Adiposity, leptin and stress reactivity in humans

Obesity: Heart Rate Variability during standardized psychosocial stress induction

Obesity is related to a higher risk of cardiovascular diseases (CVD). An altered stress reactivity of the parasympathetic nervous system (PNS) is a promising predictor of CVD and other negative health outcomes. Therefore, the aim of this study was to compare heart rate (HR) and heart rate variability parameters, root mean square successive differences (RMSSD) and power in the high frequency range 0.15-0.4 Hz (HF-HRV), of individuals with obesity and healthy weight controls during psychosocial stress induction. Thirty-four obese men and women (BMI: 33.80 ± 4.62 kg/m²), and thirty-four age- and gender-matched healthy weight controls (BMI: 22.29 ± 1.81 kg/m²) underwent the Trier Social Stress Test (TSST). Before, during, and after the TSST, their HR, RMSSD, and HF-HRV were measured. The individuals with obesity showed a lower stress reactivity in HR, and less stress recovery in RMSSD, compared to healthy weight controls. Obesity appears related to blunted HR reactivity, which is associated with CVD. In addition, impaired recovery of RMSSD also found in individuals with obesity may reflect health-damaging processes as well.

Cardiovascular stress reactivity, habituation, and adiposity

The relationship between adiposity and cardiovascular disease morbidity and mortality is complex. One pathway through which adiposity may influence future health outcomes is by altering how biological systems respond to stress. The current study aimed to examine the association between two metrics of adiposity (body mass index and waist-hip ratio) and two indices of cardiovascular stress responses (reactivity and habituation). A sample of 455 participants (Mean age = 19.47, SD = 1.25 years; BMI = 24.32, SD = 5.04 kg/m² ; 62% female; 17.9% Hispanic/Latino; 65.2% White, 18.7% Asian, 7.9% Black, 0.2% American Indian/Alaska Native, and 7% other) completed two acute psychosocial stress tasks. Heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were recorded throughout each stressor. In unadjusted and adjusted models, there were no statistically significant associations between adiposity and HR, SBP, or DBP stress reactivity or habituation. The current data do not support the hypothesis that adiposity influences health by altering cardiovascular responses to acute psychological stress. Results are at odds with prior population-level studies and the single prior study examining adiposity and habituation. At the same time, results are in line with mounting evidence that adiposity itself does not drive poor cardiovascular outcomes seen in people classified as overweight or obese.

Adiponectin, leptin, cortisol, neuropeptide Y and profile of mood states in athletes participating in an ultramarathon during winter: An observational study

Background: The Montane^® Yukon Arctic Ultra (YAU) is one of the longest (690 km) and coldest (+10.6°C-43.9°C) ultramarathons worldwide. Taking part in an ultramarathon is associated with great physiological and psychological stress, which can affect one's mood, level of hormones, and peptides. The current study aimed to identify relationships between peptides, hormones, and mood states in participants during this ultramarathon. Methods: The study cohort consisted of 36 participants (19 men, 17 women, 38.64 ± 9.12 years) split into a finisher (n = 10), non-finisher (n = 19), and control group (n = 7). Data were collected at four time points: baseline (PRE), during (D1 after 277 km, D2 after 383 km), and after the race (POST). Questionnaires were used to assess ratings of perceived exertion (RPE), total quality of recovery (TQR), and profile of mood states (POMS-SF). Serum NPY, leptin, adiponectin, and cortisol were measured. Results: Among non-finishers, scores for confusion, anger, depression, and tension-anxiety (PRE vs. D2, p < 0.05) increased, while vigor decreased (PRE vs. D1, p < 0.05). In contrast, finishers' tension-anxiety scores decreased (PRE vs. D1, p < 0.05). Fatigue increased in finishers (PRE vs. POST, p < 0.05) and non-finishers (PRE vs. D1, p < 0.05). In non-finishers, depressive mood correlated positively with leptin, anger, and confusion at several time points (p < 0.001). In finishers, NPY correlated with TQR at PRE (p < 0.05), while leptin correlated negatively with TQR at POST (p < 0.05). Tension-anxiety correlated highly with perceived exertion in non-finishers (p < 0.001) and with cortisol in finishers (p < 0.05) and non-finishers (p < 0.001). In finishers, confusion correlated negatively with NPY (p < 0.01). Conclusion: The study reveals an essential interplay between hormones and mood states affecting performance: Leptin was associated with anger and a depressive mood state in non-finishers and worse recovery in finishers. In contrast, NPY appeared linked to a lower confusion score and heightened recovery in finishers. A simultaneous increase in depressed mood, anger, tension-anxiety, and confusion might harm performance and lead to race failure.

Leptin receptor co-expression gene network moderates the effect of early life adversity on eating behavior in children

Leptin influences eating behavior. Exposure to early adversity is associated with eating behaviour disorders and metabolic syndrome, but the role of the leptin receptor on this relationship is poorly explored. We investigated whether individual differences in brain region specific leptin receptor (LepR) gene networks could moderate the effects of early adversity on eating behavior and metabolism. We created an expression-based polygenic risk score (ePRS) reflecting variations in the function of LepR gene network in prefrontal cortex and hypothalamus to investigate the interactions between a cumulative index of postnatal adversity on eating behavior in two independent birth cohorts (MAVAN and GUSTO). To explore whether variations in the prefrontal cortex or hypothalamic genetic scores could be associated with metabolic measurements, we also assessed the relationship between LepR-ePRS and fasting blood glucose and leptin levels in a third independent cohort (ALSPAC). We identified significant interaction effects between postnatal adversity and prefrontal-based LepR-ePRS on the Child Eating Behavior Questionnaire scores. In MAVAN, we observed a significant interaction effect on food enjoyment at 48 months (β = 61.58, p = 0.015) and 72 months (β = 97.78, p = 0.001); food responsiveness at 48 months (β = 83.79, p = 0.009) satiety at 48 months (β = −43.63, p = 0.047). Similar results were observed in the GUSTO cohort, with a significant interaction effect on food enjoyment (β = 30.48, p = 0.006) food fussiness score (β = −24.07, p = 0.02) and satiety score at 60 months (β = −17.00, p = 0.037). No effects were found when focusing on the hypothalamus-based LepR-ePRS on eating behavior in MAVAN and GUSTO cohorts, and there was no effect of hypothalamus and prefrontal cortex based ePRSs on metabolic measures in ALSPAC. Our study indicated that exposure to postnatal adversity interacts with prefrontal cortex LepR-ePRS to moderate eating behavior, suggesting a neurobiological mechanism associated with the development of eating behavior problems in response to early adversity. The knowledge of these mechanisms may guide the understanding of eating patterns associated with risk for obesity in response to fluctuations in stress exposure early in life.

An expression-based polygenic risk score analysis of leptin receptor (LepR) genes suggests that LepR-specific genes co-expressed in the prefrontal cortex interact with exposure to postnatal adversity, potentially modulating eating behavior in children.

