Sociodemographic, behavioral and genetic determinants of allostatic load in a Swiss population-based study

Association of Occupational and Leisure-Time Physical Activity With Allostatic Load

INTRODUCTION

Leisure-time physical activity decreases allostatic load, a measure of burden of chronic stress. However, the role of occupational physical activity is unknown. This study examined associations of occupational physical activity and leisure-time physical activity with allostatic load among workers in the U.S.

METHODS

This cross-sectional study included 6,944 U.S. workers aged 20-64 years from the National Health and Nutrition Examination Survey (2007-2018). Physical activity was assessed using the Global Physical Activity Questionnaire. Allostatic load was calculated using biomarkers of cardiovascular, metabolic, and immune systems. Associations of occupational physical activity and leisure-time physical activity with allostatic load were examined using negative binomial regressions. Analyses were conducted between August 2022 and March 2023.

RESULTS

Vigorous leisure-time physical activity inversely associated with allostatic load among all workers (count ratio=0.68, 95% CI=0.62, 0.76) and in each sex- and age-stratified group as well as in each race/ethnicity-stratified group. Vigorous occupational physical activity positively associated with allostatic load only among females aged 20-44 years (1.38, 95% CI=1.10, 1.73). Inverse associations of vigorous leisure-time physical activity with allostatic load were similar in young females with high or low vigorous occupational physical activity.

CONCLUSIONS

Increasing vigorous leisure-time physical activity associates with a lower allostatic load for all workers, whereas increasing vigorous occupational physical activity associates with a higher allostatic load only in young females. Promoting vigorous leisure-time physical activity reduces allostatic load among young females with either low or high vigorous occupational physical activity.

Association between Residential Greenness and Allostatic Load: A Cohort Study

The association between residential greenness and allostatic load (AL), a marker of composite physiological burden and predictor of chronic disease, remains understudied. This study comprised 212,600 UK Biobank participants recruited over 2007 and 2010 at the baseline. Residential greenness was modeled as the normalized difference vegetation index (NDVI) from high spatial resolution (0.50 m) color infrared imagery and measured within a 0.5 km radial catchment. AL was measured as a composite index from 13 biomarkers comprising three physiological systems (metabolic, cardiovascular, and inflammatory systems) and two organ systems (liver and kidney). Multilevel mixed-effects generalized linear models with a random intercept for UK Biobank assessment centers were employed to examine the association between residential greenness and AL. Each interquartile range (IQR = 0.24) increment in NDVI greenness was associated with lower AL (beta (β) = -0.28, 95% confidence interval (CI) = -0.55, -0.01). Consistently, relative to the lowest NDVI greenness quintile, participants in the highest quintile had lower AL (β = -0.64, 95% CI = -1.02, -0.26). The proportion of the association between greenness and AL mediated by the physical activity was 3.2%. In conclusion, residential greenness was protectively associated with AL, a composite marker of wear and tear and general health.

Berry Consumption in Relation to Allostatic Load in US Adults: The National Health and Nutrition Examination Survey, 2003-2010

INTRODUCTION

Berries are a rich source of antioxidant polyphenols and other nutrients that are associated with good health. Allostatic load (AL) is an aggregate measure of chronic stress-induced physiological dysregulations across cardiovascular, metabolic, autonomic, and immune systems; the extent of these dysregulations, collectively or in each system, can be characterized by a composite score or a domain score assessed by integrated biomarkers. It was hypothesized that the anti-inflammatory and other effects of berries lower AL. The association was determined between berry consumption and AL composite and domain scores in the 2003-2010 National Health and Nutrition Examination Survey (NHANES).

METHODS

Berry intake was measured using two 24 h dietary recalls collected from US adults in the 2003-2010 NHANES (n = 7684). The association with AL and its specific domains was examined using population weight-adjusted multivariable linear regression.

RESULTS

The mean AL composite scores for consumers of any berries (11.9), strawberries (11.6), and blueberries (11.6), respectively, were significantly lower than nonconsumers (12.3), after fully adjusting for sociodemographic, lifestyle, and dietary confounders. A significant dose-response relationship was determined between greater consumption of total berries, strawberries, and blueberries and lower mean AL composite scores (p-trend < 0.05, for all). Consistently, mean cardiovascular and metabolic domain scores remained significantly lower in the consumers of total berries (mean cardiovascular domain score: 4.73 versus 4.97 for nonconsumers; mean metabolic domain score: 2.97 versus 3.1), strawberries (4.73 versus 4.95; 2.99 versus 3.1), and blueberries (4.6 versus 4.95; 2.92 versus 3.11). Berry consumers also had significantly lower mean AL immune scores (1.52 versus 1.56) and lower mean AL autonomic scores (2.49 versus 2.57) than nonconsumers (initial sample: n = 15,620).

CONCLUSIONS

The current study indicates that consumption of berries lowers the AL composite scores and potentially reduces stress-related disease risks in the US adult population.

The urine-to-plasma urea concentration ratio is associated with eGFR and eGFR decline over time in a population cohort

BACKGROUND

Evaluation of renal function and of factors associated with its decline are important public health issues. Besides markers of glomerular function [e.g. glomerular filtration rate (GFR)], those of tubular functions are rarely evaluated. Urea, the most abundant urinary solute, is markedly concentrated in urine when compared with plasma. We explored the urine-to-plasma ratio of urea concentrations (U/P urea ratio) as a marker of tubular functions.

METHODS

We evaluated the relationship of the U/P urea ratio with eGFR at baseline in 1043 participants (48 ± 17 years) from the Swiss Kidney Project on Genes in Hypertension (SKIPOGH) population-based cohort, using mixed regression. In 898 participants, we assessed the relation between U/P urea ratio and renal function decline between two study waves 3 years apart. We studied U/P ratios for osmolarity, Na, K and uric acid for comparison.

RESULTS

In a transversal study at baseline, estimated GFR (eGFR) was positively associated with U/P-urea ratio [βscaled = 0.08, 95% CI (0.04; 0.13)] but not with the U/P ratio of osmolarity. Considering separately participants with renal function >90 or ≤90 mL/min × 1.73 m2, this association was observed only in those with reduced renal function. In the longitudinal study, eGFR declined at a mean rate of 1.2 mL/min per year. A significant association was observed between baseline U/P urea ratio and eGFR decline [βscaled = 0.08, 95% CI (0.01; 0.15)]. A lower baseline U/P urea ratio was associated with a greater eGFR decline.

CONCLUSION

This study provides evidence that the U/P urea ratio is an early marker of kidney function decline in the general adult population. Urea is easy to measure with well-standardized techniques and at low cost. Thus, the U/P urea ratio could become an easily available tubular marker for evaluating renal function decline.

The association of allostasis with alcohol use: A case-control study in males with and without alcohol use disorder

BACKGROUND

Allostatic load (AL) is associated with a heightened predisposition to disease due to prolonged activation of biological stress-response systems. Alcohol use disorder (AUD) is known to activate these systems. The primary aim of the current study was to examine the relationship between AL and AUD.

METHODS

Participants were males (100%) with DSM-IV Alcohol Dependence (n = 48) and healthy participants with no history of substance use disorder (n = 17). Participants with AUD were 4-6 weeks abstinent. The AL index used cortisol, interleukin-6 (IL-6), fibrinogen, tumor necrosis factor-alpha (TNFα), C-reactive protein (CRP), glucose, insulin, leptin, pulse, systolic blood pressure readings, diastolic blood pressure readings, and body mass index (BMI). Physiological dysregulation for each biological measure was determined based on values within the 25th or 75th percentiles; AL was calculated as the total number of physiologically dysregulated biological measures.

RESULTS

No differences in mean AL scores between the cases and controls [t(63) = .48, p = .633] were observed. Among cases, AL was not associated with lifetime drinks per drinking day (F(2,42) = .42, p = .662), lifetime total drinks (F(2,42) = 0.48, p = .620), total drinks 6 months prior to participating in the study (F(2,43) = 0.58, p = .563), or drinks per drinking day at 3-month follow-up (F(2,35) = 1.93, p = .161). AL was negatively associated with drinks per drinking day 6 months prior to study participation (F(2,42) = 3.71, p = .033).

CONCLUSIONS

The hypotheses were not supported. Given that alcohol is likely to lead to physiological dysregulation, the apparent absence of a relationship between biomarkers of cumulative stress as indicated by AL and drinking status was both unanticipated and remarkable. Based on the results, AL in the context of drinking status or drinking among males with AUD may not be applicable.

