Male–female differences in the association between socioeconomic status and atherosclerotic risk in adolescents

Explaining adverse cholesterol levels and distinct gender patterns in an Indonesian population compared with the U.S

Cardiovascular disease is among the most common causes of death around the world. As rising incomes in low and middle-income countries are accompanied by increased obesity, the burden of disease shifts towards non-communicable diseases, and lower-income settings make up a growing share of cardiovascular disease deaths. Comparative investigation of the roles of body composition, behavioral and socioeconomic factors across countries can shed light on both the biological and social drivers of cardiovascular disease more broadly. Comparing rigorously-validated measures of HDL and non-HDL cholesterol among adults in the United States and in Aceh, Indonesia, we show that Indonesians present with adverse cholesterol biomarkers relative to Americans, despite being younger and having lower body mass index. Adjusting for age, the gaps increase. Body composition, behaviors, demographic and socioeconomic characteristics that affect cholesterol do not explain between-country HDL differences, but do explain non-HDL differences, after accounting for medication use. On average, gender differences are inconsistent across the two countries and persist after controlling observed characteristics. Leveraging the richness of the Indonesian data to draw comparisons of males and females within the same household, the gender gaps among Indonesians are not explained for HDL cholesterol but attenuated substantially for non-HDL cholesterol. This finding suggests that unmeasured household resources play an important role in determining non-HDL cholesterol. More generally, they appear to be affected by social and biological forces in complex ways that differ across countries and potentially operate differently for HDL and non-HDL biomarkers. These results point to the value of rigorous comparative studies to advance understanding of cardiovascular risks across the globe.

Childhood socioeconomic conditions are associated with increased chronic low-grade inflammation over adolescence: findings from the EPITeen cohort study

OBJECTIVE

Early life adversity has been associated with increased risk of inflammation and inflammation-related diseases in adulthood. This study aimed to examine the association of childhood socioeconomic conditions with chronic low-grade inflammation over adolescence.

METHODS

We used information on 2942 members (1507 girls and 1435 boys) of the EPITeen (Epidemiological Health Investigation of Teenagers in Porto) cohort that was established in 2003 in Porto, Portugal, and included 13-year-old adolescents were further evaluated at 17 and 21 years. Mother' and father's education and occupation were used as indicators of childhood socioeconomic conditions. High-sensitivity C reactive protein (hs-CRP) was measured at three points in time (13, 17 and 21 years). hs-CRP levels were categorised in tertiles separately for each wave; chronic low-grade inflammation in adolescence was defined as having hs-CRP levels in the highest tertile in at least two waves and never in the lowest tertile.

RESULTS

Prevalence of chronic low-grade inflammation during adolescence was significantly higher among participants with low parental socioeconomic position. Low parental socioeconomic position was associated with chronic low-grade inflammation in adolescence, after adjustment for sex, perinatal and physical environment factors, health-related behaviours and health status in adolescence OR=1.6; 95% CI: 1.1 to 2.4 for lowest versus highest mother's education and OR=1.6; 95% CI: 1.1 to 2.3 for lowest versus highest father's occupation.

CONCLUSION

Low childhood socioeconomic conditions are associated with chronic low-grade inflammation during adolescence. Our results suggest that the early life socioeconomic environment has an impact on inflammatory processes over adolescence.

Do upsetting life events explain the relationship between low socioeconomic status and systemic inflammation in childhood? Results from a longitudinal study

BACKGROUND

Children from families of low socioeconomic status (SES) are more likely to be exposed to upsetting situations and stressors. Such exposures have, in turn, been linked to inflammation in some studies. In this study we explore if low SES is related to inflammation in children via such stressful life events.

METHODS

Data on 4525 children of the Avon Longitudinal Study of Parents and Children, a general population birth cohort, were used to explore associations between SES at ages 0-3 years, upsetting life events at ages 3-9 years and inflammatory markers [interleukin 6 (IL-6) and C-reactive protein (CRP)] at age 9 years. Confounders included body mass index, gender, financial problems, and upsetting life events at ages 0-3 years.

