Depression and C-reactive protein: population-based Health 2000 Study

Association of posttraumatic stress disorder and depression with all-cause and cardiovascular disease mortality and hospitalization among Hurricane Katrina survivors with end-stage renal disease

OBJECTIVES

We determined the association of psychiatric symptoms in the year after Hurricane Katrina with subsequent hospitalization and mortality in end-stage renal disease (ESRD) patients.

METHODS

A prospective cohort of ESRD patients (n = 391) treated at 9 hemodialysis centers in the New Orleans, Louisiana, area in the weeks before Hurricane Katrina were assessed for posttraumatic stress disorder (PTSD) and depression symptoms via telephone interview 9 to 15 months later. Two combined outcomes through August 2009 (maximum 3.5-year follow-up) were analyzed: (1) all-cause and (2) cardiovascular-related hospitalization and mortality.

RESULTS

Twenty-four percent of participants screened positive for PTSD and 46% for depression; 158 participants died (79 cardiovascular deaths), and 280 participants were hospitalized (167 for cardiovascular-related causes). Positive depression screening was associated with 33% higher risk of all-cause (hazard ratio [HR] = 1.33; 95% confidence interval [CI] = 1.06, 1.66) and cardiovascular-related hospitalization and mortality (HR = 1.33; 95% CI = 1.01, 1.76). PTSD was not significantly associated with either outcome.

CONCLUSIONS

Depression in the year after Hurricane Katrina was associated with increased risk of hospitalization and mortality in ESRD patients, underscoring the long-term consequences of natural disasters for vulnerable populations.

Indoleamine 2,3-dioxygenase activation and depressive symptoms: results from the Young Finns Study

OBJECTIVE

To examine whether the activation of indoleamine 2,3-dioxygenase (IDO), an enzyme involved in serotonin production, is associated with depressive symptoms.

METHODS

The participants were 544 women and 442 men (aged 24-39 years) from the population-based Young Finns Study who participated in a medical examination in 2001 (including IDO and depression) and 2007 (follow-up assessment for depression).

RESULTS

At baseline, IDO was associated with depressive symptoms (in the total cohort: B = 0.23, p < .001; women: B = 0.20, p = .007; men: B = 0.29, p = .002; p for interaction = .19). IDO at baseline was also associated with depressive symptoms at follow-up in women (B = 0.17, p = .03), which remained significant when adjusting for any of the biologic and behavioral risk factors. Adjusting for body mass index attenuated the association by 6%. In the final model including all baseline variables, none of the risk factors (except for baseline depressive symptoms) were associated with depressive symptoms at follow-up.

CONCLUSIONS

These data suggest that IDO activity may be a risk factor for future depression especially in women. IDO-induced alterations in serotonergic function may offer one biologic explanation to the well-established associations between inflammation and depression.

[C reactive protein in women with coronary heart disease and its association with depression]

OBJECTIVES

Depression is associated with increased risk and poor outcome of coronary heart disease (CHD), though the mechanisms are largely unknown. Low-grade inflammation offers a possible biological pathway, which has been confirmed in men but not in women.

METHODS

We studied the association of C reactive protein (CRP), a biomarker of inflammation, with depressive symptoms in 292 women with CHD and 300 healthy age-matched controls, considering confounder variables (BMI, age, HDL cholesterol, triglycerides, menopausal status). CRP was measured by a high sensitivity assay.

RESULTS

In the overall sample no significant association was found between depressive symptoms and CRP, whereas in the control group women with 2 or more versus 0-1 depressive symptoms showed heightened CRP (p = 0.005); there was no significant difference in CRP levels between CHD patients with 0-1 versus 2 or more depressive symptoms. Women with CHD had higher serum levels of CRP and more depressive symptoms than did controls.

CONCLUSIONS

Contrary to men and healthy controls there was no link between CRP and depressive symptoms in women with CHD. More research is needed on how the harmful effects of depression are mediated, especially in women.

Predictors of remission in depression to individual and combined treatments (PReDICT): study protocol for a randomized controlled trial

BACKGROUND

Limited controlled data exist to guide treatment choices for clinicians caring for patients with major depressive disorder (MDD). Although many putative predictors of treatment response have been reported, most were identified through retrospective analyses of existing datasets and very few have been replicated in a manner that can impact clinical practice. One major confound in previous studies examining predictors of treatment response is the patient's treatment history, which may affect both the predictor of interest and treatment outcomes. Moreover, prior treatment history provides an important source of selection bias, thereby limiting generalizability. Consequently, we initiated a randomized clinical trial designed to identify factors that moderate response to three treatments for MDD among patients never treated previously for the condition.