Allostatic load in early adolescence: gene / environment contributions and relevance for mental health

Background

Allostatic load is the cumulative "wear and tear" on the body due to chronic adversity. We aimed to test poly-environmental (exposomic) and polygenic contributions to allostatic load and their combined contribution to early adolescent mental health.

Methods

We analyzed data on N = 5,035 diverse youth (mean age 12) from the Adolescent Brain Cognitive Development Study (ABCD). Using dimensionality reduction method, we calculated and overall allostatic load score (AL) using body mass index [BMI], waist circumference, blood pressure, blood glycemia, blood cholesterol, and salivary DHEA. Childhood exposomic risk was quantified using multi-level environmental exposures before age 11. Genetic risk was quantified using polygenic risk scores (PRS) for metabolic system susceptibility (type 2 diabetes [T2D]) and stress-related psychiatric disease (major depressive disorder [MDD]). We used linear mixed effects models to test main, additive, and interactive effects of exposomic and polygenic risk (independent variables) on AL (dependent variable). Mediation models tested the mediating role of AL on the pathway from exposomic and polygenic risk to youth mental health. Models adjusted for demographics and genetic principal components.

Results

We observed disparities in AL with non-Hispanic White youth having significantly lower AL compared to Hispanic and Non-Hispanic Black youth. In the diverse sample, childhood exposomic burden was associated with AL in adolescence (beta=0.25, 95%CI 0.22-0.29, P<.001). In European ancestry participants (n=2,928), polygenic risk of both T2D and depression was associated with AL (T2D-PRS beta=0.11, 95%CI 0.07-0.14, P<.001; MDD-PRS beta=0.05, 95%CI 0.02-0.09, P=.003). Both polygenic scores showed significant interaction with exposomic risk such that, with greater polygenic risk, the association between exposome and AL was stronger. AL partly mediated the pathway to youth mental health from exposomic risk and from MDD-PRS, and fully mediated the pathway from T2D-PRS.

Conclusions

AL can be quantified in youth using anthropometric and biological measures and is mapped to exposomic and polygenic risk. Main and interactive environmental and genetic effects support a diathesis-stress model. Findings suggest that both environmental and genetic risk be considered when modeling stress-related health conditions.

Associations of Socioeconomic Factors and Unhealthy Lifestyles with Allostatic Load: A Meta-analysis

BACKGROUND

Allostatic load (AL) is a biological tool for objectively assessing chronic stress and has been discussed inconsistently for its correlation with socioeconomic factors and unhealthy lifestyles. Therefore, this meta-analysis was performed to explore the impact of socioeconomic factors and unhealthy lifestyles on AL.

METHOD

Different databases, including Web of Science, PubMed, EBSCOhost, Embase, CNKI, VIP, SinoMed, and Wanfang, were searched from inception to June 6, 2023. A total of 25 studies, reporting the correlations of seven socioeconomic factors and three unhealthy lifestyles with AL, were finally included. The pooled odds ratios (OR) and 95% confidence intervals (CIs) were examined using random-effect and fixed-effect models. Literature quality, heterogeneity, and publication bias were evaluated.

RESULTS

The meta-analysis showed a significantly increased risk of high AL in the older individuals as compared to the younger ones (OR = 1.05, 95% CI 1.04-1.06), in the individual with low education as compared to those with high education (OR = 1.25, 95% CI 1.05-1.48), and in the individuals with low physical activities as compared to those with high physical activities (OR = 1.44, 95% CI 1.26-1.64). This meta-analysis also showed a significantly decreased risk of high AL in the individuals with high income as compared to those with low income (OR = 0.77, 95% CI 0.71-0.83) and in women as compared to men (OR = 0.80, 95% CI 0.80-0.81).

CONCLUSION

This meta-analysis showed older people, men, and people having low physical activity, low income, and low education were more likely to have a high AL.

TRIAL REGISTRATION

This meta-analysis was registered on the PROSPERO database with trial registration number CRD42022326105. Instead of providing information at registration, we added an author (Tingyu Mu), who provided critical revisions to the paper in this meta-analysis.

The allostatic load model: a framework to understand the cumulative multi-system impact of work-related psychosocial stress exposure among firefighters

Firefighting is recognised as a profession where health and well-being can be affected by a variety of occupational factors, such as physical, thermal, and chemical stressors. Along with the risks intuitively associated with the fire service, however, psychosocial stress has begun to attract attention as another variable deserving of consideration. Indeed, long-term exposure to work-related psychosocial stress has been linked with poor health outcomes in many workers; however, despite this association, very little has been done to examine how such stressors become biologically embedded in firefighters. To help facilitate research into how psychosocial stress can affect health-related outcomes in the fire service, we propose a framework centered on the notion of allostatic load. First, we reviewed the occupational characteristics that may generate psychosocial stress within firefighters before introducing allostatic load (that is, dysregulation across various physiological systems caused by the need to manage ongoing stressors). Next, we provided a summary of how allostatic load can be measured and touched on the framework's utility for studying the cumulative effects of work-related stress on firefighter health. After this, factors that may influence the steps leading from stress exposure to health outcomes were discussed; in particular, we commented upon how research in this area should consider specific non-modifiable (age, sex, and ethnicity) and modifiable (psychosocial resources and behavioural habits) factors. Finally, we presented methodological barriers and opportunities that may arise when using the allostatic load framework with this professional group. By introducing the framework, we hope to provide a tool that may be used by those interested in stress-health research in firefighters to build the evidence needed to inform primary prevention measures.

The Association of Cytomegalovirus and Allostatic Load by Country of Birth and Length of Time in the United States

BACKGROUND

Cytomegalovirus (CMV) is a highly prevalent virus with a worldwide distribution. It typically remains dormant in most individuals until reactivation. Immunocompromised states are known to be potential causes for CMV reactivation. Current research has shown a link in the decline of immigrant health among those living in the US for an extended period, though the impact of CMV on this is not clear.

METHODS

This study investigated the association between country of birth, duration of US residency, allostatic load, and latent cytomegalovirus infection (CMV IgG) in a sample of US adults aged 20-49. The data utilized for our analysis was obtained from the National Health and Nutrition Examination Survey (NHANES) conducted between 2001 and 2004. Allostatic load, an index measuring the cumulative physiological strain on the body as it strives to regain stability in the presence of chronic stress, provided a valuable approach to assess stress within the context of CMV exposure. Logistic regression modeling was employed to estimate odds ratios and confidence intervals for the analysis. The chi-square test of association and Cramer's V statistic were used to assess the correlation among categorical variables, while Pearson's correlation coefficient was applied to evaluate the relationship between continuous variables. The results revealed that individuals born outside the US and those with less than 20 years of residency in the US exhibited significantly higher proportions of positive CMV IgG compared to individuals born in the US. Specifically, individuals born outside the US had more than triple the odds of CMV IgG when adjusting for the AL index (OR = 3.69, p-value = 0.0063). A similar trend was observed when examining AL risk based on the duration of US residency. Furthermore, age and sex were identified as significant predictors (p-value < 0.05) of AL risk, considering the individual's country of birth. In summary, the findings of this study significantly enhance our comprehension of the intricate interplay between cytomegalovirus (CMV) and allostatic load (AL). The investigation sheds light on how CMV and AL interact within specific demographic contexts, providing valuable insights into the underlying risk factors for CMV infection.

Genetic Variation, Stress, and Physiological Stress Response in Adults With Food Allergy or Celiac Disease

BACKGROUND

Persistently high chronic stress can lead to maladaptive psychological, behavioral, and physiological stress responses and poor mental and physical health, highlighting the importance of identifying individuals at increased risk. Chronic health condition diagnosis and genetics are 2 characteristics that can influence stress, stress response, and health outcomes.

PURPOSE

Food allergy (FA) and celiac disease (CD) require constant vigilance in daily life and can lead to increased stress. The purpose of this exploratory analysis was to examine the association of variants in selected stress-related genes with stress exposures, stress, clinical measures of physiological stress response, and mental health symptoms in adults with and without FA or CD.

METHODS

We compared stress exposures, symptoms of PTSD, depression, anxiety, and stress, BMI, and waist-hip ratio between cases and controls. We analyzed the association of SNPs in genes with known or hypothesized associations with stress-related measures in 124 cases and 124 matched controls: CRHBP (rs7718461, rs10474485), CRHR1 (rs242940) and OXTR (rs2268490). For this exploratory study, p-values ≤ 0.10 were considered suggestive.