The cholinergic anti-inflammatory pathway in humans: State-of-the-art review and future directions

The parasympathetic nervous system modulates inflammation through efferent vagus nerve signaling. Tracey (2002) termed this process as the cholinergic anti-inflammatory pathway (CAP). Interest in the potential practical use of this immune-modulatory process is increasing alongside increasing appreciation for the role of systemic inflammation in the etiology of somatic and psychological disease. A diverse literature exists providing expansive correlational evidence and some preliminary experimental evidence of the CAP in humans. However, so far this literature has not been well integrated and critically evaluated. This review describes the current state-of-the-art of research into vagus nerve driven parasympathetic control of inflammation in humans. Substantial limitations and gaps in the literature are identified, and promising directions for future research are highlighted.

Cardiovascular Stress Reactivity and Health: Recent Questions and Future Directions

OBJECTIVE

High cardiovascular reactions to psychological stress are associated with the development of hypertension, systemic atherosclerosis, and cardiovascular disease. However, it has become apparent that low biological stress reactivity also may have serious consequences for health, although less is known about the mechanisms of this. The objectives of this narrative review and opinion article are to summarize and consider where we are now in terms of the usefulness of the reactivity hypothesis and reactivity research, given that both ends of the reactivity spectrum seem to be associated with poor health, and to address some of the key criticisms and future challenges for the research area.

METHODS

This review is authored by the members of a panel discussion held at the American Psychosomatic Society meeting in 2019, which included questions such as the following: How do we measure high and low reactivity? Can high reactivity ever indicate better health? Does low or blunted reactivity simply reflect less effort on task challenges? Where does low reactivity originate from, and what is a low reactor?

RESULTS

Cardiovascular (and cortisol) stress reactivity are used as a model to demonstrate an increased understanding of the different individual pathways from stress responses to health/disease and show the challenges of how to understand and best use the reconstruction of the long-standing reactivity hypothesis given recent data.

CONCLUSIONS

This discussion elucidates the gaps in knowledge and key research issues that still remain to be addressed in this field, and that systematic reviews and meta-analyses continue to be required.

Stress-Induced Suppression of Food Intake in Overweight and Obese Adolescents

OBJECTIVE

Overweight adolescents exhibit greater cortisol reactivity in response to acute stress and are more likely to eat in response to emotional cues, which suggest an increased susceptibility to stress-induced eating. The purpose of this study was to examine the biological (cortisol and α-amylase reactivity) and behavioral (caloric intake) responses to an acute stressor in overweight adolescents.

METHODS

Fifty-one adolescents ages 14 to 19 years (47% female, 55% white; body mass index, 31.2 ± 0.8 kg/m) were exposed to the Trier Social Stress Test and a control condition on separate days. Immediately after each condition, participants were provided with snacks to eat at their leisure. Reactivity was assessed via salivary cortisol and α-amylase area under the curve (AUC), and adolescents were categorized as high or low reactors.

RESULTS

Cortisol AUC was higher during the stress condition (19.6 ± 0.2 μg/dl · min) compared with the control condition (11.4 ± 0.9 μg/dl · min, p < .001). α-Amylase AUC was not different during the stress condition (9999 ± 987 U/ml · min) compared with the control condition (8762 ± 865 U/ml · min, p = .145). Overall, adolescents consumed fewer calories during the stress condition (488 ± 51 kcal) compared with the control condition (637 ± 42 kcal, p = .007). High cortisol reactors decreased their calorie consumption from the control condition (716 ± 52 kcal) to the stress condition (457 ± 53 kcal, p = .001), whereas low cortisol reactors did not change their consumption (stress: 518 ± 87 kcal versus control: 561 ± 62 kcal, p = .574).

CONCLUSION

High cortisol reactivity in overweight adolescents resulted in decreased calorie consumption after an acute stressor. Further research is needed to understand the mechanisms underlying stress-induced suppression of food intake in overweight adolescents.

Two adipocytokines, leptin and adiponectin, independently predict osteoporotic fracture risk at different bone sites in postmenopausal women

Although associations among obesity, adipocytokines, and bone mineral density have been reported, the influence of adipocytokines on osteoporotic fractures remains unclear. This study aimed to assess the impact of the adipocytokines leptin and adiponectin on the risk of incident vertebral and long-bone fractures in postmenopausal women. Clinical data were obtained from the retrospective Nagano Cohort Study of outpatients followed at a single primary care institute in Nagano Prefecture, Japan, between 1993 and 2018. The primary outcome was the occurrence of incident vertebral or long-bone fractures. In total, 1167 Japanese postmenopausal women (mean age: 65.9 years) completed the follow-up and the average observation period was 7.2 years. The subjects were divided into 4 groups (quartile 1 to 4) based respective leptin and adiponectin values. Kaplan-Meier analysis demonstrated a significantly lower incident long-bone fracture rate in the higher quartiles of serum leptin levels (p = 0.002). A significantly higher and more rapid occurrence of incident vertebral fractures, but not long-bone fractures, was found in the highest adiponectin quartile (p < 0.001). A Cox proportional hazards model adjusted for confounders including age, body weight, and either leptin or adiponectin revealed lower leptin levels and higher adiponectin levels as significant independent risk factors for incident long-bone fractures (hazard ratio [HR] 0.70, 95% confidence interval [CI] 0.50-0.96; p = 0.03) and vertebral fractures (HR 1.18, 95% CI 1.02-1.37; p = 0.02), respectively. Therefore, serum leptin and adiponectin may be independent risk factors for osteoporotic fractures affecting different bone types and sites. Determining patient adipocytokine levels may help predict the occurrence of specific osteoporotic fractures, thereby enabling optimal treatment for osteoporosis and improving quality of life.

Determinants of Circulating Soluble Leptin Receptor and Free Leptin Index in Indonesian Pre-Pubertal Obese Male Children: A Preliminary Cross-Sectional Study

PURPOSE

This study aimed to investigate the clinical and metabolic determinants of circulating soluble leptin receptor (CSLR) and free leptin index (FLI) in pre-pubertal obese male children.

METHODS

We conducted a preliminary cross-sectional study at three tertiary hospitals and one public primary school. Eighty obese male children without growth and developmental abnormalities aged 5-9 years were recruited. In these children, obesity was solely caused by excessive food intake, and not by acute illness, medications, endocrine abnormalities, or any syndrome. Body mass index (BMI), body fat mass, carbohydrate intake, fat intake, high density lipoprotein cholesterol level, low density lipoprotein cholesterol level, triglyceride level, and Homeostatic Model Assessment for Insulin Resistance are the potential determinants for leptin regulation, which is represented by CSLR level and FLI.

RESULTS

Carbohydrate was the main source of energy. BMI and body fat mass had negative weak correlation with CSLR and positive weak correlation with FLI. Furthermore, carbohydrate intake was found to be independently associated with CSLR based on the results of the multiple linear regression analysis. Following an increase in carbohydrate intake, CSLR level decreased progressively without any negative peak.

CONCLUSION

Leptin regulation in prepubertal obese male children is associated with body composition and dietary intake. Carbohydrate intake is useful for predicting CSLR. Lipid profiles and insulin resistance are not related to both CSLR and FLI. Treatment and prevention of leptin resistance in obese children should focus on reducing BMI, fat mass, and carbohydrate intake.