RESULTS

Using Structural Equation Modelling, we found that early socioeconomic disadvantage predicted higher levels of IL-6 (β = 0.034, 95% CI = 0.005, 0.063) even after adjusting for confounders. This association was partially mediated by upsetting life events (β = 0.003, 95% CI = 0.001, 0.006).

CONCLUSIONS

In the general child population, low SES is associated with increased exposure to stressful life events, in turn associated with later inflammation. These findings highlight the role of stressors associated with poverty and disadvantage in the development of inflammation among children in the general population.

Childhood socioeconomic status and inflammation: A systematic review and meta-analysis

Recent research suggests that risk for chronic diseases of aging including cardiovascular disease, diabetes, and even cancer can be programmed early in the lifespan as a result of exposure to chronic stressors like low socioeconomic status (SES) that are hypothesized to promote a pro-inflammatory response in immune cells that results in chronic, systemic inflammation. The present paper conducted a meta-analysis to establish whether exposure to low (versus higher) SES in childhood and adolescence is associated with higher levels of inflammation (as measured by C-reactive protein, IL-6, and fibrinogen) concurrently and in adulthood. We conducted meta-analyses with both unadjusted bivariate associations between SES and inflammation and with adjusted associations that controlled for a range of covariates including demographic factors, body mass index, smoking, physical activity and current SES. A systematic review of Pubmed and PsycINFO identified a total 35 studies (26 with unadjusted and 31 adjusted effect sizes) to be included in the meta-analysis. Random-effects meta-analysis showed that individuals who were exposed to low SES in childhood and adolescence had significantly higher levels of inflammatory markers (r = -0.07, p < .001, 95% CI = -0.09, -0.05). This association remained significant in adjusted analyses (r = -0.06, p < .001, 95% CI = -0.09, -0.03). However, the relationship between childhood SES and inflammation was non-significant in a meta-analysis with longitudinal studies that all controlled for adulthood SES (r = -0.03, p = .356, 95% CI = -0.08, 0.03). Future longitudinal research should utilize measurement of inflammatory markers at multiple time points to further examine the complex relationships between SES and health both in childhood and adulthood.

Maternal experiences of intimate partner violence and C-reactive protein levels in young children in Tanzania

Intimate partner violence (IPV) is a critical public health issue that impacts women and children across the globe. Prior studies have documented that maternal experiences of IPV are associated with adverse psychological and physical health outcomes in children; however, research on the underlying physiological pathways linking IPV to these conditions is limited. Drawing on data from the 2010 Tanzania Demographic and Health Survey, we examined the relationship between maternal report of IPV in the past 12 months and inflammation among children ages 6 months to 5 years. Our study included 503 children who were randomly selected to provide a blood sample and had a mother who had ever been married and who had completed the Domestic Violence Module, which collected information on physical, sexual, and emotional violence. Analyses were stratified based on a threshold for acute immune activation status, defined by the threshold of CRP > 1.1 mg/L for young children in Tanzania. In bivariate analyses, healthy children whose mothers reported IPV showed a marginally elevated median CRP level compared to children whose mothers did not report IPV (0.35 vs. 0.41 mg/L; p = 0.13). Similarly, among children with active or recent infections, those whose mothers reported IPV had an elevated median CRP compared to children whose mothers did not (4.06 vs 3.09 mg/L; p = 0.03). In adjusted multiple variable regression models to account for child, mother, and household characteristics, maternal IPV was positively associated with (log) CRP in both healthy children and children with active or recent infection. Although longitudinal research with additional biomarkers of inflammation is needed, our results provide support for the hypothesis that inflammation may function as a biological pathway linking maternal IPV to poor psychological and physical health outcomes among children of mothers who are victimized-and this may extend to very young children and children in non-Western contexts.

Education, sex and risk of stroke: a prospective cohort study in New South Wales, Australia

OBJECTIVE

To determine whether the association between highest educational attainment and stroke differed by sex and age; and whether potential mediators of observed associations differ by sex.

DESIGN

Prospective cohort study.

SETTING

Population based, New South Wales, Australia.