RESULTS

For cases and controls, rs7718461 was associated with stress symptoms, rs2268490 with symptoms of stress and PTSD, and rs242940 with symptoms of stress, PTSD, anxiety, and depression. Further analyses found that stress-related outcomes in individuals with FA or CD may be influenced by SNP genotype.

CONCLUSIONS

Given these suggestive findings, larger prospective studies should examine similar relationships in individuals with other chronic health conditions, incorporating factors such as environmental exposures, individual experiences, and epigenetic modifications.

The Association of Combined Per- and Polyfluoroalkyl Substances and Metals with Allostatic Load Using Bayesian Kernel Machine Regression

Background/Objective: This study aimed to investigate the effect of exposure to per- and polyfluoroalkyl substances (PFAS), a class of organic compounds utilized in commercial and industrial applications, on allostatic load (AL), a measure of chronic stress. PFAS, such as perfluorodecanoic acid (PFDE), perfluorononanoic acid (PFNA), perfluorooctane sulfonic acid (PFOS), perfluoroundecanoic acid (PFUA), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHS), and metals, such as mercury (Hg), barium (Ba), cadmium (Cd), cobalt (Co), cesium (Cs), molybdenum (Mo), lead (Pb), antimony (Sb), thallium (TI), tungsten (W), and uranium (U) were investigated. This research was performed to explore the effects of combined exposure to PFAS and metals on AL, which may be a disease mediator. Methods: Data from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2014 were used to conduct this study on persons aged 20 years and older. A cumulative index of 10 biomarkers from the cardiovascular, inflammatory, and metabolic systems was used to calculate AL out of 10. If the overall index was ≥ 3, an individual was considered to be chronically stressed (in a state of AL). In order to assess the dose-response connections between mixtures and outcomes and to limit the effects of multicollinearity and other potential interaction effects between exposures, Bayesian kernel machine regression (BKMR) was used. Results: The most significant positive trend between mixed PFAS and metal exposure and AL was revealed by combined exposure to cesium, molybdenum, PFHS, PFNA, and mercury (posterior inclusion probabilities, PIP = 1, 1, 0.854, 0.824, and 0.807, respectively). Conclusions: Combined exposure to metals and PFAS increases the likelihood of being in a state of AL.

Comparison of social gradient in cardiometabolic health in Czechia and Venezuela: a cross-sectional study

OBJECTIVES

This study compared the relationships of social determinants with cardiometabolic risk in different socioeconomic contexts: sociopolitically unstable Venezuela (VE) and stable Czechia (CZ).

DESIGN

cross-sectional analysis involving two population-based studies.

SETTING

Brno, Czechia and 23 cities of Venezuela.

PARTICIPANTS

25-64 years old subjects from CZ (2013-2014, n=1579, 56% females) and VE (2014-2017, n=1652, 70% females).

MAIN OUTCOME MEASURES

The composite cardiometabolic risk score (CMRS) (scaled 0-8) was calculated using eight biomarkers (body mass index, waist circumference, blood glucose, systolic and diastolic blood pressure, total and high-density lipoprotein-cholesterol, triglycerides). Social characteristics included education in both countries, income in CZ and a composite measure of social position (SP) in VE. Sex stratified ordinal regression examined the social gradient in having less favourable CMRS.

RESULTS

In CZ, men and women with low education and women with low income had higher odds of higher CMRS compared with those with high education and income with OR 1.45 (95% CI 1.01 to 2.21), 2.29 (95% CI 1.62 to 3.24) and 1.69 (95% CI 1.23 to 2.35). In VE, women with low education and low SP had higher odds to have higher CMRS OR 1.47 (95% CI 1.09 to 1.97) and 1.51 (95% CI 1.16 to 1.97), while men with low education and low SP had lower odds to have higher CMRS OR 0.64 (95% CI 0.41 to 1.00) and 0.61 (95% CI 0.40 to 0.97), compared with those with high education and high SP. Independently of age, sex and socioeconomic characteristics, Venezuelans had higher odds to have higher CMRS than Czechs (OR 2.70; 95% CI 2.37 to 3.08).

CONCLUSIONS

The results suggest that the associations of socioeconomic status indices and cardiometabolic risk differed between CZ and VE, likely reflecting differences in the social environment among countries. Further research is needed to confirm and quantify these differences.

Diagnostic Performance of Individual Symptoms to Predict SARS-CoV-2 RT-PCR Positivity and Symptom Persistence among Suspects Presenting in Primary Care during the First Wave of COVID-19

This study aimed to estimate the diagnostic performance of patient symptoms and to describe the clinical course of RT-PCR-positive compared with RT-PCR-negative patients in primary care. Symptomatic COVID-19 suspects were assessed clinically at the initial consultation in primary care between March and May 2020, followed by phone consultations over a span of at least 28 days. Sensitivity and specificity were estimated for each symptom using the initial RT-PCR result as a reference standard. The proportions of symptomatic patients according to the RT-PCR test results were compared over time, and time to recovery was estimated. Out of 883 patients, 13.9% had a positive RT-PCR test, and 17.4% were not tested. Most sensitive symptoms were cough, myalgia, and a history of fever, while most specific symptoms were fever for ≥4 days, hypo/anosmia, and hypo/ageusia. At the final follow up (median time 55 days, range 28-105 days), 44.7% of patients still reported symptoms in the RT-PCR-positive group, compared with 18.3% in the negative group (p < 0.001), mostly with hypo/anosmia (16.3%), dyspnea (12.2%), and fatigue (10.6%). The discriminative value of individual symptoms for diagnosing COVID-19 was limited. Almost half of the SARS-CoV-2-positive patients still reported symptoms at least 28 days after the initial consultation.

Life-course socioeconomic factors are associated with markers of epigenetic aging in a population-based study

Adverse socioeconomic circumstances negatively affect the functioning of biological systems, but the underlying mechanisms remain only partially understood. Here, we explore the associations between life-course socioeconomic factors and four markers of epigenetic aging in a population-based setting. We included 684 participants (52 % women, mean age 52.6 ± 15.5 years) from a population and family-based Swiss study. We used nine life-course socioeconomic indicators as the main exposure variables, and four blood-derived, second generation markers of epigenetic aging as the outcome variables (Levine's DNAmPhenoAge, DunedinPoAm38, GrimAge epigenetic age acceleration (EAA), and the mortality risk score (MS)). First, we investigated the associations between socioeconomic indicators and markers of epigenetic aging via mixed-effect linear regression models, adjusting for age, sex, participant's recruitment center, familial structure (random-effect covariate), seasonality of blood sampling, and technical covariates. Second, we implemented counterfactual mediation analysis to investigate life-course and intermediate mechanisms underlying the socioeconomic gradient in epigenetic aging. Effect-size estimates were assessed using regression coefficients and counterfactual mediation parameters, along with their respective 95 % confidence intervals. Individuals reporting a low father's occupation, adverse financial conditions in childhood, a low income, having financial difficulties, or experiencing unfavorable socioeconomic trajectories were epigenetically older and had a higher mortality risk score than their more advantaged counterparts. Specifically, this corresponded to an average increase of 1.1-1.5 years for Levine's epigenetic age (β and 95 %CI range, β (minimum and maximum): 1.1-1.5 95 %CI[0.0-0.2; 2.3-3.0]), 1.1-1.5 additional years for GrimAge (β: 1.1-1.5 95 %CI[0.2-0.6; 1.9-3.0]), a 1-3 % higher DunedinPoAm38 age acceleration (β: 0.01-0.03 95 %CI[0.00; 0.03-0.04]), and a 10-50 % higher MS score (β: 0.1-0.4 95 %CI[0.0-0.2; 0.3-0.4]) for the aforementioned socioeconomic indicators. By exploring the life-course mechanisms underlying the socioeconomic gradient in epigenetic aging, we found that both childhood and adulthood socioeconomic factors contributed to epigenetic aging, and that detrimental lifestyle factors mediated the relation between socioeconomic circumstances in adulthood and EAA (31-89 % mediated proportion). This study provides emerging evidence for an association between disadvantaged life-course socioeconomic circumstances and detrimental epigenetic aging patterns, supporting the "sensitive-period" life-course model. Counterfactual mediation analyses further indicated that the effect of socioeconomic factors in adulthood operates through detrimental lifestyle factors, whereas associations involving early-life socioeconomic factors were less clear.

