Neurohormonal and inflammatory hyper-responsiveness to acute mental stress in depression

Increased regional body fat is associated with depressive symptoms: a cross-sectional analysis of NHANES data obtained during 2011-2018

AIMS

The findings from previous epidemiological studies of the association between regional body fat and depressive symptoms have been unclear. We aimed to determine the association between the body fat in different regions and depressive symptoms based on data from the National Health and Nutrition Examination Survey (NHANES).

METHODS

This study included 3393 participants aged ≥ 20 years from the NHANES performed during 2011-2018. Depressive symptoms were assessed using the Patient Health Questionnaire-9. The fat mass (FM) was measured in different regions using dual-energy X-ray absorptiometry to determine the total FM, trunk FM, arm FM, and leg FM. The FM index (FMI) was obtained by dividing the FM in kilograms by the square of the body height in meters. Weighted data were calculated in accordance with analytical guidelines. Linear logistic regression models were used to quantify the association between regional FMI and depressive symptoms. Univariate and stratified analyses were also performed.

RESULTS

The participants in this study comprised 2066 males and 1327 females. There were 404 (11.91%) participants with depressive symptoms, who were aged 40.89 ± 11.74 years and had a body mass index of 30.07 ± 7.82 kg/m². A significant association was found between total FMI and depressive symptoms. In the fully adjusted multivariate regression model, a higher total FMI (odds ratio = 2.18, 95% confidence interval [CI] = 1.08-4.39) was related to a higher risk of depressive symptoms, while increased total FMI (β = 1.55, 95% CI = 0.65-2.44, p = 0.001), trunk FMI (β = 0.57, 95% CI = 0.04-1.10, p = 0.036), and arm FMI (β = 0.96, 95% CI = 0.33-1.59, p = 0.004) were significantly associated with PHQ-9 (Patient Health Questionnaire-9) scores, whereas the leg FMI was not (p = 0.102). The weighted association between total FMI and depressive symptoms did not differ significantly between most of the subpopulations (all p values for interaction > 0.05). The risk of having depression was higher in individuals who were non-Hispanic Whites, smokers, drinkers, obese, and had diabetes and thyroid problems (p < 0.05).

CONCLUSION

These findings suggest that the population with a higher regional FMI is more likely to have depressive symptoms, especially in those who also have an increased total FMI. The association is more pronounced in individuals who are smokers, drinkers, obese, and have diabetes and thyroid problems.

Assessment of cardiovascular functioning following sport-related concussion: A physiological perspective

There is still much uncertainty surrounding the approach to diagnosing and managing a sport-related concussion (SRC). Neurobiological recovery may extend beyond clinical recovery following SRC, highlighting the need for objective physiological parameters to guide diagnosis and management. With an increased understanding of the connection between the heart and the brain, the utility of assessing cardiovascular functioning following SRC has gained attention. As such, this review focuses on the assessment of cardiovascular parameters in the context of SRC. Although conflicting results have been reported, decreased heart rate variability, blood pressure variability, and systolic (ejection) time, in addition to increased spontaneous baroreflex sensitivity and magnitude of atrial contraction have been shown in acute SRC. We propose that these findings result from the neurometabolic cascade triggered by a concussion and represent alterations in myocardial calcium handling, autonomic dysfunction, and an exaggerated compensatory response that attempts to maintain homeostasis following a SRC. Assessment of the cardiovascular system has the potential to assist in diagnosing and managing SRC, contributing to a more comprehensive and multimodal assessment strategy.

Plasma cytokine and growth factor response to acute psychosocial stress in major depressive disorder

BACKGROUND

Pro-inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor (TNF)-α are elevated in response to psychosocial stress; however, less is known about other inflammatory markers.

METHODS

We explored response to the Trier Social Stress Test (TSST) of 16 cytokines and growth factors in patients with major depressive disorder (MDD, n = 12) vs. healthy volunteers (HV, n = 16). Outcomes were baseline and post-stress levels estimated by area under the curve (AUCi) and peak change over 3 timepoints. We also explored correlations between biomarkers and clinical characteristics.

RESULTS

Baseline concentrations were higher in MDD for platelet-derived growth factor (PDGF)-AB/BB (p = 0.037, d = 0.70), granulocyte-macrophage colony-stimulating factor (GM-CSF, p = 0.033, d = 0.52), and IL-8 (p = 0.046, d = 0.74). After TSST, AUCi was higher in MDD for GM-CSF (p = 0.003, d = 1.21), IL-5 (p = 0.014, d = 1.62), and IL-27 (p = 0.041, d = 0.74). In MDD, depression severity correlated positively with soluble CD40L (sCD40L) for AUCi (Spearman's ρ = 0.76, p = 0.004) and with baseline vascular endothelial growth factor A (VEGFA, r = 0.85, p < 0.001), but negatively with baseline monokine induced by gamma interferon (MIG, aka CXCL9; r = -0.77, p = 0.003).

CONCLUSIONS

Effect sizes were robust in this exploratory study, although interpretation of the results must be cautious, given small sample size and multiple comparisons. Differential study of stress-induced biomarkers may have important ramifications for MDD treatment.

Ghrelin as a Biomarker of "Immunometabolic Depression" and Its Connection with Dysbiosis

Ghrelin, a gastrointestinal peptide, is an endogenous ligand of growth hormone secretagogue receptor 1a (GHSR1a), which is mainly produced by X/A-like cells in the intestinal mucosa. Beyond its initial description as a growth hormone (GH) secretagogue stimulator of appetite, ghrelin has been revealed to have a wide range of physiological effects, for example, the modulation of inflammation; the improvement of cardiac performance; the modulation of stress, anxiety, taste sensation, and reward-seeking behavior; and the regulation of glucose metabolism and thermogenesis. Ghrelin secretion is altered in depressive disorders and metabolic syndrome, which frequently co-occur, but it is still unknown how these modifications relate to the physiopathology of these disorders. This review highlights the increasing amount of research establishing the close relationship between ghrelin, nutrition, microbiota, and disorders such as depression and metabolic syndrome, and it evaluates the ghrelinergic system as a potential target for the development of effective pharmacotherapies.

Serotonin and the serotonin transporter in the adrenal gland

The adrenal glands are key components of the mammalian endocrine system, helping maintain physiological homeostasis and the coordinated response to stress. Each adrenal gland has two morphologically and functionally distinct regions, the outer cortex and inner medulla. The cortex is organized into three concentric zones which secrete steroid hormones, including aldosterone and cortisol. Neural crest-derived chromaffin cells in the medulla are innervated by preganglionic sympathetic neurons and secrete catecholamines (epinephrine, norepinephrine) and neuropeptides into the bloodstream, thereby functioning as the neuroendocrine arm of the sympathetic nervous system. In this article we review serotonin (5-HT) and the serotonin transporter (SERT; SLC6A4) in the adrenal gland. In the adrenal cortex, 5-HT, primarily sourced from resident mast cells, acts as a paracrine signal to stimulate aldosterone and cortisol secretion through 5-HT4/5-HT7 receptors. Medullary chromaffin cells contain a small amount of 5-HT due to SERT-mediated uptake and express 5-HT1A receptors which inhibit secretion. The atypical mechanism of the 5-HT1A receptors and interaction with SERT fine tune this autocrine pathway to control stress-evoked catecholamine secretion. Receptor-independent signaling by SERT/intracellular 5-HT modulates the amount and kinetics of transmitter release from single vesicle fusion events. SERT might also influence stress-evoked upregulation of tyrosine hydroxylase transcription. Transient signaling via 5-HT3 receptors during embryonic development can limit the number of chromaffin cells found in the mature adrenal gland. Together, this emerging evidence suggests that the adrenal medulla is a peripheral hub for serotonergic control of the sympathoadrenal stress response.

Depressive-Like Effects of Foreclosing: A Cross-Sectional Study of Hair Cortisol Concentration

INTRODUCTION

Foreclosing and home eviction have been associated with various negative health outcomes, probably due to exposure to such stressful circumstance, but there is no evidence about foreclosure and home eviction to elicit cortisol responses.

METHODS

Participants who recently had received a court eviction notice were compared to subjects suffering a depressive disorder and to healthy controls in terms of hair cortisol concentrations.

RESULTS

Subjects under the stressful circumstance of foreclosure and patients with depression showed comparable concentrations in most of the hair segments while healthy subjects displayed the lowest levels of cortisol.

