The role of inflammatory markers in explaining the association between depression and cardiovascular hospitalisations

Inflammatory depression is associated with selective glomerular hypofiltration

BACKGROUND

Systemic low-grade inflammation may be a pathophysiological mechanism in a subtype of depression. In this study we investigate a novel candidate mechanism of inflammatory depression - Selective Glomerular Hypofiltration Syndromes (SGHS) - which are characterized by a reduced estimated glomerular filtration rate (eGFR) based on cystatin C (cysC) relative to eGFR based on creatinine (crea). SGHS have been associated with increased blood levels of pro-inflammatory markers, but have never been investigated in a sample of depressed individuals.

METHOD

The prevalence of SGHS was compared between 313 patients with difficult-to-treat depression and 73 controls. Since there is no single established eGFRcysC/eGFRcrea-ratio cut-off to define SGHS, several cut-offs were investigated in relation to a depression diagnosis, inflammation, and symptom severity. Plasma inflammatory markers tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), interleukin (IL)-6, IL-8, and IL-10 were available from 276 depressed patients. We examined mediation effects of IL-6 on the relationship between SGHS and depression.

RESULTS

Depressed patients were more likely to have SGHS compared to controls defining SGHS as either eGFRcysC/eGFRcrea-ratio < 0.9 (33.2 % vs 20.5 %, p = 0.035) or < 0.8 (15.7 % vs 5.5 %, p = 0.023). Lower eGFRcysC/eGFRcrea-ratio was associated with higher levels of inflammatory markers in depressed patients. IL-6 partly mediated the relationship between SGHS and depression.

CONCLUSION

This is the first study to demonstrate a link between SGHS and inflammatory depression. If replicated in independent and longitudinal cohorts, this may prove to be a relevant pathophysiological mechanism in some cases of depression that could be targeted in future intervention and prevention studies.

Mediation of the association between depression and coronary heart disease by metabolic syndrome components

BACKGROUND

Depression is associated with incident coronary heart disease (CHD) via a pathway that may be causal, but the mechanisms underlying this association are unclear. We assessed the extent to which metabolic syndrome (MetS) and its components (i.e., elevated waist circumference, low high-density lipoprotein [HDL] cholesterol, elevated triglycerides, elevated blood pressure, and elevated fasting plasma glucose) may mediate this association.

METHODS

Data were Framingham Heart Study Research Materials obtained from the National Heart, Lung, and Blood Institute (NHLBI) Biologic Specimen and Data Repository Information Coordinating Center. We used Cox proportional hazards regression to estimate adjusted hazard ratios (aHR) representing the total effect (aHRTE) of probable depression, measured via the Centers for Epidemiological Studies - Depression scale, on incident CHD over approximately 18 years. Using inverse odds ratio weighting, we decomposed this estimate into natural direct effects (aHRNDE) and natural indirect effects (aHRNIE) through potential mediators (measured approximately three years after depression).

RESULTS

Probable depression was associated with incident CHD (aHRTE=1.45, 95% confidence interval [CI]: 0.93, 2.25), and elevated waist circumference partially mediated this association (aHRNDE=1.34, 95% CI: 0.76-2.32; aHRNIE=1.08, 95% CI: 0.63-1.91). We did not find evidence of additional mediation by additional MetS components.

CONCLUSIONS

Elevated waist circumference appears to play a role in the association between depression and CHD.

Mediation of the Association Between Vascular Risk Factors and Depressive Symptoms by C-Reactive Protein

Background

This study examined whether C-reactive protein (CRP), a marker of low-grade systemic inflammation, mediates the association between vascular risk factor (VRF) burden and depressive symptoms.

Methods

We drew on the prospective design of the UK Biobank to include participants with longitudinal data on VRF burden, CRP, and depressive symptoms. Total, direct, and indirect effects were estimated using regression-based mediation models while controlling for confounding by sociodemographic factors, baseline CRP, and baseline depression. Sensitivity analyses probed the robustness of results to unmeasured confounding.

