Childhood Socioeconomic Status and the Occurrence of Recent Negative Life Events as Predictors of Circulating and Stimulated Levels of Interleukin-6

Support-Giving Is Associated With Lower Systemic Inflammation

BACKGROUND

Support-giving has emerged as a health-relevant social behavior, such that giving more support is associated with better physical health. However, biological mechanisms by which support-giving and health are linked remain unclear. Whether support-giving uniquely relates to health relative to other psychosocial factors is also an open research question.

PURPOSE

Two studies test the hypothesis that support-giving is uniquely (over-and-above other psychosocial factors) related to lower systemic inflammation, a biological correlate of health.

METHODS

Cross-sectional associations of support-giving with markers of systemic inflammation (i.e., interleukin-6 [IL-6], C-reactive protein [CRP]) were examined in two independent samples of midlife adults (Study 1, n = 746; Study 2, n = 350).

RESULTS

Consistent with hypotheses, giving to more social targets (to family and friends, and also volunteering for various causes), but not receiving support from similar targets, was associated with lower IL-6. In conceptual replication and extension with a different measure of support-giving, higher frequency of support-giving behavior was associated with lower IL-6, even after adjusting for social network size and individual differences in social desirability. There were no associations between support-giving and CRP in either sample.

CONCLUSIONS

Future research needs to establish causality and directly test mechanistic pathways, but together, findings reaffirm the health-relevance of support-giving behavior and shed light on a promising biological mechanism by which such effects may occur.

Life stressors and immune aging: Protective effects of cognitive reappraisal

Stressful life events may accelerate aspects of immune aging, but habitual use of an adaptive emotion regulation strategy, cognitive reappraisal, may attenuate these effects. This study examined whether cognitive reappraisal moderates the associations between life stressor frequency and stressor desirability on aspects of immune aging, including late-differentiated CD8+ T and natural killer (NK) cells and inflammatory markers (IL-6, TNF-α, and CRP), both between and within people in a longitudinal sample of 149 older adults (mean age = 77.8, range: 64-92 years). Participants reported stressful life events, use of cognitive reappraisal, and provided blood semiannually for up to 5 years to assess aspects of immune aging. Multilevel models, adjusted for demographic and health covariates, tested the between-person (stable, trait-like differences) and within-person associations (dynamic fluctuations) among life stressors and reappraisal on immune aging. Experiencing more frequent life stressors than usual was associated with higher levels of late-differentiated NK cells within person, but this effect was accounted for by experiencing health-related stressors. Unexpectedly, experiencing more frequent and less desirable stressors were associated with lower average levels of TNF-α. As expected, reappraisal moderated the associations between life stressors and late-differentiated NK cells between people and IL-6 within people. Specifically, older adults who experienced less desirable stressors but also used more reappraisal had significantly lower proportions of late-differentiated NK cells on average and lower levels of IL-6 within-person. These results suggest cognitive reappraisal may play a protective role in attenuating the effects of stressful life events on aspects of innate immune aging in older adults.

Childhood trauma and LPS-stimulated inflammation in adulthood: Results from the Netherlands Study of Depression and Anxiety

BACKGROUND

Childhood trauma (CT) is robustly associated with psychiatric disorders including major depressive and anxiety disorders across the life span. The innate immune system may play a role in the relation between CT and stress-related psychopathology. However, whether CT influences the innate production capacity of cytokine levels following ex vivo stimulation by lipopolysaccharide (LPS), is currently unknown.

METHODS

Using data from the Netherlands Study of Depression and Anxiety (NESDA, n=1237), we examined whether CT (emotional neglect, emotional, physical, and sexual abuse before the age of 16), assessed by the Childhood Trauma Interview, was associated with levels in supernatants of interferon (IFN)γ, interleukin-2 (IL-2), IL-4, IL-6, IL-8, IL-10, IL-18, monocyte chemotactic protein-1 (MCP-1), macrophage inflammatory protein (MIP)-1α, MIP-1β, matrix metalloproteinase-2 (MMP-2), TNFα and TNFβ after ex vivo stimulation with LPS. Cytokines were analysed individually and cumulatively (overall inflammation index and number of cytokines in high-risk quartile (HRQ)) using linear regression analyses.

