Genetic predictors of depressive symptoms in cardiac patients

Risk and Resilience Variants in the Retinoic Acid Metabolic and Developmental Pathways Associated with Risk of FASD Outcomes

Fetal Alcohol Spectrum Disorder (FASD) is a common neurodevelopmental disorder that affects an estimated 2-5% of North Americans. FASD is induced by prenatal alcohol exposure (PAE) during pregnancy and while there is a clear genetic contribution, few genetic factors are currently identified or understood. In this study, using a candidate gene approach, we performed a genetic variant analysis of retinoic acid (RA) metabolic and developmental signaling pathway genes on whole exome sequencing data of 23 FASD-diagnosed individuals. We found risk and resilience alleles in ADH and ALDH genes known to normally be involved in alcohol detoxification at the expense of RA production, causing RA deficiency, following PAE. Risk and resilience variants were also identified in RA-regulated developmental pathway genes, especially in SHH and WNT pathways. Notably, we also identified significant variants in the causative genes of rare neurodevelopmental disorders sharing comorbidities with FASD, including STRA6 (Matthew-Wood), SOX9 (Campomelic Dysplasia), FDG1 (Aarskog), and 22q11.2 deletion syndrome (TBX1). Although this is a small exploratory study, the findings support PAE-induced RA deficiency as a major etiology underlying FASD and suggest risk and resilience variants may be suitable biomarkers to determine the risk of FASD outcomes following PAE.

A network medicine-based approach to explore the relationship between depression and inflammation

Background

Depression is widespread global problem that not only severely impacts individuals' physical and mental health but also imposes a heavy disease burden on nations and societies. The role of inflammation in the pathogenesis and pathophysiology of depression has received much attention, but the precise relationship between the two remains unclear. This study aims to investigate the correlation between depression and inflammation using a network medicine approach.

Methods

We utilized a degree-preserving approach to identify the large connected component (LCC) of all depression-related proteins in the human interactome. The LCC was deemed as the disease module for depression. To measure the association between depression and other diseases, we calculated the overlap between these disease protein modules using the Sab algorithm. A smaller Sab value indicates a stronger association between diseases. Building on the results of this analysis, we further explored the correlation between inflammation and depression by conducting enrichment and pathway analyses of critical targets. Finally, we used a network proximity approach to calculate drug-disease proximity to predict the efficacy of drugs for the treatment of depression. We calculated and ranked the distances between depression disease modules and 6,100 drugs. The top-ranked drugs were selected to explore their potential for treating depression based on the hypothesis that their antidepressant effects are related to reducing inflammation.

Results

In the human interactome, all depression-related proteins are clustered into a large connected component (LCC) consisting of 202 proteins and multiple small subgraphs. This indicates that depression-related proteins tend to form clusters within the same network. We used the 202 LCC proteins as the key disease module for depression. Next, we investigated the potential relationships between depression and 299 other diseases. Our analysis identified over 18 diseases that exhibited significant overlap with the depression module. Where S_AB = -0.075 for the vascular disease and depressive disorders module, S_AB = -0.070 for the gastrointestinal disease and depressive disorders module, and S_AB = -0.062 for the endocrine system disease and depressive disorders module. The distance between them S_AB < 0 implies that the pathogenesis of depression is likely to be related to the pathogenesis of its co-morbidities of depression and that potential therapeutic approaches may be derived from the disease treatment libraries of these co-morbidities. Further, considering that the inflammation is ubiquitous in some disease, we calculate the overlap between the collected inflammation module (236 proteins) and the depression module (202 proteins), finding that they are closely related (S_di = -0.358) in the human protein interaction network. After enrichment and pathway analysis of key genes, we identified the HIF-1 signaling pathway, PI3K-Akt signaling pathway, Th17 cell differentiation, hepatitis B, and inflammatory bowel disease as key to the inflammatory response in depression. Finally, we calculated the Z-score to determine the proximity of 6,100 drugs to the depression disease module. Among the top three drugs identified by drug-disease proximity analysis were Perphenazine, Clomipramine, and Amitriptyline, all of which had a greater number of targets in the network associated with the depression disease module. Notably, these drugs have been shown to exert both anti-inflammatory and antidepressant effects, suggesting that they may modulate depression through an anti-inflammatory mechanism. These findings demonstrate a correlation between depression and inflammation at the network medicine level, which has important implications for future elucidation of the etiology of depression and improved treatment outcomes.

Conclusion

Neuroimmune signaling pathways play an important role in the pathogenesis of depression, and many classes of antidepressants exhibiting anti-inflammatory properties. The pathogenesis of depression is closely related to inflammation.

The association of CNR1 genetic variants with resting-state functional connectivity in youth bipolar disorder

Cannabinoid 1 receptors coded by the CNR1 gene are implicated in mood disorders and addiction. Given the prevalence and negative correlates of cannabis use in bipolar disorder (BD), we examined CNR1 polymorphism rs1324072 in relation to resting-state functional connectivity (rsFC) in youth BD. Participants included 124 youth, ages 13-20 years: 17 BD G-carriers, 48 BD non-carriers, 16 healthy controls (HC) G-carriers, and 43 HC non-carriers. rsFC was obtained using 3T-MRI. General linear models examined main effects of diagnosis, gene, and diagnosis-by-gene interaction, controlling for age, sex, and race. Regions-of-interests in seed-to-voxel analyses included: bilateral amygdala, hippocampus, nucleus accumbens (NAc), and orbitofrontal cortex (OFC). Main effects of diagnosis were observed for rsFC between the right amygdala seed and right occipital pole, and between the left NAc seed and left superior parietal lobe. Interaction analyses identified 6 significant clusters. G-allele was associated with negative connectivity in BD and positive connectivity in HC for: left amygdala seed with right intracalcarine cortex; right NAc seed with left inferior frontal gyrus; and right hippocampal seed with bilateral cuneal cortex (all p<0.001). G-allele was associated with positive connectivity in BD and negative connectivity in HC for: right hippocampal seed with left central opercular cortex (p = 0.001), and left NAc seed with left middle temporal cortex (p = 0.002). In conclusion, CNR1 rs1324072 was differentially associated with rsFC in youth with BD in regions relevant to reward and emotion. Future studies powered to integrate CNR1 alongside cannabis use are warranted to examine the inter-relationship between rs1324072 G-allele, cannabis use, and BD.