Stress during pregnancy affected neonatal outcomes and changed cortisol and leptin levels both in mothers and newborns

BACKGROUND

The present study aimed to determine the effect of perceived stress during pregnancy on neonatal outcomes and cortisol and leptin levels in mothers and their newborns.

METHODS

This longitudinal study was carried out on 110 pregnant women in Miandoab city, Iran. Mothers, who had singleton pregnancies and gestational age of 24 to 28 weeks, were included in the study. The participants were asked to fill out Cohen's Perceived Stress Scale (PSS). The mothers were then tracked in gestational ages of 28-32 weeks, 32-36 weeks, and the time of delivery. The maternal and umbilical cord blood samples were obtained during labor in order to measure leptin and cortisol levels.

RESULTS

Umbilical cortisol level was significantly higher in newborns who had meconium stained amniotic fluid than those who did not. Maternal blood leptin levels at delivery were significantly higher in the mothers whose neonates had respiratory distress, low birth weight, low head circumference, low Apgar score, and were premature than those whose neonates did not have such problems. The level of leptin in umbilical cord blood was significantly higher in neonates who had respiratory distress than those who did not. The results also showed a significant correlation between maternal cortisol levels and PSS during weeks 24-28 and the entire pregnancy. A significant relationship was observed between umbilical leptin and maternal leptin levels.

CONCLUSIONS

It can be concluded that stress during pregnancy is accompanied by fetal distress. The probable reason for newborns distress may be related to increased maternal leptin levels.

The effect of a single, brief practice of progressive muscle relaxation after exposure to an acute stressor on subsequent energy intake

BACKGROUND

Given previous research suggests an association between stress and the intake of energy-dense foods, this study investigated whether poststressor relaxation practice can attenuate stress-induced eating.

METHODS

Twenty-five men and women were exposed to four conditions on separate days: an acute laboratory stressor (S), acute stressor followed by 20 min of relaxation (SR) in the form of Abbreviated Progressive Muscle Relaxation (APMR), relaxation alone (R), and a control condition (C). Physiological and psychological responses to stress and relaxation were assessed, in addition to the subsequent energy intake of high-energy snacks.

RESULTS

Salivary cortisol, blood pressure, heart rate, and perceived stress were transiently elevated postlaboratory stressor (S and SR compared with R and C; p < .05). Meanwhile, perceived relaxation was acutely enhanced after APMR alone (R) compared with S, SR, and C (p < .05) and in SR (immediately after the APMR) compared with S (p < .05). No difference in mean energy intake was observed between conditions (p > .05). Likewise, no differences in perceived appetite or the levels of ghrelin, leptin, and insulin were found between conditions (p > .05).

CONCLUSIONS

Much variation exists in stress-induced dietary responses, and APMR either postacute stressor or in isolation does not appear to consistently alter the intake of commonly eaten snacks.

Relationships of Trait Anxiety and Loss of Control Eating with Serum Leptin Concentrations among Youth

Loss of control (LOC) eating in youth is associated with elevated fasting serum leptin, even after accounting for adiposity. Anxiety is closely linked to, and may exacerbate, LOC eating. Yet, it remains unclear how anxiety relates to leptin, or if the relationship is moderated by the presence of LOC eating. We examined whether self-reported trait anxiety interacted with LOC eating in relation to leptin in a convenience sample of youths (n = 592; 13.1 ± 2.7 years; body mass index z-score (BMIz) = 0.9 ± 1.1; 61.8% girls; 53.5% non-Hispanic White; 36.6% with LOC eating). LOC eating was assessed by interview. Leptin was measured after an overnight fast. Exploratory analyses were conducted to examine anxiety and LOC eating in relation to laboratory intake patterns in three sub-samples. In a generalized linear model adjusting for relevant covariates, anxiety significantly interacted with LOC eating in relation to leptin (p = 0.02), such that greater trait anxiety related to higher concentrations of leptin only among youth with LOC eating. Trait anxiety was not significantly related to fasting serum leptin independently in a generalized linear model adjusting for age, race, height, sex, study type, and fat mass (kg). Exploratory mechanistic analyses of food intake patterns did not identify consistent results for participants with both anxiety and LOC eating. Among youth with LOC eating, anxiety may be associated with higher serum leptin. Prospective data are required to elucidate the directionality and mechanisms of these relationships.

Association of body fat with stress levels and dietary intakes in Indian women

A cross-sectional study of 605 women (aged 18-50 years) conducted from January 2013 to June 2014 in Gujarat, India assessed stress, dietary intakes and body fat percentage (PBF), and the inter-relationship of PBF with stress, dietary fat, and carbohydrates. The population was categorized according to PBF cutoffs for Asians. A generalized linear regression model adjusted for age was performed to assess the relationship of stress, fat, and carbohydrate intakes with PBF. PBF had a significant positive association with stress level (p = .02) and carbohydrate intake (p = .008); fat intake was not significantly associated (p = .8). Women with moderate PBF consumed significantly less carbohydrates (mean = 152.3 ± 13.3 gm/1000 kcal/day, p < .05) and had lower stress scores (mean = 9.7 ± 4.2, p < .05) than women with high PBF (mean carbohydrate intake = 156.2 ± 10.8 gm/1000 kcal/day; mean stress score = 10.9 ± 4.4) and very high PBF (mean carbohydrate intake = 156.8 ± 11.6 gm/1000 kcal/day; mean stress score = 11.2 ± 4.2). We conclude that PBF has a positive association with stress and dietary carbohydrate; women with higher stress and carbohydrate intake are more likely to accumulate higher body fat as compared to women with less stress and low carbohydrate intake.

Problematic eating behaviours, changes in appetite, and weight gain in Major Depressive Disorder: The role of leptin

BACKGROUND

Appetite and weight changes are core symptoms of Major Depressive Disorder (MDD), and those with MDD are at increased risk of obesity, cardiovascular disease and metabolic disorders. Leptin promotes satiety, with leptin dysregulation and resistance noted in obesity. However, the role of leptin in weight changes in MDD is not established. This study investigates leptin levels in relation to appetite and weight changes and problematic eating behaviours in MDD.

METHODS

Plasma leptin levels, psychopathology and biometrics were compared between participants meeting DSM-5 diagnostic criteria for MDD (n = 63) and healthy controls (n = 60). Depressed participants were also sub-categorised according to increased, decreased or unchanged appetite and weight. The Dutch Eating Behaviour Questionnaire and Yale Food Addiction Scale were examined in a subset of participants with MDD.

RESULTS

Females with increased appetite/weight had higher leptin levels than those with stable or reduced appetite/weight, however males showed the opposite effect. Leptin levels were positively correlated with problematic eating behaviours. One quarter of the depressed subset, all females, met the Yale criteria for food addiction, approximately double the rates reported in general community samples.

LIMITATIONS

The study is limited by a cross sectional design and a small sample size in the subset analysis of eating behaviours.

CONCLUSIONS

The results provide new information about associations between leptin, sex-specific weight and appetite changes and problematic eating behaviours, which may be risk factors for cardiovascular and metabolic diseases in MDD, particularly in females. Future longitudinal research investigating leptin as a risk factor for weight gain in MDD is warranted, and may lead to early interventions aimed at preventing weight gain in at-risk individuals.