Allostatic Load Measurement: A Systematic Review of Reviews, Database Inventory, and Considerations for Neighborhood Research

BACKGROUND

Neighborhoods are critical to understanding how environments influence health outcomes. Prolonged environmental stressors, such as a lack of green spaces and neighborhood socioeconomic disadvantage, have been associated with higher allostatic load levels. Since allostatic load levels experienced earlier in life have stronger associations with mortality risk, neighborhoods may be uniquely suited to monitor and mitigate the impacts of environmental stressors. Researchers often study allostatic load in neighborhoods by utilizing administrative boundaries within publicly accessible databases as proxies for neighborhoods.

METHODS

This systematic review of reviews aims to identify commonly used biomarkers in the measurement of allostatic load, compare measurement approaches, inventory databases to study allostatic load, and spotlight considerations referenced in the literature where allostatic load is studied in neighborhoods. The review was conducted using the search term "allostatic load" in the MEDLINE, CINAHL, and PsychINFO databases. The search results were filtered to include reviews.

RESULTS

The search returned 499 articles after deduplication. Overall, 18 synthesis reviews met the inclusion criteria and were retained for extraction. The synthesis reviews analyzed represented 238 studies published from 1995 to 2020. The original ten biomarkers were most often used to measure allostatic load. More recently, body mass index and C-reactive protein have additionally been frequently used to measure allostatic load burden.

CONCLUSIONS

The scientific contributions of this study are that we have identified a clear gap in geographic considerations when studying allostatic load. The implication of this study is that we have highlighted geographic concepts when conducting neighborhood-level research using administrative databases as a neighborhood proxy and outlined emerging future trends that can enable future study of allostatic load in the neighborhood context.

The Association of Cytomegalovirus IgM and Allostatic Load

Background: Cytomegalovirus (CMV) is a deoxyribonucleic acid virus that affects a significant proportion of the worldwide population; after primary infection, it goes into a latent state and can be reactivated, primarily after a reduction in host immune defenses. Methods: This study evaluated the association of acute cytomegalovirus infection (CMV IgM) and Allostatic Load (AL) by sociodemographic factors using data from the National Health and Nutrition Examination Survey (NHANES) 2001–2004 among participants (aged 20–49 years). CMV infection was determined by the level of CMV IgM antibody in serum samples. AL was assessed as a combination of 10 biomarkers from the cardiovascular, inflammatory, and metabolic systems. The evaluation of the association between CMV infection and AL included descriptive statistics and logistic regression models, which were adjusted for demographic and behavioral covariates. Results: AL was more elevated among those who were older, male, those with lower education, those performing limited physical activity, and smokers. CMV was more elevated in females than males among those who consumed alcohol and cigarette smokers. In Pearson’s correlation analysis, there was a slight positive correlation between CMV IgM and AL, with triglycerides and Body Mass Index (BMI) the most strongly correlated with AL. Binary logistic regression showed no significant relationship between high AL and positive CMV IgM but did show a significant relationship between high AL and age (OR = 1.0592, 95% CI 1.0215–1.0983, p = 0.00715). The findings of this study provide insight into the relationship between CMV and AL and provide awareness of factors that affect their relationship.

Increased allostatic load associated with ambient air pollution acting as a stressor: Cross-sectional evidence from the China multi-ethnic cohort study

BACKGROUND

Allostatic load measures the cumulative biological burden imposed by chronic stressors. Emerging experimental evidence supports that air pollution acting as a stressor activates the neuroendocrine system and then produces multi-organ effects, leading to allostatic load. However, relevant epidemiological evidence is limited.

OBJECTIVES

We aim to explore the relationships between chronic exposure to ambient air pollution (PM₁, PM_2.5, PM₁₀, and O₃) and allostatic load in Chinese adults.

METHODS

This cross-sectional study included 85,545 participants aged 30-79 from the baseline data of the China Multi-Ethnic Cohort (CMEC). Ambient air pollution levels were evaluated by a satellite-based random forest approach. The previous three-year average exposure concentrations were calculated for each participant based on the residential address. The outcome allostatic load was identified through the sum of the sex-specific scores of twelve biomarkers belonging to four major categories: cardiovascular, metabolic, anthropometric, and inflammatory parameters. We performed statistical analysis using a doubly robust approach which relies on inverse probability weighting and outcome model to adjust for confounding.

RESULTS

Long-term exposure to ambient air pollution was significantly associated with an increased risk of allostatic load, with relative risk (95% confidence interval) of 1.040 (1.024, 1.057), 1.029 (1. 018, 1. 039), and 1.087 (1.074, 1.101) for each 10 μg/m³ increase in ambient PM_2.5, PM₁₀, and O₃, respectively. No significant relationship was observed between chronic exposure to PM₁ and allostatic load. The associations between air pollution and allostatic load are modified by some intrinsic factors and non-chemical stressors. The people with older, minority, lower education, and lower-income levels had a significantly higher allostatic load induced by air pollution.

CONCLUSIONS

Chronic exposure to ambient PM_2.5, PM₁₀, and O₃ may increase the allostatic load. This finding provides epidemiological evidence that air pollution may be a chronic stressor, leading to widespread physiological burdens.

Explaining the Craving for Cigarette Smoking Based on Adverse Childhood Experiences and Subjective Socioeconomic Status among University Students in Isfahan, Iran

Background: Adverse childhood experiences are linked to a wide range of physical, social, sexual, and family dysfunctions. These experiences, such as smoking, may have negative health consequences. Objective: The goal of this study was to explain the desire to smoke in university students in Isfahan, Iran based on adverse childhood events and subjective socioeconomic status. Methods: This cross-sectional study was conducted on 450 young adults who were recruited randomly from Isfahan universities in 2020. To collect data, a checklist of adverse childhood events, craving for smoking, and a question about subjective socioeconomic status were used. Multivariate logistic regression was used to analyze the data. Results: According to the findings, 46.5 percent of all university students had at least one Adverse Childhood Experience, and 68.8 percent of all university students had some level of smoking craving. Controlling for demographic variables, respondents with one to five adverse childhood experiences (OR: 1.84; 95 percent of CI: 1.11-3.04) and six or more adverse childhood experiences (OR: 5.37; 95 percent of CI: 2.58-11.71) were more likely to crave smoking than respondents with no adverse childhood experiences. Furthermore, among all students, a higher subjective socioeconomic status reduced the likelihood of smoking by 19%. Conclusions and implications: It can be concluded that university students who have had adversity in their childhood are more likely to engage in high-risk behaviors like smoking. Because smoking is recognized as a coping mechanism for stressful events, it is suggested that personal, local, and national strategies aimed at young adults in Iran be developed.

Investigating the Relations Between Caffeine-Derived Metabolites and Plasma Lipids in 2 Population-Based Studies

OBJECTIVE

To investigate the relations between caffeine-derived metabolites (methylxanthines) and plasma lipids by use of population-based data from 2 European countries.

METHODS

Families were randomly selected from the general population of northern Belgium (FLEMENGHO), from August 12, 1985, until November 22, 1990, and 3 Swiss cities (SKIPOGH), from November 25, 2009, through April 4, 2013. We measured plasma concentrations (FLEMENGHO, SKIPOGH) and 24-hour urinary excretions (SKIPOGH) of 4 methylxanthines-caffeine, paraxanthine, theobromine, and theophylline-using ultra-high-performance liquid chromatography-tandem mass spectrometry. We used enzymatic methods to estimate total cholesterol, high-density lipoprotein cholesterol, and triglyceride levels and the Friedewald equation for low-density lipoprotein cholesterol levels in plasma. We applied sex-specific mixed models to investigate associations between methylxanthines and plasma lipids, adjusting for major confounders.

RESULTS

In both FLEMENGHO (N=1987; 1055 [53%] female participants) and SKIPOGH (N=990; 523 [53%] female participants), total cholesterol, low-density lipoprotein cholesterol, and triglyceride levels increased across quartiles of plasma caffeine, paraxanthine, and theophylline (total cholesterol levels by caffeine quartiles in FLEMENGHO, male participants: 5.01±0.06 mmol/L, 5.05±0.06 mmol/L, 5.27±0.06 mmol/L, 5.62±0.06 mmol/L; female participants: 5.24±0.06 mmol/L, 5.15±0.05 mmol/L, 5.25±0.05 mmol/L, 5.42±0.05 mmol/L). Similar results were observed using urinary methylxanthines in SKIPOGH (total cholesterol levels by caffeine quartiles, male participants: 4.54±0.08 mmol/L, 4.94±0.08 mmol/L, 4.87±0.08 mmol/L, 5.27±0.09 mmol/L; female participants: 5.12±0.07 mmol/L, 5.21±0.07 mmol/L, 5.28±0.05 mmol/L, 5.28±0.07 mmol/L). Furthermore, urinary caffeine and theophylline were positively associated with high-density lipoprotein cholesterol in SKIPOGH male participants.

