCLUSIONS

These results suggest that a high CAR represents a time-limited risk factor for onsets of MDEs, which increases risk for depression independently of future major stressful life events. Possible explanations for the stronger effect of the CAR for predicting MDE recurrences than first onsets are discussed.

Cortisol and depression: three questions for psychiatry

BACKGROUND

Cortisol plays a multifaceted role in major depression disorder (MDD). Diurnal rhythms are disturbed, there is increased resistance to the feedback action of glucocorticoids, excess cortisol may induce MDD, basal levels may be higher and the post-awakening cortisol surge accentuated in those at risk for MDD. Does this suggest new avenues for studying MDD or its clinical management?

METHOD

The relevant literature was reviewed.

RESULTS

Cortisol contributes to genetic variants for the risk for MDD and the way that environmental events amplify risk. The corticoids' influence begins prenatally, but continues into adulthood. The impact of cortisol at each phase depends not only on its interaction with other factors, such as psychological traits and genetic variants, but also on events that have, or have not, occurred previously.

CONCLUSIONS

This review suggests that the time is now right for serious consideration of the role of cortisol in a clinical context. Estimates of cortisol levels and the shape of the diurnal rhythm might well guide the understanding of subtypes of MDD and yield additional indicators for optimal treatment. Patients with disturbed cortisol rhythms might benefit from restitution of those rhythms; they may be distinct from those with more generally elevated levels, who might benefit from cortisol blockade. Higher levels of cortisol are a risk for subsequent depression. Should manipulation of cortisol or its receptors be considered as a preventive measure for some of those at very high risk of future MDD, or to reduce other cortisol-related consequences such as long-term cognitive decline?

Interaction between the BDNF gene Val/66/Met polymorphism and morning cortisol levels as a predictor of depression in adult women

BACKGROUND

Common genetic variants, such as the brain-derived neurotrophic factor (BDNF) Val/66/Met polymorphism (rs6265), are known to interact with environmental factors such as early adversity to increase the risk of subsequent major depression. Much less is known about how they interact with individual differences in cortisol, although these also represent a risk for major depression.

AIMS

To determine whether this BDNF variant moderated the risk represented by higher levels of morning salivary cortisol in adult women.

METHOD

We recruited 279 premenopausal women who were at high risk of major depressive disorder because of either negative self-evaluation, unsupportive core relationship or chronic subclinical symptoms of depression or anxiety. Morning salivary cortisol was measured daily for up to 10 days at entry. Participants were followed up for about 12 months by telephone calls at 3-4 monthly intervals. Major depression and severe life events were assessed through interviews at baseline and follow-up; DNA was obtained from the saliva.

RESULTS

There were 53 onsets (19%) of depressive episodes during follow-up. There was a significant U-shaped relationship between adjusted morning cortisol levels at baseline and the probability of depression onset during follow-up. In total, 51% experienced at least one severe life event/difficulty, and this strongly predicted subsequent onsets of depressive episodes. The BDNF Val/66/Met genotype was not directly associated with onsets of depression or with cortisol levels, but there was significant interaction between Val/66/Met and cortisol: the association between baseline cortisol and depression was limited to those with the Val/66/Val variant. There was no interaction between life events and either this BDNF polymorphism or cortisol levels.

CONCLUSIONS

Morning salivary cortisol interacts with the BDNF Val/66/Met polymorphism in predicting new depressive episodes. This paper adds to the evidence that single gene polymorphisms interact with endogenous factors to predict depression.

GDNF and BDNF gene interplay in chronic tinnitus

BACKGROUND

Glial cell-derived neurotrophic factor (GDNF) and brain-derived neurotrophic factor (BDNF) play key roles in the early development of the central auditory pathway and the inner ear. Both have been successfully employed to treat experimental forms of hearing loss and are likely to operate in a broad spectrum of auditory phenotypes, including phantom perceptions of sound. We conducted a genetic association study addressing five biallelic candidate variants in 240 Caucasian subjects who had been diagnosed with tinnitus for more than 6 months.

FINDINGS

Allele frequencies were determined for three GDNF and two BDNF markers, including a functional missense substitution (V66M). When data were compared to previously examined control populations, no significant allelic associations were noted after corrections for multiple testing. However, using a multiple regression approach and scores from a validated self-report questionnaire, GDNF and BDNF genotypes jointly predicted tinnitus severity in women (N=69, uncorrected p=0.04) but not in men (N=171, n.s.).