Results

We analyzed data from 10,470 participants from the UK Biobank (mean age = 56.75 years at baseline). Net of covariates, VRFs at baseline were associated with higher depressive symptoms at follow-up (total effect = 0.099; 95% CI, 0.002-0.163). CRP mediated this association (indirect effect = 0.010; 95% CI, 0.004-0.017), accounting for 10.0% (95% CI, 0.3%-30.0%) of the total effect of VRF burden on depressive symptoms. Exploratory analyses suggested that the total and indirect effects pertained to somatic depressive symptoms (tiredness and appetite).

Conclusions

These results suggest that inflammation-promoting effects of VRFs may contribute to depressive symptoms in mid- and later life. However, the mediating pathway via CRP explains only a small part of the association between VRFs and depression after accounting for important covariates and may pertain to specific depressive symptoms. Future studies leveraging similar longitudinal designs are needed to further disentangle the time-varying effects between VRFs, inflammation, and certain depressive symptoms while addressing important confounders.

New Perspectives on Treatment of Depression in Coronary Heart Disease

ABSTRACT

It has been 35 years since we published a study in Psychosomatic Medicine showing that patients with coronary heart disease (CHD) and major depression were at twice the risk of having a cardiac event as were nondepressed patients (Carney et al. Psychosom Med. 1988;50:627-33). This small study was followed a few years later by a larger, more convincing report from Frasure-Smith et al. (JAMA. 1993;270:1819-25) showing that depression increased the rate of mortality in patients with a recent acute myocardial infarction. Since the 1990s, there have been many more studies of depression as a risk factor for cardiac events and cardiac-related mortality from all over the world, and many clinical trials designed to determine whether treating depression improves medical outcomes in these patients. Unfortunately, the effects of depression treatment in patients with CHD remain unclear. This article considers why it has been difficult to determine whether treatment of depression improves survival in these patients. It also proposes several lines of research to address this question, with the goal of definitively establishing whether treating depression can extend cardiac event-free survival and enhance quality of life in patients with CHD.

Irrational beliefs, depression and anxiety, in relation to 10-year cardiovascular disease risk: the ATTICA Epidemiological Study

BACKGROUND AND OBJECTIVES

Various bio-psychosocial mechanisms underlying the link between anxiety, depression and cardiovascular disease risk, remain unknown. We investigated the role of irrational beliefs in conjunction with anxiety and depression in the 10-year cardiovascular disease (CVD) incidence, and the effect of biochemical and socio-behavioral factors.

DESIGN

853[453 men (45 ± 13 years) and 400 women (44 ± 18 years)] from the ATTICA study (2002-2012) and without evidence of CVD were assessed.

METHODS

The Irrational Beliefs Inventory (IBI), the Zung Self-Rating-Depression-Scale (ZDRS) and the State-Trait-Anxiety-Inventory (STAI) were used for the assessments. Incidence of CVD was defined according to the International Coding Diseases (ICD)-10 criteria.

RESULTS

Participants with high irrational beliefs and anxiety symptoms had a 138% greater risk of developing CVD during the 10-year follow-up (2.38; 95%CI 1.75, 3.23) as compared to those without anxiety. Among others, C-reactive protein, interleukin-6 and total antioxidant capacity were mediators in the tested association. Interaction of irrational beliefs and depression was not associated with the 10-year CVD in all models.

CONCLUSIONS

Inflammation and oxidative stress, partially explained the associations between irrational beliefs and anxiety in predicting CVD risk. These findings advance psychological research in the area of primary prevention of mental health and cardiovascular diseases.

Longitudinal association between cardiovascular risk factors and depression in young people: a systematic review and meta-analysis of cohort studies

BACKGROUND

Depression is a common and serious mental illness that begins early in life. An association between cardiovascular disease (CVD) and subsequent depression is clear in adults. We examined associations between individual CVD risk factors and depression in young people.

METHODS

We searched MEDLINE, EMBASE, and PsycINFO databases from inception to 1 January 2020. We extracted data from cohort studies assessing the longitudinal association between CVD risk factors [body mass index (BMI), smoking, systolic blood pressure (SBP), total cholesterol, high-density lipoprotein] and depression, measured using a validated tool in individuals with mean age of 24 years or younger. Random effect meta-analysis was used to combine effect estimates from individual studies, including odds ratio (OR) for depression and standardised mean difference for depressive symptoms.