RESULTS

After adjustment for demographic, lifestyle, and health-related covariates, total CT severity was associated with the overall inflammation index (β = 0.085, P_FDR = 0.011), the number of cytokines in HRQ (β = 0.063, P_FDR = 0.036), and individual markers of IL-2 (β = 0.067, P_FDR = 0.036), IL-6 (β = 0.091 P_FDR = 0.011), IL-8 (β = 0.085 P_FDR = 0.011), IL-10 (β = 0.094 P_FDR = 0.011), MCP-1 (β = 0.081 P_FDR = 0.011), MIP-1α (β = 0.061 P_FDR = 0.047), MIP1-β (β = 0.077 P_FDR = 0.016), MMP-2 (β = 0.070 P_FDR = 0.027), and TNFβ (β = 0.078 P_FDR = 0.016). Associations were strongest for individuals with severe CT, reporting multiple types or higher frequencies of trauma. Half of the findings persisted after adjustment for psychiatric status. The findings were consistent across different CT types.

CONCLUSION

Childhood Trauma is associated with increased LPS-stimulated cytokine levels, with evidence for a dose-response relationship. Our results highlight a dysregulated innate immune system capacity in adults with CT, which could contribute to an increased vulnerability for psychopathology and somatic disorders across the lifespan.

Psychometric Evaluation of a Big Five Personality State Scale for Intensive Longitudinal Studies

Despite enthusiasm for using intensive longitudinal designs to measure day-to-day manifestations of personality underlying differences between people, the validity of personality state scales has yet to be established. In this study, we evaluated the psychometrics of 20-item and 10-item daily, Big Five personality state scales in three independent samples (N = 1,041). We used multilevel models to separately examine the validity of the scales for assessing personality variation at the between- and within-person levels. Results showed that a five-factor structure at both levels fits the data well, the scales had good convergent and discriminative associations with external variables, and personality states captured similar nomological nets as established global, self-report personality inventories. Limitations of the scales were identified (e.g., low reliability, low correlations with external criterion) that point to a need for more, systematic psychometric work. Our findings provide initial support for the use of personality state scales in intensive longitudinal designs to study between-person traits, within-person processes, and their interrelationship.

Early life adversity, inflammation, and immune function: An initial test of adaptive response models of immunological programming

Much research indicates that exposure to early life adversity (ELA) predicts chronic inflammatory activity, increasing one's risk of developing diseases of aging later in life. Despite its costs, researchers have proposed that chronic inflammation may be favored in this context because it would help promote immunological vigilance in environments with an elevated risk of infection and injury. Although intuitively appealing, the assumption that exaggerated inflammatory activity predicts favorable immunological outcomes among those exposed to ELA has not been tested. Here, we seek to address this gap, examining the links between exposure to ELA, inflammation, and immune function. Consistent with others' work, results revealed that those from low socioeconomic status (SES) childhood environments exhibited exaggerated unstimulated inflammatory activity relative to what was observed among those from higher SES childhood environments. Further, results revealed that - although levels of inflammation predicted the magnitude of immunological responses in those from higher SES backgrounds - for those who grew up in low SES environments, higher levels of inflammation were unrelated to the magnitude of immunological responses. Results suggest that exaggerated inflammatory activity in the context of ELA may not predict improved ability to manage acute immunological threats.

Adverse Childhood Experiences and Immune System Inflammation in Adults Residing on the Blackfeet Reservation: The Moderating Role of Sense of Belonging to the Community

BACKGROUND

Previous research documents an association between adverse childhood experiences (ACEs) and immune system inflammation. High chronic inflammation is believed to be one biological pathway through which childhood adversity may affect health into adulthood. The Blackfeet tribal community has high rates of childhood trauma and community members are disproportionately affected by inflammatory diseases.

PURPOSE

To investigate whether belonging to the tribal community may moderate the relationship between childhood trauma and immune system inflammation in the Blackfeet tribal community.

METHODS

In a sample of 90 adults residing on the Blackfeet reservation, we measured ACEs belonging to the tribal community and two markers of immune system inflammation, interleukin-6 (IL-6) and C-reactive protein (CRP).