CONCLUSION

The findings show that foreclosure and home eviction are associated with increased cumulative hair cortisol and with depressive-like symptoms. Foreclosing procedures yielded to maintain high levels of cortisol which may increase the risk to develop major depression.

Internal but not external locus of control predicts acute stress response

Fluctuation patterns of physiological response after acute stress might indicate one's coping potential with stress, yet this relationship has not been widely examined. The present study investigated how Locus of Control (LOC) can influence cortisol and HR responses in an uncontrollable stressful situation. Seventy-three participants were exposed to acute stress through the Trier Social Stress Test (TSST) after finishing the LOC measures. Multilevel regression results suggested that a curvilinear function best captured the shape of the cortisol trajectories which was further moderated by the level of internal LOC. Moreover, higher internality was associated with greater cortisol reactivity and faster recovery. Our study reveals the link between internal control and endocrine stress response. Finally, cortisol upregulation was discussed, as well as the internality-related accelerated recovery of cortisol, which may be involved in the effect of motivation arousal for better adaptation.

Stress induced proinflammatory adaptations: Plausible mechanisms for the link between stress and cardiovascular disease

Initiating from Hans Selye’s conceptualization of stress physiology, to our present understanding of allostatic load as the cumulative burden of chronic psychological stress and life events, investigators have sought to identify the physiological mechanisms that link stress to health and disease. Of particular interest has been the link between psychological stress and cardiovascular disease (CVD), the number one cause of death in the United States. In this regard, attention has been directed toward alterations in the immune system in response to stress that lead to increased levels of systemic inflammation as a potential pathway by which stress contributes to the development of CVD. More specifically, psychological stress is an independent risk factor for CVD, and as such, mechanisms that explain the connection of stress hormones to systemic inflammation have been examined to gain a greater understanding of the etiology of CVD. Research on proinflammatory cellular mechanisms that are activated in response to psychological stress demonstrates that the ensuing low-grade inflammation mediates pathways that contribute to the development of CVD. Interestingly, physical activity, along with its direct benefits to cardiovascular health, has been shown to buffer against the harmful consequences of psychological stress by “toughening” the SAM system, HPA axis, and immune system as “cross-stressor adaptations” that maintain allostasis and prevent allostatic load. Thus, physical activity training reduces psychological stress induced proinflammation and attenuates the activation of mechanisms associated with the development of cardiovascular disease. Finally, COVID-19 associated psychological stress and its associated health risks has provided another model for examining the stress-health relationship.

Sleep and Healthy Aging Research on Depression (SHARE-D) randomized controlled trial: Protocol overview of an experimental model of depression with insomnia, inflammation, and affect mechanisms in older adults

Depression, one of the most common diseases in older adults, carries significant risk for morbidity and mortality. Because of the burgeoning population of older adults, the enormous burden of late-life depression, and the limited efficacy of current antidepressants in older adults, biologically plausible models that translate into selective depression prevention strategies are needed. Insomnia predicts depression recurrence and is a modifiable target to prevent incident and recurrent depression in older adults. Yet, it is not known how insomnia gets converted into biological- and affective risk for depression, which is critical for identification of molecular targets for pharmacologic interventions, and for refinement of insomnia treatments that target affective responding to improve efficacy. Sleep disturbance activates inflammatory signaling and primes immune responses to subsequent inflammatory challenge. In turn, inflammatory challenge induces depressive symptoms, which correlate with activation of brain regions implicated in depression. This study hypothesizes that insomnia serves as a vulnerability factor for inflammation-related depression; older adults with insomnia will show heightened inflammatory- and affective responding to inflammatory challenge as compared to those without insomnia. To test this hypothesis, this protocol paper describes a placebo-controlled, randomized, double-blind study of low dose endotoxin in older adults (n = 160; 60-80 y) with insomnia vs. comparison controls without insomnia. The aims of this study are to examine differences in depressive symptoms, measures of negative affective responding, and measures of positive affective responding as a function of insomnia and inflammatory challenge. If the hypotheses are confirmed, older adults with two "hits", insomnia and inflammatory activation, would represent a high risk group to be prioritized for monitoring and for depression prevention efforts using treatments that target insomnia or inflammation. Moreover, this study will inform the development of mechanism-based treatments that target affect responses in addition to sleep behaviors, and which might also be coupled with efforts to reduce inflammation to optimize efficacy of depression prevention.

Metabolic syndrome and its associated factors among epileptic patients at Dessie Comprehensive Specialized Hospital, Northeast Ethiopia; a hospital-based comparative cross-sectional study

INTRODUCTION

Metabolic syndrome is a group of metabolic risk factors which are associated with an increased risk of cardiovascular disease and type2 diabetes. Nowadays, several studies have shown that the burden of metabolic syndrome is increasing among epileptic patients, and leads to MS-associated complications, including cardiovascular disease. However, getting published documents has been limited in Ethiopia and the study area. Therefore, we aimed to analyze the magnitude and associated factors of metabolic syndrome among epileptic patients in Dessie Comprehensive Specialized Hospital in compression with respective controls.

METHODS

Hospital-based comparative cross-sectional study design was implemented from June 25 to August 20, 2021. A total of 204 participants with an equal number of cases and controls (n = 102 each) were included. The data was collected through face-to-face interviews and biochemical analyses such as fasting blood glucose and lipid profiles were done through the enzymatic technique. The magnitude of metabolic syndrome was determined using both National Cholesterol Education Program Adult Treatment Panel III and International Diabetes Federation definition criteria. The STATA version 14 was used for statistical data analysis, and a comparison of categorical and continuous variables was done with χ2 and an independent t-test, respectively. The multivariable binary logistic regression analysis was used to identify factors associated with metabolic syndrome, and variables having a P-value of <0.05 were considered statistically significant.

RESULT

The prevalence of metabolic syndrome among the epileptic group was (25.5% in National Cholesterol Education Program Adult Treatment Panel III and 23.5% in International Diabetes Federation criteria), whereas it was 13.7% in National Cholesterol Education Program Adult Treatment Panel III and 14.7% in International Diabetes Federation criteria among control groups. According to the International Diabetes Federation criteria, low physical activity (adjusted odds ratio = 4.73, 95% CI: 1.08-20.68), taking multiple antiepileptic drugs (adjusted odds ratio = 8.08, 95% CI: 1.52-42.74), having a total cholesterol level of ≥ 200 mg/dl (adjusted odds ratio = 5.81, 95%: 1.32-41.13) and body mass index (adjusted odds ratio = 1.57, 95% CI = 1.16-2.11) were significantly associated with metabolic syndrome among epileptic participants. Applying National Cholesterol Education Program Adult Treatment Panel III criteria, taking multiple antiepileptic drugs (adjusted odds ratio = 6.81, 95% CI: 1.29-35.92), having a total cholesterol level > 200 mg/dl (adjusted odds ratio = 7.37, 95% CI: 1.32-41.13) and body mass index (adjusted odds ratio = 1.53, 96% CI: 1.16-2.01) were also significantly associated.

CONCLUSION

The prevalence of metabolic syndrome among epileptic patients was higher than that of control groups and reaches statistically significant by National Cholesterol Education Program Adult Treatment Panel III. Being on multiple antiepileptic drugs, body mass index, having low physical activity and raised total cholesterol were significantly associated with metabolic syndrome among the epileptic group. Therefore, it is better to focus on controlling weight, having sufficient physical exercise, and regular monitoring of total cholesterol levels in epileptic patients.

The longitudinal connection between depressive symptoms and inflammation: Mediation by sleep quality

Although there is a strong association between depressive symptoms and markers of inflammation, it remains unclear whether depressive symptoms at one point in life may predict inflammation later in life. Moreover, despite extant literature linking sleep with both depressive symptoms and inflammation, there is little research investigating poor sleep as a mechanism linking depressive symptoms with later inflammation. The links between depression and physical health can also vary by gender. In longitudinal analyses with data from the Midlife in the United States (MIDUS) study, we examined whether depressive symptoms were associated with inflammatory markers 11 years later and whether these associations were mediated by sleep disturbances or moderated by gender. Participants reported depressive symptoms and demographic information at baseline. At 11-year follow-up, the same participants (n = 968) reported depressive symptoms, sleep quality and duration using validated scale items, and provided a blood sample from which inflammatory markers interleukin-6 (IL-6) and C-reactive protein (CRP) were quantified. Actigraphy assessment of sleep was obtained in a subsample (n = 276). After adjusting for concurrent depressive symptoms and other relevant covariates, baseline depressive symptoms were associated with CRP 11 years later in the full sample, and with IL-6 among women. Subjective sleep quality mediated the association between depressive symptoms and CRP. Results suggest that depressive symptoms may be longitudinally associated with inflammation; however, directionality issues cannot be determined from the present work, particularly as inflammation markers (which might have been associated with baseline depressive symptoms) were not available at baseline. Findings further suggest that longitudinal associations between depressive symptoms and inflammation may potentially be explained by sleep and may reflect gender specific patterns.