PARTICIPANTS

253 657 stroke-free participants from the New South Wales 45 and Up Study.

OUTCOME MEASURES

First-ever stroke events, identified through linkage to hospital and mortality records.

RESULTS

During mean follow-up of 4.7 years, 2031 and 1528 strokes occurred among men and women, respectively. Age-standardised stroke rate was inversely associated with education level, with the absolute risk difference between the lowest and highest education group greater among women than men. In relative terms, stroke risk was slightly more pronounced in women than men when comparing low versus high education (age-adjusted HRs: 1.41, 95% CI 1.16 to 1.71 and 1.25, 95% CI 1.07 to 1.46, respectively), but there was no clear evidence of statistical interaction. This association persisted into older age, but attenuated. Much of the increased stroke risk was explained by modifiable lifestyle factors, in both men and women.

CONCLUSION

Low education is associated with increased stroke risk in men and women, and may be marginally steeper in women than men. This disadvantage attenuates but persists into older age, particularly for women. Modifiable risk factors account for much of the excess risk from low education level. Public health policy and governmental decision-making should reflect the importance of education, for both men and women, for positive health throughout the life course.

Socioeconomic status inequalities in low-grade inflammation during childhood

BACKGROUND

Family socioeconomic status (SES) is an important source of child health disparities in the USA. Chronic stress is one way SES may impact children's physiology with implications for later health inequalities. These processes may work differently across childhood due to differences in exposure and susceptibility to stressors at different ages. We assess associations between family SES and one biomarker of chronic stress exposure-low-grade inflammation detected by elevated C reactive protein (CRP)-and evaluate differences in the associations by child age.

METHODS

We used nationally representative data from the National Health and Nutrition Examination Survey and Tobit regression models to estimate SES associations with CRP and the moderating effects of age for children age 2-18 years. Our sample was limited to CRP ≤10 mg/l to focus on low-grade inflammation (N=13 165).

RESULTS

Children whose parent had less than a high school degree had 35% higher CRP than those with a college graduate parent; and, poor children had 24% higher CRP than those with high family income, net of controls. When children's body mass index was accounted for, low education and poverty associations were reduced to 19% and 15%, respectively. Child age interactions were negative and significant for both parental education and family income.

CONCLUSIONS

This study provides new evidence that SES is associated with low-grade inflammation in children, and that these associations may be particularly strong during early and mid-childhood. Future research should further our understanding of stressors related to low family SES that may lead to immune system dysregulation during childhood.

Home sweet home? Home physical environment and inflammation in children

The home environment includes important social and physical contexts within which children develop. Poor physical home environments may be a potential source of stress for children through difficult daily experiences. Using a sub-sample from the Los Angeles Family and Neighborhood Survey (N = 425), we consider how the home physical environment affects stress-related immune system dysregulation in children ages 3-18 years. Results indicated that children in poorer quality homes had higher inflammation (measured by C-reactive protein). The associations were particularly strong for younger children. We also found that part of the home physical environment association with CRP worked through increased risk of obesity for children living in low-quality homes. Future research should assess how home physical environments could be improved to reduce stress and improve health outcomes in children.

Adversity in preschool-aged children: Effects on salivary interleukin-1β

Exposure to early life adversity is linked to impaired affective, cognitive, and behavioral functioning and increases risk for various psychiatric and medical conditions. Stress-induced increases in pro-inflammatory cytokines may be a biological mechanism of these effects. Few studies have examined cytokine levels in children experiencing early life adversity, and very little research has investigated cytokines or other markers of inflammation in saliva. In the present study, we examined salivary interleukin (IL)-1β and C-reactive protein (CRP) levels in relation to stress exposure in 40 children aged 3 to 5 years who were enrolled in a larger study of early life adversity. Childhood maltreatment status was assessed via review of child welfare records. Contextual stress exposure, traumatic life event history, and symptoms of psychopathology were assessed via caregiver interviews at a home visit. In a subsequent visit, salivary IL-1β and CRP were obtained before and after participation in four emotion-eliciting tasks. The number of past-month contextual stressors, lifetime contextual stressors, and traumatic life events each demonstrated a significant main effect on IL-1β. Baseline IL-1β was positively associated with each of the significant main-effect adversities. Postchallenge IL-1β displayed positive associations with each adversity variable, but these were not significant. CRP was not significantly associated with any of the adversity variables. Given the evidence suggesting the involvement of IL-1β in the neuropathology of psychiatric conditions, these results may have important implications for developmental outcomes.