RESULTS

We found that independent of age, gender, annual income, body mass index, and depressive symptoms, belonging to the tribal community and ACEs interacted to predict levels of both IL-6 and CRP (B= -.37, t[81] = -3.82, p < .001, R2 change = .07 and B = -.29, t[81] = -2.75, p = .01, R2 change = .08, respectively). The association between ACEs and markers of immune system inflammation was statistically significant for community members who reported low levels of belonging to the community.

CONCLUSIONS

The findings of this study have important implications for intervention research seeking to reduce risk for inflammatory diseases for at-risk populations. Fostering stronger connections to the larger tribal community may positively affect risk for inflammatory diseases. Future work should examine the behavioral and psychosocial pathways through which stronger connections to community may confer health benefits.

The prospective association between stressful life events and inflammation among adolescents with a history of early institutional rearing

Early adversity has been shown to sensitize individuals to the effects of later stress and enhance risk of psychopathology. Using a longitudinal randomized trial of foster care as an alternative to institutional care, we extend the stress sensitization hypothesis to examine whether early institutional rearing sensitizes individuals to stressful events in adolescence engendering chronic low-grade inflammation. At baseline, institutionalized children in Romania (ages 6-31 months) were randomly assigned to foster care or to remain in usual care within institutions. A group of never-institutionalized children was recruited as an in-country comparison sample. At ages 12 and 16, participants reported stressful events. At age 16, Interleukin-6 (IL-6) and C-reactive protein (CRP) were derived from blood spots. Among children assigned to care as usual, more stressful events at age 12, but not age 16, were associated with higher IL-6. In the same group, stressful events at age 16 were associated with higher CRP, though these effects attenuated after adjusting for covariates. These associations were not observed in the foster care or never-institutionalized groups. The findings suggest that heightened inflammation following stress exposure is one pathway through which early neglect could compromise physical health. In contrast, early family care might buffer against these risks.

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.

Testing Life Course Models Whereby Juvenile and Adult Adversity Combine to Influence Speed of Biological Aging

The present study extends prior research on the links between social adversity and aging by employing more comprehensive measures of adversity and a new gene expression index of aging. Hierarchical regression and 20 years of data from a sample of 381 black Americans were used to test models regarding the impact of social adversity on speed of aging. Consistent with the early life sensitivity model, early adversity continued to predict accelerated aging after controlling for adult adversity. Contrary to the pathway model, adult adversity was not related to aging following controls for early adversity. The cumulative stress model received partial support as high adversity during adulthood amplified the effect of early adversity on aging. Finally, consonant with the social change model, low adversity during adulthood buffered the effect of early adversity on aging. These findings held after controlling for health behaviors such as smoking, diet, and exercise.

Development of a Biomedical Program of Research in the Blackfeet Community: Challenges and Rewards

American Indian (AI) communities have high levels of stress and trauma and are disproportionately affected by numerous preventable diseases. Here, we describe an academic-community partnership based on a collaboration between Blackfeet Community College students and faculty in Psychology and Immunology at Montana State University (MSU). The collaboration, which has spanned over 5 years, was sparked by community interest in the relationship between stress and disease on the Blackfeet reservation. Specifically, community members wanted to understand how the experience of psychological stress and trauma may affect disease risk in their community and identify factors that promote resilience. In doing so, they hoped to identify pathways through which health could be improved for individual community members. Here, we discuss all stages of the collaborative process, including development of measures and methods and themes of research projects, challenges for community members and non-indigenous collaborators, future directions for research, and the lessons learned. Finally, we note the ways in which this partnership and experience has advanced the science of community engagement in tribal communities, with the hope that our experiences will positively affect future collaborations between indigenous community members and non-indigenous scientists.

Early life disadvantage, phenotypic programming, and health disparities

Much research finds that early life socioeconomic disadvantage predicts poorer health later in life, even among those whose conditions improve in adulthood. Although there are numerous factors that contribute to this association, recent research suggests that growing up in adverse socioecological environments may promote developmental patterns that facilitate pre-reproductive survival in harsh environments, but can also come at the cost of reduced longevity. Here, we review recent research demonstrating that early life exposure to low socioeconomic status can become embedded in the mechanisms that regulate (a) bodily inflammatory activity and (b) energy regulation in ways that contribute to poor health. This research offers new insights into ways that early life environments can get under one's skin to impact health and longevity.

