The neural circuitry of social homeostasis: Consequences of acute versus chronic social isolation.

Social homeostasis is the ability of individuals to detect the quantity and quality of social contact, compare it to an established set-point in a command center, and adjust the effort expended to seek the optimal social contact expressed via an effector system. Social contact becomes a positive or negative valence stimulus when it is deficient or in excess, respectively. Chronic deficits lead to set-point adaptations such that reintroduction to the previous optimum is experienced as a surplus. Here, we build upon previous models for social homeostasis to include adaptations to lasting changes in environmental conditions, such as with chronic isolation.

Impaired insulin signalling and allostatic load in Alzheimer disease.

The discovery of insulin in 1921 revolutionized the treatment of diabetes and paved the way for numerous studies on hormone signalling networks and actions in peripheral tissues and in the central nervous system. Impaired insulin signalling, a hallmark of diabetes, is now established as a key component of Alzheimer disease (AD) pathology. Here, we review evidence showing that brain inflammation and activation of cellular stress response mechanisms comprise molecular underpinnings of impaired brain insulin signalling in AD and integrate impaired insulin signalling with AD pathology. Further, we highlight that insulin resistance is an important component of allostatic load and that allostatic overload can trigger insulin resistance. This bidirectional association between impaired insulin signalling and allostatic overload favours medical conditions that increase the risk of AD, including diabetes, obesity, depression, and cardiovascular and cerebrovascular diseases. Finally, we discuss how the integration of biological, social and lifestyle factors throughout the lifespan can contribute to the development of AD, underscoring the potential of social and lifestyle interventions to preserve brain health and prevent or delay AD.

Allostatic load in children: The cost of empathic concern.

Early-life adversity affects long-term health outcomes but there is considerable interindividual variability in susceptibility to environmental influences. We proposed that positive psychological characteristics that reflect engagement with context, such as being concerned about people or performance on tasks (i.e., empathic concern), could moderate the interindividual variation in sensitivity to the quality of the early environment. We studied 526 children of various Asian nationalities in Singapore (46.6% female, 13.4% below the poverty line) with longitudinal data on perinatal and childhood experiences, maternal report on empathic concern of the child, and a comprehensive set of physiological measures reflecting pediatric allostatic load assessed at 6 y of age. The perinatal and childhood experiences included adversities and positive experiences. We found that cumulative adverse childhood experience was positively associated with allostatic load of children at 6 y of age at higher levels of empathic concern but not significantly associated at lower levels of empathic concern. This finding reveals evidence for the importance of empathic concern as a psychological characteristic that moderates the developmental impact of environmental influences, serving as a source for vulnerability to adversities in children.

The Implications of Racialized Economic Segregation and Allostatic Load on Mortality in Patients with Breast Cancer.

BACKGROUND: The objective of this study was to examine the association between racialized economic segregation, allostatic load (AL), and all-cause mortality in patients with breast cancer. PATIENTS AND METHODS: Women aged 18+ years with stage I-III breast cancer diagnosed between 01/01/2012 and 31/12/2020 were identified in the Ohio State University cancer registry. Racialized economic segregation was measured at the census tract level using the index of concentration at the extremes (ICE). AL was calculated with biomarkers from the cardiac, metabolic, immune, and renal systems. High AL was defined as AL greater than the median. Univariable and multivariable regression analyses using restricted cubic splines examined the association between racialized economic segregation, AL, and all-cause mortality. RESULTS: Among 4296 patients, patients residing in neighborhoods with the highest racialized economic segregation (Q1 versus Q4) were more likely to be Black (25% versus 2.1%, p < 0.001) and have triple-negative breast cancer (18.2% versus 11.6%, p < 0.001). High versus low racialized economic segregation was associated with high AL [adjusted odds ratio (aOR) 1.40, 95% confidence interval (CI) 1.21-1.61] and worse all-cause mortality [adjusted hazard ratio (aHR) 1.41, 95% CI 1.08-1.83]. In dose-response analyses, patients in lower segregated neighborhoods (relative to the 95th percentile) had lower odds of high AL, whereas patients in more segregated neighborhoods had a non-linear increase in the odds of high AL. DISCUSSION: Racialized economic segregation is associated with high AL and a greater risk of all-cause mortality in patients with breast cancer. Additional studies are needed to elucidate the causal pathways and mechanisms linking AL, neighborhood factors, and patient outcomes.

Allostatic Load in Childhood, Adolescence, and Young Adulthood: Are Assumptions of Measurement Invariance Warranted?