Characteristics of single-channel electroencephalogram in depression during conversation with noise reduction technology

Background

Previous studies have attempted to characterize depression using electroencephalography (EEG), but results have been inconsistent. New noise reduction technology allows EEG acquisition during conversation.

Methods

We recorded EEG from 40 patients with depression as they engaged in conversation using a single-channel EEG device while conducting real-time noise reduction and compared them to those of 40 healthy subjects. Differences in EEG between patients and controls, as well as differences in patients’ depression severity, were examined using the ratio of the power spectrum at each frequency. In addition, the effects of medications were examined in a similar way.

Results

In comparing healthy controls and depression patients, significant power spectrum differences were observed at 3 Hz, 4 Hz, and 10 Hz and higher frequencies. In the patient group, differences in the power spectrum were observed between asymptomatic patients and healthy individuals, and between patients of each respective severity level and healthy individuals. In addition, significant differences were observed at multiple frequencies when comparing patients who did and did not take antidepressants, antipsychotics, and/or benzodiazepines. However, the power spectra still remained significantly different between non-medicated patients and healthy individuals.

Limitations

The small sample size may have caused Type II error. Patients’ demographic characteristics varied. Moreover, most patients were taking various medications, and cannot be compared to the non-medicated control group.

Conclusion

A study with a larger sample size should be conducted to gauge reproducibility, but the methods used in this study could be useful in clinical practice as a biomarker of depression.

Linking the Triad of Telomere Length, Inflammation, and Gut Dysbiosis in the Manifestation of Depression

Telomere length is an indispensable marker for cellular and biological aging, and it also represents an individual's physical and mental health status. Telomere shortening has been observed in chronic inflammatory conditions, which in turn accelerates aging and risk for psychiatric disorders, including depression. Considering the influence of inflammation and telomere shortening on the gut-brain axis, herein we describe a plausible interplay between telomere attrition, inflammation, and gut dysbiosis in the neurobiology of depression. Telomere shortening and hyperinflammation are well reported in depression. A negative impact of augmented inflammation has been noted on the intestinal permeability and microbial consortia and their byproducts in depressive patients. Moreover, gut dysbiosis provokes host-immune responses. As the gut microbiome is gaining importance in the manifestation and management of depression, herein we discuss whether telomere attrition is connected with the perturbation of commensal microflora. We also describe a pathological connection of cortisol with hyperinflammation, telomere shortening, and gut dysbiosis occurring in depression. This review summarizes how the triad of telomere attrition, inflammation, and gut dysbiosis is interconnected and modulates the risk for depression by regulating the systemic cortisol levels.

Association between high-sensitivity C-reactive protein levels and depression: Moderation by age, sex, obesity, and aerobic physical activity

BACKGROUND

Low-grade systemic inflammation evidenced by elevated serum high-sensitivity C-reactive protein (hsCRP) levels can be a biomarker for depression. This study aimed to investigate the association between serum hsCRP levels and depressive symptoms and to explore the potential moderating effects of age, sex, body mass index (BMI), and aerobic physical activity on the association.

METHODS

Data of 10,702 adults (≥ 19 years) were obtained from the nationwide cross-sectional Korea National Health and Nutrition Examination Surveys of 2016 and 2018. Significant depressive symptoms were defined as ≥ 10 on the Patient Health Questionnaire-9, and high hsCRP level was defined as > 3.0 mg/L.

RESULTS

Adults with high hsCRP levels were more likely to have depressive symptoms (odds ratio [OR]: 1.41, 95% confidence interval [CI]: 1.07-1.84) and suicidal ideation (OR: 1.39, 95% CI: 1.07-1.80) than those with low hsCRP levels. In the age- and sex-stratified analysis, high hsCRP levels were associated with depressive symptoms in the non-geriatric population (age ≤ 64 years) alone, with a higher OR in males than females. In subgroup analyses, the association between them was observed only among obese adults and adults without aerobic physical activity.

LIMITATIONS

Causal interpretation is limited due to the cross-sectional design.

CONCLUSIONS

Our results replicate previous findings of an association between high hsCRP levels and depressive symptoms in adults using a large nationally representative sample. The association between them was more prominent in the non-geriatric population, males, obese adults, and those without aerobic physical activity.

Association of Psychological Stress with Physical Fitness in a Military Cohort: The CHIEF Study

INTRODUCTION

Psychological stress is associated with sedentary behavior, which may impair exercise performance. The aim of our study was to examine the association between psychological stress and physical fitness in military personnel.

METHOD

A military cohort of 4080 subjects in Taiwan was used for the analysis. The Brief Symptoms Rating Scale (BSRS-5) includes items of anxiety, depression, hostility, interpersonal sensitivity, and insomnia measured by a five-point Likert-type scale of 0-4. Psychological stress was defined as normal (n = 3657), slight (n = 314), and great (n = 109) by BSRS-5 score ≤5, 6-9, and ≥10, respectively. Aerobic fitness and anaerobic fitness were evaluated by the time of 3000-meter running and the numbers of 2-min sit-ups and 2-min push-ups, respectively. Multiple linear and logistic regression analyses were used to determine the relationship.

RESULTS

As compared with normal stress, slight and great stress were positive dose-dependently correlated with 3000-meter running time (β = 9.09 and 14.44; P = 0.0032 and 0.048, respectively) after adjusting for age, sex, service specialty, body mass index, systolic blood pressure, cigarette smoking, alcohol intake, hemoglobin levels, and exercise frequency. Similarly, those with slight stress were more likely to be the worst 10% performers in the 3000-meter run test relative to the normal individuals (odds ratio and 95% confidence intervals: 1.50, 1.00-2.24). By contrast, there was no relationship of psychological stress with the numbers of 2-min sit-ups and 2-min push-ups.

CONCLUSIONS

Our findings suggest that the presence of higher psychological stress on military personnel may reduce their cardiorespiratory fitness but not affect the anaerobic fitness.

Removal of vasopressin cells from the paraventricular nucleus of the hypothalamus enhances lipopolysaccharide-induced sickness behaviour in mice

Vasopressin (AVP) cells in the paraventricular nucleus of the hypothalamus (PVN) are activated during sickness and project to multiple nuclei responsible for the anxiety, social and motivated behaviours affected during sickness, suggesting that these cells may play a role in sickness behaviours, typically expressed as reduced mobility, increased anxiety, anhedonia and social withdrawal. In the present study, we selectively ablated AVP neurones in the PVN of male and female mice (Mus musculus) and induced sickness behaviour via injection of bacterial lipopolysaccharide (LPS). We found that PVN AVP ablation increased the effects of LPS, specifically by further decreasing sucrose preference in males and females and decreasing the social preference of males, monitored within 24 hours of LPS injection. These results suggest that PVN AVP contributes to the change in motivated behaviours during sickness and may help promote recovery from infection..

Psychological stress in heart failure: a potentially actionable disease modifier

Psychological stress is common in patients with heart failure, due in part to the complexities of effective disease self-management and progressively worsening functional limitations, including frequent symptom exacerbations and hospitalizations. Emerging evidence suggests that heart failure patients who experience higher levels of stress may have a more burdensome disease course, with diminished quality of life and increased risk for adverse events, and that multiple behavioral and pathophysiological pathways are involved. Furthermore, the reduced quality of life associated with heart failure can serve as a life stressor for many patients. The purpose of this review is to summarize the current state of the science concerning psychological stress in patients with heart failure and to discuss potential pathways responsible for the observed effects. Key knowledge gaps are also outlined, including the need to understand patterns of exposure to various heart failure-related and daily life stressors and their associated effects on heart failure symptoms and pathophysiology, to identify patient subgroups at increased risk for stress exposure and disease-related consequences, and the effect of stress specifically for patients who have heart failure with preserved ejection fraction. Stress is a potentially modifiable factor, and addressing these gaps and advancing the science of stress in heart failure is likely to yield important insights about actionable pathways for improving patient quality of life and outcomes.