RESULTS

Based on meta-analysis of seven studies, comprising 15 753 participants, high BMI was associated with subsequent depression [pooled OR 1.61; 95% confidence interval (CI) 1.21-2.14; I2 = 31%]. Based on meta-analysis of eight studies, comprising 30 539 participants, smoking was associated with subsequent depression (pooled OR 1.73; 95% CI 1.36-2.20; I2 = 74%). Low, but not high, SBP was associated with an increased risk of depression (pooled OR 3.32; 95% CI 1.68-6.55; I2 = 0%), although this was based on a small pooled high-risk sample of 893 participants. Generalisability may be limited as most studies were based in North America or Europe.

CONCLUSIONS

Targeting childhood/adolescent smoking and obesity may be important for the prevention of both CVD and depression across the lifespan. Further research on other CVD risk factors including blood pressure and cholesterol in young people is required.

Myeloperoxidase as a Potential Biomarker of Acute-Myocardial-Infarction-Induced Depression and Suppression of the Innate Immune System

While myeloperoxidase (MPO) serves as an indicator of both neutrophil and innate-immune-system function, the potential suppression of the innate immune system in patients with acute myocardial infarction (AMI)-induced depression might be evidenced by a decrease in MPO serum levels. The aim of this prospective study was to (1) determine whether serum concentrations of MPO vary immediately and 6 months after AMI and (2) to investigate whether MPO concentrations at the time of the AMI are significant predictors of AMI-induced depression and the depression-associated suppression of the innate immune system. A total of 109 AMI patients were assessed with the Hamilton Depression Scale (HAMD-17) immediately after admission to the hospital and 6 months later. The MPO status was assessed with serum samples, which were also collected immediately and 6 months after AMI. The depressive patients showed significantly lower MPO blood levels immediately and 6 months after the AMI compared to the patients without depression (ANCOVA: MPO (depression) F = 4.764, df = 1, p = 0.031). The baseline MPO was observed as a significant predictor (p = 0.027) of AMI-induced depression 6 months after AMI. MPO is a potential biomarker for AMI-induced depression, indicating a depression-associated suppression of the innate immune system.

Role of leukocytes, gender, and symptom domains in the influence of depression on hospitalization and mortality risk: Findings from the Moli-sani study

Background

Major depressive disorder is a mental illness associated with chronic conditions like cardiovascular disease (CVD). Circulating inflammation has been proposed as a potential mechanism underlying this link, although the role of specific biomarkers, gender, and symptom domains is not well elucidated.

Methods

We performed multivariable Cox regressions of first hospitalization/all-cause mortality and CVD, ischemic heart (IHD), and cerebrovascular disease (CeVD) causes vs. depression severity in an Italian population cohort (N = 13,191; age ≥ 35 years; 49.3% men; 4,856 hospitalizations and 471 deaths, median follow-up 7.28 and 8.24 years, respectively). In models adjusted for age, sex, and socioeconomic status, we estimated the proportion of association explained by C-reactive protein (CRP), platelet count, granulocyte-to-lymphocyte ratio (GLR), and white blood cell count (WBC). Gender-by-depression interaction and gender-stratified analyses were performed. Associations of polychoric factors tagging somatic and cognitive symptoms with incident clinical risks were also tested, as well as the proportion explained by a composite index of circulating inflammation (INFLA score).

Results

Significant proportions of the influence of depression on clinical risks were explained by CRP (4.8% on IHD hospitalizations), GLR (11% on all-cause mortality), and WBC (24% on IHD/CeVD hospitalizations). Gender-by-depression interaction was significantly associated only with all-cause mortality (p = 0.03), with moderate depression showing a + 60% increased risk in women, but not in men. Stable associations of somatic, but not of cognitive, symptoms with increased hospitalization risk were observed (+ 16% for all causes, + 14% for CVD causes), with INFLA score explaining small but significant proportions of these associations (2.5% for all causes, 8.6% for IHD causes).

Conclusions

These findings highlight the importance of cellular components of inflammation, gender, and somatic depressive symptoms in the link between depression and clinical (especially CVD) risks, pointing to the existence of additional pathways through which depression may play a detrimental effect on the cardiovascular system.