CONCLUSIONS

The present findings serve as an incentive for further explorations of neurotrophic factors' role in predicting clinical features of tinnitus. Possible implications of sexually dimorphic at-risk genotypes are discussed with regard to hearing and neural plasticity.

Future directions in vulnerability to depression among youth: integrating risk factors and processes across multiple levels of analysis

Depression is a developmental phenomenon. Considerable progress has been made in describing the syndrome, establishing its prevalence and features, providing clues as to its etiology, and developing evidence-based treatment and prevention options. Despite considerable headway in distinct lines of vulnerability research, there is an explanatory gap in the field's ability to more comprehensively explain and predict who is likely to become depressed, when, and why. Still, despite clear success in predicting moderate variance for future depression, especially with empirically rigorous methods and designs, the heterogeneous and multi-determined nature of depression suggests that additional etiologies need to be included to advance knowledge on developmental pathways to depression. This paper advocates for a multiple levels of analysis approach to investigating vulnerability to depression across the lifespan and providing a more comprehensive understanding of its etiology. One example of a multiple levels of analysis model of vulnerabilities to depression is provided that integrates the most accessible, observable factors (e.g., cognitive and temperament risks), intermediate processes and endophenotypes (e.g., information-processing biases, biological stress physiology, and neural activation and connectivity), and genetic influences (e.g., candidate genes and epigenetics). Evidence for each of these factors as well as their cross-level integration is provided. Methodological and conceptual considerations important for conducting integrative, multiple levels of depression vulnerability research are discussed. Finally, translational implications for how a multiple levels of analysis perspective may confer additional leverage to reduce the global burden of depression and improve care are considered.

Depressive symptoms during adolescence: comparison between epidemiological and high risk sampling

PURPOSE

Both epidemiological (unselected) and high risk (screening on known risk criteria) samplings have been used to investigate the course of affective disorders. Selecting individuals on multiple risk criteria may create a sample not comparable to individuals with similar risk criteria within the general population. This study compared depressive symptoms across the two sampling methods to test this possibility.

METHODS

The high risk Cambridge Hormones and Moods Project (CHAMP) screened and recruited adolescents aged 12 to 16. A total of 905 (710 high risk) individuals participated and were reassessed at three follow-ups. The ROOTS epidemiological sample consisted of 1,208 14-year-olds reassessed at 15.5 and 17 years. The risk profile for CHAMP was recreated in the ROOTS study. Both samples completed the Moods and Feelings Questionnaire, a self-report measure of current depressive symptoms.

RESULTS

Comparing individuals with the same high risk profiles across the CHAMP and ROOTS studies revealed no significant differences in mean depression scores. Combining the samples revealed that for females, mean depression scores were maintained from 12 to 15 years then declined by 17 years. For males, scores declined from 12 throughout adolescence. High risk status led to consistently higher levels of depressive symptoms in female adolescents but result in little change within male adolescents.

CONCLUSIONS

The high risk design recruited adolescents with a depression symptoms profile comparable to the general population for both sexes. High risk status may alter the trajectory of depressive symptoms in female adolescents only. Males may be less sensitive to recent adversity.

Genetic sensitivity to the caregiving context: the influence of 5httlpr and BDNF val66met on indiscriminate social behavior

Evidence that gene×environment interactions can reflect differential sensitivity to the environmental context, rather than risk or resilience, is increasing. To test this model, we examined the genetic contribution to indiscriminate social behavior, in the setting of a randomized controlled trial of foster care compared to institutional rearing. Children enrolled in the Bucharest Early Intervention Project (BEIP) were assessed comprehensively before the age of 30 months and subsequently randomized to either care as usual (CAUG) or high quality foster care (FCG). Indiscriminate social behavior was assessed at four time points, baseline, 30 months, 42 months and 54 months of age, using caregiver report with the Disturbances of Attachment Interview (DAI). General linear mixed-effects models were used to examine the effect of the interaction between group status and functional polymorphisms in Brain Derived Neurotrophic Factor (BDNF) and the Serotonin Transporter (5htt) on levels of indiscriminate behavior over time. Differential susceptibility, relative to levels of indiscriminate behavior, was demonstrated in children with either the s/s 5httlpr genotype or met 66 BDNF allele carriers. Specifically children with either the s/s 5httlpr genotype or met66 carriers in BDNF demonstrated the lowest levels of indiscriminate behavior in the FCG and the highest levels in the CAUG. Children with either the long allele of the 5httlpr or val/val genotype of BDNF demonstrated little difference in levels of indiscriminate behaviors over time and no group×genotype interaction. Children with both plasticity genotypes had the most signs of indiscriminate behavior at 54 months if they were randomized to the CAUG in the institution, while those with both plasticity genotypes randomized to the FCG intervention had the fewest signs at 54 months. Strikingly children with no plasticity alleles demonstrated no intervention effect on levels of indiscriminate behavior at 54 months. These findings represent the first genetic associations reported with indiscriminate social behavior, replicate previous gene×gene×environment findings with these polymorphisms, and add to the growing body of literature supporting a differential susceptibility model of gene×environment interactions in developmental psychopathology.