OVERVIEW: Allostatic load represents the cumulative toll of chronic mobilization of the body's stress response systems, as indexed by biomarkers. Higher levels of stress and disadvantage predict higher levels of allostatic load, which, in turn, predict poorer physical and mental health outcomes. To maximize the efficacy of prevention efforts, screening for stress- and disadvantage-associated health conditions must occur before middle age-that is, during childhood, adolescence, and young adulthood. However, this requires that models of allostatic load display properties of measurement invariance across age groups. Because most research on allostatic load has featured older adults, it is unclear if these requirements can be met. METHODS: To address this question, we fit a series of exploratory and confirmatory analytic models to data on eight biomarkers using a nationally representative sample of N = 4260 children, adolescents, and young adults drawn from the National Health and Nutrition Examination Survey dataset. RESULTS: Exploratory and confirmatory models indicated that, consistent with allostatic load theory, a unidimensional model was a good fit to the data. However, this model did not display properties of measurement invariance; post-hoc analyses suggested that the biomarkers included in the final confirmatory model were most strongly intercorrelated among young adults and most weakly intercorrelated among adolescents. CONCLUSIONS: These results underscore the importance of testing assumptions about measurement invariance in allostatic load before drawing substantive conclusions about stress, disadvantage, and health by directly comparing levels of allostatic load across different stages of development, while underscoring the need to expand investigations of measurement invariance to samples of longitudinal data.

Associations Between Structural Stigma and Allostatic Load Among Sexual Minorities: Results From a Population-Based Study.

OBJECTIVE: Structural forms of stigma and discrimination are associated with adverse health outcomes across numerous stigmatized groups, including lesbian, gay, and bisexual (LGB) individuals. However, the biological consequences of structural stigma among LGB populations are understudied. To begin to address this gap, we assessed associations between indicators of structural stigma (i.e., state-level policies) targeting LGB individuals and allostatic load (AL) indices representing physiological dysregulations. METHODS: Pooled data from the continuous 2001-2014 National Health and Nutritional Examination Survey were analyzed (LGB: n = 864; heterosexual: n = 20,310). Ten state-level LGB-related policies (e.g., employment nondiscrimination protections, same-sex marriage) were used to operationalize structural stigma. A sex-specific AL index representing 11 immune, metabolic, and cardiovascular biomarkers was estimated. Multilevel models were used to examine associations between structural stigma and AL, net of nine individual-level characteristics (e.g., education, race/ethnicity, age, and health behaviors). RESULTS: Sexual minority men living in states with low levels of structural stigma experienced significantly lower AL ( ß = -0.45, p = .02) compared with sexual minority men living in states with high structural stigma (i.e., fewer protective policies). There was no significant association between structural stigma and AL among sexual minority women. CONCLUSIONS: By demonstrating direct associations between structural stigma and indices of physiological dysregulation, our findings provide a mechanistic understanding of how the social environment can "get under the skin and skull" for sexual minority men in the United States. Future research should explore whether these mechanisms generalize to other marginalized groups exposed to structural stigma.

Household Food Security Status and Allostatic Load among United States Adults: National Health and Nutrition Examination Survey 2015-2020.

BACKGROUND: Household food insecurity has been linked to adverse health outcomes, but the pathways driving these associations are not well understood. The stress experienced by those in food-insecure households and having to prioritize between food and other essential needs could lead to physiologic dysregulations [i.e., allostatic load (AL)] and, as a result, adversely impact their health. OBJECTIVE: To assess the association between household food security status and AL and differences by gender, race and ethnicity, and Supplemental Nutrition Assistance Program (SNAP) participation. METHODS: We used data from 7640 United States adults in the 2015-2016 and 2017-March 2020 National Health and Nutrition Examination Survey to estimate means and prevalence ratios (PR) for AL scores (based on cardiovascular, metabolic, and immune biomarkers) associated with self-reported household food security status from multivariable linear and logistic regression models. RESULTS: Adults in marginally food-secure [mean = 3.09, standard error (SE) = 0.10] and food-insecure households (mean = 3.05; SE = 0.08) had higher mean AL than those in food-secure households (mean = 2.70; SE = 0.05). Compared with adults in food-secure households in the same category, those more likely to have an elevated AL included: SNAP participants [PR = 1.12; 95% confidence interval (CI):  1.03, 1.22] and Hispanic women (PR = 1.20; 95% CI: 1.05, 1.37) in marginally food-secure households; and non-Hispanic Black women (PR = 1.14; 95% CI: 1.03, 1.26), men (PR = 1.13; 95% CI: 1.02, 1.26), and non-SNAP non-Hispanic White adults (PR = 1.22; 95% CI: 1.08, 1.39) in food-insecure households. CONCLUSIONS: AL may be one pathway by which household food insecurity affects health and may vary by gender, race and ethnicity, and SNAP participation.