Repetitive transcranial direct current stimulation modulates the brain-gut-microbiome axis in obese rodents

Background

Complex interactions between the brain, gut and adipose tissue allow to recognize obesity as a neurometabolic disorder. The recent data have shown that gut microbiota can play a potential role in obesity development. Transcranial direct current stimulation (tDCS) is a safe and non-invasive technique to modulate the activity of cerebral cortex and other connected brain areas also in context of appetite control. The objective of this study was to evaluate the effects of repetitive anodal tDCS (AtDCS) of prefrontal cortex on feeding behavior, metabolic status and selected phyla of gut microbiota in rats with obesity induced by high-calorie diet (HCD).

Methods

32 female Wistar rats were equally divided into 4 subgroups depending on diet effect (lean versus obese) and type of stimulation (active versus sham tDCS versus no stimulation). Feed intake, body weight, blood lipoproteins and leptin levels as well as Firmicutes and Bacteroidetes in intestines and stool were examined.

Results

HCD changed feeding behavior and metabolic parameters typically for obesity-related ranges and resulted in an abundance of Firmicutes at the expanse of Bacteroidetes in the large intestine and stool. AtDCS decreased appetite, body weight, and cholesterol levels. In addition, AtDCS reduced ratio of the average number of Firmicutes to average number of Bacteroidetes in all examined tissues.

Conclusions

Repetitive AtDCS is not only effective for appetite restriction but can also modulate gut microbiome composition which demonstrates the existence of the brain–gut–microbiome axis and points at this technique as a promising complementary treatment for obesity. However, the effects should be further replicated in human studies.

Investigating data-driven biological subtypes of psychiatric disorders using specification-curve analysis

BACKGROUND

Cluster analyses have become popular tools for data-driven classification in biological psychiatric research. However, these analyses are known to be sensitive to the chosen methods and/or modelling options, which may hamper generalizability and replicability of findings. To gain more insight into this problem, we used Specification-Curve Analysis (SCA) to investigate the influence of methodological variation on biomarker-based cluster-analysis results.

METHODS

Proteomics data (31 biomarkers) were used from patients (n = 688) and healthy controls (n = 426) in the Netherlands Study of Depression and Anxiety. In SCAs, consistency of results was evaluated across 1200 k-means and hierarchical clustering analyses, each with a unique combination of the clustering algorithm, fit-index, and distance metric. Next, SCAs were run in simulated datasets with varying cluster numbers and noise/outlier levels to evaluate the effect of data properties on SCA outcomes.

RESULTS

The real data SCA showed no robust patterns of biological clustering in either the MDD or a combined MDD/healthy dataset. The simulation results showed that the correct number of clusters could be identified quite consistently across the 1200 model specifications, but that correct cluster identification became harder when the number of clusters and noise levels increased.

CONCLUSION

SCA can provide useful insights into the presence of clusters in biomarker data. However, SCA is likely to show inconsistent results in real-world biomarker datasets that are complex and contain considerable levels of noise. Here, the number and nature of the observed clusters may depend strongly on the chosen model-specification, precluding conclusions about the existence of biological clusters among psychiatric patients.

Cardiometabolic disease risk among siblings of patients with major depressive disorder

Studies have suggested an association between metabolic and cerebrocardiovascular diseases and major depressive disorder (MDD). However, the risk of metabolic and cerebrocardiovascular diseases in the unaffected siblings of patients with MDD remains uncertain. Using the Taiwan National Health Insurance Research Database, 22,438 unaffected siblings of patients with MDD and 89,752 age-/sex-matched controls were selected and followed up from 1996 to the end of 2011. Individuals who developed metabolic and cerebrocardiovascular diseases during the follow-up period were identified. Compared with the controls, the unaffected siblings of patients with MDD had a higher prevalence of metabolic diseases, such as hypertension (5.0% vs. 4.5%, p = 0.007), dyslipidemia (5.6% vs. 4.8%, p < 0.001), and obesity (1.7% vs. 1.5%, p = 0.028), and cerebrocardiovascular diseases, such as ischemic stroke (0.6% vs. 0.4%, p < 0.005) and ischemic heart disease (2.1% vs. 1.7%, p < 0.001). Logistic regression analyses revealed that the unaffected siblings of patients with MDD were more likely to develop hypertension, dyslipidemia, ischemic stroke, and ischemic heart diseases during the follow-up period than the controls. Our study revealed a familial coaggregation between MDD and metabolic and cerebrocardiovascular diseases. Additional studies are required to investigate the shared pathophysiology of MDD and metabolic and cerebrocardiovascular diseases.

Association of FKBP5 genotype with depressive symptoms in patients with coronary heart disease: a prospective study

Depression and coronary heart disease (CHD) are prevalent and often co-occurring disorders. Both have been associated with a dysregulated stress system. As a central element of the stress system, the FKBP5 gene has been shown to be associated with depression. In a prospective design, this study aims to investigate the association of FKBP5 with depressive symptoms in CHD patients. N = 268 hospitalized CHD patients were included. Depressive symptoms were measured using the Hospital Anxiety and Depression Scale (HADS-D) at four time points (baseline, and after 1 month, 6 months, and 12 months). The functional FKBP5 single-nucleotide polymorphism (SNP) rs1360780 was selected for genotyping. Linear regression models showed that a higher number of FKBP5 C alleles was associated with more depressive symptoms in CHD patients both at baseline (p = 0.015) and at 12-months follow-up (p = 0.025) after adjustment for confounders. Further analyses revealed that this effect was driven by an interaction of FKBP5 genotype with patients’ prior CHD course. Specifically, only in patients with a prior myocardial infarction or coronary revascularization, more depressive symptoms were associated with a higher number of C alleles (baseline: p = 0.046; 1-month: p = 0.026; 6-months: p = 0.028). Moreover, a higher number of C alleles was significantly related to a greater risk for dyslipidemia (p = .016). Our results point to a relevance of FKBP5 in the association of the two stress-related diseases depression and CHD.