Life stress, sense of belonging and sleep in American Indian college students

OBJECTIVES

In a sample of 90 American Indian (AI) college students (Age M(SD) = 21.47(3.02), 61.1% female), we investigated relationships between stress (perceived psychological stress and recent negative life events), sense of belonging to the university community and tribal community and sleep. We hypothesized that belonging and stress would associate with sleep.

METHODS

Participants wore a wrist accelerometer for 7 nights and answered surveys during an in-lab visit.

RESULTS

Sense of belonging to the university community associated with actigraphy-measured wake after sleep onset (WASO) (β = -.45, t(80) = -3.98, P < .001, R² change = 0.16), total sleep time (β = .30, t(80) = 2.49, P = .02, R² change = .07), sleep efficiency (β = .38, t(80) = 3.29, P = .001, R² change = .11) and subjective global sleep quality (β = -.44, t(75) = -4.82, P < .001, R² change = .15). Sense of belonging to the tribal community predicted average wake after sleep onset (β = -.29, t(80) = -2.64, P = .01, R² change = 0.08). Total negative life events in the preceding year associated with WASO (β = .24, t(80) = 2.19, P = .03, R² change = 0.05), while perceived psychological stress associated with actigraphy-measured sleep efficiency (β = -.28, t(80) = -2.25, P = .03, R² change = 0.06) and subjective global sleep quality (β = .40, t(78) = 3.94, P < .001, R² change = 0.16).

CONCLUSIONS

Stress and sense of belonging associate with sleep in AI college students. Future research should investigate whether life stress and belonging may affect health in this population by affecting patterns of sleep and investigate psychosocial resources that may moderate the relationships between stress, belonging and sleep.

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.

Youth Adversities Amplify the Association between Adult Stressors and Chronic Inflammation in a Domain Specific Manner: Nuancing the Early Life Sensitivity Model

There is strong evidence that chronic, systemic inflammation hastens onset of the diseases of old age that ultimately lead to death. Importantly, several studies suggest that childhood adversity predicts chronic inflammation. Unfortunately, this research has been plagued by retrospective reports of childhood adversity, an absence of controls for adult stressors, and a failure to investigate various competing models of the link between childhood adversity and chronic inflammation. The present study was designed to address these limitations. Using 18 years of data collected from 413 African Americans (58% female) included in the Family and Community Health Study, hierarchical regression analyses provided support for a nuanced early life sensitivity explanation for the link between early adversity and adult chronic inflammation. Controlling for health risk behaviors and adult SES, late childhood (ages 10-12) adversity amplified the association between adult adversity (age 29) and chronic inflammation. This interaction operated in a domain-specific fashion. Harsh parenting amplified the relation between intimate partner hostility and inflammation, whereas early discrimination amplified the relation between adult discrimination and inflammation. These findings suggest that individuals may be primed to respond physiologically to adverse adult circumstances that resemble those experienced earlier in life.

How adverse childhood experiences relate to single and multiple health risk behaviours in German public university students: a cross-sectional analysis

Background

Adverse childhood experiences (ACEs) have been shown to be linked to health risk behaviours (HRBs). This study aims to identify risk factors for ACEs and to examine the associations between ACEs and single and multiple HRBs in a sample of university students in Germany.

Methods

An online-based cross-sectional study was conducted among public university students (N = 1466). The widely applied ACE questionnaire was used and extended to operationalise 13 categories of childhood adversity. First, variables for each type of ACE and HRB were dichotomised (single ACEs and single HRBs), and then used for cumulative scores (multiple ACEs and multiple HRBs). Frequencies were assessed, and (multinomial) logistic regression analyses were performed.

Results

Prevalence rates of ACEs ranged from 3.9 to 34.0%, depending on the type of childhood adversity. Sociodemographic risk and protective factors for single/multiple ACEs varied strongly depending on the outcome. In particular, a high family socioeconomic status seemed to be a consistent protective factor for most ACEs. After adjusting for sociodemographic characteristics, both single and multiple HRBs were associated with single events of ACEs. Moreover, dose-response relationships between multiple ACEs and various single and multiple HRBs were found.