Internalizing and externalizing behaviors predict elevated inflammatory markers in childhood

BACKGROUND

Children with behavior problems, such as internalizing or externalizing disorders, are at increased risk for poorer physical health in adulthood. Inflammation has been posited as a potential biological mediator underlying this association. However, it is unclear how early in development associations between behavior problems and inflammation may be detected, and whether associations are present for both internalizing and externalizing behaviors in pre-pubertal children.

METHODS

Using data from children in the Avon Longitudinal Study of Parents and Children, we examined associations between behavior problems at age 8 (assessed via the parent-report Strengths and Difficulties Questionnaire) and inflammatory markers assessed at age 10. Inflammatory markers included C-reactive protein (CRP; n=4069) and interleukin-6 (IL-6; n=4061). We further evaluated whether body mass index (BMI) mediated associations, and tested for potential reverse causality by considering whether age 10 inflammation was associated with changes from initial levels to age 12 behavior problems.

RESULTS

After adjusting for relevant covariates, age 8 externalizing behaviors were associated with elevated CRP at age 10, and age 8 internalizing and externalizing behaviors were associated with elevated IL-6 at age 10 (p's<0.05). We found no evidence that observed associations were mediated by BMI or that inflammatory markers at age 10 were associated with increased internalizing or externalizing behavior problems at age 12.

CONCLUSIONS

These findings document an association between behavior problems and elevated concentrations of CRP and IL-6 at 10 years. Heightened inflammation in childhood may be a pathway through which early behavior problems increase risk for adult chronic diseases.

Adversity and inflammation among adolescents: a possible pathway to long-term health risk

It has been suggested that childhood adversity programs an inflammatory phenotype characterized by higher levels of systemic inflammation and increased health risk in later life. If this is the case, one might expect associations of early childhood adversity with elevated levels of circulating inflammatory molecules in adolescence. To date, evidence for this association is mixed. This issue of Psychosomatic Medicine includes two studies by Pietras and Goodman and Low et al. that extend the existing literature and provide initial evidence that coping styles and perceived social standing may buffer against the impact of adversity on inflammation among adolescents. The current commentary considers these interesting findings in the context of the existing literature and discusses a critical need for longitudinal studies examining whether individual risk and resilience factors moderate the long-term health effects of childhood adversity, possibly via early programming of inflammatory pathways.

Socioeconomic status gradients in inflammation in adolescence

OBJECTIVE

To determine whether lower socioeconomic status (SES), broadly defined, is associated with increased inflammation in adolescence and whether adiposity mediates these relationships.

METHODS

Fasting blood samples from 941 non-Hispanic black and white adolescents enrolled in a suburban, Midwestern school district were assayed for proinflammatory biomarkers (interleukin-6 [IL-6], tumor necrosis factor α soluble receptor 2 fibrinogen). A parent reported objective SES (parent education [E1 ≤ high school, E2 = some college, E3 = college graduate, E4 = professional degree], household income), and youth perceived SES (PSES). Multivariable linear regressions assessed the relationship of SES measures to biomarkers adjusting for age, race, sex, and puberty status. In the final step, body mass index (BMI) z score (BMIz) was added to models, and Sobel tests were performed to assess mediation by adiposity.

RESULTS

Parent education was inversely associated with IL-6 (βE1 = .11, βE2 = .10, βE3 = .02; p < .001). This association was attenuated but remained significant after BMIz adjustment (p = .01). Sobel testing confirmed BMIz's partial mediating role (p < .001). Parent education was also inversely associated with sTNFR2 (βE1 = .03, βE2 = .02, βE3 = .001; p = .01); this relationship was mediated by BMIz. Although no main effect was noted for PSES, PSES by race interactions was observed for sTNFR2 (p = .02) and IL-6 (p = .06). High PSES was associated with lower sTNFR2 and IL-6 for white but not black youth. There were no associations with household income.