CONCLUSION

Plasma and urinary caffeine, paraxanthine, and theophylline were positively associated with plasma lipids, whereas the associations involving theobromine were less clear. We postulate that the positive association between caffeine intake and plasma lipids may be related to the sympathomimetic function of methylxanthines, mitigating the overall health-beneficial effect of caffeine intake.

Sulfur mustard and biological ageing: A multisystem biological health score approach as an extension of the allostatic load in Sardasht chemical veterans

BACKGROUND

Mustard gas as a chemical weapon has been used in wars and its long-term side effects are substantial in the human body. This study was aimed to apply an extension of allostatic load, known as synthetic biological health score (BHS), including the wear-and-tear of four physiological systems (endocrine, inflammatory, cardiovascular and metabolic systems) and two organs (liver and kidney) to estimate biological aging caused by sulfur mustard (SM) gas poisoning.

METHODS

The plasma samples were prepared from two following groups of people; 1) 446 individuals exposed to SM gas in 1987. 2) 115 healthy members, at the same range of age and residence, as the non-exposed group. These people were chosen from the same patients' families and have not had any exposure to SM or pulmonary dysfunction. To estimate BHS, 18 blood-derived biomarkers of the mentioned systems and organs were measured and the relative contribution of many social and body parameters across the age groups was explored.

RESULTS

It was revealed, in BHS calculation, the cardiovascular system had the most effect. Also, in the SM group, BHS was significantly higher than in the control group. This feature has a positive correlation with physical parameter (BMI) and a negative correlation with social parameters (salary and educational levels).

CONCLUSION

The multisystem BHS could be useful in the evaluation of biological aging due to SM exposure. Social (education, good-paying job) and physical (BMI) parameters could influence BHS and the higher BHS indicates the progress of biological aging due to mustard gas.

Does allostatic load predict incidental coronary events differently among sexes?

Background

One measure to quantify the degree of dysregulation is allostatic load (AL). Typically, AL incorporates information on diverse biomarkers and is associated with health outcomes such as cardiovascular diseases or the incidence of coronary events (C-E).

Aims

This study investigates the predictive performance of different AL scoring methods on the incidence of coronary events (C-E). This study also elaborates sex differences in the baseline risks of C-E and the AL associated risks of C-E.

Design

Longitudinal data analysis of the Heinz Nixdorf Recall Study (Risk Factors, Evaluation of Coronary Calcification, and Lifestyle) of 4327 participants free of C-E at study baseline aged 45–75. The data contains over 13 biomarkers measuring AL.

Methods

After conducting multiple imputations on missing values on AL for 826 participants, the analysis sample consisted of N = 4327 participants. We applied the two most commonly used methods of AL scoring AL (count-based and Z-score) and a recently developed logistic regression weighting method (LRM) approach. Cox regression was used to predict the incidence of C-E for each AL score. Results were estimated without (M0) and with (M1) covariate adjustment, and in a final model (M2), with an interaction between AL and sex.

Results

We found no violation of the proportional hazard assumption and significant differences in the survival curves between the sexes for C-E (Log-rank test: prob. > Chi² = 0.000). In M0, all AL-scoring methods predicted C-E significantly, with the LRM based AL-score having the best performance (hazard ratio = 3.133; CI: [2.630, 3.732]; Somer's D = 0.717). After covariate inclusion, differences between the scoring methods levelled, though the count-based method and LRM performed better than the Z-scoring method. The interaction analysis in M2 showed a significant multiplicative interaction for the count-based method (1.254; [1.066, 1.475]) and for the LRM (1.746; [1.132, 2.692]). The additive relative excess risk due to interaction (RERI) measure was negative for the count-based method (RERI = −1.967; [-3.778; −0.156]) and the LRM (RERI = −1.909 [-3.910; 0.091]), indicating subadditivity.

Conclusion

AL scores are suitable for predicting C-E. Differences between the AL-scoring algorithms were only present after including interactions. We value the count-based method as suitable for clinical practice since its calculation is relatively simple, and performance was among the best. Interaction analysis revealed that despite strong sex differences in baseline C-E, the effect of AL is more pronounced for females at high levels of AL; thus, females could benefit more from a potential intervention on AL. We suggest further investigation of sex differences concerning the mediation by physiological and psychological intermediates.

Allostatic Load and Its Impact on Health: A Systematic Review

INTRODUCTION

Allostatic load refers to the cumulative burden of chronic stress and life events. It involves the interaction of different physiological systems at varying degrees of activity. When environmental challenges exceed the individual ability to cope, then allostatic overload ensues. Allostatic load is identified by the use of biomarkers and clinical criteria.

OBJECTIVE

To summarize the current knowledge on allostatic load and overload and its clinical implications based on a systematic review of the literature.

METHODS

PubMed, PsycINFO, Web of Science, and the Cochrane Library were searched from inception to December 2019. A manual search of the literature was also performed, and reference lists of the retrieved articles were examined.We considered only studies in which allostatic load or overload were adequately described and assessed in either clinical or non-clinical adult populations.

RESULTS

A total of 267 original investigations were included. They encompassed general population studies, as well as clinical studies on consequences of allostatic load/overload on both physical and mental health across a variety of settings.

CONCLUSIONS

The findings indicate that allostatic load and overload are associated with poorer health outcomes. Assessment of allostatic load provides support to the understanding of psychosocial determinants of health and lifestyle medicine. An integrated approach that includes both biological markers and clinimetric criteria is recommended.

Association between health behaviours and cardiometabolic dysregulation: a population-based survey among healthy adults in Hong Kong

OBJECTIVE

To explore the association between cardiometabolic dysregulation, an integral component of allostatic load, and health risk behaviours (HRBs) of the Hong Kong healthy adult population.

DESIGN

Secondary analysis of cross-sectional anonymous data.

SETTING

Data on sociodemographics, self-reported health status, HRBs and biomarkers were extracted from the Hong Kong Population Health Survey 2014/2015.

PARTICIPANTS

One thousand five hundred and fifty-one participants aged 18-64 years without self-reported diagnoses of hypertension, diabetes mellitus, hyperlipidaemia, cardiovascular disease, cognitive impairment or cancer.

PRIMARY OUTCOME MEASURES

Cardiometabolic dysregulation index (CMDI), ranging from 0 to 6, was calculated by counting the number of biomarkers including systolic blood pressure, diastolic blood pressure, waist to hip ratio, glycated haemoglobin, total cholesterol to high-density lipoprotein cholesterol ratio, and triglycerides that were above the respective normal level suggested by international guidelines and literature. HRBs including smoking, dietary habits and sleeping hours were collected by self-report questionnaire. Alcohol consumption was assessed by the 10-item Alcohol Use Disorders Identification Test, while physical activity level was measured using the Global Physical Activity Questionnaire. A composite HRB score, ranging from 0 to 5, was calculated as the cumulative number of HRBs. The effect of HRB on CMDI was evaluated by negative binomial regression with adjustment for socioeconomic status, health awareness and comorbidities of the participants.

RESULTS

The mean CMDI of the studied population was 1.6; 29.5% had a CMDI of 0, whereas 1.5% had a CMDI of 6. Significant difference was observed in mean CMDI between gender and different age groups. Sleeping less than 6 hours (incidence rate ratio (IRR)=1.26, p<0.001), smoking (IRR=1.15, p=0.027), insufficient physical activity (IRR=1.12, p=0.007) and higher composite HRB score (IRR=1.12, 95% CI 1.06 to 1.18) were significantly associated with higher CMDI.

CONCLUSION

Smoking, physical inactivity and inadequate sleep-an essential yet often overlooked health behaviour-were associated with higher CMDI in the Hong Kong healthy adult population.

Allostatic score and its associations with demographics, healthy behaviors, tumor characteristics, and mitochondrial DNA among breast cancer patients

INTRODUCTION

Allostatic load (AL), a composite index, has been used to capture variation in life-course stresses. However, few studies have been carried out among breast cancer patients.