Does inflammation mediate the effects of depression on heart disease? That may depend on the symptoms

Preparation of this manuscript was supported in part by grant number R01HL089336 from the National Heart, Lung, and Blood Institute of the National Institutes of Health, Bethesda, Maryland USA, Robert M. Carney.

Direction of association between Cardiovascular risk and depressive symptoms during the first 18 years of life: A prospective birth cohort study

BACKGROUND

Cardiovascular disease (CVD) and depression are bidirectionally associated in adults. However, the direction of association between CVD risk and depressive symptoms in young people and potential mechanisms are poorly understood.

METHODS

Using longitudinal birth cohort data, we created a CVD risk score age at 15 using age, ethnicity, physical activity, maternal social status, maternal smoking, own smoking, BMI, systolic blood pressure, LDL, HDL and triglycerides. We used regression analysis to test: (1) association between CVD risk score at age 15 and depressive symptoms at ages 12 and 18; (2) association of IL-6 and CRP at age 9 with depressive symptoms at age 12 and CVD risk score at age 15; and (3) mediating effects of CVD risk score on associations of IL-6/CRP at age 9 with depressive symptoms at age 18.

RESULTS

The risk set comprised 5007 participants. CVD risk score in mid-adolescence was associated with depressive symptoms in early-adulthood (adjusted beta=0.06; standard error (SE)=0.02; p<0.001). Depressive symptoms in childhood were not associated with CVD risk score in mid-adolescence (adjusted beta=0.03; SE=0.02; p=0.11). Childhood inflammatory markers were associated with CVD risk score in mid-adolescence. Adolescent CVD risk score mediated the associations between childhood inflammatory markers and depressive symptoms in early-adulthood.

LIMITATIONS

The cohort primarily comprises White individuals, limiting generalisability. Sample attrition required imputation for missing data.

CONCLUSIONS

Association between CVD risk and depression in childhood/adolescence is unidirectional, with higher CVD risk increasing the risk of depressive symptoms. Childhood inflammation may increase risk of depression by influencing adolescent CVD risk.

White blood cell count as a mediator of the relationship between depressive symptoms and all-cause mortality: A community-based cohort study

BACKGROUND AND OBJECTIVES

One possible pathway by which depressive symptoms influence all-cause mortality is through their relationship with markers of inflammatory response. We aimed to examine whether white blood cell (WBC) count mediated the relationship between the presence of depressive symptoms and all-cause mortality among older Chinese people.

METHODS

This community-based cohort study targeted 4053 individuals aged 60 years or over. A bootstrapping approach was applied to examine whether WBC count mediated the relationship between the presence of depressive symptoms and all-cause mortality. WBC count was evaluated as a mediator. The presence of depressive symptoms was assessed by the nine-item Patient Health Questionnaire (PHQ-9). The mediating effect was considered significant if the 95% confidence interval (CI) did not include 0.

RESULTS

Mediation analysis indicated that WBC count played an important mediating role in the relationship between PHQ-9 score and all-cause mortality based on the significance of indirect effect (β = -0.0039, 95% CI = -0.01, -0.0009). The direct effect from PHQ-9 score to all-cause mortality was not statistically significant (P = 0.11) after adjusting for WBC count.

CONCLUSION

WBC count was associated with depressive symptoms and all-cause mortality. The association of depressive symptoms with all-cause mortality was fully mediated by WBC count.

Combined influence of depression severity and low-grade inflammation on incident hospitalization and mortality risk in Italian adults

BACKGROUND

Depression and low-grade systemic inflammation are associated risk factors for hospitalizations and mortality, although the nature of this relationship is under-investigated.

METHODS

We performed multivariable Cox regressions of first hospitalization/mortality for all and specific causes vs depression severity, in an Italian population cohort (N=13,176; age≥35 years; 49.4% men), incrementally adjusting for sociodemographic, health and lifestyle factors. We tested potential mediation, additive and interactive effects of INFLA-score, a composite circulating inflammation index, and potential concurrent mediations of main lifestyles and chronic conditions.