Length Polymorphisms in the Angiotensin I-Converting Enzyme Gene and the Serotonin-Transporter-Linked Polymorphic Region Constitute a Risk Haplotype for Depression in Patients with Coronary Artery Disease

Genetic variations affecting the course of depressive symptoms in patients with coronary artery disease (CAD) have not yet been well studied. Therefore, we set out to investigate whether distinct haplotypes of the two insertion/deletion polymorphisms in the serotonin-transporter-linked polymorphic region (5-HTTLPR) and the angiotensin I-converting enzyme (ACE) gene located on chromosome 17 can be identified as risk factors for trajectories of depression. Clinical and genotyping data were derived from 507 depressed CAD patients participating in the randomized, controlled, multicenter Stepwise Psychotherapy Intervention for Reducing Risk in Coronary Artery Disease (SPIRR-CAD) trial, of whom the majority had an acute cardiac event before study inclusion. Depression scores on the Hospital Anxiety and Depression Scale (HADS) were assessed at baseline and at five follow-up time points up to 2 years after study entrance. At baseline, depression scores did not significantly differ between patients carrying the risk haplotype ACE D/D, 5-HTTLPR I/I (n = 46) and the non-risk haplotypes (n = 461, 10.9 ± 2.7 versus 10.4 ± 2.5, p = 0.254). HADS-depression scores declined from study inclusion during the first year irrespective of the genotype. At each follow-up time point, HADS-depression scores were significantly higher in ACE D/D, 5-HTTLPR I/I carriers than in their counterparts. Two years after study inclusion, the mean HADS depression score remained 1.8 points higher in patients with the risk haplotype as compared to subjects not carrying this haplotype (9.9 ± 4.2 versus 8.1 ± 4.0, p = 0.009). In summary, the presence of the ACE D/D, 5-HTTLPR I/I haplotype may be a vulnerability factor for comorbid depressive symptoms in CAD patients.

Childhood Adversity Moderates the Effects of HTR2A Epigenetic Regulatory Polymorphisms on Rumination

The serotonin system has been suggested to moderate the association between childhood maltreatment and rumination, with the latter in its turn reported to be a mediator in the depressogenic effect of childhood maltreatment. Therefore, we investigated whether the associations of two epigenetic regulatory polymorphisms in the HTR2A serotonin receptor gene with Ruminative Responses Scale rumination and its two subtypes, brooding and reflection, are moderated by childhood adversity (derived from the Childhood Trauma Questionnaire) among 1,501 European white adults. We tested post hoc whether the significant associations are due to depression. We also tested the replicability of the significant results within the two subsamples of Budapest and Manchester. We revealed two significant models: both the association of methylation site rs6311 with rumination and that of miRNA binding site rs3125 (supposed to bind miR-1270, miR-1304, miR-202, miR-539 and miR-620) with brooding were a function of childhood adversity, and both interaction findings were significantly present both in the never-depressed and in the ever-depressed group. Moreover, the association of rs3125 with brooding could be replicated across the separate subsamples, and remained significant even when controlling for lifetime depression and the Brief Symptom Inventory depression score. These findings indicate the crucial importance of involving stress factors when considering endophenotypes and suggest that brooding is a more promising endophenotype than a broader measure of rumination. Transdiagnostic relevance of the brooding endophenotype and the potential of targeting epigenetic regulatory polymorphisms of HTR2A in primary and secondary prevention of depression and possibly of other disorders are also discussed.

The relationship of depressive symptoms and functional and structural markers of subclinical atherosclerosis: A systematic review and meta-analysis

Objectives

The relationship of depressive symptoms and subclinical atherosclerosis remains controversial. We performed a systematic review and meta-analysis to evaluate the effect of depressive symptoms on the functional and structural markers of subclinical atherosclerosis as measured by carotid intima-media thickness (IMT), pulse wave velocity (PWV) and flow-mediated vasodilation (FMD).

Methods

A systematic literature search was performed electronically. Studies relating IMT, PWV or FMD to depressive symptoms were included. Standard/weighted mean differences (SMD/WMD) and corresponding 95% confidence intervals (95% CIs) were pooled in overall and subgroup analyses (age, sex, depression diagnosis, region, study design, site measured and sample size). Sensitivity analysis and publication bias were also conducted.

Results

Thirty-eight articles involving 5947 patients with depressive symptoms and 34,423 controls without depressive symptoms were included. Compared with controls without depressive symptoms, patients with depressive symptoms showed a significantly thicker IMT (SMD (95% CI) = 0.137 (0.047–0.227), p = 0.003), a higher PWV (SMD (95% CI) = 0.216 (0.139–0.293), p < 0.001) and a lower FMD (WMD (95% CI) = –2.554 (–3.709 to –1.399), p < 0.001). When analyzing subgroups with age and female ratio, all results were still significant ( p < 0.05) except IMT and FMD in age < 50 years subgroups ( p > 0.05). There was no statistical significance in sensitivity analysis and publication bias ( p > 0.05).

Conclusions

Depressive symptoms contributed toward subclinical atherosclerosis, and resulted in impaired functional and structural markers of subclinical atherosclerosis, which holds great promise in early prevention of cardiovascular disease.