Conclusions

The study provides strong evidence that ACEs are associated with HRBs. The number of ACEs may play a role in single or multiple HRBs. Reducing the number of ACEs could thus decrease HRBs, which account for many of the leading causes of morbidity and death. The findings highlight the importance of trauma-informed health interventions designed to prevent the occurrence of ACEs, and build capacity among children and adults.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5926-3) contains supplementary material, which is available to authorized users.

Difference in proinflammatory cytokines produced by monocytes between patients with major depressive disorder and healthy controls

BACKGROUND

Immune activation and suppression in patients with major depressive disorders (MDD) have been both reported in different studies. We assume that these findings may indicate innate immunological tolerance in MDD, with subclinical elevated level of proinflammatory cytokines and the decrease in innate immune response while encountering pathogens.

METHODS

Peripheral monocytes of 50 untreated patients with MDD and 40 healthy controls were isolated and cultured, with or without 10 ng/ml lipopolysacchride (LPS) for 6 h (6 h, LPS+/-), and with LPS for 18 h (18, LPS+). The cell culture supernatants were collected to measure concentrations of tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), and interleukin 1 beta (IL-1β).

RESULTS

The baseline concentrations of IL-6 and IL-1β (6 h, LPS-) were significantly higher in the MDD group than those in the control group. There was no significant difference of TNF-α between the two groups. The fold changes of LPS-induced secretion of IL-6 and TNF-α from monocytes cultured for 6 and 18 h were all lower in the patient groups, and that was true for IL-1β as monocytes cultured for 18 h.

LIMITATIONS

Given the gap between the results of in vitro experiments and the actual response that happens in vivo when the immune system encounters pathogens from the external world, future research should include in vivo methods to test the results of the current study.

CONCLUSIONS

Patients with MDD may have subclinical inflammation during a depressive episode, and the reduced response to LPS in monocytes indicates innate immunological tolerance.

Family Socioeconomic Status, Cortisol, and Physical Health in Early Childhood: The Role of Advantageous Neighborhood Characteristics

OBJECTIVE

Children from families with lower socioeconomic status (SES) evidence greater physiological dysregulation and poorer health. Despite recognition of environmental contributors, little is known about the influence of neighborhood characteristics. The present study examined the moderating role of community-level risks and resources on the relation of family SES to children's daily cortisol output and physical health during the kindergarten year.

METHODS

In fall and spring of kindergarten, children's (N = 338) daily total cortisol was measured and parents and teachers rated children's global physical health. Parents reported family SES. Neighborhood characteristics were assessed using the Child Opportunity Index, a population-level tool that evaluates the quality of multiple domains of neighborhood attributes.

RESULTS

In fall, children reared in lower SES family environments had higher cortisol when residing in lower quality (lower opportunity) neighborhoods (b = -.097, p < .001), but there was no relation between family SES and children's cortisol in more advantaged (higher opportunity) neighborhoods (b = -.023, p = .36). Lower family SES was prospectively associated with poorer physical health in spring (controlling for fall health) only among children living in lower opportunity neighborhoods (b = -.250, p = .018) and was unrelated to physical health among children residing in higher opportunity neighborhoods (b = .042, p = .70).

CONCLUSIONS

Higher opportunity neighborhoods may protect against the negative consequences of low family SES on children's stress physiology and physical health. Public health interventions that bolster neighborhood opportunities may benefit young children reared in socioeconomically disadvantaged family environments.

Early life socioeconomic status associates with interleukin-6 responses to acute laboratory stress in adulthood