METHODS/DESIGN

Treatment-naïve adults aged 18 to 65 years with moderate-to-severe, non-psychotic MDD are randomized equally to one of three 12-week treatment arms: (1) cognitive behavior therapy (CBT, 16 sessions); (2) duloxetine (30-60 mg/d); or (3) escitalopram (10-20 mg/d). Prior to randomization, patients undergo multiple assessments, including resting state functional magnetic resonance imaging (fMRI), immune markers, DNA and gene expression products, and dexamethasone-corticotropin-releasing hormone (Dex/CRH) testing. Prior to or shortly after randomization, patients also complete a comprehensive personality assessment. Repeat assessment of the biological measures (fMRI, immune markers, and gene expression products) occurs at an early time-point in treatment, and upon completion of 12-week treatment, when a second Dex/CRH test is also conducted. Patients remitting by the end of this acute treatment phase are then eligible to enter a 21-month follow-up phase, with quarterly visits to monitor for recurrence. Non-remitters are offered augmentation treatment for a second 12-week course of treatment, during which they receive a combination of CBT and antidepressant medication. Predictors of the primary outcome, remission, will be identified for overall and treatment-specific effects, and a statistical model incorporating multiple predictors will be developed to predict outcomes.

DISCUSSION

The PReDICT study's evaluation of biological, psychological, and clinical factors that may differentially impact treatment outcomes represents a sizeable step toward developing personalized treatments for MDD. Identified predictors should help guide the selection of initial treatments, and identify those patients most vulnerable to recurrence, who thus warrant maintenance or combination treatments to achieve and maintain wellness.

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.

Treatment response and cognitive impairment in major depression: association with C-reactive protein

Levels of inflammatory markers have been found to be significantly associated with major depressive disorder (MDD) and cognitive impairment. The aim of this study was to investigate whether the level of C-reactive protein (CRP) is correlated with depressive mood and cognitive impairment in MDD patients. In 149 subjects with MDD, the 21-item Hamilton Rating Scale for Depression (HAM-D), Continuous Performance Test (CPT), Finger-Tapping Test (FTT), and Wisconsin Card-Sorting Test (WCST) were administered before and after antidepressant treatment. Besides, the level of CRP was measured. After 6weeks of treatment, the total HAM-D scores decreased significantly. In addition, the subjects' performance in the masked CPT and the WCST with completed categories significantly improved (p<0.001 and p=0.027, respectively) after the reliable change indices were corrected for practice effects. The CRP levels had increased significantly after six weeks of treatment after adjustment for age and gender (p<0.001). In addition, the CRP levels remained significantly high after six weeks of treatment in patients with a higher baseline level (r=0.657, p<0.001). Although the association between baseline CRP level and HAM-D score was not significant, the baseline CRP level was significantly correlated with treatment response at week 2 (r=0.327, p=0.020). The baseline CRP level was also negatively correlated with performance in the FTT before treatment (r=-0.580, p=0.006). Moreover, the baseline CRP level was significantly correlated with performance in the FTT (r=-0.501, p=0.021) and WCST with completed categories (r=-0.521, p=0.015) at week 6. The cognitive function of patients with high baseline CRP levels might remain impaired even if their mood symptoms improve after antidepressant treatment. Whether adjunctive anti-inflammatory medication may help to preserve cognitive function merits further investigation.

Depressive symptoms in a general population: associations with obesity, inflammation, and blood pressure

To determine whether obesity, inflammation, or conventional risk factors are related to depressive symptoms (DeprSy) in the general population. Responses to 3 questions served to assess sense of depression. Body mass index (BMI), C-reactive protein (CRP), and other epidemiologic data of participants were available. In 1940, individuals who consulted a psychiatrist in the preceding year, or felt depressed (together DeprSy), 248 were female. Logistic regressions for adjusted associations of BMI with DeprSy were not significant as was serum CRP level. Diabetes and, in men, fasting glucose concentrations were associated with DeprSy. Systolic blood pressure (SBP) was robustly inversely associated with DeprSy in diverse models at ORs of 0.74 (95%CI 0.63; 0.89) independent of confounders, including antihypertensive and lipid-lowering medication. The use of antidepressants could not explain the reduced BP. Women are predisposed to depression with which, not BMI and CRP, but SBP is inversely associated. Anti-inflammatory substances produced in depressed persons might explain the slightly lower BP.