Evidence for Inflammation-Associated Depression

This chapter explores the evidence supporting inflammation-associated depression. Data to date suggest a bidirectional relationship between inflammation and depression wherein one process can drive the other. A wealth of animal and clinical studies have demonstrated an association between concentrations of pro-inflammatory cytokines - specifically interleukin (IL)-1β, IL-6, and tumor necrosis factor-α - and depressive symptoms. There is also evidence that this pro-inflammatory state is accompanied by aberrant inflammation-related processes including platelet activation factor hyperactivity, oxidative and nitrosative stress, and damage to mitochondria. These complex and interrelated mechanisms can collectively contribute to negative neurobiological outcomes that may, in part, underlie the etiopathology of depression. Mounting evidence has shown a concomitant reduction in both depressive symptoms and pro-inflammatory cytokine concentrations following treatment with pharmacological anti-inflammatory interventions. Taken together, the reviewed preclinical and clinical findings may suggest the existence of a distinct inflammatory subtype of depression in which these patients exhibit unique biochemical and clinical features and may potentially experience improved clinical outcomes with inflammation-targeted pharmacotherapy.

Genetic Contributions of Inflammation to Depression

This paper describes the effects of immune genes genetic variants and mRNA expression on depression's risk, severity, and response to antidepressant treatment, through a systematic review on all papers published between 2000 and 2016. Our results, based largely on case-control studies, suggest that common genetic variants and gene-expression pathways are involved in both immune activation and depression. The most replicated and relevant genetic variants include polymorphisms in the genes for interleukin (IL)-1β, IL-6, IL-10, monocyte chemoattractant protein-1, tumor necrosis factor-alpha, C-reactive protein, and phospholipase A2. Moreover, increased blood cytokines mRNA expression (especially of IL-1β) identifies patients that are less likely to respond to conventional antidepressants. However, even for the most replicated findings there are inconsistent results, not only between studies, but also between the immune effects of the genetic variants and the resulting effects on depression. We find evidence that these discrepant findings may be explained, at least in part, by the heterogeneity of the depression immunophenotype, by environmental influences and gene × environment interactions, and by the complex interfacing of genetic variants with gene expression. Indeed, some of the most robust findings have been obtained in patients developing depression in the context of treatment with interferon-alpha, a widely used model to mimic depression in the context of inflammation. Further 'omics' approaches, through GWAS and transcriptomics, will finally shed light on the interaction between immune genes, their expression, and the influence of the environment, in the pathogenesis of depression.

Environmental and genetic determinants of childhood depression: The roles of DAT1 and the antenatal environment

Research on adolescent and adult populations has linked depression to variation in several monoaminergic genes, but genetic association studies on depression in children are limited. Additionally, few studies have investigated whether stressors occurring very early in development moderate the influence of certain genes on depression. The aim of this study was to investigate whether single nucleotide polymorphisms (SNPs) from monoaminergic genes interacted with measures of early life stress to influence depressive symptoms in children. Participants were members of the Auckland Birthweight Collaborative cohort. Small for gestational age (SGA) and maternal stress during pregnancy were measured at birth and used as indicators of early life stress. At age 11, depressive symptoms were measured using the Centre for Epidemiological Studies Depression Scale for Children (CES-DC) and DNA samples were collected for genotyping. A two-way ANOVA revealed that SGA and a SNP from the dopamine transporter gene DAT1 had an interactive effect on children's depressive symptoms. Specifically, symptoms were greater in children born SGA who are T homozygous for the rs1042098 SNP. These findings suggest that adverse intrauterine environments leading to low birth weight also seem to exacerbate the effects of certain DAT1 variants on depression.

BDNF val66met polymorphism and depressive disorders in patients with acute coronary syndrome

INTRODUCTION

Brain-derived neurotrophic factor (BDNF) may be the key to understanding the development of depression in patients with acute coronary syndrome (ACS), as it is associated with both conditions. Because the expression of BDNF is influenced by genetic polymorphisms, in this study we investigated the association between the BDNF polymorphism val66met and both the risk of depression in ACS and the treatment response.

METHODS

Among the 969 patients with recent ACS at baseline, 711 were re-evaluated after 1 year of follow-up. Depressive disorder status was assessed according to the DSM-IV criteria both at baseline and at follow-up. Baseline prevalence, follow-up incidence, and the persistence of depression were also determined. Of the 378 patients diagnosed with depression at baseline, 255 were randomized to a 24-week double-blind placebo-controlled trial of escitalopram; the remaining 123 received the usual care. Associations between the BDNF val66met polymorphism and both depression status and treatment response were investigated using logistic regression models.

RESULTS

The prevalence and persistence, but not the incidence of depressive disorders were significantly associated with BDNF met alleles. Patients in the escitalopram group who carried the met allele had a significantly higher rate of remission than those who did not. Depressive disorders tended to persist at 1 year in patients managed with placebo or medical treatment only, and particularly those patients positive for BDNF met alleles, although the difference was not statistically significant.

LIMITATIONS

The generalizability should be considered since this study conducted in a single center.

CONCLUSIONS

ACS patients positive for BDNF met alleles are vulnerable to depressive disorders at baseline and to its persistence. Antidepressant treatment may be effective in this subgroup of patients and may prevent the persistence of depression.