RESULTS

Over 4,856 hospitalizations (median follow-up 7.28 years), we observed an increased incident risk of events by 24% (CI=17-32%) and 59% (30-90%) for moderate and severe depression, which also showed a 125% (33-281%) increased risk of all-cause mortality (over 471 deaths, 8.24 years). These remained stable after adjustment for lifestyles, health conditions and INFLA-score, which explained 2.1%, 7.6%, 16.3% and 8%, 14.9% and 12% of depression influence on hospitalizations and mortality risk, respectively. These proportions remained substantially stable after reciprocal adjustments. INFLA-score showed significant additive (but not interactive) effects on both hospitalizations and mortality risk.

LIMITATIONS

Depression severity was defined using a sub-version of Patient Health Questionnaire 9, which was validated here. Directionality links among exposures could not be established since they were collected simultaneously.

CONCLUSIONS

These findings suggest a combined influence of depression and low-grade inflammation on health, which is partly intertwined and dependent on lifestyles and chronic conditions. This suggests the existence of pathways other than inflammation through which depression may play its detrimental effect.

Sex- and Gender-Stratified Risks of Psychological Factors for Incident Ischemic Heart Disease: Systematic Review and Meta-Analysis

Background

Psychological factors are associated with an increased risk of developing ischemic heart disease (IHD). Women more often report psychological factors, and sex and gender differences are present in IHD. In this meta‐analysis we examine the risks of psychological factors for IHD incidence in women and men. We hypothesize that a broad range of psychological factors are related to a higher risk for incident IHD, with a higher risk for women.

Methods and Results

PubMed, EMBASE, and PsycINFO were searched for studies assessing the risk between psychological factors and incident IHD. Psychological factors included depression, anxiety or panic disorder, social support, hostility, anger, personality (type D), type A behavior pattern, posttraumatic stress disorder, and psychological distress. In the primary analyses, 62 studies (77 separate reports) that included 2 145 679 women and 3 119 879 men and reported confounder‐adjusted hazard ratios or relative risks were included. Pooled effect confounder‐adjusted estimates from random‐effects models showed that psychological factors (all combined) were associated with incident IHD in women (hazard ratio: 1.22; 95% CI, 1.14–1.30) and men (hazard ratio: 1.25; 95% CI, 1.19–1.31). No sex and gender differences were found for these pooled effect estimates (P=0.547).

Conclusions

Psychological factors are associated with incident IHD in both women and men, but no significant differences were observed between women and men. IHD is predominantly being studied as obstructive coronary artery disease, which is more prevalent in men. Data are needed on psychological predictors and other manifestations of IHD such as coronary microvascular disease, which is more common in women.

Does physical activity influence the association between depressive symptoms and low-grade inflammation in adults? A study of 8,048 adults

This study investigated whether physical activity (PA) influences the association between depression risk and low-grade inflammation. This was a cross-sectional study including 8,048 adults (18-59y). Depression symptoms were evaluated with the Beck depression inventory (BDI) and physical activity through the international physical activity questionnaire. Adults with infectious and inflammatory diseases were excluded. Blood samples were collected, including high sensitivity C-reactive protein (CRP), a marker of low-grade inflammation when ≥3mg/L. Additional measures of LDL-C, HDL-C, triglycerides and fasting glucose were also determined. Sex, chronological age, tobacco smoking, alcohol drinking, body mass index, dyslipidemia, high blood pressure and fasting glucose were used as covariates. Mediation models were conducted using the procedures of Karlson Holm Breen. Adults with elevated CRP (≥3mg/L) compared to those with low CRP (<3mg/L) presented with higher BDI scores [8.5%(95%CI:7.2%-10.1%) vs. 5.8%(95%CI:5.2-6.4)] as well as higher prevalence of physical inactivity 67.4% (95%CI:64.9-69.9) vs. 59.7% (95%CI:58.4-60.9). The prevalence of elevated CRP was highest in physically inactive adults with greater depression risk. Models revealed that physical activity risk explained 13% of the association between depression risk and elevated CRP (p=0.035), independently of potential confounders. Physical activity may reduce the association between depression symptoms and elevated CRP. Future longitudinal research is required to determine the directionality of the relationships observed.