Examining emotion regulation and inflammation as predictors of maternal mental health after fetal anomaly diagnosis.

OBJECTIVE: Fetal anomalies occur in approximately 3% of pregnancies and receiving the diagnosis may be a potentially traumatic experience for families. The mental health of mothers receiving diagnoses and what predicts resilience or poor mental health is understudied. Emotion regulation is an important, modifiable, transdiagnostic factor of mental health, and may be protective post-diagnosis. Evaluating biomarkers of stress, including IL-6 and Allostatic Load (AL), can also serve as early indicators of risk, indicative of early intervention. This study assessed whether reappraisal, suppression, IL-6, and AL was associated with mental health outcomes and resilience in women after receiving a fetal anomaly diagnosis. METHODS: Pregnant women (N=108) presenting to a fetal concerns clinic for initial consultation completed measures of emotion regulation (i.e., reappraisal and suppression), depression, anxiety, posttraumatic stress symptoms, and resilience between 2019-2022. A blood draw was used to assess IL-6 and create composite allostatic load measure including: IL-6, blood pressure, heart rate, glucose, cortisol, and body mass index. RESULTS: Linear regressions controlling for age, gestational age, and perceived fetal diagnosis severity, demonstrated that IL-6 was negatively associated with resilience and positively associated with depression. Reappraisal was positively associated to resilience and negatively associated with depression, anxiety, and PTSD, whereas state insurance status was positively associated to anxiety and PTS symptoms. Suppression and allostatic load were not significant. CONCLUSIONS: Women experiencing fetal anomaly diagnosis represent an understudied population with unaddressed mental health needs. Reappraisal serves as not only a protective factor, but one that can be enhanced to promote maternal resilience and mental health. Furthermore, elevated IL-6 may be a critical early indicator of potential intervention needs among women who are pregnant, to mitigate negative psychological states and enhance resilience.

Defining the brain control of physiological stability.

The last few decades have seen major advances in neurobiology and uncovered novel genetic and cellular substrates involved in the control of physiological set points. In this Review, I discuss the limitations in the definition of homeostatic set points established by Walter B Canon and highlight evidence that two other physiological systems, namely rheostasis and allostasis provide distinct inputs to independently modify set-point levels. Using data collected over the past decade, the hypothalamic and genetic basis of regulated changes in set-point values by rheostatic mechanisms are described. Then, the role of higher-order brain regions, such as hippocampal circuits, for experience-dependent, allostatic induced changes in set-points are outlined. I propose that these systems provide a hierarchical organization of physiological stability that exists to maintain set-point values. The hierarchical organization of physiology has direct implications for basic and medical research, and clinical practice.

Association of allostatic load with overall survival in epithelial ovarian cancer.

OBJECTIVE: Elevated allostatic load (AL), an integrated, cumulative marker of physiologic damage due to socioenvironmental stress, is associated with increased mortality in patients with breast, lung, and other cancers. The relationship between allostatic load and mortality in ovarian cancer patients remains unknown. We examined the relationship between allostatic load and overall survival in ovarian cancer patients. METHODS: This cross-sectional study used data from 201 patients enrolled in a prospective observational ovarian cancer cohort study at a National Cancer Institute-designated Comprehensive Cancer Center from October 2012 through June 2022. All patients underwent debulking surgery and completed a full course of standard-of-care platinum-based chemotherapy. Follow-up was completed through January 2024. Allostatic load was calculated as a summary score by assigning one point to the worst sample quartile for each of ten biomarkers measured within 45 days before the ovarian cancer diagnosis. High allostatic load was defined as having an allostatic load in the top quartile of the summary score. A Cox proportional hazard model with robust variance tested the association between allostatic load and overall survival. RESULTS: There were no associations between allostatic load and ovarian cancer clinical characteristics. After accounting for demographic, clinical, and treatment factors, high allostatic load was associated with a significant increase in mortality (hazard ratio 2.17 [95%CI, 1.13-4.15]; P = 0.02). CONCLUSION: Higher allostatic load is associated with worse survival among ovarian cancer patients. Allostatic load could help identify patients at risk for poorer outcomes who may benefit from greater socioenvironmental support during treatment.