Interpersonal capitalization moderates the associations of chronic caregiving stress and depression with inflammation

Chronic stress and depression can enhance chronic low-grade inflammation. Interpersonal factors may buffer the impact of stress and depression on inflammation. Interpersonal capitalization is a social support process in which one discloses positive personal events and experiences to close others. Greater capitalization may attenuate the deleterious impact of chronic stress and depression. The goal of the current study was to assess whether interpersonal capitalization is associated with inflammation and whether it moderates the association of chronic stress and depression with inflammation. In this cross-sectional study of chronic caregiving stress, 222 caregiving mothers of adolescents with developmental disabilities or comparison mothers of typically developing adolescents completed a self-reported daily diary assessment of capitalization, the Center for Epidemiological Study-Depression scale, and provided blood samples to assess interleukin-6, tumor necrosis factor-α, and C-reactive protein, three circulating inflammatory markers. Regression analysis indicated that there was no main effect of capitalization on inflammation, p = .24, R² = .006. However, there was a significant three-way interaction among capitalization, chronic caregiving stress, and depressive symptoms, p = .01, R² = .02. Among participants with lower capitalization, greater depressive symptoms were associated with higher inflammation in the caregiving group, but not in the comparison group. Among participants with higher capitalization, greater depressive symptoms were no longer significantly associated with higher inflammation among caregivers, but were marginally related to inflammation in the comparison group. Capitalization may thus be an interpersonal process mitigating the effects of chronic stress and depression on inflammation.

Gender differences in the link between depressive symptoms and ex vivo inflammatory responses are associated with markers of endotoxemia

Depressive symptoms are often linked with higher inflammation and inflammatory responses, although these associations are not always consistent. In a recent study (N = 160, 25–65 years, 67% women), our group reported gender differences relevant to this association: In men higher depressive symptoms were related to heightened ex vivo inflammatory responses to lipopolysaccharide (LPS), whereas in women higher depressive symptoms were related to attenuated inflammatory responses. In the present manuscript, we investigate markers of endotoxemia – i.e., markers of the presence of endotoxin in the blood, presumably due to bacterial translocation from the gut – as factors that elicit gender-dependent immune responses that may be associated with links between depressive symptoms and inflammation. We examined ex vivo inflammatory responses in whole blood via a composite index of LPS-stimulated cytokines. The ratio of LPS-binding protein to soluble CD14 receptor (LBP:sCD14) was quantified as an index of endotoxemia that captures the relative reliance on pro-inflammatory versus non-inflammatory pathways for bacterial clearance. Levels of endotoxemia markers in blood were found to moderate gender differences in the link between depressive symptoms and stimulated inflammation (Gender × Depressive Symptoms × Endotoxemia: B = −0.039, 95%CI [-0.068, 0.009], p = 0.010). At lower LBP:sCD14 levels, depressive symptoms and stimulated inflammation were unrelated in both men and women. However, with higher levels of LBP:sCD14, men showed an increasingly positive correlation and women showed a negative correlation between depressive symptoms and stimulated inflammation. Hence, men and women exhibited similar associations between depressive symptoms and inflammatory responses at lower endotoxin marker levels, but these associations became divergent at higher levels of endotoxin markers. This information provides a novel perspective on risk factors for depression-linked alterations in inflammation, which may help to determine susceptibility to the downstream physical consequences of depressive symptomatology.

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Depressive symptoms link to higher inflammation in men, lower inflammation in women.

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These gender differences were only apparent at moderate or higher endotoxemia.

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Men’s inflammation may be particularly sensitive to depressed mood and endotoxemia.

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Endotoxemia may be an important factor in gender, depression and inflammation links.

Executive Control, Cytokine Reactivity to Social Stress, and Depressive Symptoms: Testing the Social Signal Transduction Theory of Depression

Social Signal Transduction Theory of Depression hypothesizes that social stress upregulates inflammatory activity, which in turn contributes to depression for some individuals. However, the specific cognitive processes underlying social stress-induced increases in inflammatory activity remain unclear. We addressed this issue by examining two separate relations: (1) between executive control measured following a laboratory-based social stress induction and individuals' pro-inflammatory cytokine responses to the same stress induction and (2) between pro-inflammatory cytokine responses and participants' depressive symptom levels. Healthy young participants (Mage = 18.58 years old) were randomly assigned to either a stress condition or control condition. Executive control, and the inflammatory cytokines interleukin-1β, interleukin-6, and tumor necrosis factor-α, were measured before and after the social stress induction or control task. Regression analyses (stress condition, n = 20; control condition, n = 16) demonstrated that in the stress condition only, greater increases in interleukin-6 were associated with more depressive symptoms. Additional analyses in the stress condition (n = 16) indicated that greater impairment in executive control following the social stress induction was related to greater social stress-induced increases in interleukin-6. These findings are consistent with Social Signal Transduction Theory of Depression and with the hypothesis that impairment in executive control during times of stress may be one process that contributes to stress-induced inflammatory activity, which may in turn increase risk for depression.Lay SummarySocial Signal Transduction Theory of Depression hypothesizes that social stress upregulates inflammatory activity, which in turn contributes to depression, and that cognitive processes play a role in structuring these effects. Consistent with this theory, greater social stress-induced increases in the inflammatory cytokine interleukin-6 were associated with more depressive symptoms. In addition, greater impairment in executive control following the social stress induction was related to greater social stress-induced increases in interleukin-6, highlighting potential links between social stress, cognition, inflammation, and depression.

An initial exploration of hair cortisol responses to antidepressants in unmedicated patients with depression

OBJECTIVE

Major depressive disorder is associated with abnormal functioning of the hypothalamic-pituitary-adrenal (HPA) axis. Studies using hair cortisol to measure the effect of antidepressants on the HPA axis are lacking. The aim of this study was to explore the long-term effects of antidepressants on hair cortisol concentration (HCC).

METHODS

Participants were 42 patients and 36 healthy individuals. The patients took antidepressants for 4 weeks. Patient HCC was measured pre-treatment and post-treatment. The HCC of healthy controls was also measured.

RESULTS

Patient post-treatment HCC (mean ± standard deviation: 34.40 ± 32.57 pmol/mg) was significantly higher than patient pre-treatment HCC (17.42 ± 12.40 pmol/mg) and healthy control HCC (10.22 ± 7.99 pmol/mg). No significant correlation was found between Hamilton Depression Rating Scale scores and HCC at pre-treatment or post-treatment.

CONCLUSIONS

Hair cortisol concentration analysis could be used to monitor the dynamics of the effects of antidepressants on the HPA axis.

The brain-adipocyte-gut network: Linking obesity and depression subtypes

Major depressive disorder (MDD) and obesity are dominant and inter-related health burdens. Obesity is a risk factor for MDD, and there is evidence MDD increases risk of obesity. However, description of a bidirectional relationship between obesity and MDD is misleading, as closer examination reveals distinct unidirectional relationships in MDD subtypes. MDD is frequently associated with weight loss, although obesity promotes MDD. In contrast, MDD with atypical features (MDD-AF) is characterised by subsequent weight gain and obesity. The bases of these distinct associations remain to be detailed, with conflicting findings clouding interpretation. These associations can be viewed within a systems biology framework-the psycho-immune neuroendocrine (PINE) network shared between MDD and metabolic disorders. Shared PINE subsystem perturbations may underlie increased MDD in overweight and obese people (obesity-associated depression), while obesity in MDD-AF (depression-associated obesity) involves more complex interactions between behavioural and biomolecular changes. In the former, the chronic PINE dysfunction triggering MDD is augmented by obesity-dependent dysregulation in shared networks, including inflammatory, leptin-ghrelin, neuroendocrine, and gut microbiome systems, influenced by chronic image-associated psychological stress (particularly in younger or female patients). In MDD-AF, behavioural dysregulation, including hypersensitivity to interpersonal rejection, fundamentally underpins energy imbalance (involving hyperphagia, lethargy, hypersomnia), with evolving obesity exaggerating these drivers via positive feedback (and potentially augmenting PINE disruption). In both settings, sex and age are important determinants of outcome, associated with differences in emotional versus cognitive dysregulation. A systems biology approach is recommended for further research into the pathophysiological networks underlying MDD and linking depression and obesity.

Examining reactivity patterns in burnout and other indicators of chronic stress

INTRODUCTION

Burnout symptomatology is associated with various negative health consequences; however, the mechanisms underlying these associations remain unclear. One potential pathway involves alterations in the acute stress response. The aims of the present study were to examine burnout-associated alterations in stress-reactivity patterns, during a standardized social stressor compared to a control condition, as well as to examine whether effects associated with greater burnout symptomatology were distinct from other, conceptually overlapping indicators of chronic stress (i.e. depressive symptomatology and elevated hair cortisol concentration [HCC]).