Major Depressive Disorder and Bipolar Disorder Predispose Youth to Accelerated Atherosclerosis and Early Cardiovascular Disease: A Scientific Statement From the American Heart Association

In the 2011 "Expert Panel on Integrated Guidelines for Cardiovascular Health and Risk Reduction in Children and Adolescents," several medical conditions among youth were identified that predispose to accelerated atherosclerosis and early cardiovascular disease (CVD), and risk stratification and management strategies for youth with these conditions were elaborated. Major depressive disorder (MDD) and bipolar disorder (BD) among youth satisfy the criteria set for, and therefore merit inclusion among, Expert Panel tier II moderate-risk conditions. The combined prevalence of MDD and BD among adolescents in the United States is ≈10%, at least 10 times greater than the prevalence of the existing moderate-risk conditions combined. The high prevalence of MDD and BD underscores the importance of positioning these diseases alongside other pediatric diseases previously identified as moderate risk for CVD. The overall objective of this statement is to increase awareness and recognition of MDD and BD among youth as moderate-risk conditions for early CVD. To achieve this objective, the primary specific aims of this statement are to (1) summarize evidence that MDD and BD are tier II moderate-risk conditions associated with accelerated atherosclerosis and early CVD and (2) position MDD and BD as tier II moderate-risk conditions that require the application of risk stratification and management strategies in accordance with Expert Panel recommendations. In this scientific statement, there is an integration of the various factors that putatively underlie the association of MDD and BD with CVD, including pathophysiological mechanisms, traditional CVD risk factors, behavioral and environmental factors, and psychiatric medications.

Serum proteomic profiling of major depressive disorder

Much has still to be learned about the molecular mechanisms of depression. This study aims to gain insight into contributing mechanisms by identifying serum proteins related to major depressive disorder (MDD) in a large psychiatric cohort study. Our sample consisted of 1589 participants of the Netherlands Study of Depression and Anxiety, comprising 687 individuals with current MDD (cMDD), 482 individuals with remitted MDD (rMDD) and 420 controls. We studied the relationship between MDD status and the levels of 171 serum proteins detected on a multi-analyte profiling platform using adjusted linear regression models. Pooled analyses of two independent validation cohorts (totaling 78 MDD cases and 156 controls) was carried out to validate our top markers. Twenty-eight analytes differed significantly between cMDD cases and controls (P < 0.05), whereas 10 partly overlapping markers differed significantly between rMDD cases and controls. Antidepressant medication use and comorbid anxiety status did not substantially impact on these findings. Sixteen of the cMDD-related markers had been assayed in the pooled validation cohorts, of which seven were associated with MDD. The analytes prominently associated with cMDD related to diverse cell communication and signal transduction processes (pancreatic polypeptide, macrophage migration inhibitory factor, ENRAGE, interleukin-1 receptor antagonist and tenascin-C), immune response (growth-regulated alpha protein) and protein metabolism (von Willebrand factor). Several proteins were implicated in depression. Changes were more prominent in cMDD, suggesting that molecular alterations in serum are associated with acute depression symptomatology. These findings may help to establish serum-based biomarkers of depression and could improve our understanding of its pathophysiology.

Genetic Predictors of Depressive Symptoms in the Look AHEAD Trial

OBJECTIVES

Numerous studies have found elevated depressive symptoms among individuals with Type 2 diabetes, yet the mechanisms remain unclear. We examined whether genetic loci previously associated with depressive symptoms predict depressive symptoms among overweight/obese individuals with Type 2 diabetes or change in depressive symptoms during behavioral weight loss.

METHODS

The Illumina CARe iSelect (IBC) chip and Cardiometabochip were characterized in 2118 overweight or obese participants with Type 2 diabetes from Look AHEAD (Action for Health in Diabetes), a randomized trial to determine the effects of intensive life-style intervention and diabetes support and education on cardiovascular morbidity and mortality. Primary analyses focused on baseline Beck Depression Inventory (BDI) scores and depressive symptom change at 1 year.

RESULTS

Of eight single nucleotide polymorphisms (SNPs) in six loci, three a priori SNPs in two loci (chromosome 5: rs60271; LBR: rs2230419, rs1011319) were associated with baseline BDI scores, but in the opposite direction of prior research. In joint analysis of 90,003 IBC and Cardiometabochip SNPs, rs1543654 in the region of KCNE1 predicted change in BDI scores at Year 1 in diabetes support and education (β = -1.05, standard error [SE] = 0.21, p = 6.9 × 10(-7)) at the level of chip-wide significance, while also showing a nominal association with baseline BDI (β = 0.35, SE = 0.16, p = .026). Adjustment for antidepressant medication and/or limiting analyses to non-Hispanic white individuals did not meaningfully alter results.

CONCLUSIONS

Previously reported genetic associations with depressive symptoms did not replicate in this cohort of overweight/obese individuals with Type 2 diabetes. We identified KCNE1 as a potential novel locus associated with depressive symptoms.

An update on the interaction between the serotonin transporter promoter variant (5-HTTLPR), stress and depression, plus an exploration of non-confirming findings

In the three years since the most recent meta-analysis of the association between the serotonin transported promoter polymorphism (5-HTTLPR), stress and the development of depression, another 27 studies have been published on this issue, which is an increase of 50% more studies than were previously reviewed. In addition, previous findings of inconsistency of results across studies argued for further exploration of this relationship. From the 81 studies identified to June 2013, the significant relationship between the short form of the 5-HTTLPR was confirmed (p=.0000009), which is stronger than the relationship reported in the most recent meta-analysis in 2011. However, nearly 26% of the 81 studies reviewed failed to show any significant association between the 5-HTTLPR, stress and depression, and four studies found opposite results to those expected. Examination of the methodologies of all studies failed to indicate any flaws in the opposite or unequivocal studies, and the latter had larger sample sizes than those studies which supported the expected association, arguing that the null results were not an outcome of insufficient statistical power. The need to consider aspects of samples and measures of depression, particularly the presence of subtypes of depression in future research is discussed.

Depression as a risk factor for poor prognosis among patients with acute coronary syndrome: systematic review and recommendations: a scientific statement from the American Heart Association

BACKGROUND

Although prospective studies, systematic reviews, and meta-analyses have documented an association between depression and increased morbidity and mortality in a variety of cardiac populations, depression has not yet achieved formal recognition as a risk factor for poor prognosis in patients with acute coronary syndrome by the American Heart Association and other health organizations. The purpose of this scientific statement is to review available evidence and recommend whether depression should be elevated to the status of a risk factor for patients with acute coronary syndrome.