Parent-child coregulation as a dynamic system: a commentary on Wass et al. (2024).

In this commentary, I argue that including and operationalizing allostatic processes will become increasingly important in future research on parent-child biobehavioral coregulation. In particular, the conceptualization and modeling of dyadic oscillatory rhythms that align in expected ways with the child's developmental stage and that distinguish typical and atypical development will be useful in future work. Despite the inherent asymmetry characteristic of parent-child relationships, we should not forget to consider the child's effects on the parent within and across time, the additional environmental demands upon parents that shape parent-child coregulation, and variations in parent-child asymmetry by parental risk factors. Studying risk factors that are dyadic in nature, such as child maltreatment, may be particularly informative in gaining a deeper understanding of how parent-child coregulation interfaces with developmental psychopathology. To best model parent-child coregulation as a dynamic system, it will be critical to employ more nonlinear analytic models and better represent the multiple hierarchical domains of coregulation and their interactions, including affect, cognition, behavior, and biology. Finally, in future research, a deeper application of existing dyadic and dynamic theories, as well as the generation of new dyadic developmental theories, will aid us in obtaining a stronger understanding of the developmental function and intervention implications of parent-child biobehavioral coregulation.

The Role of Online Well-Being Therapy in Overcoming Allostatic Overload in Medical Workers: A Pilot Randomized Controlled Study.

INTRODUCTION: Stress may lead to allostatic overload. Well-being therapy (WBT) might mitigate it by enhancing psychological well-being and protecting from psychological symptoms. Since no reports are available on the use of WBT in allostatic overload, we evaluated online WBT effects in reducing allostatic overload in medical workers during the coronavirus pandemic. METHODS: Sixty-six participants with allostatic overload were enrolled and randomly assigned to eight sessions of online WBT (n = 32) or eight sessions of an online psychoeducation program on healthy lifestyle (CON) (n = 34). The primary outcome was the prevalence rate of allostatic overload in the two groups at session 8 (T2). Secondary analyses were performed on changes in the PsychoSocial Index (PSI) and Psychological Well-Being (PWB) scales scores at the same time points. Generalized estimating equation models were employed. RESULTS: The WBT group showed a significantly lower rate of allostatic overload at T2 than the CON group (28.13% vs. 70.59%, p < 0.001); similar results were found at T1, T3, and T4 (p < 0.001). Compared to CON, WBT produced a significant decrease in psychological distress (p < 0.001) and abnormal illness behavior (p = 0.031), as well as a significant improvement in PWB autonomy, environmental mastery, personal growth, positive relations with others, purpose in life, and self-acceptance (p < 0.001). CONCLUSION: Online WBT may be an effective non-pharmacological therapeutic strategy for individuals with allostatic overload. These findings need to be further validated in different clinical populations.

Allostatic load and risk of invasive breast cancer among postmenopausal women in the U.S.

OBJECTIVE: Allostatic load can reflect the body's response to chronic stress. However, little is known about the association between allostatic load and risk of breast cancer in postmenopausal women. This study used a large prospective cohort in the United States to examine the relationship between allostatic load and invasive breast cancer risk, and to evaluate the relationship by racial and ethnic identity and breast cancer subtypes. METHODS: Among 161,808 postmenopausal participants in Women's Health Initiative, eligible were a subsample of 27,393 postmenopausal women aged 50-79 years old, who enrolled from 1993 to 1998, had serum test biomarkers, and were followed for breast cancer incidence through February 2022. Allostatic load at enrollment was computed based on eight biomarkers from lab serum tests and a questionnaire about participants' prescription drug use. The associations between allostatic scores and risk of breast cancer (overall and by subtypes) were assessed using Cox proportional hazards models. The race and ethnic differences were examined. RESULTS: Over a median follow-up time of 17.24 years, 1722 invasive breast cancer cases were identified. High allostatic load was associated with an increased risk of breast cancer (HR = 1.36, 95%CI: 1.20, 1.54 for third tertile vs first tertile, Ptrend < 0.0001). Similar trends were found in White women and non-Hispanic women. Higher allostatic load was associated with hormone receptor-positive and HER2/Neu-negative breast cancer (HR = 1.54, 95%CI: 1.30, 1.80 for third tertile vs first tertile, Ptrend < 0.0001). CONCLUSION: In this study, we found that higher allostatic load was significantly associated with an increased risk of breast cancer in postmenopausal women.