Salivary Cortisol Does Not Correlate with Metabolic Syndrome Markers or Subjective Stress in Overweight Children

OBJECTIVE

Being overweight is a risk factor for metabolic syndrome in children, but not all overweight children develop metabolic syndrome. Cortisol excess from chronic psychological stress has been proposed as an independent risk factor for metabolic syndrome in this already at-risk population. The present study assesses the relationship of biochemical and body composition radiographic markers of metabolic syndrome to salivary cortisol and self-report of chronic psychological stress in a cohort of overweight children.

METHODS

This cross-sectional study took place in a multi-disciplinary pediatric obesity clinic at a tertiary care hospital, and involved fifteen children with BMI at or above the 85th percentile for age and sex, 10 of whom provided salivary cortisol samples. The main outcomes measured were salivary bedtime cortisol, first-waking cortisol, and cortisol awakening response (CAR-the rise in cortisol in the first half hour after waking); fasting serum triglycerides, HDL cholesterol, glucose and insulin for HOMA-IR; the ratio of abdominal fat to total body fat by DXA scan; and scores of validated stress and bullying questionnaires (PANAS-C, PSS, and SEC-Q).

RESULTS

In this pilot study, no correlation was found between salivary cortisol measures and questionnaire scores of subjective stress or bullying, and no correlation was found between any of these measures and markers of metabolic syndrome (dyslipidemia, insulin resistance, increased abdominal fat).

CONCLUSIONS

These results suggest that measures of psychological stress, whether biochemical or subjective, do not appear to predict risk of metabolic syndrome in overweight children. While ease of collection and demonstrated utility both in detection of pediatric Cushing disease and in adult psychological research make salivary cortisol assessment an attractive clinical tool, further investigation into the value of salivary measures in pediatric stress research is needed.

Myostatin and adipokines: The role of the metabolically unhealthy obese phenotype in muscle function and aerobic capacity in young adults

Obesity is often associated with metabolic disorders. However, some obese people can present a metabolically healthy phenotype, despite having excessive body fat. Obesity-related cytokines, such as myostatin (MSTN), leptin (LP) and adiponectin (ADP) appear to be key factors for the regulation of muscle and energy metabolism. Our aim was to compare lipid, glucose-insulin and inflammatory (tumor necrosis factor alpha; TNF-α) profiles, muscle function, energy expenditure and aerobic capacity between healthy normal-weight (NW) adults, metabolically healthy obese (MHO) and metabolically unhealthy obese (MUHO) adults; to study the associations between these outcomes and the cytokines MSTN, ADP, LP; and to establish cutoffs for MSTN and LP/ADP to identify the MUHO phenotype. Sixty-one young adults (NW, n = 24; MHO, n = 16; MUHO, n = 21) underwent body composition (body fat -BF and muscle mass - MM), energy expenditure at rest (RER) and aerobic capacity (VO_2peak) evaluation, muscle strength and endurance tests and blood profile characterization (glucose-insulin homeostasis and serum MSTN, ADP, LP and TNF-α). MHO and MUHO had a BMI ≥ 30 kg m^-2. MUHO was defined as presenting ≥3 criteria for metabolic syndrome (NCEP/ATPIII) in association with insulin resistance (HOMA-IR ≥3.46). MSTN and LP/ADP were associated with MM, MetS and glucose-insulin profile; MSTN was associated with TNF-α and only LP/ADP was associated with parameters of obesity and VO_2peak. Neither MSTN nor LP/ADP was associated with muscle functions (p < .05 for adjusted correlations). Both of them were able to discriminate the MUHO phenotype: MSTN [AUC(95%CI) = 0.71(0.55-0.86), MSTN > 517.3 pg/mL] and LP/ADP [AUC(95%CI) = 0.89(0.81-0.97), LP/ADP > 2.14 pg/ng]. In conclusion, high MSTN and LP/ADP are associated with MetS, glucose-insulin homeostasis impairment and low muscle mass. Myostatin is associated with TNF-α and leptin-to-adiponectin ratio is associated with body fatness and aerobic capacity. Neither MSTN nor LP/ADP is associated with energy expenditure, muscle strength and endurance. Myostatin and adipokines cutoffs can identify the metabolically unhealthy obese phenotype in young adults with acceptable accuracy.

Independent Effects of Neighborhood Poverty and Psychosocial Stress on Obesity Over Time

The objective of the study was to examine the independent effects of neighborhood poverty and psychosocial stress on increases in central adiposity over time. Data are from a community sample of 157 Non-Hispanic Black, Non-Hispanic White, and Hispanic adults collected in 2002-2003 and 2007-2008, and from the 2000 Decennial Census. The dependent variable was waist circumference. Independent variables included neighborhood poverty, perceived neighborhood physical environment, family stress, safety stress, everyday unfair treatment, and a cumulative stress index. Weighted 3-level hierarchical linear regression models for a continuous outcome were used to assess the effects of neighborhood poverty and psychosocial stress on central adiposity over time. We also assessed whether psychosocial stress mediated the association between neighborhood poverty and central adiposity. Neighborhood poverty and everyday unfair treatment at baseline were independently associated with increases in central adiposity over time, accounting for the other indicators of stress. Perceptions of the neighborhood physical environment and cumulative stress mediated associations between neighborhood poverty and central adiposity. Results suggest that residing in neighborhoods with higher concentrations of poverty and exposure to everyday unfair treatment independently heighten risk of increased central adiposity over time. Associations between neighborhood poverty and central adiposity were mediated by perceptions of the neighborhood physical environment and by the cumulative stress index. Public health strategies to reduce obesity should consider neighborhood poverty and exposure to multiple sources of psychosocial stress, including everyday unfair treatment.

Relation of antioxidant capacity of diet and markers of oxidative status with C-reactive protein and adipocytokines: a prospective study

BACKGROUND

The role of dietary antioxidants and plasma oxidant-antioxidant status in low-grade chronic inflammation and adipocytokine levels is not established yet.

OBJECTIVES

We aimed to evaluate whether total dietary antioxidant capacity (assessed by dietary ferric reducing antioxidant potential (FRAP)), serum uric acid (UA) and gamma glutamyltransferase (GGT) were associated with low-grade chronic inflammation and circulating adipocytokines.

METHODS

Data of 4506 participants aged ≥55years from the Rotterdam Study were analyzed. Baseline (1990-1993) FRAP score was assessed by a food frequency questionnaire. Baseline UA and GGT levels were assessed in non-fasting serum samples. Serum high sensitivity C-reactive protein (hs-CRP) was measured at baseline and 10years later. Plasma leptin, adiponectin, plasminogen activator inhibitor-1 (PAI-1) and resistin levels were assessed 10years later.