METHODS AND RESULTS

Writing group members were approved by the American Heart Association's Scientific Statement and Manuscript Oversight Committees. A systematic literature review on depression and adverse medical outcomes after acute coronary syndrome was conducted that included all-cause mortality, cardiac mortality, and composite outcomes for mortality and nonfatal events. The review assessed the strength, consistency, independence, and generalizability of the published studies. A total of 53 individual studies (32 reported on associations with all-cause mortality, 12 on cardiac mortality, and 22 on composite outcomes) and 4 meta-analyses met inclusion criteria. There was heterogeneity across studies in terms of the demographic composition of study samples, definition and measurement of depression, length of follow-up, and covariates included in the multivariable models. Despite limitations in some individual studies, our review identified generally consistent associations between depression and adverse outcomes.

CONCLUSIONS

Despite the heterogeneity of published studies included in this review, the preponderance of evidence supports the recommendation that the American Heart Association should elevate depression to the status of a risk factor for adverse medical outcomes in patients with acute coronary syndrome.

Depression and cardiovascular disorders

During the past two decades, research in the field of depression and cardiovascular disorders has exploded. Multiple studies have demonstrated that depression is more prevalent in populations with cardiovascular disease, is a robust risk factor for the development of cardiovascular disease in healthy populations, and is predictive of adverse outcomes (such as myocardial infarction and death) among populations with preexisting cardiovascular disease. Mechanistic studies have shown that poor health behaviors, such as physical inactivity, medication nonadherence, and smoking, strongly contribute to this association. Small randomized trials have found that antidepressant therapies may improve cardiac outcomes. Based on this accumulating evidence, the American Heart Association has recommended routine screening for depression in all patients with coronary heart disease. This review examines the key epidemiological literature on depression and cardiovascular disorders and discusses our current understanding of the mechanisms responsible for this association. We also examine current recommendations for screening, diagnosis, and management of depression. We conclude by highlighting new research areas and discussing therapeutic management of depression in patients with cardiovascular disorders.

Differential associations of depressive symptom dimensions with cardio-vascular disease in the community: results from the Gutenberg health study

A current model suggested that the somatic symptom dimension accounts for the adverse effect of depression in patients with coronary heart disease (CHD). In order to test this model we sought to determine in a large population-based sample how symptom dimensions of depression are associated with CHD, biomarkers and traditional risk factors. The associations of cognitive and somatic symptom dimensions of depression with CHD, risk factors, endothelial function, and biomarkers of inflammation and myocardial stress were analyzed cross-sectionally in a sample of n = 5000 Mid-Europeans aged 35–74 years from the Gutenberg Health Study (GHS). Only the somatic symptom dimension of depression was associated with CHD, biomarkers (inflammation, vascular function) and cardio-vascular risk factors. When multivariable adjustment was applied by demographic and cardiovascular risk factors, the weak associations of the somatic symptom dimension with the biomarkers disappeared. However, the associations of the somatic symptom dimension with CHD, myocardial infarction, obesity, dyslipidemia and family history of myocardial infarction remained. Both dimensions of depression were independently associated with a previous diagnosis of depression and distressed personality (type D). Thus, our results partly confirm current models: Somatic, but not cognitive-affective symptom dimensions are responsible for the association between depression and CHD, inflammation, vascular function and cardiovascular risk factors in the general population. However, our findings challenge the assumptions that somatic depression might be due to inflammation or vascular dysfunction as consequence of progressed atherosclerotic disease. They rather emphasize a close interplay with life-style factors and with a family history of MI.

The role of immune genes in the association between depression and inflammation: a review of recent clinical studies

The role for dysregulation of the immune system in the pathogenesis of depressive disorder is well established, and emerging research suggests the role of an underlying genetic vulnerability. The purpose of this review is to summarize the existing literature on the genetic variants involved in neurobiological pathways associated with both immune activation and depression. Using PubMed, Scopus, The Cochrane Library, Embase, Ovid of Medline, PsycINFO and ISI web of Knowledge, we selected 52 papers which are relevant for this literature review. Findings across the literature suggest that functional allelic variants of genes for interleukin-1beta (IL)-1β, tumor necrosis factor-alpha (TNF-α) and C-reactive protein (CRP), as well as genetic variations affecting T-cell function, may increase the risk for depression. Moreover, single nucleotide polymorphisms (SNPs) in the IL-1β, IL-6 and IL-11 genes, and in those regulating T-cell function may be associated with reduced responsiveness to antidepressant therapy. There is also some evidence indicative of a role of genetic variants of the enzymes, Cyclo-oxygenase2 (COX-2) and Phospholipase2 (PLA2), in the aetiology of depression. Finally, SNPs in genes related to the serotonin pathway may play a fundamental role in the shared genetic liability to both immune activation and depressive symptoms. Our review confirms that genetic variants influence the biological mechanisms by which the innate immune system contributes to the development of depression. However, future studies are necessary to identify the molecular mechanisms underlying these associations.