Association between social isolation and inflammatory markers in depressed and non-depressed individuals: results from the MONICA/KORA study

INTRODUCTION

Depressed individuals not only suffer from chronic low grade inflammation, but also exhibit an inflammatory hyper-responsiveness to acute stress. We investigate whether chronic stress also induces an exaggerated inflammatory response in individuals with increased depression features. As model for chronic stress, social isolation was chosen.

METHODS

Interleukin (IL)-6 and hs-CRP levels were assessed in 1547 subjects (847 men and 700 women), derived from the population-based MONICA/KORA study. Standardized questionnaires were used to assess depressed mood (depression and exhaustion subscale) and social isolation (social network index). The relationship between the two inflammatory markers, social isolation and depressed mood was examined taking into account interactions social isolation × depressed mood using multivariable linear regression models, adjusted for age, BMI, smoking, alcohol, and physical activity. Analyses were performed in men and women separately.

RESULTS

We observed a significant interaction between depressed mood and social isolation regarding IL-6 and hs-CRP, respectively in men (p-value=0.02 for IL-6 and <0.01 for hs-CRP), evidencing a substantial synergistic effect of social isolation, and depressed mood on inflammatory responses. Furthermore, depressed and socially isolated men had highly significantly elevated IL-6 levels (geometric mean: 3.76 vs. 1.92 pg/ml, p-value <0.01) and heightened hs-CRP levels (geometric mean: 2.01 vs. 1.39 mg/l, p=0.08) in comparison with non-depressed and socially integrated men. In women, no significant associations were seen.

CONCLUSION

The interaction of depressed mood and social isolation elicits a substantial synergistic impact on inflammatory markers in men, but not in depressed women.

Moderating effect of indoleamine 2,3-dioxygenase (IDO) activation in the association between depressive symptoms and carotid atherosclerosis: evidence from the Young Finns study

BACKGROUND

Depression and inflammation have been suggested to be involved in the atherosclerotic processes, but empirical evidence is mixed. We tested the hypothesis that depressive symptoms are associated with atherosclerosis only when combined with other risk factors, such as inflammation indicated by indoleamine 2,3-dioxygenase (IDO) activation.

METHODS

Participants were 544 women and 442 men (aged 24-39 years) who participated in the Young Finns Study medical examinations in 2001 and 2007. At baseline (in 2001), IDO activity (tryptophan and kynurenine ratio) and other biological and behavioral risk factors were assessed and depressive symptoms were determined using a modified 21-item Beck Depression Inventory. Carotid atherosclerosis was measured on the basis of carotid intimamedia thickness (IMT) at baseline and again in 2007.

RESULTS

In women, IDO activity moderated the association between depressive symptoms and IMT (p=0.02), so that a longitudinal association between depressive symptoms and IMT was found only in combination with high IDO activity (B=0.21, p=0.009). This association was robust to adjustment for other risk factors except body mass index and lipids which largely removed the association.

LIMITATIONS

The results of this study need to be confirmed using larger data sets and studies using clinical cut-off point for depression.

CONCLUSIONS

These data suggest that depressive symptoms are associated with preclinical y carotid atherosclerosis only if they are linked to inflammation, and that this association is present only in women. Underlying mechanisms are unknown but probably relate to adiposity.