RESULTS

A high FRAP score was associated with lower levels of UA and GGT. Overall, no association was found between FRAP and hs-CRP levels. FRAP score was associated with lower levels of leptin and PAI-1, higher levels of adiponectin, and no difference in resistin levels. Increased levels of UA were associated with higher levels of hs-CRP, PAI-1 and leptin; lower levels of adiponectin and no difference in resistin levels. Similarly, GGT was associated with higher levels of hs-CRP whereas no association was observed between GGT and adipocytokines.

CONCLUSION

These findings suggest that overall antioxidant capacity of diet and low levels of UA are associated with circulating adipocytokines whereas no consistent association was found with hs-CRP.

The Relationship between Stress and Severe Obesity: A Case-Control Study

Background

Several etiological factors for obesity have been identified, whereas other factors related to obesity, such as stress, remain poorly understood. This study used psychiatric methods to examine the relationship between stress and obesity.

Methods

Matched study and control groups were established, and the female and male control subjects were selected separately by random sampling. The control subjects were matched with the case subjects with respect to place of residence, sex, age, date that a pension was granted, and occupation. Psychiatric and psychological methods were assessed using a questionnaire and statistical analyses.

Results

Psychiatric interviews indicated that stress was more prevalent in the study group than in the control group. Separation from parents was nearly significantly more frequently in the study group than in the control group. The questionnaire on coping mechanisms revealed that case subjects tended to resolve their problems in an active manner.

Conclusions

The aim of this case-control study was to examine the relationship between stress and obesity in individuals receiving a disability pension. We identified stress factors that affect the development of obesity. We believe our study is both necessary and important, as these findings provide valuable insight into the relationship between severe obesity and stress.

Effects of Rosuvastatin Alone or in Combination with Omega-3 Fatty Acid on Adiponectin Levels and Cardiometabolic Profile

BACKGROUND

Adiponectin is an important adipocyte-related protein that has been postulated to participate in prevention of the development of metabolic syndrome. The relationship between adiponectin serum levels and risk of coronary artery disease (CAD) has been widely investigated and remains controversial. The aim of the present study was to evaluate the effects of rosuvastatin and/or omega-3 fatty acid on adiponectin serum levels in patients with insulin resistance (IR) and CAD.

PATIENTS AND METHODS

This study involved 87 patients with CADs and IR of different etiology, the patients were divided into three groups; 24 patients on treatment with rosuvastatin, 22 patients on treatment with omega-3 fatty acid, 23 patients on treatment with omega-3 fatty acid and rosuvastatin, 18 patients were not previously or currently treated with either rosuvastatin or omega-3 fatty acid, those regarded as control patients. Anthropometric measures, adiponectin serum levels, and other biochemical parameters were assessed in each treated group.

RESULTS

Rosuvastatin therapy leads to a significant elevation in adiponectin serum levels from 4.1 ± 0.99 ng/mL to 6.76 ± 1.03 ng/mL compared to control P < 0.01. Omega-3 fatty acid therapy leads to a significant elevation in adiponectin serum levels from 4.1 ± 0.99 ng/mL to 6.11 ± 1.29 ng/mL compared to control P < 0.01. Rosuvastatin plus omega-3 fatty acid therapy lead to a significant elevation in adiponectin serum levels from 4.1 ± 0.99 ng/mL to 7.99 ± 1.76 ng/mL compared to control P < 0.01.

CONCLUSIONS

Rosuvastatin and/or omega-3 fatty acid lead to significant cardiometabolic protection through an increment in adiponectin serum levels.

Mathematical detection of aortic valve opening (B point) in impedance cardiography: A comparison of three popular algorithms

The preejection period (PEP) is an index of left ventricle contractility widely used in psychophysiological research. Its computation requires detecting the moment when the aortic valve opens, which coincides with the B point in the first derivative of impedance cardiogram (ICG). Although this operation has been traditionally made via visual inspection, several algorithms based on derivative calculations have been developed to enable an automatic performance of the task. However, despite their popularity, data about their empirical validation are not always available. The present study analyzes the performance in the estimation of the aortic valve opening of three popular algorithms, by comparing their performance with the visual detection of the B point made by two independent scorers. Algorithm 1 is based on the first derivative of the ICG, Algorithm 2 on the second derivative, and Algorithm 3 on the third derivative. Algorithm 3 showed the highest accuracy rate (78.77%), followed by Algorithm 1 (24.57%) and Algorithm 2 (13.82%). In the automatic computation of PEP, Algorithm 2 resulted in significantly more missed cycles (48.57%) than Algorithm 1 (6.3%) and Algorithm 3 (3.5%). Algorithm 2 also estimated a significantly lower average PEP (70 ms), compared with the values obtained by Algorithm 1 (119 ms) and Algorithm 3 (113 ms). Our findings indicate that the algorithm based on the third derivative of the ICG performs significantly better. Nevertheless, a visual inspection of the signal proves indispensable, and this article provides a novel visual guide to facilitate the manual detection of the B point.

NEIGHBOURHOOD POVERTY, PERCEIVED DISCRIMINATION AND CENTRAL ADIPOSITY IN THE USA: INDEPENDENT ASSOCIATIONS IN A REPEATED MEASURES ANALYSIS

This study examines the independent effects of neighbourhood context (i.e. neighbourhood poverty) and exposure to perceived discrimination in shaping risk of obesity over time. Weighted three-level hierarchical linear regression models for a continuous outcome were used to assess the independent effects of neighbourhood poverty and perceived discrimination on obesity over time in a sample of 157 non-Hispanic Black, non-Hispanic White and Hispanic adults in Detroit, USA, in 2002/2003 and 2007/2008. Independent associations were found between neighbourhood poverty and perceived discrimination with central adiposity over time. Residents of neighbourhoods with high concentrations of poverty were more likely to show increases in central adiposity compared with those in neighbourhoods with lower concentrations of poverty. In models adjusted for BMI, neighbourhood poverty at baseline was associated with a greater change in central adiposity among participants who lived in neighbourhoods in the second (B=3.79, p=0.025) and third (B=3.73, p=0.024) poverty quartiles, compared with those in the lowest poverty neighbourhoods. The results from models that included both neighbourhood poverty and perceived discrimination showed that both were associated with increased risk of increased central adiposity over time. Residents of neighbourhoods in the second (B=9.58, p<0.001), third (B=8.25, p=0.004) and fourth (B=7.66, p=0.030) quartiles of poverty were more likely to show greater increases in central adiposity over time, compared with those in the lowest poverty quartile, with mean discrimination at baseline independently and positively associated with increases in central adiposity over time (B=2.36, p=0.020). The results suggest that neighbourhood poverty and perceived discrimination are independently associated with a heightened risk of increase in central adiposity over time. Efforts to address persistent disparities in central adiposity in the USA should include strategies to reduce high concentrations of neighbourhood poverty as well as discrimination.