It is proposed that environmental exposures in early life influence immune programming. Specifically, socioeconomic disadvantage is thought to program an immune phenotype that is prone to inflammation and associated with increased risk for inflammatory disease later in life. Existing literature shows an inverse association of early childhood socioeconomic status (SES) with adult levels of systemic inflammation. Here, we extend that literature to examine whether early childhood SES also relates to the magnitude of inflammatory response to acute psychological stress in adulthood. Healthy volunteers (N = 110; 40-58 years; 59% female; 90% white) performed a laboratory stress protocol, with blood samples drawn at the end of a 30-min baseline, a 5-min speech task, and a 30-min recovery to assess interleukin (IL)-6 stress responses. An early childhood SES index was derived from reports of parental home and vehicle ownership, and number of bedrooms per child in the home across ages 1-2, 3-4, and 5-6. Regressions adjusted for current age, sex, race, and BMI showed that lower SES at age 1-2 was associated with larger IL-6 stress responses in adulthood (ΔR² = 0.05, β = -0.24, p = .03). This association was independent of adult SES and task-evoked affective responses. No association was found between SES at ages 3-4 or 5-6 and IL-6 responses. These results provide initial evidence for a link between disadvantage in the first 2 years of life and heightened inflammatory response to stress in adulthood; this link may contribute to the increased disease risk that accompanies being raised in disadvantaged socioeconomic circumstances.

Testing the biological embedding hypothesis: Is early life adversity associated with a later proinflammatory phenotype?

Accumulating evidence suggests that the experience of early life adversity is a risk factor for a range of poor outcomes across development, including poor physical health in adulthood. The biological embedding model of early adversity (Miller, Chen, & Parker, 2011) suggests that early adversity might become embedded within immune cells known as monocytes/macrophages, programming them to be overly aggressive to environmental stimuli and insensitive to inhibitory signals, creating a "proinflammatory phenotype" that increases vulnerability to chronic diseases across the life span. We tested this hypothesis in the present study. Adolescent girls (n = 147) had blood drawn every 6 months across a 2.5-year period. To assess inflammatory responses to challenge, their monocytes were stimulated in vitro with a bacterial product, and production of the cytokine interleukin-6 was quantified. Hydrocortisone was added to cultures to assess the cells' sensitivity to glucocorticoids' anti-inflammatory signal. Using cluster analyses, we found that early life adversity was associated with greater odds of displaying a proinflammatory phenotype characterized by relatively larger interleukin-6 responses and relatively less sensitivity to glucocorticoids. In contrast, ongoing social stress was not associated with increasing odds of being categorized in the proinflammatory cluster. These findings suggest that early life adversity increases the probability of developing a proinflammatory phenotype, which, if sustained, could forecast risk for health problems later in life.

Socioeconomic Disadvantage Moderates the Association between Peripheral Biomarkers and Childhood Psychopathology

BACKGROUND

Socioeconomic disadvantage (SED) has been consistently associated with early life mental health problems. SED has been shown to impact multiple biological systems, including the regulation of neurotrophic proteins, immune-inflammatory and oxidative stress markers, which, conversely, have been reported to be relevant to physiological and pathological neurodevelopment This study investigated the relationship between SED, different domains of psychopathology, serum levels of interleukin-6 (IL6), thiobarbituric acid-reactive substance (TBARS) and brain-derived neurotrophic factor (BDNF). We hypothesized that a composite of socioeconomic risk would be associated with psychopathology and altered levels of peripheral biomarkers. In addition, we hypothesized that SED would moderate the associations between mental health problems, IL6, TBARS and BDNF.

METHODS AND FINDINGS

Using a cross-sectional design, we measured the serum levels of IL6, TBARS and BDNF in 495 children aged 6 to 12. We also investigated socio-demographic characteristics and mental health problems using the Child Behaviour Checklist (CBCL) DSM-oriented scales. SED was evaluated using a cumulative risk model. Generalized linear models were used to assess associations between SED, biomarkers levels and psychopathology. SED was significantly associated with serum levels of IL6 (RR = 1.026, 95% CI 1.004; 1.049, p = 0.020) and TBARS (RR = 1.077, 95% CI 1.028; 1.127, p = 0.002). The association between SED and BDNF was not statistically significant (RR = 1.031, 95% CI 0.997; 1.066, p = 0.077). SED was also significantly associated with all CBCL DSM-oriented scales (all p < 0.05), whereas serum biomarkers (i.e. IL6, TBARS, BDNF) were associated with specific subscales. Moreover, the associations between serum biomarkers and domains of psychopathology were moderated by SED, with stronger correlations between mental health problems, IL6, TBARS, and BDNF being observed in children with high SED.

CONCLUSIONS

In children, SED is highly associated with mental health problems. Our findings suggest that this association may be moderated via effects on multiple interacting neurobiological systems.