MATERIALS AND METHODS

In a randomized two-factor design a total of 70 employed males with varying burnout symptoms but without evidence of physical or psychiatric disease were exposed to the Trier Social Stress Test for Groups (TSST-G) or a non-stressful control condition. Acute stress reactivity was assessed using self-report stress measures and non-invasive biomarkers. Associations among acute stress reactivity, burnout and depressive symptoms (assessed with self-report measures), as well as HCC were analysed using repeated measure ANCOVAs and moderation analysis.

RESULTS

Burnout symptomatology was associated with elevated stress perception independent of the experimental condition. In addition, depressive symptomatology was associated with enhanced anticipatory appraisal, whereas HCC was not related to any subjective stress measure. On a physiological level, burnout and depressive symptomatology, as well as HCC were associated with a pattern of blunted cardiovascular reactivity, however the timing of this effect varied.

CONCLUSION

Our results indicate burnout-associated modulations in stress reactivity, which diverge, at least partly, from other indicators of chronic stress.

Stress and inflammation - The need to address the gap in the transition between acute and chronic stress effects

Stress responses help us navigate our environment and respond appropriately to threats. Stress systems communicate threats to the entire organism, and as such, also stimulate inflammatory mechanisms. This modulation might serve protective functions in the short term, but sustained low-grade inflammation has severe long-term health consequences. While we have reached a reasonable level of understanding of acute, as well as chronic stress effects on inflammatory mechanisms, there is a significant gap in our understanding of the transitional phase between acute and chronic stress. The purpose of this review is to first summarize current knowledge of our understanding of acute stress effects on inflammation, as well as of chronic stress effects on inflammation, and to then analyze the state of knowledge about the transitional phase between acute and chronic stress. Research discussed here shows that we are beginning to understand the early phase of repeated acute stress, but lack information on longer term exposure to repeated acute stress experiences. More research is needed to bridge this important gap und our conceptualization and understanding of the stress and health relationship.

Glucocorticoid Resistance: Is It a Requisite for Increased Cytokine Production in Depression? A Systematic Review and Meta-Analysis

Background: Glucocorticoid resistance-reduced function of the glucocorticoid receptor (GR)-is seen in many depressed patients. It is argued that this resistance to glucocorticoids leads to failure of normal feedback regulation on the immune system. High levels of pro-inflammatory cytokines result. Purpose: We sought to identify evidence supporting or refuting a link between glucocorticoid resistance and immune dysregulation in depression and to summarize retrieved evidence in aggregate form. Methods: We systematically reviewed and meta-analyzed studies that examined cytokine levels in depressed patients compared with controls and that also reported a measure of glucocorticoid resistance. These measures included plasma cortisol, the dexamethasone suppression test (DST), GR expression levels, and the results of in vitro assays of GR function. We conducted four separate meta-analyses to test for moderating effects of glucocorticoid resistance on cytokine production in depression. Results: After sub-grouping 32 studies by the ratio of cortisol levels in patients compared with controls, we observed a trend for increasing glucocorticoid resistance (i.e., the most hypercortisolemic patients) to be associated with increased production of interleukin (IL)-6 [d = 0.94; 95% CI (0.29, 1.59)] and tumour necrosis factor (TNF)-α [d = 0.46; 95% CI (0.12, 0.79)]. We stratified nine studies that reported DST results by relative glucocorticoid resistance between patients and controls, identifying a trend for higher glucocorticoid resistance in patients, compared with controls, to be associated with higher cytokine production in patients (170 patients and 187 controls). This was particularly evident when studies were sub-grouped by source of cytokine-plasma (d = 1.04; 95% CI, 0.57-1.50) versus in vitro (d = 0.24; 95% CI, -0.20 to 0.67). Stratifying the four studies (147 patients and 118 controls) that used in vitro assays of GR function or GR expression to quantify glucocorticoid resistance revealed variable contributions to cytokine production in patients compared with controls (overall effect size: d = 1.35; 95% CI 0.53-2.18). Combining our analyses of studies that reported DST results with those that used in vitro assays of GR function or GR expression to quantify glucocorticoid resistance (302 patients and 277 controls), we noted that although depressed patients produced more cytokines than controls (d = 1.02; 95% CI, 0.55-1.49), there was no evident positive correlation between glucocorticoid resistance and inflammation. Conclusions: Our work provides some support for a model conceptualizing glucocorticoid resistance as a requisite for increased inflammation in depression. The limited number of studies identified highlights the need for purpose-designed investigations that directly examine the relationship between glucocorticoid resistance and cytokine production in depression.

The Interplay Between Stress, Inflammation, and Emotional Attention: Relevance for Depression

Depression is among the most significant public mental health issues. A growing body of research implicates inflammation in the etiology and pathophysiology of depression. Yet, the results are somewhat inconsistent, leading to burgeoning attempts to identify associations between components of innate immune system involved in inflammation and specific symptoms of depression, including attention to emotional information. Negative attentional bias, defined as a tendency to direct attention toward negatively valenced information, is one of the core cognitive features of depression and is reliably demonstrated in depressed and vulnerable individuals. Altered attentional processing of emotional information and immunological changes are often precipitated by stressful events. Psychological stress triggers inflammatory activity and affective-cognitive changes that play a critical role in the onset, maintenance, and recurrence of depression. Using various designs, recent studies have reported a positive relationship between markers of inflammation and negative attentional bias on behavioral and neural levels, suggesting that the association between inflammation and emotional attention might represent a neurobiological pathway linking stress and depression. This mini-review summarizes current research on the reciprocal relationships between different types of stressors, emotional attention, inflammation, and depression, and discusses potential neurobiological mechanisms underlying these interactions. The integration provided aims to contribute toward understanding how biological and psychological processes interact to influence depression outcomes.

The impact of acute mental stress on brachial artery flow-mediated dilation in women diagnosed with depression

Endothelial function, assessed by flow-mediated dilation (FMD), may be transiently attenuated in healthy adults following acute mental stress. However, the impact of acute mental stress on endothelial function in the context of clinical depression is unknown. This study examined the impact of acute mental stress on FMD in women with a diagnosis of a depressive disorder. Forty-three otherwise healthy women (33 ± 14 years) participated. Brachial artery diameter and blood velocity were assessed with ultrasound. FMD was assessed immediately prior to and 15 min following the Trier Social Stress Test (TSST). The FMD protocol included 5 min of forearm cuff occlusion (pressure = 250 mm Hg), followed by release. Shear stress was estimated by calculating shear rate (SR = brachial artery blood velocity/diameter). Stress reactivity was assessed via changes in mean arterial pressure (MAP), heart rate (HR) and salivary cortisol. Results are mean ± SD. A significant stress response was elicited by the TSST [MAP, HR and salivary cortisol increased (p < 0.05)]. Neither the SR stimulus nor FMD response differed pre-versus post-stress (p = 0.124 and p = 0.641, respectively). There was a modest negative correlation between cortisol reactivity and change in FMD from pre- to post-stress (R = -0.392, p = 0.011). To conclude, acute mental stress did not consistently impair endothelial function in women diagnosed with a depressive disorder; however, higher cortisol reactivity may increase the likelihood of post-stress endothelial dysfunction. Further research is required to better understand the factors influencing the relationship between acute mental stress, cortisol and endothelial function in women with depression.

Marriage, divorce, and the immune system

This article reviews evidence from several lines of work to describe how marriage and divorce can provoke health-relevant immune alterations, including ways that marital closeness can be perilous for health and divorce can be beneficial. The multiple stresses of a troubled relationship are depressogenic, and the development of a mood disorder sets the stage for psychological and biological vulnerability. Depression provides a central pathway to immune dysregulation, inflammation, and poor health; gender-related differences in depression and inflammation can heighten risk for women compared to men. Sleep and obesity can simultaneously feed off depression as they promote it. In addition, spousal similarities in health behaviors, gene expression, immune profiles and the gut microbiota offer new ways to consider the health advantages and risks of marriage and divorce, providing new perspectives on couples' interdependence, as well as new directions for research. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

The role of inflammation in core features of depression: Insights from paradigms using exogenously-induced inflammation

A wealth of evidence has implicated inflammation in the development of depression. Yet, the heterogeneous nature of depression has impeded efforts to understand, prevent, and treat the disease. The purpose of this integrative review is to summarize the connections between inflammation and established core features of depression that exhibit more homogeneity than the syndrome itself: exaggerated reactivity to negative information, altered reward processing, decreased cognitive control, and somatic syndrome. For each core feature, we first provide a brief overview of its relevance to depression and neurobiological underpinnings, and then review evidence investigating a potential role of inflammation. We focus primarily on findings from experimental paradigms of exogenously-induced inflammation. We conclude that inflammation likely plays a role in exaggerated reactivity to negative information, altered reward reactivity, and somatic symptoms. There is less evidence supporting an effect of inflammation on cognitive control as assessed by standard neuropsychological measures. Finally, we discuss implications for future research and recommendationsfor how to test the role of inflammation in the pathogenesis of heterogeneous psychiatric disorders.