Metabolic pathways link childhood adversity to elevated blood pressure in midlife adults

Childhood adversity is a risk factor for adult health outcomes, including obesity and hypertension. This study examines whether childhood adversity predicted mean arterial pressure through mechanisms of central obesity and leptin, adiponectin, and/or insulin resistance, and including dietary quality. 210 Black/African Americans and White/European Americans, mean age=45.8; ±3.3 years, were studied cross-sectionally. Path analyses were used to specify a chain of predictive variables in which childhood adversity predicted waist-hip ratio and dietary quality, circulating levels of hormones, and in turn, mean arterial pressure, adjusting for race, gender, and antihypertensive medications. Direct paths were found between childhood adversity, waist-hip ratio, and leptin levels and between leptin and dietary quality to mean arterial pressure. Systolic and diastolic blood pressures were similarly predicted. Early adversity appears to developmentally overload and dysregulate endocrine systems through increased risk for obesity, and through a direct impact on leptin that in turn, impacts blood pressure.

Carbohydrate-enriched diet predispose to anxiety and depression-like behavior after stress in mice

OBJECTIVES

Obesity is a chronic disease frequently associated with serious co-morbidities, such as diabetes type II, metabolic syndrome, and psychiatric disorders. Little is known, however, regarding the behavioral consequences of modified diet constituents and the propensity to development of stress related disorders. Thus, the aim of this study was to verify whether chronic exposure to a normocaloric/high-carbohydrate diet will modify the animal's behavior after different stressful stimuli.

METHODS

BALB/c mice were fed for 12 weeks with a standard chow diet or high refined carbohydrate-containing diet (HC). Following this period, independent groups of animals were exposed to different stress paradigms: 1 - two hours of restraint stress followed by exposure to the Elevated Plus Maze test (EPM) 24 hours later; 2 - The contextual fear conditioning (CFC) test and 3 - the tail suspension test (TST).

RESULTS

Despite no change on total body weight, animals fed with HC diet showed increase in serum leptin levels and higher adiposity compared to diet control group. In behavioral tests, animals from HC diet group displayed reduction in the percentage of entries into the open arms of the EPM, evaluated 24 hours after restraint stress, suggesting an anxiogenic-like effect. It is also observed increase in aversive memory in the CFC test and depressive-like behavior in TST.

DISCUSSION

Our results suggest that a moderate obesity, induced by high refined carbohydrate diet, may facilitate the development of anxiety and depressive-like behaviors after the stress. The mechanisms responsible for such effects remain to be elucidated.

Effect of Diet and Exercise on the Peripheral Immune System in Young Balb/c Mice

Although diet and exercise clearly have an influence on immune function, studies are scarce on the effect caused by exercise and the consumption of a carbohydrate-rich or fat-rich diet on the peripheral immune system. The aim of the present study was to evaluate the effect of exercise and the two aforementioned unbalanced diets on young Balb/c mice, especially in relation to BMI, the level of glucose, and the percentage of lymphocyte subpopulations in peripheral blood. The changes found were then related to the synthesis of leptin and adiponectin as well as the production of oxidative stress. The increase in BMI found with the carbohydrate-rich and fat-rich diets showed correlation with the levels of leptin and adiponectin. An increase in leptin and a decrease in adiponectin directly correlated with an increase in total lymphocytes and CD4+ cells and with a decrease in B cells. The increase in leptin also correlated with an increase in CD8+ cells. Glycemia and oxidative stress increased with the two unbalanced diets, negatively affecting the proliferation of total lymphocytes and the percentage of B cells, apparently by causing alterations in proteins through carbonylation. These alterations caused by an unbalanced diet were not modified by moderate exercise.

Lean heart: Role of leptin in cardiac hypertrophy and metabolism

Leptin is an adipokine that has been linked with the cardiovascular complications resulting from obesity such as hypertension and heart disease. Obese patients have high levels of circulating leptin due to increased fat mass. Clinical and population studies have correlated high levels of circulating leptin with the development of cardiac hypertrophy in obesity. Leptin has also been demonstrated to increase the growth of cultured cardiomyocytes. However, several animal studies of obese leptin deficient mice have not supported a role for leptin in promoting cardiac hypertrophy so the role of leptin in this pathological process remains unclear. Leptin is also an important hormone in the regulation of cardiac metabolism where it supports oxidation of glucose and fatty acids. In addition, leptin plays a critical role in protecting the heart from excess lipid accumulation and the formation of toxic lipids in obesity a condition known as cardiac lipotoxicity. This paper focuses on the data supporting and refuting leptin’s role in promoting cardiac hypertrophy as well as its important role in the regulation of cardiac metabolism and protection against cardiac lipotoxicity.

Effects of insomnia disorder and knee osteoarthritis on resting and pain-evoked inflammatory markers

Osteoarthritis is the most prevalent arthritic condition. Systemic inflammatory cytokines appear to have an important role in the onset and maintenance of the disease. Sleep disturbances are prevalent in osteoarthritis and associated with alterations in systemic inflammatory cytokines, suggesting a common pathophysiology across these conditions. A comparative investigation of the effects of insomnia disorder and osteoarthritis on pain-evoked cytokine responses has yet to be undertaken. We examined the influence of symptomatic knee osteoarthritis and insomnia disorder on resting C-reactive protein (CRP), interleukin (IL)-6, and IL-10 levels, and pain-evoked IL-6 and IL-10 responses. Participants were N=117 older adults (mean age=59.7years; 61.8% women) rigorously evaluated for knee osteoarthritis and insomnia disorder using established diagnostic guidelines. Results revealed no association of osteoarthritis or insomnia disorder with CRP. Resting IL-6 was greater in osteoarthritis participants versus those without osteoarthritis, although this association was largely attributable to BMI. IL-10 was highest among participants with osteoarthritis or insomnia disorder. Growth curve modeling revealed that participants with insomnia disorder had greater pain-evoked IL-6 responses than participants without insomnia disorder or osteoarthritis. These findings highlight the utility of laboratory pain testing methods for understanding individual differences in inflammatory cytokines. Moreover, our findings provide evidence for amplified pain-evoked pro-inflammatory cytokine reactivity among older adults with clinically diagnosed insomnia disorder, even after controlling for individual differences in BMI and age. Additional research will be required determine whether an amplified pain-related cytokine response contributes to OA, and possibly other age-related disease, associated with insomnia disorder.

Obesity, adipokines and neuroinflammation

Global levels of obesity are reaching epidemic proportions, leading to a dramatic increase in incidence of secondary diseases and the significant economic burden associated with their treatment. These comorbidities include diabetes, cardiovascular disease, and some psychopathologies, which have been linked to a low-grade inflammatory state. Obese individuals exhibit an increase in circulating inflammatory mediators implicated as the underlying cause of these comorbidities. A number of these molecules are also manufactured and released by white adipose tissue (WAT), in direct proportion to tissue mass and are collectively known as adipokines. In the current review we focused on the role of two of the better-studied members of this family namely, leptin and adiponectin, with particular emphasis on their role in neuro-immune interactions, neuroinflammation and subsequent brain diseases. This article is part of a Special Issue entitled 'Neuroimmunology and Synaptic Function'.