CONCLUSIONS

Social disadvantage, specifically low parent education, is associated with increased inflammation in adolescence. Adiposity explains some but not all associations, suggesting that other mechanisms link lower SES to inflammation. High PSES is associated with lower inflammation for white but not black youth.

Socioeconomic and other social stressors and biomarkers of cardiometabolic risk in youth: a systematic review of less studied risk factors

Background

Socioeconomic disadvantage and other social stressors in childhood have been linked with cardiometabolic diseases in adulthood; however the mechanisms underlying these observed associations and the timing of their emergence are unclear. The aim of this review was to evaluate research that examined relationships between socioeconomic disadvantage and other social stressors in relation to less-studied cardiometabolic risk factors among youth, including carbohydrate metabolism-related factors, lipids, and central adiposity.

Methods

We searched PubMed and ISI Web of Science to identify relevant publications between 2001 and 2013.Studies were selected based on 4 criteria: (1) the study examined an association between at least one social or economic stressor and one relevant outcome prior to age 21; (2) the sample originated from a high-income country; (3) the sample was not selected based on a health condition; and (4) a central aim was to evaluate the effect of the social or economic stressor on at least one relevant outcome. Abstracts were screened and relevant publications were obtained and evaluated for inclusion criteria. We abstracted data from selected articles, summarized them by exposures and outcomes, and assigned an evidence grade.

Results

Our search identified 37 publications from 31 studies. Socioeconomic disadvantage was consistently associated with greater central adiposity. Research to date does not provide clear evidence of an association between childhood stressors and lipids or carbohydrate metabolism-related factors.

Conclusions

This review demonstrates a paucity of research on the relationship of socioeconomic disadvantage and other social stressors to lipid and carbohydrate metabolism-related factors in youth. Accordingly, it is not possible to form strong conclusions, particularly with regard to stressors other than socioeconomic disadvantage. Findings are used to inform priorities for future research. An improved understanding of these pathways is critical for identifying novel prevention targets and intervention opportunities to protect the long-term health of children and adolescents.

Childhood adversity and cell-mediated immunity in young adulthood: does type and timing matter?

Childhood adversity can have powerful effects on health over the life course. Persistent changes in cell-mediated immune function may be one pathway linking adverse childhood experiences with later disease risk. However, limited research has examined childhood adversity in relation to cell-mediated immune function, and in particular, immune response to latent viruses in adulthood. The present study investigated the association of two types of childhood adversity, socioeconomic disadvantage during adolescence and abuse prior to age 18, with Epstein-Barr Virus (EBV) antibody titers in a large nationally representative sample of young adults aged 24-32years. Data were drawn from the National Longitudinal Study on Adolescent Health, Wave 4 (n=13,162). We examined the associations of three indicators of adolescent SES (parental education, household income, and occupational status) and frequency and timing of physical and sexual abuse with EBV antibodies, controlling for age, sex, race/ethnicity, and presence of a smoker in the household during adolescence. Lower parental occupational status and some categories of lower education were associated with elevated EBV antibodies (p<.05), and individuals who reported sexual abuse that occurred more than 10times had elevated EBV antibodies relative to individuals who were not sexually abused (p=0.03). Among individuals exposed to physical abuse, those who were first abused at age 3-5years had heightened EBV antibodies relative to those first abused during adolescence (p=0.004). This study extends prior research linking early adversity and immune function, and provides initial evidence that childhood adversity has a persistent influence on immune responses to latent infection in adulthood.

Childhood adversity and inflammatory processes in youth: a prospective study

BACKGROUND

Retrospective studies show that childhood adversity is associated with systemic inflammation in adulthood. Few prospective studies have examined whether childhood adversity influences inflammation in an observable manner during childhood or adolescence and if these effects are sustained over time.