Review on depression and coronary heart disease

The impact of psychological factors on somatic disorders - and vice versa - and the involvement of biological mechanisms in psychic disorders have generated considerable interest in recent years, notably thanks to cutting-edge investigation techniques (immunohistochemistry, functional imaging, genetics, etc.). In the field of psychosomatics, coronary heart disease (CHD) is a frequent co-morbidity of mental disorders, particularly mood disorders. Indeed, there is a bidirectional relationship between CHD and mood disorders, with a strong co-occurrence of the two diseases accompanied by a reciprocal worsening of the prognosis for the two conditions. Various epidemiological studies have shown that depression is a psychic risk factor for CHD and that CHD is present in almost 30% of patients with affective disorders. In this review of the literature, we tackle the crucial question of the diagnosis of depression during myocardial infarction. This clinical approach is essential given the underevaluation of this psychic problem. Then, various psychological, biological and genetic arguments are presented in support of the hypothesis that various aetiological mechanisms of the two disorders are partly shared. We finally deal with the treatment of depression in the context of CHD with its pharmacological and psychological specificities. In conclusion, this review reiterates the need for a multidisciplinary approach, which is necessary to understand, diagnose and then treat this frequent co-morbid condition of heart disease and depression.

Heartache and heartbreak--the link between depression and cardiovascular disease

The close, bidirectional relationship between depression and cardiovascular disease is well established. Major depression is associated with an increased risk of coronary artery disease and acute cardiovascular sequelae, such as myocardial infarction, congestive heart failure, and isolated systolic hypertension. Morbidity and mortality in patients with cardiovascular disease and depression are significantly higher than in patients with cardiovascular disease who are not depressed. Various pathophysiological mechanisms might underlie the risk of cardiovascular disease in patients with depression: increased inflammation; increased susceptibility to blood clotting (owing to alterations in multiple steps of the clotting cascade, including platelet activation and aggregation); oxidative stress; subclinical hypothyroidism; hyperactivity of the sympatho-adrenomedullary system and the hypothalamic-pituitary-adrenal axis; reductions in numbers of circulating endothelial progenitor cells and associated arterial repair processes; decreased heart rate variability; and the presence of genetic factors. Early identification of patients with depression who are at risk of cardiovascular disease, as well as prevention and appropriate treatment of cardiovascular disease in these patients, is an important and attainable goal. However, adequately powered studies are required to determine the optimal treatment regimen for patients with both depression and cardiovascular disorders.

Incidence rates and predictors of major and minor depression in patients with heart failure

AIMS

Depression is common in heart failure (HF) and associated with adverse outcomes. This study aimed to investigate incidence rates and predictors of depression in patients sampled from four subprojects of the German Competence Network Heart Failure.

METHODS

Eight hundred thirty nine symptomatic HF patients free of depression at baseline underwent repeat depression screening (Patient Health Questionnaire, PHQ-9) after 12 months. Ordered logistic regression analysis was employed to search for predictors of incident depression.

RESULTS

Incident minor (major) depression was observed in 61 (7.3%) and 47 (5.6%) of the population. Depression was recurrent in 15 (25%) and 16 (34%), respectively. Multiple regression analysis revealed seven variables predicting minor or major depression: Previous depressive episode (odds ratio [OR] 4.04, 95% confidence interval [CI] 2.37-6.89, p ≤ 0.001), previous resuscitation (OR 2.44, CI 1.23-4.81, p=0.010), current smoking (OR 2.06, CI 1.08-3.50, p=0.008), >4 visits/year to general practitioner (OR 1.67, CI 1.06-2.63, p=0.026), New York Heart Association class (OR 1.54/class, 95% CI 1.05-2.25, p=0.027), PHQ-9 baseline sum-score (OR 1.18/point, CI 1.11-1.27, p<0.001), and SF-36 physical functioning (OR 1.08/-5 points, CI 1.03-1.13, p=0.002).

CONCLUSIONS

In these HF patients initially free of depression annual incidence rates were high. Several independent predictors allowed identification of patients at particular risk. Although obtained in a selected cohort these findings call, in view of the grave prognosis of HF patients with comorbid depression, for regular depression screening and development of specific supportive strategies to improve patient care and outcomes in HF.

Serotonergic and BDNF genes associated with depression 1 week and 1 year after mastectomy for breast cancer

OBJECTIVE

Polymorphisms of serotonin transporter (5-HTT) and brain-derived neurotrophic factor (BDNF) genes have been investigated as candidate genes for depression occurring in medical disorders. The serotonin 2a receptor (5-HTR2a) genes have been investigated as risk factors for depression but rarely in combination with medical conditions. This study aimed to investigate whether polymorphisms of interest in 5-HTT, 5-HTR2a, and BDNF genes are associated with depression after mastectomy for breast cancer.

METHODS

A total of 309 patients with breast cancer were evaluated 1 week after mastectomy, and 244 patients (79%) were followed up 1 year later. Depression (major and minor depressive disorders) was diagnosed according to DSM-IV criteria using the Mini-International Neuropsychiatric Interview and was classified into prevalent, persistent, and incident depression. Individual associations with 5-HTT gene-linked promoter region, serotonin transporter intron 2 variable number tandem repeat, 5-HTR2a 1438A/G, 5-HTR2a 102T/C, and BDNF Val66Met polymorphisms were estimated using logistic regression models, and gene-gene interactions were investigated using the generalized multifactor dimensionality reduction method.

RESULTS

At baseline, 74 patients (24%) were classified with prevalent depression, and at follow-up, 19 patients (8%) and 25 patients (10%) were classified with persistent and incident depression, respectively. The BDNF Met/Met genotype was independently associated with prevalent (odds ratio = 2.63, 95% confidence interval = 1.12-6.14) and persistent (odds ratio = 8.07, 95% confidence interval = 1.26-51.6) depression. No associations with 5-HTT and 5-HTR2a genes (all p values > .21) were found, and no significant gene-gene interactions were identified (all p values > .36).

CONCLUSIONS

Our findings support a role of BDNF, not serotonin, in the etiology of depression occurring in women with breast cancer who received a mastectomy.

Serotonin, depression, and cardiovascular disease: sex-specific issues

The comorbidity of cardiovascular disease (CVD) and depression/anxiety disorders is well established, but the mechanisms are not well understood. This paper will review the epidemiological and biological evidence for the role of depression in CVD, as well as the pathophysiological process underlying both depression and CVD. The focus will be on the roles of serotonin, platelets, and the immune system, with an emphasis on the relevance of sex differences in both depression/anxiety and CVD as they pertain to women.