METHODS

In this study, we examined the cross-sectional association of AL with demographics, healthy behaviors, tumor characteristics, and mitochondrial DNA copy number in breast cancer patients. The study used a sub-sample of 934 women with newly diagnosed breast cancer at M.D. Anderson from 2013 to 2018. To construct the AL score, the study used a battery of seventeen factors that represents the activity of five physiological systems: metabolic, cardiovascular, immunological, renal, and liver.

RESULTS

AL was positively associated with the age of disease diagnosis (P = 0.002), and was higher in Black and Hispanic populations than White (P = 0.001 and 0.032, respectively). AL was also found more abundant in those who experienced marital dissolution (P = 0.006), lacked a college education (P = 0.045), currently smoked (P = 0.011), and had low levels of physical activity (P = 0.037) than their counterparts. The study then found that higher AL was associated with increased odds of having poorly differentiated tumors (Odds ratio (OR): 1.40, 95% confidence interval (CI): 1.28, 1.62). An additional significant association was observed between AL with estrogen receptor negative (ER-) (OR = 1.56, 95%CI: 1.02, 2.36) among Black patients. Finally, we observed a significant positive correlation between AL with leukocyte mitochondrial DNA copy number variation (P < 0.001).

CONCLUSIONS

We conclude AL is influenced by selected demographics and healthy behaviors, and further is correlated with tumor characteristics and mitochondrial DNA copy number in breast cancer patients.

Does the choice of Allostatic Load scoring algorithm matter for predicting age-related health outcomes?

Allostatic Load (AL) is posited to provide a measure of cumulative physiological dysregulation across multiple biological systems and demonstrates promise as a sub-clinical marker of overall health. Despite the large heterogeneity of measures employed in the literature to represent AL, few studies have investigated the impact of different AL scoring systems in predicting health. This study uses data for 4477 participants aged 50+ years participating in the Irish Longitudinal Study on Ageing (TILDA) to compare the utility of 14 different scoring algorithms that have been used to operationalise AL (i.e. count-based high-risk quartiles, deciles, two-tailed cut-points, z-scores, system-weighted indices, clinical cut-points, sex-specific scores, and incorporating medication usage). Model fit was assessed using R², Bayesian Information Criterion (BIC), and the area under the Receiver Operating Characteristic curve (AUC). The measure incorporating medications predicted walking speed and SRH marginally better than others. In general, AL was not predictive of grip strength. Overall, the results suggest that the choice of AL scoring algorithm exerts a relatively modest influence in predicting a number of important health outcomes.

Decomposing the educational gradient in allostatic load across European populations. What matters the most: differentials in exposure or in susceptibility?

Background

We investigate whether socially disadvantaged individuals are more susceptible to the detrimental effects of smoking and alcohol intake on allostatic load (AL), a marker of physiological ‘wear and tear’, resulting from adaptation to chronic stress.

Methods

In a cross-sectional analysis, 27 019 men and 26 738 women aged 35–74 years were identified from 21 European cohorts in the BiomarCaRE consortium. We defined three educational classes (EDs) according to years of schooling and an AL score as the sum of z-scores of eight selected biomarkers from the cardiovascular, metabolic and inflammatory systems. We used the Oaxaca-Blinder decomposition to disentangle the ED gradient in AL score into the differential exposure (DE, attributable to different distribution of smoking and alcohol intake across EDs) and the differential susceptibility (DS, attributable to a different effect of risk factors on AL across EDs) components.

Results

Less-educated men (mean AL difference: 0.68, 95% CI 0.57 to 0.79) and women (1.52, 95% CI 1.40 to 1.64) had higher AL scores. DE accounted for 7% and 6% of the gradient in men and women, respectively. In men, combining smoking and alcohol intake, DS accounted for 42% of the gradient (smoking DS coefficient=0.177, 26% of the gradient; alcohol DS coefficient=0.109; 16%, not statistically significant). DS contribution increased to 69% in metabolic markers. DS estimates were consistent across age groups, irrespective of comorbidities and robust to unmeasured confounding. No DS was observed in women.

Conclusions

In men, a DS mechanism substantially contributes to the educational class gradient in allostatic load.

Greater tree cover near residence is associated with reduced allostatic load in residents of central North Carolina

BACKGROUND

Among urban residents, increased contacts with nature are associated with reduced morbidity and mortality. The concept of allostatic load, a biomarker-based composite measure of physiological dysregulation, can be applied to study subclinical benefits of exposure, and to elucidate pathways leading to improved health.

OBJECTIVE

This research explored associations between residential vegetated land cover and an allostatic load index calculated using the statistical distance measure known as Mahalanobis distance.

METHODS

This cross-sectional population-based study involved 186 adult residents of the Durham-Chapel Hill, North Carolina metropolitan area. Measures of tree and grass cover within 500 m of residence were derived from the U.S. Environmental Protection Agency's EnviroAtlas land cover database. Fifteen biomarkers of immune, neuroendocrine, and metabolic functions were analyzed in serum samples. Regression analysis was conducted using generalized additive models with thin-plate spline functions of geographic coordinates, adjusting for modelled traffic air pollution from local sources and sociodemographic covariates.

RESULTS

The second and third tertiles of distance-weighted tree cover were associated with 14% (95% Confidence Limits 20%; 8%) and 15% (21%; 8%) reduction in adjusted median allostatic load, respectively, compared to the first tertile. The same tertiles of tree cover were also associated with 0.16 (0.03; 0.76) and 0.04 (0.01; 0.35) adjusted odds ratios of having allostatic load index above the 90th percentile of the sample distribution. Grass cover was inversely correlated with tree cover and was not associated with reduced allostatic load.

CONCLUSIONS

Subclinical beneficial health effects of green spaces demonstrated in this study are consistent with reduced susceptibility to acute environmental and social stressors, and reduced risks of morbidity and mortality.

The contribution of sleep to social inequalities in cardiovascular disorders: a multi-cohort study

AIMS

Sleep disturbances exhibit a strong social patterning, and inadequate sleep has been associated with adverse health outcomes, including cardiovascular disorders (CVD). However, the contribution of sleep to socioeconomic inequalities in CVD is unclear. This study pools data from eight European cohorts to investigate the role of sleep duration in the association between life-course socioeconomic status (SES) and CVD.

METHODS AND RESULTS

We used cross-sectional data from eight European cohorts, totalling 111 205 participants. Life-course SES was assessed using father's and adult occupational position. Self-reported sleep duration was categorized into recommended (6-8.5 h/night), long (>8.5 h/night), and short (<6 h/night). We examined two cardiovascular outcomes: coronary heart disease (CHD) and stroke. Main analyses were conducted using pooled data and examined the association between life-course SES and CVD, and the contribution of sleep duration to this gradient using counterfactual mediation. Low father's occupational position was associated with an increased risk of CHD (men: OR = 1.19, 95% CI [1.04; 1.37]; women: OR = 1.25, 95% CI [1.02; 1.54]), with marginal decrease of the gradient after accounting for adult occupational position (men: OR = 1.17, 95% CI [1.02; 1.35]; women: OR = 1.22, 95% CI [0.99; 1.52]), and no mediating effect by short sleep duration. Low adult occupational position was associated with an increased risk of CHD in both men and women (men: OR = 1.48, 95% CI [1.14; 1.92]; women: OR = 1.53, 95% CI [1.04; 2.21]). Short sleep duration meaningfully contributed to the association between adult occupational position and CHD in men, with 13.4% mediation. Stroke did not exhibit a social patterning with any of the variables examined.

CONCLUSION

This study suggests that inadequate sleep accounts to a meaningful proportion of the association between adult occupational position and CHD, at least in men. With sleep increasingly being considered an important cardiovascular risk factor in its own terms, our study additionally points to its potential role in social inequalities in cardiovascular disease.

Adverse Childhood Experiences, Smoking and Alcohol Use, and Allostatic Load Among People Living with HIV

Allostatic load is an indicator of multisystem physiologic dysregulation that may arise from prolonged or accumulated exposure to stress, including adverse childhood experiences (ACEs) and chronic stressors persisting into adulthood. People living with HIV (PLWH) may be particularly vulnerable given their high burdens of adversity across the life course. Using data from a cohort of middle aged PLWH, we examined associations between ACEs and two measures of allostatic load. In order to determine whether the negative impact of ACEs on allostatic load operates through increasing the adoption of adverse coping behaviors, we tested for mediation by smoking and alcohol use. PLWH who had experienced 4 or more ACEs had on average higher allostatic load in adulthood compared to those who experienced fewer. Neither smoking nor alcohol use mediated this relationship, however, suggesting alternative mechanisms may be at play.