METHODS

Using longitudinal data from the Avon Longitudinal Study of Parents and Children, we examined associations between acute adverse events at seven time points prior to age 8 and inflammation at ages 10 and 15. Inflammatory markers at age 10 included interleukin-6 (IL-6; N=4655) and C-reactive protein (CRP; N=4647), and CRP was measured again at age 15 (N=3286). We further evaluated whether body mass index (BMI), depression, or cigarette smoking mediated associations between adverse events and inflammation.

RESULTS

Adverse events in middle childhood (occurring between ages 6 to 8), as well as cumulative adversity from birth to 8 years, were associated with higher levels of IL-6 and CRP at age 10. Adverse events reported in early childhood (1.5years) or middle childhood, and cumulative adversity from birth through 8years predicted increased levels of CRP at age 15, and these associations persisted after adjustment for CRP at age 10. Some, but not all, of these associations were mediated by BMI.

CONCLUSIONS

This study documents that exposure to adverse events prior to age 8 is associated with elevated inflammation at age 10 and in mid-adolescence. These findings provide prospective evidence for a biological mechanism by which early experiences may shape long-term health. Future studies with earlier assessments of inflammation are necessary in order to elucidate potential sensitive periods and mechanisms that link childhood adversity to later disease vulnerability.

Elevated C-reactive protein in children from risky neighborhoods: evidence for a stress pathway linking neighborhoods and inflammation in children

BACKGROUND

Childhood socioeconomic status is linked to adult cardiovascular disease and disease risk. One proposed pathway involves inflammation due to exposure to a stress-inducing neighborhood environment. Whether CRP, a marker of systemic inflammation, is associated with stressful neighborhood conditions among children is unknown.

METHODS AND RESULTS

The sample included 385 children 5-18 years of age from 255 households and 101 census tracts. Multilevel logistic regression analyses compared children and adolescents with CRP levels >3 mg/L to those with levels ≤ 3 mg/L across neighborhood environments. Among children living in neighborhoods (census tracts) in the upper tertile of poverty or crime, 18.6% had elevated CRP levels, in contrast to 7.9% of children living in neighborhoods with lower levels of poverty and crime. Children from neighborhoods with the highest levels of either crime or poverty had 2.7 (95% CI: 1.2-6.2) times the odds of having elevated CRP levels when compared to children from other neighborhoods, independent of adiposity, demographic and behavioral differences.

CONCLUSIONS

Children living in neighborhoods with high levels of poverty or crime had elevated CRP levels compared to children from other neighborhoods. This result is consistent with a psychosocial pathway favoring early development of cardiovascular risk that involves chronic stress from exposure to socially- and physically-disordered neighborhoods characteristic of poverty.

Childhood adversity and immune and inflammatory biomarkers associated with cardiovascular risk in youth: a systematic review

BACKGROUND

Research suggests that adverse experiences in childhood affect the development of cardiovascular disease (CVD), and immune and inflammation dysregulation has been postulated to play role. However, it is unclear whether the effects of social adversity on immune-related biomarkers are evident in early life, and if these biomarkers may provide an early risk marker for targeting prevention and intervention. The purpose of this review is to evaluate research on the relationship between adversity and CVD-relevant immune biomarkers in youth, assess the consistency of the findings, and consider what additional research is needed.

METHODS

PubMed and PsycINFO searches were conducted through September 2011. Studies were selected using criteria related to the childhood exposure, biomarker outcome, age range, and sample selection. Twenty articles were identified, examining associations between childhood adversity and immune biomarkers (assessed during childhood) that are potential risk markers for CVD later in life.

RESULTS

Although childhood adversity was not consistently related to youth levels of inflammatory and other immune markers relevant to CVD, a trend toward positive findings was observed. No detectable patterns were evident based on measure of adversity, biomarker, study design, or sample size.

CONCLUSIONS

Overall, our findings suggest this avenue of research is worth continued investigation. We offer recommendations for future research related to (1) study design and sample, (2) definition and measurement of adversity, (3) statistical analysis, and (4) outcomes that will help distinguish whether there are immunologic alterations related to adversity and subsequent CVD risk that can be reliably detected in childhood.