Chronic depressive symptoms and Framingham coronary risk in HIV-infected and HIV-uninfected women

Depression is common in people with cardiovascular diseases (CVD) and those with HIV, and is a risk factor for CVD-related mortality. However, little is known about whether HIV influences the relationship between depression and cardiovascular risk. A total of 526 HIV-infected and 132 uninfected women from the Women's Interagency HIV Study were included in an analysis of women who completed twice-yearly study visits over 9.5 years. CVD risk was calculated at baseline and approximately 9.5 years later using the Framingham Risk Score (FRS). Chronic depressive symptoms were defined as Center for Epidemiologic Studies Depression Scale scores of 16 or greater at ≥75% of study visits. Over the follow-up period, 22.8% of HIV-infected women and 15.9% of HIV-uninfected women had chronic depressive symptoms (p=0.08). Baseline FRS was similar between HIV-infected and uninfected women (M=-5.70 ± SE=0.30 vs. M=-6.90 ± SE=0.60, p=0.07) as was follow-up FRS (M=0.82 ± SE=0.30 vs. M=-0.44 ± SE=0.73, p=0.11). Among HIV-infected and HIV-uninfected women, together, follow-up FRS was higher among women with chronic depressive symptoms as compared to those without (M=1.3 ± SE=0.6 vs. M=-0.3 ± SE=0.40, p<0.01), after adjusting for baseline FRS and other covariates. HIV status did not modify the relationship between chronic depressive symptoms and FRS. Chronic depressive symptoms accelerated CVD risk scores to a similar extent in both HIV-infected and-uninfected women. This implies that the diagnosis and treatment of depression may be an important consideration in CV risk reduction in the setting of HIV-infection. The determination of factors that mediate the depression/CVD relationship merits further study.

Association between depression and inflammation--differences by race and sex: the META-Health study

OBJECTIVE

To test whether the association between depression and inflammation differs by race and sex. Depressive symptoms have been associated with higher levels of C-reactive protein (CRP). However, few studies have examined this association in samples including a significant number of African Americans, or examined whether the association differs by race and sex.

METHODS

Depressive symptoms and CRP were assessed in 512 African American and white participants, age 30 to 65 years, as part of the community-based Morehouse and Emory Team up to Eliminate Health Disparities (META-Health) Study. Depression was determined by responses to the Beck Depression Inventory II (BDI-II). Multivariable linear regression models were used to adjust for demographic and metabolic risk factors.

RESULTS

African American men had higher total BDI-II scores than white men (p = .03), whereas there was no difference in women. There was a significant race-sex-depression interaction in predicting CRP levels (p = .02). White women with mild to severe depressive symptoms had higher levels of CRP compared with those with minimal to no depressive symptoms (p < .05). There were no differences in levels of CRP by severity of depressive symptoms in white men or African Americans of either sex. Higher BDI-II scores were related to higher CRP levels in white women after adjusting for age and level of education (β = 0.227, p = .006). However, the association was eliminated after further adjustment for metabolic risk factors (β = 0.077, p = .35).

CONCLUSIONS

Although depressive symptoms are associated with inflammation, the association varies by race and sex.

Psychological distress and C-reactive protein: do health behaviours and pathophysiological factors modify the association?

The objective of this study is to examine the association of psychological distress to high-sensitivity C-reactive protein (hsCRP) levels and to examine the potential mediating role of health behaviours and pathophysiological factors. A total of 883 (393 men and 490 women) subjects, aged 36-56 years, participated in a population-based, cross-sectional study from 1997 to 1998 in Pieksämäki, Finland. Various clinical, biochemical and behavioural factors were measured, including hsCRP concentration. Psychological distress was measured using the 12-item General Health Questionnaire (GHQ-12). Subjects with low psychological distress (0 points in GHQ-12) were younger and more physically active, and their mean hsCRP level was lower when compared to subjects with medium (1-3 points) or high (4-12 points) psychological distress (1.26 ± 1.36, 1.53 ± 1.75 and 1.70 ± 1.68 mg/l, respectively, P for linearity = 0.003). Psychological distress was also associated with high relative cardiovascular risk (hsCRP >3.00 mg/l). After adjusting for gender, age, BMI, smoking, use of alcohol and leisure time physical activity, odds ratios for hsCRP >3.00 mg/l in the groups that had medium and high psychological distress were 1.32 (95% CI: 0.81-2.16) and 1.79 (95% CI: 1.05-3.04), respectively, compared with the low distress group (P for linearity 0.032). Psychological distress was associated with elevated hsCRP levels representing high relative cardiovascular risk. This association remained after adjusting for health behaviours and pathophysiological factors, supporting a direct, physiological link between psychological distress and inflammation. CRP could be an important pathophysiological mechanism through which psychological factors are associated with cardiovascular disease.