Discrimination Increases the Association Between Parental and Adolescent Allostatic Load in Chinese Rural-to-Urban Migrants

PURPOSE

This study was designed to examine the extent to which parents' allostatic load (AL) and adolescents' perceived discrimination are interrelated in the prediction of adolescents' AL among rural-to-urban migrants in China, as well as the possible buffering role of social support.

METHODS

Multi-informant data were collected in this study. A total of 158 rural-to-urban migrant adolescents (Mean_age = 11.62 years) and one of each of their parents (Mean_age = 39.84 years) were recruited from the suburbs of Beijing, China. Both adolescents' and parents' AL scores were based on 10 physiological indices. Migrant adolescents were asked to report their perceived discrimination and social support.

RESULTS

Parents' AL was significantly positively related to adolescents' AL. The relationship between parents' and adolescents' AL was stronger among adolescents reporting higher perceived discrimination than among those reporting lower. Social support moderated the adverse effects of parents' AL and perceived discrimination on adolescents' AL. Specifically, among adolescents reporting higher social support, the relationships between parents' and adolescents' AL were not significant for those with either high or low perceived discrimination. However, among adolescents reporting lower social support, the positive association was significant for those with high perceived discrimination but not for those with low perceived discrimination.

CONCLUSIONS

Parents' AL was a strong predictor of migrant adolescents' AL, and perceived discrimination acted as a catalyst to increase the association. The relationships of parental AL and perceived discrimination with AL were not significant for adolescents who received high social support.

Age, aging and physiological dysregulation in safety-critical work: a retrospective longitudinal study of helicopter emergency medical services pilots

PURPOSE

Concurrent progressive physiological dysregulation in different organ systems may be a driver of phenotypical frailty and is associated with morbidity and performance declines. In aging societies, health and performance of older workers are given increased scrutiny. However, there are few studies researching the effect of age on physiological dysregulation specifically in the working population and none for high-risk occupations with close medical supervision. Here, we aim to investigate this association cross-sectionally and longitudinally in a healthy sample of European helicopter emergency medical services pilots.

METHODS

Using a retrospective cohort design, we constructed indices of (a) physiological dysregulation state (N = 52 participants) and (b) pace of change (N = 41 participants, average follow-up 7.9 years) based on measurements of 18 health risk-associated biomarkers, as documented in the participating pilots' aeromedical examination records. The relationship of these two indices with average age (range 27.9-60.6 years) and average baseline age (29.3-57.2 years), respectively, was modeled by weighted least squares regression, adjusting for region of origin, smoking, and medication.

RESULTS

Longitudinally, dysregulation significantly increased over the follow-up period, but the pace of change did not increase with baseline age. Cross-sectionally, we observed a significant negative quadratic effect of age on physiological dysregulation state, with maximum estimated physiological dysregulation at ages 45-50.

CONCLUSIONS

As hypothesized, progression of dysregulation over approximately 8 years is observable in a healthy occupational sample but it does not accelerate (i.e., does not increase with baseline age). Increases in dysregulation are counteracted by what appears to be a strong healthy worker survivor effect. The study shows that the development of physiological dysregulation in high-risk occupations differs from that in the general population and that physiological dysregulation indices may be helpful in reconciling safety concerns and fair treatment of aging workers in safety-critical jobs.

Association of Hair Cortisol Concentration with Prevalence of Major Cardiovascular Risk Factors and Allostatic Load

Background

The high prevalence of cardiovascular diseases cannot be explained completely by conventional risk factors such as older age, smoking, diabetes mellitus, hypertension, obesity, and dyslipidemia. Results of recent studies indicate that chronic stress may be an independent risk factor for cardiovascular morbidity and mortality. Thus, the aim of our study was to investigate the associations between the hair cortisol concentration (HCC), which is considered as a potential biomarker of long-term psychosocial stress, and traditional cardiovascular risk factors, including smoking, dyslipidemia, hypertension, and obesity.

Material/Methods

Fasting blood samples and anthropometric and lifestyle data were collected from 163 apparently healthy men. HCC was determined using high-performance liquid chromatography. Allostatic load (AL) index, defined as an integrated score of multiple interacting systems involved in the adaptation to adverse physical or psychosocial situations, was also calculated.

Results

We found that many prevalent cardiovascular risk factors, including hypertension, smoking, higher than recommended waist circumference (WC), and low-density lipoprotein cholesterol (LDL-C) median values, are associated with higher HCC. Hair cortisol level was also positively associated with the manifestation of individual cardiovascular risk factors such as higher-than-recommended total cholesterol, LDL-C, non-high-density lipoprotein cholesterol, body mass index, and WC median values. Moreover, a significant positive relationship between HCC and AL index was observed.

Conclusions

The results of this study suggest that increased prevalence of traditional cardiovascular risk factors is associated with higher HCC. Also, both HCC and AL index might be appropriate markers for the evaluation of chronic stress level.

Reference intervals for the urinary steroid metabolome: The impact of sex, age, day and night time on human adult steroidogenesis

OBJECTIVE

Urinary steroid metabolomics by GC-MS is an established method in both clinical and research settings to describe steroidogenic disorders. However, population-based reference intervals for adults do not exist.

METHODS

We measured daytime and night time urinary excretion of 40 steroid metabolites by GC-MS in 1128 adult participants of European ancestry, aged 18 to 90 years, within a large population-based, multicentric, cross-sectional study. Age and sex-related patterns in adjacent daytime and night time urine collections over 24 hours were modelled for each steroid metabolite by multivariable linear mixed regression. We compared our results with those obtained through a systematic literature review on reference intervals of urinary steroid excretion.

RESULTS

Flexible models were created for all urinary steroid metabolites thereby estimating sex- and age-related changes of the urinary steroid metabolome. Most urinary steroid metabolites showed an age-dependence with the exception of 6β-OH-cortisol, 18-OH-cortisol, and β-cortol. Reference intervals for all metabolites excreted during 24 hours were derived from the 2.5th and 97.5th percentile of modelled reference curves. The excretion rate per period of metabolites predominantly derived from the adrenals was mainly higher during the day than at night and the correlation between day and night time metabolite excretion was highly positive for most androgens and moderately positive for glucocorticoids.

CONCLUSIONS

This study gives unprecedented new insights into sex- and age-specificity of the human adult steroid metabolome and provides further information on the day/night variation of urinary steroid hormone excretion. The population-based reference ranges for 40 GC-MS-measured metabolites will facilitate the interpretation of steroid profiles in clinical practice.

Foreign-Born Hispanic Women's Health Patterns in Allostatic Load Converge to U.S.-Born Hispanic Women at a Slower Tempo Compared With Men

OBJECTIVES

We investigated the patterns of foreign-born Hispanic health convergence to U.S.-born Hispanics using an allostatic load index, a subjective biological risk health profile, and we explored whether the health convergence patterns differ by sex.

METHODS

The analytic sample consisted of 3,347 Hispanics from the pooled 2005-2010 National Health and Nutrition Examination Survey. We used negative binomial regression models to investigate the association between duration in the United States and the allostatic load index, while controlling for potential covariates.

RESULTS

Foreign-born Hispanics who had lived in the United States for 0-9 years and 10-19 years had lower levels of allostatic load than U.S.-born Hispanics; however, those who had lived in the United States for 20 or more years had a level of allostatic load similar to their U.S.-born counterparts. The pattern of immigrant health convergence shows a clear sex difference. In the sex-stratified models, we found that foreign-born Hispanic men converged to the level of allostatic load of U.S.-born Hispanic men after having lived in the United States for approximately 10 years. The health convergence pattern qualitatively differed for foreign-born Hispanic women, who remained healthier than U.S.-born Hispanic women regardless of duration in the United States.

CONCLUSIONS

Foreign-born Hispanics are healthier than their U.S.-born counterparts, providing support for the healthy migrant hypothesis. This relatively better health of foreign-born Hispanics disappears with a longer duration in the United States, providing support for the health convergence hypothesis, but is most noticeable for men. Foreign-born Hispanic women converge to U.S.-born Hispanic women's health status at a slower tempo, compared with foreign-born Hispanic men.