Depression and cardiovascular disease: Shared molecular mechanisms and clinical implications

Depression is a highly prevalent risk factor for both the onset of cardiovascular disease (CVD) and the mortality of CVD patients, and people suffering from CVD are more likely to develop depression than healthy individuals. The aim of this review is to summarize recent findings regarding the underlying relationship between CVD and depression. Literature search and review were conducted using PubMed, Google Scholar, Wanfang Med Online, and Baidu Scholar databases. CVD and depression are intimately related and researchers from around the world have proposed and validated various mechanisms that may potentially explain the comorbidity of CVD and depression. Recent studies have suggested that depression and CVD may manifest as two distinct clinical conditions in two different organs, the brain and the heart, respectively, but may also be linked by shared mechanisms. Of these, inflammation involving the immune system is thought to be a common mechanism of depression and heart disease, with specific inflammatory cytokines or pathways being potential targets for the prevention and treatment of the concurrent diseases. Therefore, inflammation may play an important role in bridging the link between depression and CVD, a finding that can have important clinical implications for the prevention and early intervention of these conditions.

Combined influence of depressive symptoms and systemic inflammation on all-cause and cardiovascular mortality: evidence for differential effects by gender in the English Longitudinal Study of Ageing

BACKGROUND

Depressive symptoms and inflammation are risk factors for cardiovascular disease (CVD) and mortality. We investigated the combined association of these factors with the prediction of CVD and all-cause mortality in a representative cohort of older men and women.

METHODS

We measured C-reactive protein (CRP) and depressive symptoms in 5328 men and women aged 52-89 years in the English Longitudinal Study of Ageing. Depressive symptoms were measured using the eight-item Centre for Epidemiological Studies Depression Scale. CRP was analysed from peripheral blood. Mortality was ascertained from national registers and associations with depressive symptoms and inflammation were estimated using Cox proportional hazard models.

RESULTS

We identified 112 CVD related deaths out of 420 all-cause deaths in men and 109 CVD related deaths out of 334 all-cause deaths in women over a mean follow-up of 7.7 years. Men with both depressive symptoms and high CRP (3-20 mg/L) had an increased risk of CVD mortality (hazard ratio; 95% confidence interval: 3.89; 2.04-7.44) and all-cause mortality (2.40; 1.65-3.48) after adjusting for age, socioeconomic variables and health behaviours. This considerably exceeds the risks associated with high CRP alone (CVD 2.43; 1.59-3.71, all-cause 1.49; 1.20-1.84). There was no significant increase in mortality risk associated with depressive symptoms alone in men. In women, neither depressive symptoms or inflammation alone or the combination of both significantly predicted CVD or all-cause mortality.

CONCLUSIONS

The combination of depressive symptoms and increased inflammation confers a considerable increase in CVD mortality risk for men. These effects appear to be independent, suggesting an additive role.

Depression, Quality of Life, Physical Activity, and the Impact of Drugs on Sexual Activity in a Population-Based Sample, Ages 20-59 Years

Sexual quality of life is important for many individuals; therefore, this study examined the frequency of depression in a younger and middle-aged population-based sample, and the impact on physical activity, quality of life, and sexual activity, and the role of antidepressant and cardiac drugs on sexual function. The sample, ages 20 to 59 years, completed relevant items for depression, sexual activity, physical activity, quality of life, and drugs. Data were analyzed using descriptive statistics, Pearson correlations, t-tests, and analysis of variance. Those sexually active had lower mean depression scores and higher ratings of quality of life, while those sexually inactive had greater depression and took more drugs. Thorough assessment of drugs, depression, cardiac and other medical conditions, and interest and engagement in sexual activity should be routinely assessed in all patients, regardless of age.

[Association of inflammatory genes with neuroticism, anxiety and depression in male patients with coronary heart disease]

AIM

To explore the relationship of depression and its endophenotypes (neuroticism and trait anxiety) with inflammatory genes in patients with coronary heart disease (CHD).

MATERIAL AND METHODS

A sample consisted of 78 male CHD patients with depression, 91 CHD patients without depression and 127 healthy men. Polymorphisms of the genes encoding interleukine-4 (IL-4 -589 C/T), interleukine-6 (IL-6 -174 G/C), tumor-necrosis factor alpha (TNF-α -308 G/A) and C-reactive protein (CRP -717A/G) were studied.