Measurement of Allostatic Load in Caregivers of Older Hispanic People With Alzheimer Disease and Related Disorders.

BACKGROUND: Allostatic load (AL) has been studied in the context of biomarkers that may be affected by environmental and contextual stressors, including social determinants of health. The specific stressor studied here is the provision of caregiving to older persons with Alzheimer disease and related disorders. The aims were to examine the factor structure of stress and nonstress biomarkers, different methods for calculating AL, and the relationship of AL with other variables. METHODS: Latent variable models were used to examine biomarkers. Regression analyses were performed with the outcomes: AL calculated as percentile-based and clinically-based for both stress and nonstress components. The sample was 187 Hispanic caregivers to individuals with dementia. RESULTS: The results of the confirmatory factor analyses (CFAs) suggested defining 2 factors: nonstress and stress-related. Performance was better for the CFA results and the associations with covariates when stress and nonstress components were examined separately. Despite some limitations, this is one of the first studies of biomarkers in Hispanic caregivers to patients with dementia. It was possible to explain almost 30% of the variance in the nonstress AL component. CONCLUSION: It may be important to differentiate among biomarkers indicative of cardiovascular, metabolic, and immune response as contrasted with the more stress-related biomarkers.

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 (ß) = -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 (ß = -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.

What Explains the Link Between Hearing and Vision Impairment and Cognitive Function? Analysis of Mediating Effects in the USA, England and Ireland.

OBJECTIVES: Hearing and vision impairments are associated with cognitive decline and dementia risk. Explanations for this include age-related processes impacting on sensory and cognitive function (common cause), or sensory impairments having a direct or indirect impact on cognition via social engagement, depression and physical activity (cascade). We tested whether associations between hearing, vision and episodic memory were mediated by allostatic load, social engagement, depression and physical activity. METHODS: We used structural equation modelling with cross-sectional data from the USA (n = 4746, aged 50-101), England (n = 4907, aged 50-89) and Ireland (4292, aged 50-80) to model factors related to the common cause (indexed by allostatic load) and the cascade hypothesis with respect to cognitive ability (episodic memory). RESULTS: Poorer hearing/vision was associated with lower social engagement, depression and sedentary lifestyle. Poor vision was not related to allostatic load, and poor hearing was associated with allostatic load in only one data set, contributing to a common-cause hypothesis. Lower social engagement, depression and a sedentary lifestyle were associated with poorer episodic memory, contributing to the cascade hypothesis. Using effect estimates to calculate the proportion of the total effects mediated by the combined mediator variables, up to two fifths of the relationship between hearing and vision with episodic memory can be explained by the mediators. CONCLUSIONS: The association between hearing, vision and episodic memory is mediated by allostatic load, social engagement, depression, and physical activity. The finding that social engagement, depression, and physical activity mediate the association between sensory abilities and cognitive function supported the cascade hypotheses. Interventions to improve healthy lifestyle, reduce depression and foster social engagement of older people with sensory impairments are likely to be beneficial in preventing cognitive decline and dementia.

Migraine chronification as an allostatic disorder: a proof-of-concept study.

OBJECTIVE: The underpinning biologics of migraine chronification are not well understood. We aim to investigate the role of the cumulative burden of stress, namely the allostatic load, in migraine chronification. METHODS: This was a cross-sectional study. The allostatic load was measured with a composite multi-system score (BALI: Bologna Allostatic Load Index), evaluating 20 biomarkers representing four physiological systems: immune, metabolic, cardiovascular, and neuroendocrinological systems. BALI score was subdivided into high score and low score based on the distribution in controls. Migraine patients were included and subclassified into low-frequency episodic migraine group (low-EM group), high-frequency episodic migraine group (high-EM group), and chronic migraine group (CM group). RESULTS: The distribution of BALI high-score increased in parallel with headache attacks monthly frequency: 16% in low-EM group (n = 10), 24% in high-EM group (n = 12), and 40% in CM group (n = 21) (p = 0.017). In a multivariable analysis, the odds ratio of having a high-score BALI in CM patients (vs. low-EM patients) was 2.78 (95% CI 1.07-7.22; p = 0.036). Individual BALI biomarkers values which were significantly different among migraine subgroups included systolic blood pressure (p = 0.018), diastolic blood pressure (p < 0.001), and heart rate (p = 0.019). CONCLUSION: Our study substantiates this emerging concept of migraine chronification as an allostatic disorder.

Allostatic load, adverse childhood experiences, executive functions, and BMI status in adolescents and young adults.