Gene-environment interactions in geriatric depression

In older adults, several environmental challenges can potentially trigger the onset of an episode of major depression. Vulnerability to these challenges can be influenced by genetics. There is accumulating evidence for an interaction between stress and a serotonin transporter polymorphism, though there is also heterogeneity among studies. Other relevant genes include those encoding for the neuroendocrine stress axis, growth factors, and other monoaminergic systems. Each of these may interact with either predisposing traumas in early childhood or precipitating events later in life.

A topographical map of the causal network of mechanisms underlying the relationship between major depressive disorder and coronary heart disease

OBJECTIVE

Major depressive disorder (MDD) and coronary heart disease (CHD) are both clinically important public health problems. Depression is linked with a higher incidence of ischaemic cardiac events and MDD is more prevalent in patients with CHD. No single comprehensive model has yet described the causal mechanisms linking MDD to CHD. Several key mechanisms have been put forward, comprising behavioural mechanisms, genetic mechanisms, dysregulation of immune mechanisms, coagulation abnormalities and vascular endothelial dysfunction, polyunsaturated omega-3 free fatty acid deficiency, and autonomic mechanisms. It has been suggested that these mechanisms form a network, which links MDD and CHD. The aim of this review is to examine the causal mechanisms underlying the relationship between MDD and CHD, with the aim of constructing a topological map of the causal network which describes the relationship between MDD and CHD.

METHODS

The search term 'depression and heart disease' was entered into an electronic multiple database search engine. Abstracts were screened for relevance and individually selected articles were collated.

RESULTS

This review introduces the first topological map of the causal network which describes the relationship between MDD and CHD.

CONCLUSIONS

Viewing the causal pathways as an interdependent network presents a new paradigm in this field and provides fertile ground for further research. The causal network can be studied using the methodology of systems biology, which is briefly introduced. Future research should focus on the creation of a more comprehensive topological map of the causal network and the quantification of the activity between each node of the causal network.

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

CONTEXT

Two recent meta-analyses assessed the set of studies exploring the interaction between a serotonin transporter promoter polymorphism (5-HTTLPR) and stress in the development of depression and concluded that the evidence did not support the presence of the interaction. However, even the larger of the meta-analyses included only 14 of the 56 studies that have assessed the relationship between 5-HTTLPR, stress, and depression.

OBJECTIVE

To perform a meta-analysis including all relevant studies exploring the interaction.

DATA SOURCES

We identified studies published through November 2009 in PubMed.

STUDY SELECTION

We excluded 2 studies presenting data that were included in other larger studies.

DATA EXTRACTION

To perform a more inclusive meta-analysis, we used the Liptak-Stouffer z score method to combine findings of primary studies at the level of significance tests rather than the level of raw data.

DATA SYNTHESIS

We included 54 studies and found strong evidence that 5-HTTLPR moderates the relationship between stress and depression, with the 5-HTTLPR s allele associated with an increased risk of developing depression under stress (P = .00002). When stratifying our analysis by the type of stressor studied, we found strong evidence for an association between the s allele and increased stress sensitivity in the childhood maltreatment (P = .00007) and the specific medical condition (P = .0004) groups of studies but only marginal evidence for an association in the stressful life events group (P = .03). When restricting our analysis to the studies included in the previous meta-analyses, we found no evidence of association (Munafò et al studies, P = .16; Risch et al studies, P = .11). This suggests that the difference in results between meta-analyses was due to the different set of included studies rather than the meta-analytic technique.

CONCLUSION

Contrary to the results of the smaller earlier meta-analyses, we find strong evidence that the studies published to date support the hypothesis that 5-HTTLPR moderates the relationship between stress and depression.

Current developments and controversies: does the serotonin transporter gene-linked polymorphic region (5-HTTLPR) modulate the association between stress and depression?

PURPOSE OF REVIEW

Human observational studies have shown that, in interaction with life stress, the short or S-allele of the serotonin transporter gene-linked polymorphic region (5-HTTLPR) is associated with an enhanced risk for depression. However, this gene-by-environment interaction (G×E) has recently been questioned by two meta-analyses. We aim to provide an overview and appraisal of recent developments and controversies.

RECENT FINDINGS

The statistical approach of the meta-analyses aimed at a very strict replication of the initial finding and, accordingly, included only a minority of all available studies. Furthermore, the negative results of the meta-analyses appear to be predominantly driven by a few large studies that used retrospective, self-report measures of life stress. In contrast, among 19 studies using interview-based or more objective measures of stress, there were 13 replications, five part-replications and only one nonreplication. Finally, a broader approach based on evidence from different research fields and methodologies supports a 5-HTTLPR by stress interaction.

SUMMARY

Whereas there is no doubt that the meta-analyses are methodologically sound, it appears that this technique is only in part suitable for appraising all of the available evidence. Furthermore, convergent evidence is accumulating from different research fields that 5-HTTLPR is indeed closely associated with different biological pathways associated with stress regulation and depression.

The impact of depression in heart disease

Depression and heart disease affect millions of people worldwide. Studies have shown that depression is a significant risk factor for new heart disease and that it increases morbidity and mortality in established heart disease. Many hypothesized and studied mechanisms have linked depression and heart disease, including serotonergic pathway and platelet dysfunction, inflammation, autonomic nervous system and hypothalamic-pituitary-adrenal axis imbalance, and psychosocial factors. Although the treatment of depression in cardiac patients has been shown to be safe and modestly efficacious, it has yet to translate into reduced cardiovascular morbidity and mortality. Understanding the impact and mechanisms behind the association of depression and heart disease may allow for the development of treatments aimed at altering the devastating consequences caused by these comorbid illnesses.