Emotional functioning at age 7 years is associated with C-reactive protein in middle adulthood

OBJECTIVE

Few have considered whether and how child emotional functioning is associated with inflammation later in life. Therefore, we evaluated whether child emotional functioning at age 7 years is associated with C-reactive protein (CRP), an indicator of systemic inflammation, in middle adulthood.

METHODS

We studied adult offspring (mean age 42.2 years) of participants in the National Collaborative Perinatal Project, a national cohort of pregnant women enrolled between 1959 and 1966. Three measures of child emotional functioning were derived from psychologist ratings of child behavior at age 7 years: inappropriate self-regulation (ISR), distress proneness, and behavioral inhibition. Multiple linear regression models were fit to investigate the association between childhood emotional functioning and adulthood CRP and also to evaluate potential mediators of this association. Model n's were from 400 for Model 1 to 379 for Model 4 depending on covariates included and missing data on those covariates.

RESULTS

Children with high ISR and distress proneness at age 7 years had significantly higher CRP as adults (ISR: β = 0.86; standard error [SE] = 0.28; p = .002; distress proneness: β = 1.23; SE = 0.57; p = .03). In contrast, children with high levels of behavioral inhibition had lower CRP as adults (β = -0.58; SE = 0.38; p = .04). Furthermore, there was evidence that associations of ISR and distress proneness with CRP may be mediated in part by adulthood body mass index (Sobel significance tests of mediation: ISR: p = .003; distress proneness: p = .07).

CONCLUSIONS

Findings suggest that poor childhood emotional functioning is associated with inflammation in adulthood. These results suggest a potential childhood origin of adult inflammatory risk.

The relationship between psychosocial stress, age, BMI, CRP, lifestyle, and the metabolic syndrome in apparently healthy subjects

The aim of this cross-sectional study was to examine the factors which may be associated with the metabolic syndrome by exploring the relationship between psychosocial stress, age, body mass index (BMI), C-reactive protein (CRP), lifestyle factors, and the components of the metabolic syndrome, such as glycated hemoglobin (HbA1c), fasting blood sugar (FBS), body fat percentage, and triglyceride concentration, among apparently healthy subjects. Psychosocial stress was measured by the use of the inventory to measure psychosocial stress (IMPS). One thousand four hundred and ninety-nine people out of 1,941 public school workers admitted to a hospital for a medical check-up responded to the IMPS, yielding a response rate of 77.2%. A total of 1,201 workers excluding 298 who were taking medication for various diseases were analyzed with the use of hierarchical multiple regression models. It was found that IMPS-measured stress score, age, BMI, and smoking habit were associated with an increase in glycated hemoglobin among men, while alcohol consumption was associated with a decrease in glycated hemoglobin. Stress score, age, BMI, and alcohol consumption were found to be associated with an increase in FBS among men, while smoking and exercise habits were associated with a decrease in FBS. CRP was found to be associated with an increase in body fat percentage among men, though stress score was not associated with an increase in body fat percentage. Stress score, age, and BMI were associated with an increase in triglyceride concentration among women. The findings of the present study seem to be in line with the hypothesis that psychosocial stress plays an important role in developing the metabolic syndrome, which may be associated with inflammatory processes in the vascular wall, resulting in atherosclerosis and cardiovascular disease.

Psychological distress predicts the development of the metabolic syndrome: a prospective population-based study

OBJECTIVE

To examine prospectively the association of psychological distress with the development of the metabolic syndrome (MetS) and the potential influence of demographic characteristics, health behaviors, and inflammation in this association.

METHODS

A total of 466 (n = 185 males; 281 females) subjects, aged 36 to 56 years, and free of MetS at baseline, participated in a population-based study from 1997 to 1998 and again from 2004 to 2005. Mean observation time was 6.4 years. Various clinical, biochemical, and behavioral factors were measured at baseline, including assessment of psychological distress using the 12-item General Health Questionnaire. The development of MetS was measured at follow-up based on National Cholesterol Education Program criteria.

RESULTS

Subjects with high psychological distress at baseline (General Health Questionnaire scores, 4-12) were more than twice as likely to develop MetS than those with low psychological distress (odds ratio, 2.18; 95% confidence interval, 1.30-3.64). Adjustments for 1) age, gender, and sociodemographic variables; 2) health behaviors (smoking, alcohol use, and leisure time physical activity); and 3) C-reactive protein in the analysis diminished the odds of developing MetS in the distressed group (odds ratio, 1.87; 95% confidence interval, 1.83 and 1.81, respectively); however, the association remained statistically significant (p = .025-.038).