Adrenal serotonin derives from accumulation by the antidepressant-sensitive serotonin transporter

Adrenal chromaffin cells comprise the neuroendocrine arm of the sympathetic nervous system and secrete catecholamines to coordinate the appropriate stress response. Deletion of the serotonin (5-HT) transporter (SERT) gene in mice (SERT^-/- mice) or pharmacological block of SERT function in rodents and humans augments this sympathoadrenal stress response (epinephrine secretion). The prevailing assumption is that loss of CNS SERT alters central drive to the peripheral sympathetic nervous system. Adrenal chromaffin cells also prominently express SERT where it might coordinate accumulation of 5-HT for reuse in the autocrine control of stress-evoked catecholamine secretion. To help test this hypothesis, we have generated a novel mouse model with selective excision of SERT in the peripheral sympathetic nervous system (SERT^ΔTH), generated by crossing floxed SERT mice with tyrosine hydroxylase Cre driver mice. SERT expression, assessed by western blot, was abolished in the adrenal gland but not perturbed in the CNS of SERT^ΔTH mice. SERT-mediated [³H] 5-HT uptake was unaltered in midbrain, hindbrain, and spinal cord synaptosomes, confirming transporter function was intact in the CNS. Endogenous midbrain and whole blood 5-HT homeostasis was unperturbed in SERT^ΔTH mice, contrasting with the depleted 5-HT content in SERT^-/- mice. Selective SERT excision reduced adrenal gland 5-HT content by ≈ 50% in SERT^ΔTH mice but had no effect on adrenal catecholamine content. This novel model confirms that SERT expressed in adrenal chromaffin cells is essential for maintaining wild-type levels of 5-HT and provides a powerful tool to help dissect the role of SERT in the sympathetic stress response.

Mental health consequences of exercise withdrawal: A systematic review

OBJECTIVE

A sedentary lifestyle has been associated with mental health disorders. Many medical conditions result in the cessation of exercise, which may increase the risk of developing mental health problems. The purpose of this article is to systematically review the literature examining the effects of exercise withdrawal on mental health.

METHOD

Literature was searched using PubMed, PsycINFO, and SPORTdiscus for studies that experimentally manipulated the withdrawal of exercise and included mental health as outcome measure.

RESULTS

A total of 19 studies met inclusion criteria (total N=689 with 385 individuals participating in an exercise withdrawal condition). Exercise withdrawal consistently resulted in increases in depressive symptoms and anxiety. Other mental health outcomes were investigated infrequently. Severe mental health issues requiring clinical intervention after experimentally controlled exercise withdrawal was rare. Heterogeneity in methods and outcomes was observed, especially in terms of the duration of exercise withdrawal (range 1 to 42days, median=7days), with stronger effects if exercise withdrawal exceeded 2weeks.

CONCLUSION

Experimentally controlled exercise withdrawal has adverse consequences for mental health. These observations in healthy individuals may help to understand the onset of mental health problems in response to acute and chronic medical conditions associated with reduced physical activity. Future research is needed to investigate potential mechanisms explaining the adverse mental health consequences of cessation of exercise that will provide new targets for clinical interventions.

The effects of acute psychological stress on circulating and stimulated inflammatory markers: A systematic review and meta-analysis

Inflammatory reactivity to acute laboratory stress is thought to reflect individual differences in responsivity to environmental stressors and may confer future health risk. To characterize this response, we conducted a meta-analysis of 34 studies that measured circulating inflammatory markers and 15 studies that measured stimulated production of inflammatory markers before and after exposure to laboratory challenge. Results showed significant stress-related increases in circulating interleukin (IL)-1β (d=0.66, p<0.001), IL-6 (d=0.35, p<0.001), IL-10 (d=0.69, p<0.001), and tumor necrosis factor(TNF)-α (d=0.28, p<0.001), but not IL-1ra, IL-2, interferon-γ, or C-reactive protein. There were sufficient data to assess the time course of IL-6, IL-1β, and TNF-α reactivity. IL-6 increased from baseline to measures taken 40-50, 60-75, 90, and 120min following stress, with the largest effect at 90min post-stress (d=0.70, p<0.001). IL-1β increased from baseline to 20-30, 40-50, and 60-70min following stress, with the largest effect between 40 and 50min post-stress (d=0.73, p=0.02). For TNF-α, there was a significant increase from baseline to 31-50min post stress (d=0.44, p=0.01), but not at later times. There was no difference in magnitude of IL-6 reactivity as a function of type of stress (social-evaluative versus other). For stimulated inflammatory markers, results showed stress-related increases in IL-1β when measured 20-120min post-stress (d=1.09, p<0.001), and in IL-4 and interferon-γ when measured 0-10min post stressor (d=-0.42, p<0.001 and d=0.47, p<0.001). These results extend findings from a prior meta-analysis (Steptoe et al., 2007) to show reliable increases in circulating IL-6, IL-1β, IL-10 and TNF-α and stimulated IL-1β, IL-4 and interferon-γ in response to acute stress. It is possible that these responses contribute to associations between exposure to life challenges and vulnerability to inflammatory disease.

Serotonin and Serotonin Transporters in the Adrenal Medulla: A Potential Hub for Modulation of the Sympathetic Stress Response

Serotonin (5-HT) is an important neurotransmitter in the central nervous system where it modulates circuits involved in mood, cognition, movement, arousal, and autonomic function. The 5-HT transporter (SERT; SLC6A4) is a key regulator of 5-HT signaling, and genetic variations in SERT are associated with various disorders including depression, anxiety, and autism. This review focuses on the role of SERT in the sympathetic nervous system. Autonomic/sympathetic dysfunction is evident in patients with depression, anxiety, and other diseases linked to serotonergic signaling. Experimentally, loss of SERT function (SERT knockout mice or chronic pharmacological block) has been reported to augment the sympathetic stress response. Alterations to serotonergic signaling in the CNS and thus central drive to the peripheral sympathetic nervous system are presumed to underlie this augmentation. Although less widely recognized, SERT is robustly expressed in chromaffin cells of the adrenal medulla, the neuroendocrine arm of the sympathetic nervous system. Adrenal chromaffin cells do not synthesize 5-HT but accumulate small amounts by SERT-mediated uptake. Recent evidence demonstrated that 5-HT1A receptors inhibit catecholamine secretion from adrenal chromaffin cells via an atypical mechanism that does not involve modulation of cellular excitability or voltage-gated Ca2+ channels. This raises the possibility that the adrenal medulla is a previously unrecognized peripheral hub for serotonergic control of the sympathetic stress response. As a framework for future investigation, a model is proposed in which stress-evoked adrenal catecholamine secretion is fine-tuned by SERT-modulated autocrine 5-HT signaling.

The cholinergic anti-inflammatory pathway: An innovative treatment strategy for neurological diseases

Acetylcholine (ACh), as a classical neurotransmitter, regulates the neuronal network in response to internal and external stimuli. In recent decades, the biology of ACh has been endowed with unparalleled new insights, especially with respect to cholinergic anti-inflammatory properties in non-neuronal cells. In fact, a mechanism frequently referred to as the "cholinergic anti-inflammatory pathway" has been termed to describe interactions between the central nervous system (CNS) and the immune system via vagus nerve. As well documented, immune cells express choline acetyltransferase, a direct synthetase for ACh, and other corresponding cholinergic components. Alternatively, the ACh released from immune cells or cholinergic neurons modulates immune function in an autocrine/paracrine manner by acting on its receptors. Moreover, muscarinic or nicotinic ACh receptors on various immune cells and CNS glial cells administer the work of their respective agonists, causing functional and biochemical changes. In this review, we focus on the anti-inflammatory benefits of non-neuronal and neuronal ACh as a means of providing new insights into treating inflammation-related neurological diseases, as exemplified by those described herein.