Cortisol levels in response to starting school in children at increased risk for social phobia

BACKGROUND

Research on depression has identified hyperactivity of the HPA axis as a potential contributory factor to the intergenerational transmission of affective symptoms. This has not yet been examined in the context of social phobia. The current study compared HPA axis activity in response to a universal social stressor (starting school) in children of 2 groups of women: one with social phobia and one with no history of anxiety (comparison group). To determine specificity of effects of maternal social phobia, a third group of children were also examined whose mothers had generalised anxiety disorder (GAD).

METHOD

Children provided salivary cortisol samples in the morning, afternoon and at bedtime across 3 time-blocks surrounding the school start: a month before starting school (baseline), the first week at school (stress response), and the end of the first school term (stress recovery). Child behavioural inhibition at 14 months was assessed to explore the influence of early temperament on later stress responses.

RESULTS

All children displayed an elevation in morning and afternoon cortisol from baseline during the first week at school, which remained elevated until the end of the first term. Children in the social phobia group, however, also displayed an equivalent elevation in bedtime cortisol, which was not observed for comparison children or for children of mothers with GAD. Children in the social phobia group who were classified as 'inhibited' at 14 months displayed significantly higher afternoon cortisol levels overall.

SUMMARY

A persistent stress response to school in the morning and afternoon is typical for all children, but children of mothers with social phobia also display atypical elevations in evening cortisol levels when at school--signalling longer-term disruption of the circadian rhythm in HPA axis activity. This is the first study to report HPA axis disruption in children at increased risk of developing social phobia. Future research should determine whether this represents a pathway for symptom development, taking early temperament into account.

Childhood adversity and allostatic overload of the hypothalamic-pituitary-adrenal axis: a vulnerability model for depressive disorders

Childhood adversity is associated with increased risk for onset of depressive episodes. This review will present evidence that allostatic overload of the hypothalamic-pituitary-adrenal axis (HPAA) partially mediates this association. The HPAA is the physiological system that regulates levels of the stress hormone cortisol. First, data from animals and humans has shown that early environmental adversity is associated with long-term dysregulation of the HPAA. This may occur due to permanent epigenetic modification of the glucocorticoid receptor. Second, data from humans has demonstrated that HPAA dysregulation is associated with increased risk of future depression onset in healthy individuals, and pharmacological correction of HPAA dysregulation reduces depressive symptoms. HPAA dysregulation may result in corticoid-mediated abnormalities in neurogenesis in early life and/or neurotoxicity on neural systems that subserve emotion and cognition.

Response time variability and response inhibition predict affective problems in adolescent girls, not in boys: the TRAILS study

The present study examines the relationship between neurocognitive functioning and affective problems through adolescence, in a cross-sectional and longitudinal perspective. Baseline response speed, response speed variability, response inhibition, attentional flexibility and working memory were assessed in a cohort of 2,179 adolescents (age 10-12 years) from the TRacking Adolescents' Individual Lives Survey (TRAILS). Affective problems were measured with the DSM-oriented Affective Problems scale of the Youth Self Report at wave 1 (baseline assessment), wave 2 (after 2.5 years) and wave 3 (after 5 years). Cross-sectionally, baseline response speed, response time variability, response inhibition and working memory were associated with baseline affective problems in girls, but not in boys. Longitudinally, enhanced response time variability predicted affective problems after 2.5 and 5 years in girls, but not in boys. Decreased response inhibition predicted affective problems after 5 years follow-up in girls, and again not in boys. The results are discussed in light of recent insights in gender differences in adolescence and state-trait issues in depression.