CONCLUSIONS

Psychological distress at baseline increases the risk of developing MetS during follow-up. This association remained robust after adjusting for age, gender, sociodemographic variables, baseline health behaviors, and C-reactive protein. These prospective findings are evidence of a significant association between psychological distress and the development of MetS.

Biological basis of depression in adults with diabetes

Diabetes and depression are common comorbid conditions. Although certain health behaviors and risk factors partially explain the association of depression and diabetes, other potential mechanisms have yet to be elucidated. Certain neuroendocrine alterations such as activation of the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS) may contribute to the association. Additionally, presence of a proinflammatory state shown in recent literature in both diabetes and depression may contribute to this as well. The objectives of this review are to summarize and review the recent evidence showing alterations of these three biological systems-HPA axis, SNS, and inflammatory cascade--in depression, diabetes, and diabetes-related risk factors.

C-reactive protein-associated genetic variants and cancer risk: findings from FINRISK 1992, FINRISK 1997 and Health 2000 studies

BACKGROUND

Evidence from prospective observational studies suggests that elevated circulating C-reactive protein (CRP) concentrations are associated with cancer risk, but it is unclear whether this association is causal. In order to examine this, we investigated whether genetic variants that are associated with circulating CRP concentrations are associated with cancer risk.

METHODS

We pooled data from three population-based prospective Finnish studies: FINRISK 1992 (n = 5289), FINRISK 1997 (n = 7160) and Health 2000 (n = 6299). Cancer cases were identified from cancer registrations. Thirteen CRP-associated SNPs, identified from genome-wide association studies, were genotyped. We examined the associations of the SNPs and cancer risk using Cox, probit and instrumented probit regression models.

RESULTS

Compared to common allele homozygotes, individuals carrying one or two variant T alleles at rs1892534 had 1.05-fold (95% confidence interval (CI): 0.90, 1.23) and 1.2-fold (95% CI: 1.01, 1.42) increased overall cancer risk, respectively. Individuals with one or two variant A alleles at rs1169300 or rs2464196 had approximately 1.5- and 2-fold increased risk of lung cancer, respectively (p trend for both: 0.007). CRP SNPs were not associated with colorectal, prostate or breast cancer risk nor was CRP-associated with the probability of developing cancer in the instrumented probit analyses.

CONCLUSIONS

We found some evidence for an association of a small number of CRP-associated SNPs with the overall cancer risk and lung cancer risk. Our instrumental variable analyses provided no clear evidence for a causal association of CRP and cancer. These findings suggest that circulating CRP concentrations are unlikely to have a causal role in cancer.

Psychobiological differences between depression and somatization

BACKGROUND

Comorbidity studies have shown that depression and somatization (multiple somatoform symptoms) often overlap. Therefore it has been suggested to classify at least some patients with somatization syndromes under the category of depressive disorders. We wanted to investigate whether psychobiological investigations confirm the lumping of somatization and depression, or whether psychobiological pathways favor distinguishing these disorders.

METHOD

An overview is presented summarizing psychobiological studies including patients with depression and/or somatization-associated syndromes. We focus on the following topics: heritability, polymorphisms in special candidate genes, immune activation, hypothalamic-pituitary-adrenal (HPA) axis reactivity, serotonergic pathways, monoamino acids, and fatty acid concentrations.

RESULTS

Immunological activation seems to be associated with specific features of somatoform disorders, namely, sickness behavior and pain thresholds. Genetic factors can also contribute to somatic complaints, e.g., via serotonergic pathways, HPA-axis response, immune activation, and other biological systems that contribute to the self-description of not being healthy. Some results indicate that psychobiological aspects of depression and somatization overlap in part (e.g., the relevance of serotonergic pathways), but there is clearly more evidence for discrepancies of psychobiological pathways in depression and somatization (e.g., the relevance of proinflammatory immune processes; HPA-axis activity; monoamino acid availability; omega-3-concentration; the role of triallelic subtypes of 5-HTTLPR).

CONCLUSION

Many psychobiological pathways act differently in depression and somatization. These differences in psychobiology favor the distinction of these syndromes in classification approaches.