Lipopolysaccharide-binding protein and leptin are associated with stress-induced interleukin-6 cytokine expression ex vivo in obesity

Obesity is associated with enhanced inflammation and mental stress, but limited information has addressed the potential additive effect of psychological stress on obesity-associated inflammation. This study examined whether obese subjects would elicit a greater host immune response (IL-6 mRNA and cytokine) to lipopolysaccharide (LPS) in response to mental stress. Blood samples for LPS-stimulated IL-6 mRNA and cytokine were collected prior to and following mental stress. Results showed that obese subjects elicited a greater LPS-induced IL-6 along with its mRNA expression following mental stress compared to normal-weight subjects. Stress-induced IL-6 cytokine response to LPS was correlated with the baseline levels of plasma LPS binding protein (LBP) and leptin. These findings are consistent with the idea that endogenous inflammatory agents (e.g., LBP and leptin), often elevated with obesity, enhance inflammatory responses to psychological stress.

High-fat diet consumption disrupts memory and primes elevations in hippocampal IL-1β, an effect that can be prevented with dietary reversal or IL-1 receptor antagonism

High-fat diet (HFD)-induced obesity is reaching worldwide proportions. In addition to causing obesity, HFDs also induce a variety of health disorders, which includes cognitive decline. Hippocampal function may be particularly vulnerable to the negative consequences of HFD, and it is suspected that 'primed' neuroinflammatory processes may mediate this response. To examine the link between diet, hippocampal function and neuroinflammation, male Wistar rats were fed a medium or HFD. Hippocampal memory function was measured using contextual pre-exposure fear conditioning (CPE-FC). Rats fed a HFD demonstrated impaired memory, an effect that was augmented with longer duration of HFD consumption. HFD-induced memory impairments were linked to potentiated levels of interleukin-1 beta (IL-1β) protein in the hippocampus 2h after the foot-shock that occurs during CPE-FC. Central IL-1 receptor antagonism, with intracisterna magna (ICM) administration of hIL-1RA prior to the foot-shock prevented the diet-induced memory disruption, suggesting a critical role for IL-1β in this phenomenon. Additionally, obese animals whose diet regimen was reversed from HFD back to standard chow recovered memory function and did not demonstrate a foot-shock-induced hippocampal IL-1β increase. Interestingly, dietary reversal neutralized the negative impact of HFD on memory and IL-1β, yet animals maintained physiological evidence of obesity (increased body mass and serum leptin), indicating that dietary components, not body mass, may mediate the negative effects on memory.

Measures of adiposity predict interleukin-6 responses to repeated psychosocial stress

OBJECTIVE

Overweight and obese individuals, who comprise approximately two-thirds of the U.S. population, are at increased risk for developing a range of diseases. This increased risk may be due in part to maladaptive stress responses within this group, including heightened low-grade inflammation and HPA axis non-habituation. In this study we tested the relationship between adiposity, plasma interleukin-6 (IL-6) and HPA axis responses to repeated stress.

METHODS

Sixty-seven healthy participants were exposed to the Trier Social Stress Test (TSST) on two consecutive days. We collected saliva for cortisol measurements at baseline and at 1, 10, 30, 60 and 120min post-TSST, and blood for plasma IL-6 measurements at baseline and 30 and 120min post-TSST.

RESULTS

Stress exposure induced significant increases of cortisol and IL-6 on both days (cortisol: F=38, p<0.001; IL-6: F=90.8; p<0.001), and repeated exposure was related with cortisol habituation (F=8.2; p<0.001) and IL-6 sensitization (F=5.2; p=0.022). BMI and body fat were related with higher cortisol responses to repeated stress (BMI: beta=0.34; p=0.014; body fat: beta=0.29; p=0.045), and with higher IL-6 responses to repeated stress (BMI: beta=0.27, p=0.044; body fat: beta=0.37; p=0.006).

CONCLUSIONS

Taken together, individuals with higher measures of adiposity showed less efficient HPA axis habituation as well as sensitization of IL-6 responses to repeated acute stress. These findings point to maladaptive stress response patterns in overweight humans, which, through exposure to higher levels of inflammatory mediators, might partially explain diseases related with overweight and/or obesity.

Leptin, adiponectin, and heart rate variability among police officers

OBJECTIVES

Police officers have a high prevalence of cardiovascular disease (CVD). Reduced heart rate variability (HRV) is known to increase CVD risk. Leptin and adiponectin may be related to CVD health. Therefore, our objective was to investigate the relationship between these variables and HRV.

METHODS

Leptin and adiponectin levels were measured in 388 officers from the Buffalo Cardio-Metabolic Occupational Police Stress study. HRV was assessed according to methods published by the Task Force of the European Society of Cardiology and the North American Society of Pacing Electrophysiology for measurement and analysis of HRV. Mean values of high-frequency (HF) and low-frequency (LF) HRV were compared across tertiles of leptin and adiponectin using analysis of variance and analysis of covariance; trends were assessed using linear regression models.

RESULTS

Leptin, but not adiponectin, was significantly and inversely associated with HRV. Body mass index (BMI) and percent body fat significantly modified the association between leptin and LF (but not HF) HRV. Among officers with BMI < 25 kg/m(2) , leptin was not significantly associated with HRV. However, among officers with BMI ≥ 25 kg/m(2) , leptin was inversely associated with HRV, after adjustment for age, gender, and race/ethnicity; HF HRV, P = 0.019 and LF HRV, P < 0.0001. Similarly, among officers with percent body fat ≥ 25.5%, leptin and LF HRV showed significant, inverse associations (adjusted P = 0.001).

CONCLUSIONS

Leptin levels were inversely associated with LF HRV, especially among officers with increased adiposity. Increased leptin levels may be associated with CVD-related health problems.

Adolescent adrenocortical activity and adiposity: differences by sex and exposure to early maternal depression

Prior research has linked either basal cortisol levels or stress-induced cortisol responses to adiposity; however, it remains to be determined whether these distinct cortisol measures exert joint or independent effects. Further, it is unclear how they interact with individual and environmental characteristics to predict adiposity. The present study aims to address whether morning cortisol levels and cortisol responses to a psychosocial stressor independently and/or interactively influence body mass index (BMI) in 218 adolescents (117 female) participating in a longitudinal community study, and whether associations are moderated by sex and exposure to early maternal depression. Reports of maternal depressive symptoms were obtained in infancy and preschool. Salivary cortisol measures included a longitudinal morning cortisol measure comprising sampling points across ages 11, 13, 15, and 18 and measures of stress-induced cortisol responses assessed via the Trier Social Stress Test (TSST) at age 18. Lower morning cortisol and higher TSST cortisol reactivity independently predicted higher age 18 BMI. Morning cortisol also interacted with sex and exposure to early maternal depression to predict BMI. Specifically, girls exposed to lower levels of early maternal depression displayed a strong negative morning cortisol-BMI association, and girls exposed to higher levels of maternal depression demonstrated a weaker negative association. Among boys, those exposed to lower levels of maternal depression displayed no association, while those exposed to higher levels of maternal depression displayed a negative morning cortisol-BMI association. Results point to the independent, additive effects of morning and reactive cortisol in the prediction of BMI and suggest that exposure to early maternal depression may exert sexually dimorphic effects on normative cortisol-BMI associations.