The first multi-zoo application of an allostatic load index to western lowland gorillas (Gorilla gorilla gorilla)

Vertebrate stress responses are highly adaptive biological functions, maximizing survival probability in life-threatening situations. However, experiencing repeated and/or chronic stressors can generate physiological dysregulation and lead to disease. Because stress responses are multi-systemic and involve a wide range of physiological functions, identifying responses to stressors is best accomplished using integrated biomarker models. Allostatic load, defined as the physiological dysregulation that accumulates over the lifespan due to stressful experiences, is one such model. Allostatic load is measured using allostatic load indices, which are composites of biomarkers from multiple somatic systems. Previously, we reported the use of a 7-biomarker allostatic load index (albumin, CRH, cortisol, DHEA-S, glucose, IL-6, TNF-α) in western lowland gorillas housed at a single zoo. Herein, this index is expanded to examine allostatic load responses to lifetime stressors in gorillas from two additional zoos (n = 63) as well as two pooled samples. The index was created using quartile cut-points for each biomarker. Significant associations were observed between multiple predictor variables and allostatic load, including sex, age, number of stressful events (anesthetic events, zoo transfers, agonistic interactions with wounding, pregnancies), and rearing history (mother-reared, nursery-reared, wild-caught). Additionally, allostatic load was associated with indicators of morbidity (creatinine, cholesterol, triglycerides), age at death, and mortality risk. These results are consistent with those reported in human allostatic load research, suggesting allostatic load indices have potential as an investigative and clinical tool for gorillas and other great apes.

Early life predictors of midlife allostatic load: A prospective cohort study

BACKGROUND

Allostatic load has been suggested as a pathway through which experiences become biologically embedded to influence health. Research on childhood predictors of allostatic load has focused on socioeconomic and psychosocial exposures, while few studies include prospective measures of biomedical exposures. Further, findings on sex differences in the association of childhood predictors with various health outcomes related to allostatic load are ambiguous.

AIMS

To examine the influence of early life biomedical and social factors in the first year of life on midlife allostatic load, assessing potential sex differences.

METHODS

This prospective cohort study includes early life information collected at birth and a one year examination for 1,648 members of the Copenhagen Perinatal Cohort who also participated in the Copenhagen Aging and Midlife Biobank study (aged 49-52 years, 56% women). Allostatic load based on 14 biomarkers was selected as a measure of midlife health status. Early life factors were categorized as predominantly biomedical or social, and their associations with midlife allostatic load were examined in domain-specific and combined sex-stratified multiple regression models.

RESULTS

The biomedical factors model explained 6.6% of the variance in midlife allostatic load in men and 6.7% in women, while the social model explained 4.1% of the variance in men and 7.3% in women. For both sexes, parental socioeconomic position at one year and maternal BMI significantly predicted midlife allostatic load in a model containing all early life factors. For women, additional significant predictors were complications at birth, birth weight and not living with parents at one year.

CONCLUSION

The results confirm an association of lower childhood socioeconomic position with higher adult allostatic load while demonstrating the importance of other prenatal and early life exposures and highlighting potential sex differences.

Relationships between allostatic load, unhealthy behaviors, and depressive disorder in U.S. adults, 2005-2012 NHANES

Unhealthy behaviors may modify relationships between chronic stress and depression among diverse older adults. We analyzed nationally representative cross-sectional data from participants aged 40-79 years of the 2005-2012 National Health and Nutrition Examination Survey. Unhealthy behaviors included current smoking, excessive/binge drinking, insufficient physical activity, and fair/poor diet. Allostatic load was defined by 10 biomarkers indicating the cumulative physiologic burden of stress. Depressive disorder was assessed using the Patient Health Questionnaire. Multivariable logistic regression examined whether current smoking, excessive/binge drinking, insufficient physical activitiy, and fair/poor diet modified relationships between allostatic load and depressive disorder. Mean age of 12,272 participants was 55.6 years (standard error = 0.19), 51.9% were women, and most had at least a high school education (81.8%). Latinos (11.3%) and African Americans (10.4%) were more likely than Whites (7.1%; p < 0.001) to meet depressive disorder criteria. Allostatic load was not associated independently with depressive disorder in any racial/ethnic group and this lack of a relationship did not differ by the extent of unhealthy behaviors. Although Latinos and African Americans report higher levels of depression than Whites, physiological markers of stress do not appear to explain these differences.

Vegetated land cover near residence is associated with reduced allostatic load and improved biomarkers of neuroendocrine, metabolic and immune functions

BACKGROUND

Greater exposure to urban green spaces has been linked to reduced risks of depression, cardiovascular disease, diabetes and premature death. Alleviation of chronic stress is a hypothesized pathway to improved health. Previous studies linked chronic stress with a biomarker-based composite measure of physiological dysregulation known as allostatic load.

OBJECTIVE

This study's objective was to assess the relationship between vegetated land cover near residences and allostatic load.

METHODS

This cross-sectional population-based study involved 206 adult residents of the Durham-Chapel Hill, North Carolina metropolitan area. Exposure was quantified using high-resolution metrics of trees and herbaceous vegetation within 500m of each residence derived from the U.S. Environmental Protection Agency's EnviroAtlas land cover dataset. Eighteen biomarkers of immune, neuroendocrine, and metabolic functions were measured in serum or saliva samples. Allostatic load was defined as a sum of potentially unhealthy biomarker values dichotomized at 10th or 90th percentile of sample distribution. Regression analysis was conducted using generalized additive models with two-dimensional spline smoothing function of geographic coordinates, weighted measures of vegetated land cover allowing decay of effects with distance, and geographic and demographic covariates.

RESULTS

An inter-quartile range increase in distance-weighted vegetated land cover was associated with 37% (95% Confidence Limits 46%; 27%) reduced allostatic load; significantly reduced adjusted odds of having low level of norepinephrine, dopamine, and dehydroepiandrosterone, and high level of epinephrine, fibrinogen, vascular cell adhesion molecule-1, and interleukin-8 in serum, and α-amylase in saliva; and reduced odds of previously diagnosed depression.

CONCLUSIONS

The observed effects of vegetated land cover on allostatic load and individual biomarkers are consistent with prevention of depression, cardiovascular disease and premature mortality.

Allostatic load and reduced cortical thickness in schizophrenia

Structural imaging studies have consistently found reduced gray matter thickness of the cerebral cortex in schizophrenia, a finding that is evident in first episode psychosis and may be progressive in some cases. Although genetic predisposition and medication effects may contribute to cortical thinning, we hypothesize that the cumulative effects of stress may represent an environmental factor impacting brain morphology in schizophrenia. We examined the relationship between allostatic load, an index of peripheral biomarkers representing the cumulative effects of stress, and cortical thickness. Allostatic load was calculated for 44 patients with schizophrenia spectrum disorders (SSD) and 33 normal controls (NC) based on 13 cardiovascular, neuroendocrine, immune, and metabolic measurements. Controlling for age, SSD had significantly elevated allostatic load as compared with NC (p=0.008). Controlling for age, whole brain average cortical thickness was lower in SSD patients compared to NC (p=0.008). However, once allostatic load was accounted for, the group difference in cortical thickness became marginal (p=0.058). Exploratory analyses on subcomponents of allostatic load suggested that elevated immune marker C-reactive protein, stress hormones, and cardiovascular indices within allostatic load were more strongly associated with reduced cortical thickness in SSD. In NC, only the association between immune marker C-reactive protein and cortical thickness was replicated. These results support the hypothesis that allostatic load may account for some of the gray matter deficits observed in schizophrenia. Among the allostatic indices, the inflammatory mechanism appears particularly relevant to cortical thickness in both schizophrenia patients and normal controls.

The epigenetic impacts of social stress: how does social adversity become biologically embedded?

Epigenetic mechanisms are implicated in the processes through which social stressors erode health in humans and other animals. Here I review progress in elucidating the biological pathways underlying the social gradient in health, with particular emphasis on how behavioral stresses influence epigenomic variation linked to health. The evidence that epigenetic changes are involved in embedding of social status-linked chronic stress is reviewed in the context of current knowledge about behavior within animal dominance hierarchies and the impacts of social position on behaviors that affect health. The roles of epigenetic mechanisms in responses to trauma and the evidence for their involvement in intergenerational transmission of the biological impacts of traumatic stress are also considered. Taken together, the emerging insights have important implications for development of strategies to improve societal health and well-being.