Cortisol stress reactivity across psychiatric disorders: A systematic review and meta-analysis

The hypothalamus-pituitary-adrenal (HPA) axis and its end product cortisol are essential for an adequate response to stress. Considering the role of stress as a risk factor for psychiatric disorders, it is not surprising that cortisol stress reactivity has frequently been investigated in patients versus healthy individuals. However, the large heterogeneity in measures of the cortisol stress response has hampered a systematic evaluation of the evidence. We here report of a systematic literature review and meta-analysis on cortisol reactivity to psychosocial stress across psychiatric disorders. Original data from authors were obtained to construct standardized cortisol outcomes (the areas under the curve with respect to increase (AUCi) and ground (AUCg)) and to examine the influence of sex and symptomatic state on cortisol stress reactivity. Fourteen studies on major depressive disorder (MDD) (n=1129), 9 on anxiety disorders (n=732, including social anxiety disorder (SAD), posttraumatic stress disorder, panic disorder and mixed samples of anxiety disorders) and 4 on schizophrenia (n=180) were included that used the Trier Social Stress Test or an equivalent psychosocial stress task. Sex-dependent changes in stress reactivity were apparent in MDD and anxiety disorders. Specifically, women with current MDD or an anxiety disorder exhibited a blunted cortisol stress response, whereas men with current MDD or SAD showed an increased cortisol response to psychosocial stress. In individuals with remitted MDD, altered cortisol stress reactivity was less pronounced in women and absent in men. For schizophrenia, cortisol stress reactivity was blunted in both men and women, but the number of studies was limited and showed evidence for publication bias. These findings illustrate that sharing individual data to disentangle the effects of sex, symptom levels and other factors is essential for further understanding of the alterations in cortisol stress reactivity across psychiatric disorders.

Peripheral Inflammatory Markers Contributing to Comorbidities in Autism

This study evaluates the contribution of peripheral biomarkers to comorbidities and clinical findings in autism. Seventeen autistic children and age-matched typically developing (AMTD), between three to nine years old were evaluated. The diagnostic followed the Diagnostic and Statistical Manual of Mental Disorders 4th Edition (DMS-IV) and the Childhood Autism Rating Scale (CARS) was applied to classify the severity. Cytokine profile was evaluated in plasma using a sandwich type ELISA. Paraclinical events included electroencephalography (EEG) record. Statistical analysis was done to explore significant differences in cytokine profile between autism and AMTD groups and respect clinical and paraclinical parameters. Significant differences were found to IL-1β, IL-6, IL-17, IL-12p40, and IL-12p70 cytokines in individuals with autism compared with AMTD (p < 0.05). All autistic patients showed interictalepileptiform activity at EEG, however, only 37.5% suffered epilepsy. There was not a regional focalization of the abnormalities that were detectable with EEG in autistic patients with history of epilepsy. A higher IL-6 level was observed in patients without history of epilepsy with interictalepileptiform activity in the frontal brain region, p < 0.05. In conclusion, peripheral inflammatory markers might be useful as potential biomarkers to predict comorbidities in autism as well as reinforce and aid informed decision-making related to EEG findings in children with Autism spectrum disorders (ASD).

Cortisol and BDNF levels in depression within schizophrenia structure: approach to treating

To evaluate the effect of depression on the level of cortisol and BDNF in patients with schizophrenia 25 inpatients, who met the diagnostic criteria for ICD-10 schizophrenia (F20), were examined. The examination included clinical, psychopathological, laboratory and psychometric methods. Patients were examined twice: at admission and after 6 weeks of treatment. It was found that the level of BDNF in schizophrenic patients with depressive symptoms was significantly lower than that of non-depressed patients, and the level of cortisol in patients with depression was significantly higher.

Antidepressant therapies inhibit inflammation and microglial M1-polarization

Macrophages and their counterparts in the central nervous system, the microglia, detect and subsequently clear microbial pathogens and injured tissue. These phagocytic cells alter and adapt their phenotype depending on their prime activity, i.e., whether they participate in acute defence against pathogenic organisms ('M1'-phenotype) or in clearing damaged tissues and performing repair activities ('M2'-phenotype). Stimulation of pattern recognition receptors by viruses (vaccines), bacterial membrane components (e.g., LPS), alcohol, or long-chain saturated fatty acids promotes M1-polarization. Vaccine or LPS administration to healthy human subjects can result in sickness symptoms and low mood. Alcohol abuse and abdominal obesity are recognized as risk factors for depression. In the M1-polarized form, microglia and macrophages generate reactive oxygen and nitrogen radicals to eradicate microbial pathogens. Inadvertently, also tetrahydrobiopterin (BH4) may become oxidized. This is an irreversible reaction that generates neopterin, a recognized biomarker for depression. BH4 is a critical cofactor for the synthesis of dopamine, noradrenaline, and serotonin, and its loss could explain some of the symptoms of depression. Based on these aspects, the suppression of M1-polarization would limit the inadvertent catabolism of BH4. In the current review, we evaluate the evidence that antidepressant treatments (monoamine reuptake inhibitors, PDE4 inhibitors, lithium, valproate, agomelatine, tianeptine, electroconvulsive shock, and vagus nerve stimulation) inhibit LPS-induced microglia/macrophage M1-polarization. Consequently, we propose that supplementation with BH4 could limit the reduction in central monoamine synthesis and might represent an effective treatment for depressed mood.

Modulatory effects of α7 nAChRs on the immune system and its relevance for CNS disorders

The clinical development of selective alpha-7 nicotinic acetylcholine receptor (α7 nAChR) agonists has hitherto been focused on disorders characterized by cognitive deficits (e.g., Alzheimer's disease, schizophrenia). However, α7 nAChRs are also widely expressed by cells of the immune system and by cells with a secondary role in pathogen defense. Activation of α7 nAChRs leads to an anti-inflammatory effect. Since sterile inflammation is a frequently observed phenomenon in both psychiatric disorders (e.g., schizophrenia, melancholic and bipolar depression) and neurological disorders (e.g., Alzheimer's disease, Parkinson's disease, and multiple sclerosis), α7 nAChR agonists might show beneficial effects in these central nervous system disorders. In the current review, we summarize information on receptor expression, the intracellular signaling pathways they modulate and reasons for receptor dysfunction. Information from tobacco smoking, vagus nerve stimulation, and cholinesterase inhibition is used to evaluate the therapeutic potential of selective α7 nAChR agonists in these inflammation-related disorders.

The effect of experimentally induced sedentariness on mood and psychobiological responses to mental stress

BACKGROUND

Evidence suggests a link between sedentary behaviours and depressive symptoms. Mechanisms underlying this relationship are not understood, but inflammatory processes may be involved. Autonomic and inflammatory responses to stress may be heightened in sedentary individuals contributing to risk, but no study has experimentally investigated this.

AIMS

To examine the effect of sedentary time on mood and stress responses using an experimental design.

METHOD

Forty-three individuals were assigned to a free-living sedentary condition and to a control condition (usual activity) in a cross-over, randomised fashion and were tested in a psychophysiology laboratory after spending 2 weeks in each condition. Participants completed mood questionnaires (General Health Questionnaire and Profile of Mood States) and wore a motion sensor for 4 weeks.

RESULTS

Sedentary time increased by an average of 32 min/day (P = 0.01) during the experimental condition compared with control. Being sedentary resulted in increases in negative mood independent of changes in moderate to vigorous physical activity (ΔGHQ = 6.23, ΔPOMS = 2.80). Mood disturbances were associated with greater stress-induced inflammatory interleukin-6 (IL-6) responses (β = 0.37).

CONCLUSIONS

Two weeks of exposure to greater free-living sedentary time resulted in mood disturbances independent of reduction in physical activity. Stress-induced IL-6 responses were associated with changes in mood.