Stress task specific impairments of cardiovascular functioning in obese participants

The role that excess adipose tissue plays in chronic inflammation gives rise to its importance as an independent risk factor in cardiovascular dysfunction. Operationalizing chronic stress as obesity, we sought to explore the relationship between obesity, perceived stress and cardiovascular reactivity and recovery from laboratory stressors. Cardiovascular function was assessed using blood pressure and heart rate. Two stress tasks (mental arithmetic and cold pressor) were employed to examine potential differences between type of stress and cardiovascular response. Body mass index (BMI) was able to predict dysfunction in both cardiovascular reactivity and recovery. Participants with a higher BMI exhibited blunted systolic blood pressure and heart rate reactivity to the mental arithmetic task. In contrast, BMI has an incongruent effect on blood pressure reactivity to the cold pressor task that is dependent on the level of perceived stress. This suggests that in some instances the effect of BMI on cardiovascular response to acute stress may be moderated by perceived stress. Further, we found greater adiposity was related to delayed heart rate recovery following both stress tasks.

Poor sleep quality potentiates stress-induced cytokine reactivity in postmenopausal women with high visceral abdominal adiposity

Sleep disturbance is a key behavioral risk factor for chronic medical conditions observed at high rates among overweight and obese individuals. Systemic inflammation, including that induced by stress, may serve as a common biological mechanism linking sleep, adiposity, and disease risk. To investigate these relationships, 48 postmenopausal women (mean age=61.8) completed a standardized laboratory stress task during which time blood was collected at baseline and 30, 50 and 90+ min after stressor onset to assess circulating levels of interleukin (IL)-6, IL-10, and IL-6/IL-10 ratio. Self-reported global sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) while adiposity was estimated by body mass index. Sagittal diameter was obtained in clinic to estimate visceral abdominal adiposity. Multi-level growth curve models revealed that poorer self-reported sleep quality was associated with greater stress-induced increases in IL-6/IL-10 ratio. In terms of adiposity, higher sagittal diameter, but not BMI, was associated with greater IL-6 reactivity (p's<0.05). Further, associations between sleep quality and cytokine reactivity varied as a function of sagittal diameter. Among poor sleepers (1 SD above mean of PSQI score), stress-induced increases in IL-6 and IL-6/IL-10 ratio were significantly steeper in those with high visceral adiposity (1 SD above the mean of sagittal diameter) compared to those with low visceral adiposity (1 SD below the mean of sagittal diameter). In sum, poorer sleep quality and greater visceral adiposity, separately and especially in combination, are associated with greater stress-related increases in systemic inflammation. This research may help elucidate the complex link between sleep, obesity and inflammatory disease risk.

Blunted cortisol response to stress is associated with higher body mass index in low-income preschool-aged children

No known studies have tested the hypothesis that a blunted pattern of cortisol reactivity to stress, which is often found following exposure to chronic life stressors, is associated with a higher body mass index (BMI) in very young children. Low-income children (n=218, mean age 56.6 (range: 38.1-78.5; SD 7.0) months, 49.1% male, 56.4% white, 16.1% black, 11.5% Hispanic/Latino) participated in a series of behavioral tasks designed to elicit stress. Cortisol was sampled in saliva 5 times during the protocol, and area under the curve (AUC), representing total cortisol output during stress elicitation, was calculated. Children were weighed and height measured and body mass index (BMI) z-score was calculated. Linear regression was used to evaluate the association between cortisol AUC and BMI z-score, controlling for child age, sex, and race/ethnicity (non-Hispanic white vs. not); primary caregiver weight status (overweight, defined as BMI ≥ 25 vs. not); and family income-to-needs ratio. Mean child BMI z-score was 0.88 (SD=1.03). Mean cortisol AUC was 6.11 μg/dL/min (SD=10.44). In the fully adjusted model, for each 1-standard deviation unit decrease in cortisol AUC, the child's BMI z-score increased by 0.17 (SE 0.07) standard deviation units (p<0.02). A blunted cortisol response to stress, as is often seen following chronic stress exposure, is associated with increased BMI z-score in very young children. Further work is needed to understand how associations between stress, cortisol, and elevated body mass index may develop very early in the lifespan.

Cardiovascular and cortisol reactions to acute psychological stress and adiposity: cross-sectional and prospective associations in the Dutch Famine Birth Cohort Study

OBJECTIVE

In recent analyses of data from a large community sample, negative cross-sectional and prospective associations between cardiac stress reactivity and obesity were observed. The present study reexamined the association between cardiovascular reactivity and adiposity in the Dutch Famine Birth Cohort, with the additional aim of examining the association between cortisol reactivity and adiposity.

METHODS

Blood pressure, heart rate, and salivary cortisol were measured at rest and in response to standard laboratory stress tasks in 725 adults. Height, weight, waist-and-hip circumference, and skinfold thickness were measured. Between 4 to 7 years later, 460 participants reported current height and weight. Obesity was defined as a body mass index of 30 kg/m(2) or higher.

RESULTS

Those with a greater body mass index (β = -0.39 beats per minute (bpm)), waist-to-hip ratio (β = -0.15 bpm), and triceps and subscapular skinfold thicknesses (β = -1.0 and -1.8 bpm) or who were categorized as obese (-3.9 bpm) displayed smaller cardiac reactions to acute stress (all p < .001). With the exception of waist-to-hip ratio, the same negative associations emerged for cortisol reactivity (all p ≤ .01). In prospective analyses, low cardiac reactivity was associated with an increased likelihood of becoming or remaining obese in the subsequent 4 to 7 years (odds ratio = 1.03, p = .01). All associations withstood adjustment for a range of possible confounders.

CONCLUSIONS

The present analyses provide additional support for the hypothesis that it is low not high cardiac and cortisol stress reactivity that is related to adiposity.

Psychoneuroimmunology meets neuropsychopharmacology: translational implications of the impact of inflammation on behavior

The potential contribution of chronic inflammation to the development of neuropsychiatric disorders such as major depression has received increasing attention. Elevated biomarkers of inflammation, including inflammatory cytokines and acute-phase proteins, have been found in depressed patients, and administration of inflammatory stimuli has been associated with the development of depressive symptoms. Data also have demonstrated that inflammatory cytokines can interact with multiple pathways known to be involved in the development of depression, including monoamine metabolism, neuroendocrine function, synaptic plasticity, and neurocircuits relevant to mood regulation. Further understanding of mechanisms by which cytokines alter behavior have revealed a host of pharmacologic targets that may be unique to the impact of inflammation on behavior and may be especially relevant to the treatment and prevention of depression in patients with evidence of increased inflammation. Such targets include the inflammatory signaling pathways cyclooxygenase, p38 mitogen-activated protein kinase, and nuclear factor-κB, as well as the metabolic enzyme, indoleamine-2,3-dioxygenase, which breaks down tryptophan into kynurenine. Other targets include the cytokines themselves in addition to chemokines, which attract inflammatory cells from the periphery to the brain. Psychosocial stress, diet, obesity, a leaky gut, and an imbalance between regulatory and pro-inflammatory T cells also contribute to inflammation and may serve as a focus for preventative strategies relevant to both the development of depression and its recurrence. Taken together, identification of mechanisms by which cytokines influence behavior may reveal a panoply of personalized treatment options that target the unique contributions of the immune system to depression.