Neurogenetics and Epigenetics in Impulsive Behaviour: Impact on Reward Circuitry

Adverse, unfavourable life conditions, particularly during early life stages and infancy, can lead to epigenetic regulation of genes involved in stress-response, behavioral disinhibition, and cognitive-emotional systems. Over time, the ultimate final outcome can be expressed through behaviors bedeviled by problems with impulse control, such as eating disorders, alcoholism, and indiscriminate social behavior. While many reward gene polymorphisms are involved in impulsive behaviors, a polymorphism by itself may not translate to the development of a particular behavioral disorder unless it is impacted by epigenetic effects. Brain-derived neurotrophic factor (BDNF) affects the development and integrity of the noradrenergic, dopaminergic, serotonergic, glutamatergic, and cholinergic neurotransmitter systems, and plasma levels of the neurotrophin are associated with both cognitive and aggressive impulsiveness. Epigenetic mechanisms associated with a multitude of environmental factors, including premature birth, low birth weight, prenatal tobacco exposure, non-intact family, young maternal age at birth of the target child, paternal history of antisocial behavior, and maternal depression, alter the developmental trajectories for several neuropsychiatric disorders. These mechanisms affect brain development and integrity at several levels that determine structure and function in resolving the final behavioral expressions.

BDNF polymorphism predicts the rate of decline in skilled task performance and hippocampal volume in healthy individuals

Numerous studies have indicated a link between the presence of polymorphism in brain-derived neurotrophic factor (BDNF) and cognitive and affective disorders. However, only a few have studied these effects longitudinally along with structural changes in the brain. This study was carried out to investigate whether valine-to-methionine substitution at position 66 (val66met) of pro-BDNF could be linked to alterations in the rate of decline in skilled task performance and structural changes in hippocampal volume. Participants consisted of 144 healthy Caucasian pilots (aged 40-69 years) who completed a minimum of 3 consecutive annual visits. Standardized flight simulator score (SFSS) was measured as a reliable and quantifiable indicator for skilled task performance. In addition, a subset of these individuals was assessed for hippocampal volume alterations using magnetic resonance imaging. We found that val66met substitution in BDNF correlated longitudinally with the rate of decline in SFSS. Structurally, age-dependent hippocampal volume changes were also significantly altered by this substitution. Our study suggests that val66met polymorphism in BDNF can be linked to the rate of decline in skilled task performance. Furthermore, this polymorphism could be used as a predictor of the effects of age on the structure of the hippocampus in healthy individuals. Such results have implications for understanding possible disabilities in older adults performing skilled tasks who are at a higher risk for cognitive and affective disorders.Translational Psychiatry (2011) 1, e51; doi:10.1038/tp.2011.47; published online 25 October 2011.

Biomarkers for major depression and its delineation from neurodegenerative disorders

Major depressive disorders (MDD) are among the most debilitating diseases worldwide and occur with a high prevalence in elderly individuals. Neurodegenerative diseases (in particular Alzheimer's disease, AD) do also show a strong age-dependent increase in incidence and prevalence among the elderly population. A high number of geriatric patients with MDD show cognitive deficits and a very high proportion of AD patients present co-morbid MDD, which poses difficult diagnostic and prognostic questions. Especially in prodromal and in very early stages of AD, it is almost impossible to differentiate between pure MDD and MDD with underlying AD. Here, we give a comprehensive review of the literature on the current state of candidate biomarkers for MDD ("positive MDD markers") and briefly refer to established and validated diagnostic AD biomarkers in order to rule out underlying AD pathophysiology in elderly MDD subjects with cognitive impairments ("negative MDD biomarkers"). In summary, to date there is no evidence for positive diagnostic MDD biomarkers and the only way to delineate MDD from AD is to use "negative MDD" biomarkers. Because of this highly unsatisfactory current state of MDD biomarker research, we propose a research strategy targeting to detect and validate positive MDD biomarkers, which is based on a complex (genetic, molecular and neurophysiological) biological model that incorporates current state of the art knowledge on the pathobiology of MDD. This model delineates common pathways and the intersection between AD and MDD. Applying these concepts to MDD gives hope that positive MDD biomarkers can be successfully identified in the near future.