Inflammation: depression fans the flames and feasts on the heat

Depression and inflammation fuel one another. Inflammation plays a key role in depression's pathogenesis for a subset of depressed individuals; depression also primes larger cytokine responses to stressors and pathogens that do not appear to habituate. Accordingly, treatment decisions may be informed by attention to questions of how (pathways) and for whom (predispositions) these links exist, which are the focus of this article. When combined with predisposing factors (moderators such as childhood adversity and obesity), stressors and pathogens can lead to exaggerated or prolonged inflammatory responses. The resulting sickness behaviors (e.g., pain, disturbed sleep), depressive symptoms, and negative health behaviors (e.g., poor diet, a sedentary lifestyle) may act as mediating pathways that lead to further, unrestrained inflammation and depression. Depression, childhood adversity, stressors, and diet can all influence the gut microbiome and promote intestinal permeability, another pathway to enhanced inflammatory responses. Larger, more frequent, or more prolonged inflammatory responses could have negative mental and physical health consequences. In clinical practice, inflammation provides a guide to potential targets for symptom management by signaling responsiveness to certain therapeutic strategies. For example, a theme across research with cytokine antagonists, omega-3 fatty acids, celecoxib, and exercise is that anti-inflammatory interventions have a substantially greater impact on mood in individuals with heightened inflammation. Thus, when inflammation and depression co-occur, treating them in tandem may enhance recovery and reduce the risk of recurrence. The bidirectional links between depression, inflammation, and disease suggest that effective depression treatments could have a far-reaching impact on mood, inflammation, and health.

Cumulative meta-analysis of interleukins 6 and 1β, tumour necrosis factor α and C-reactive protein in patients with major depressive disorder

Cumulative meta-analyses are used to evaluate the extent to which further studies are needed to confirm or refute a hypothesis. We used this approach to assess observational evidence on systemic inflammation in individuals with major depressive disorder. We identified 58 studies of four common inflammatory markers in a literature search of PubMed, Embase and PsychInfo databases in May 2014. Pooled data from the earliest eight studies already showed an association between interleukin-6 concentrations and major depression; 23 more recent studies confirmed this finding (d=0.54, p<0.0001). A significant association between C-reactive protein levels and major depression was noted after 14 studies and this did not change after addition of six more studies (d=0.47, p<0.0001). For these two inflammatory markers, there was moderate heterogeneity in study-specific estimates, subgroup differences were small, and publication bias appeared to be an unlikely explanation for the findings. Sensitivity analyses including only high-quality studies and subjects free of antidepressant medication further verified the associations. While there was a link between tumour necrosis factor-α levels and major depression (d=0.40, p=0.002), the cumulative effect remained uncertain due to the extensive heterogeneity in study-specific estimates and inconsistencies between subgroups. No evidence was found for the association between interleukin-1β levels and major depression (d=-0.05, p=0.86). In conclusion, this cumulative meta-analysis confirmed higher mean levels of interleukin-6 and C-reactive protein in patients with major depression compared to non-depressed controls. No consistent association between tumour necrosis factor-α, interleukin-1β and major depression was observed. Future studies should clarify the specific immune mechanisms involved as well as continue testing anti-inflammatory therapies in patients suffering from major depression.

Telomere length and cortisol reactivity in children of depressed mothers

A growing body of research demonstrates that individuals diagnosed with major depressive disorder (MDD) are characterized by shortened telomere length, which has been posited to underlie the association between depression and increased instances of medical illness. The temporal nature of the relation between MDD and shortened telomere length, however, is not clear. Importantly, both MDD and telomere length have been associated independently with high levels of stress, implicating dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and anomalous levels of cortisol secretion in this relation. Despite these associations, no study has assessed telomere length or its relation with HPA-axis activity in individuals at risk for depression, before the onset of disorder. In the present study, we assessed cortisol levels in response to a laboratory stressor and telomere length in 97 healthy young daughters of mothers either with recurrent episodes of depression (i.e., daughters at familial risk for depression) or with no history of psychopathology. We found that daughters of depressed mothers had shorter telomeres than did daughters of never-depressed mothers and, further, that shorter telomeres were associated with greater cortisol reactivity to stress. This study is the first to demonstrate that children at familial risk of developing MDD are characterized by accelerated biological aging, operationalized as shortened telomere length, before they had experienced an onset of depression; this may predispose them to develop not only MDD but also other age-related medical illnesses. It is critical, therefore, that we attempt to identify and distinguish genetic and environmental mechanisms that contribute to telomere shortening.

A review of the neuro- and systemic inflammatory responses in post concussion symptoms: Introduction of the "post-inflammatory brain syndrome" PIBS

Post-concussion syndrome is an aggregate of symptoms that commonly present together after head injury. These symptoms, depending on definition, include headaches, dizziness, neuropsychiatric symptoms, and cognitive impairment. However, these symptoms are common, occurring frequently in non-head injured controls, leading some to question the existence of post-concussion syndrome as a unique syndrome. Therefore, some have attempted to explain post-concussion symptoms as post-traumatic stress disorder, as they share many similar symptoms and post-traumatic stress disorder does not require head injury. This explanation falls short as patients with post-concussion syndrome do not necessarily experience many key symptoms of post-traumatic stress disorder. Therefore, other explanations must be sought to explain the prevalence of post-concussion like symptoms in non-head injury patients. Many of the situations in which post-concussion syndrome like symptoms may be experienced such as infection and post-surgery are associated with systemic inflammatory responses, and even neuroinflammation. Post-concussion syndrome itself has a significant neuroinflammatory component. In this review we examine the evidence of neuroinflammation in post-concussion syndrome and the potential role systemic inflammation plays in post-concussion syndrome like symptoms. We conclude that given the overlap between these conditions and the role of inflammation in their etiologies, a new term, post-inflammatory brain syndromes (PIBS), is necessary to describe the common outcomes of many different inflammatory insults. The concept of post-concussion syndrome is in its evolution therefore, the new term post-inflammatory brain syndromes provides a better understanding of etiology of its wide-array of symptoms and the wide array of conditions they can be seen in.

Analysis of hair cortisol level in first-episodic and recurrent female patients with depression compared to healthy controls

BACKGROUND

Although accumulating evidence has shown increased cortisol levels in serum, saliva, or 24-h urine samples in depression, a number of studies did not find the association between cortisol levels and depression. Hair cortisol levels reflect long-term and historical information of cortisol and hair cortisol analysis has been applied in the research of psychiatric diseases. The aim of this study is to compare the hair cortisol levels between patients with depression and healthy controls.

METHODS

Hair cortisol levels of 22 first-episodic and 13 recurrent female patients with depression and 30 healthy controls were measured and compared using the electrochemiluminescence immunoassay. The relationship between hair cortisol levels and Hamilton depression scale (HAMD) or Hamilton anxiety scale (HAMA) scores were also examined.

RESULTS

Before disease episode, no significant differences were observed among healthy controls, first-episodic patients and recurrent patients. In disease episode, the hair cortisol level in first-episodic patients was significantly higher than that in healthy controls or recurrent patients, while no significant difference was observed between recurrent patients and healthy controls. No significant correlation was found between HAMD or HAMA scores and hair cortisol levels in patients.

LIMITATIONS

First, long-term effects of antidepressants on the results cannot be excluded without detailed medication information of the recurrent patients. Second, sample sizes might be relatively small.

CONCLUSIONS

Our results indicate that hair cortisol levels increased in disease episode in first-episodic, but not recurrent patients with depression, which may suggest that episodes of disease have influence on cortisol levels.

Osteopathic manipulative therapy induces early plasma cytokine release and mobilization of a population of blood dendritic cells

It has been claimed that osteopathic manipulative treatment (OMT) is able to enhance the immune response of individuals. In particular, it has been reported that OMT has the capability to increase antibody titers, enhance the efficacy of vaccination, and upregulate the numbers of circulating leukocytes. Recently, it has been shown in human patients suffering chronic low back pain, that OMT is able to modify the levels of cytokines such as IL-6 and TNF-α in blood upon repeated treatment. Further, experimental animal models show that lymphatic pump techniques can induce a transient increase of cytokines in the lymphatic circulation. Taking into account all these data, we decided to investigate in healthy individuals the capacity of OMT to induce a rapid modification of the levels of cytokines and leukocytes in circulation. Human volunteers were subjected to a mixture of lymphatic and thoracic OMT, and shortly after the levels of several cytokines were evaluated by protein array technology and ELISA multiplex analysis, while the profile and activation status of circulating leukocytes was extensively evaluated by multicolor flow cytometry. In addition, the levels of nitric oxide and C-reactive protein (CRP) in plasma were determined. In this study, our results show that OMT was not able to induce a rapid modification in the levels of plasma nitrites or CRP or in the proportion or activation status of central memory, effector memory or naïve CD4 and CD8 T cells. A significant decrease in the proportion of a subpopulation of blood dendritic cells was detected in OMT patients. Significant differences were also detected in the levels of immune molecules such as IL-8, MCP-1, MIP-1α and most notably, G-CSF. Thus, OMT is able to induce a rapid change in the immunological profile of particular circulating cytokines and leukocytes.