RESULTS

There was the association between the IL-6 -174 G/C and depression comorbid to CHD (р=0.01; OR=2.3 CI 95% 1.2-4.3). The frequency of the 'high expression' allele G in this group was higher compared to controls. The association between IL-4 -589 C/T and CHD was found. Compared to the control group, the frequency of the IL-4 -589CC genotype was higher in patients regardless of whether they had symptoms of depression (р=0.007; OR=2.1 CI 95% 1.2-3.4). No association between the TNF-α -308G/A and the CRP -717A/G with depression in CHD was observed. There were no differences between neuroticism and anxiety scores in patients with different IL-4 -589 C/T, IL-6 -174 G/C, TNF-α -308 G/A, CRP -717A/G genotypes.

CONCLUSION

The finding of the association between the IL-6 -174G/C and depression, comorbid to CHD, is in line with literature on a role of IL-6 in the development of depression in patients with CHD.

Chronic pain, depression and cardiovascular disease linked through a shared genetic predisposition: Analysis of a family-based cohort and twin study

BACKGROUND

Depression and chronic pain are the two most important causes of disability (Global Burden of Disease Study 2013). They occur together more frequently than expected and both conditions have been shown to be co-morbid with cardiovascular disease. Although shared socio-demographic risk factors (e.g. gender, deprivation) might explain the co-morbidity of these three conditions, we hypothesised that these three long-term, highly prevalent conditions co-occur and may be due to shared familial risk, and/or genetic factors.

METHODS AND FINDINGS

We employed three different study designs in two independent cohorts, namely Generation Scotland and TwinsUK, having standardised, validated questionnaire data on the three traits of interest. First, we estimated the prevalence and co-occurrence of chronic pain, depression and angina among 24,024 participants of a population-based cohort of extended families (Generation Scotland: Scottish Family Health Study), adjusting for age, gender, education, smoking status, and deprivation. Secondly, we compared the odds of co-morbidity in sibling-pairs with the odds in unrelated individuals for the three conditions in the same cohort. Lastly, examination of similar traits in a sample of female twins (TwinsUK, n = 2,902), adjusting for age and BMI, allowed independent replication of the findings and exploration of the influence of additive genetic (A) factors and shared (C) and non-shared (E) environmental factors predisposing to co-occurring chronic widespread pain (CWP) and cardiovascular disease (hypertension, angina, stroke, heart attack, elevated cholesterol, angioplasty or bypass surgery). In the Generation Scotland cohort, individuals with depression were more than twice as likely to have chronic pain as those without depression (adjusted OR 2·64 [95% CI 2·34-2·97]); those with angina were four times more likely to have chronic pain (OR 4·19 [3·64-4·82]); those with depression were twice as likely to have angina (OR 2·20 [1·90-2·54]). Similar odds were obtained when the outcomes and predictors were reversed and similar effects seen among sibling pairs; depression in one sibling predicted chronic pain in the other (OR 1·34 [1·05-1·71]), angina predicted chronic pain in the other (OR 2·19 [1·63-2·95]), and depression, angina (OR 1·98 [1·49-2·65]). Individuals with chronic pain and angina showed almost four-fold greater odds of depression compared with those manifesting neither trait (OR 3·78 [2·99-4·78]); angina showed seven-fold increased odds in the presence of chronic pain and depression (OR 7·76 [6·05-9·95]) and chronic pain nine-fold in the presence of depression and angina (OR 9·43 [6·85-12·98]). In TwinsUK, the relationship between CWP and depression has been published (R = 0.34, p<0.01). Considering the CWP-cardiovascular relationship, the most suitable model to describe the observed data was a combination of A, C and E, with a small but significant genetic predisposition, shared between the two traits (2·2% [95% CI 0·06-0·23]).

CONCLUSION

We found an increased co-occurrence of chronic pain, depression and cardiovascular disease in two independent cohorts (general population-based cohort, twins cohort) suggesting a shared genetic contribution. Adjustment for known environmental influences, particularly those relating to socio-economic status (Generation Scotland: age, gender, deprivation, smoking, education; Twins UK: age,BMI) did not explain the relationship observed between chronic pain, depression and cardiovascular disease. Our findings from two independent cohorts challenge the concept of traditional disease boundaries and warrant further investigation of shared biological mechanisms.