OBJECTIVES: Chronic stress induces preclinical changes in the metabolic, cardiovascular, and immune systems. This phenomenon, known as allostatic load (AL), can impair executive functions (EF), which may be even more affected in individuals with excess weight due to their characteristic inflammatory state and cardiometabolic changes. Adverse childhood experiences (ACEs) contribute to AL and may influence executive functioning presumably via alterations within the hypothalamic-pituitary axis, including epigenetic modifications. We assess the relationship between AL and EF in youth with and without excess weight, and the effect ACEs on executive functioning. METHODS: One hundred eighty-two adolescents and young adults (85 with normal weight and 97 with overweight/obesity; 10-21 years) were recruited. The estimated AL index included the following: systolic and diastolic blood pressure, glycated hemoglobin, high- and low-density lipoprotein cholesterol, triglycerides, high-sensitivity C-reactive protein, fibrinogen, and cortisol. ACEs were measured using the Juvenile Victimization Questionnaire. The neuropsychological evaluation included the assessment of inhibition, working memory, and cognitive flexibility processes. RESULTS: AL was not significantly associated with executive functioning, and this relationship did not depend on body-weight status. ACEs, available for 57 of 182 participants, were significantly associated with poorer executive functioning. CONCLUSIONS: Our study shows that AL is not associated with executive functioning in adolescents and young adults. Since the current sample was young, we hypothesize that a longer exposure to AL might be required for its negative effects to surface. Nevertheless, exposure to early adversity seems to be associated with poorer executive functioning in youth.

Enriched housing differentially alters allostatic load and cardiopulmonary responses to wildfire-related smoke in male and female mice.

Living conditions are an important modifier of individual health outcomes and may lead to higher allostatic load (AL). However, housing-induced cardiovascular and immune effects contributing to altered environmental responsiveness remain understudied. This investigation was conducted to examine the influence of enriched (EH) versus depleted housing (DH) conditions on cardiopulmonary functions, systemic immune responses, and allostatic load in response to a single wildfire smoke (WS) exposure in mice. Male and female C57BL/6J mice were divided into EH or DH for 22 weeks, and cardiopulmonary assessments measured before and after exposures to either one-hr filtered air (FA) or flaming eucalyptus WS exposure. Male and female DH mice exhibited increased heart rate (HR) and left ventricular mass (LVM), as well as reduced stroke volume and end diastolic volume (EDV) one week following exposure to WS. Female DH mice displayed significantly elevated levels of IL-2, IL-17, corticosterone and hemoglobin A1c (HbA1c) following WS, while female in EH mice higher epinephrine levels were detected. Female mice exhibited higher AL than males with DH, which was potentiated post-WS exposure. Thus, DH increased susceptibility to extreme air pollution in a gender-dependent manner suggesting that living conditions need to be evaluated as a modifier of toxicological responses.

Comparison between grip strength and relative grip strength in their relationship with allostatic load among adolescents.

PURPOSE: To assess the associations of muscle strength, measure by grip strength and relative grip strength (grip strength divided by body weight), on the allostatic load (AL) index in adolescent boys and girls. METHODS: A total of 1,323 students were recruited (boys = 776, girls = 547). Data on general demographic characteristics, anthropometric indicators, grip strength, blood pressure, pulse rate, and biological samples were collected. A 20-indicator-based AL index (using the AL1, AL2, and AL3 calculation methods) was used as the dependent variable. Multiple linear regression models were used to evaluate the association between grip strength, relative grip strength, and AL. All analyses were stratified by sex. RESULTS: The mean age of the participants was 14.17 ± 1.45 years. Overall, the linear regression model adjusting for demografic characteristics showed that greater grip strength was associated with higher AL1 scores (R2 = 10.1%, ß = 0.096, P < 0.001). Then, we further adjusted for body weight, and negative associations were observed between grip strength and AL1 (R2 = 35.3%, ß = -0.027, P = 0.030). However, after sex stratification, this association was not statistically significant in girls. Moreover, relative grip strength was negatively associated with AL1 (R2 = 14.8%, ß = -8.529, P < 0.001) after adjusting for demographic characteristics in the total sample. Specifically, relative grip strength was more strongly associated with the AL1 burden in boys than in girls. Finally, sensitivity analyses of AL2 and AL3 yielded similar results. CONCLUSION: We observed that compared with grip strength, relative grip strength might be a useful indicator for the identification of AL burden in adolescents. The results suggest that strengthening relative handgrip strength in adolescents might help reduce the AL burden, especially in boys.