Trajectories of relationship stress and inflammatory processes in adolescence

White blood cells in a healthy adolescent population according to social and health characteristics

BACKGROUND

The immune system constitutes a sensory system both for heritable and non-heritable factors. Among the latter, social and environmental determinants of health may influence and shape the immune system in early life. To study the relationship between leukocytes and determinants of health in adolescence, we assessed total and differential white blood cells (WBC) according to social and environmental determinants of health in a healthy adolescent population.

METHODS

As part of the population-based cohort Epidemiological Health Investigation of Teenagers in Porto (EPITeen), 1213 adolescents were evaluated at the age of 13. Total and differential WBC were evaluated through a venous blood sample using an automated blood counter (Sysmex®XE-5000, Hyogo, Japan). Sociodemographic, behavioral, and clinical data were collected through self-administered questionnaires.

RESULTS

Participants with better socioeconomic conditions (enrolled at private schools or higher parental education) had significantly lower total WBC levels, and the latter showed a lower percentage of neutrophils and higher percentage of lymphocytes. Those who practiced sports had significantly lower total WBC levels and neutrophil percentage, as well as a significantly higher percentage of eosinophils and lymphocytes. Adolescents with chronic disease, chronic medication, or allergic diseases had a significantly higher percentage of eosinophils and a lower percentage of monocytes. With increasing body mass index and systemic inflammation, we found a significant increase in total WBC levels.

CONCLUSION

WBC linked to different immune response patterns are associated with several social and environmental determinants of health in adolescence.

Community Violence Exposure and Stress Reactivity in African American and Non-Latino White Adolescents With Overweight/Obesity

Adolescents who experience community violence are exposed to toxic stressors at a critical period of growth and development. The purpose of this study was to examine the relationship between community violence exposure and stress reactivity in African American and non-Latino white adolescents with overweight/obesity. Fifty-one adolescents (47% female, 55% African American; aged 14-19) participated in this study. Community violence was assessed using the Survey of Children's Exposure to Community Violence. Stress reactivity was assessed via salivary cortisol and alpha-amylase area under the curve (AUC) during a Trier Social Stress Test (TSST). Race was a significant predictor of alpha-amylase reactivity (β = 10740±3665, p = 0.0006), with a higher alpha-amylase AUC observed in African American compared to non-Latino white adolescents. There was also a significant difference in the relationship between community violence exposure and alpha-amylase AUC by race (β = -3561±1226, p = 0.007). At similar increases in violence exposure, African Americans demonstrated a significant decline in alpha-amylase AUC while non-Latino whites demonstrated a significant increase in alpha-amylase AUC. Neither race nor violence exposure were significant predictors of cortisol AUC and there were no significant differences in the relationship between community violence exposure and cortisol AUC by race (all p's > .05). These preliminary findings suggest exposure to community violence may act to exacerbate autonomic dysregulation in African American adolescents with overweight/obesity. Longitudinal studies are needed to confirm the mechanisms by which community violence exposure differentially impacts stress responses by race.

Psychological Stress During Childhood and Adolescence and Its Association With Inflammation Across the Lifespan: A Critical Review and Meta-Analysis

Psychological stress during childhood and adolescence increases risk of health problems across the lifecourse, and inflammation is implicated as an underlying mechanism. To evaluate the viability of this hypothesis, we used meta-analysis to quantify the association between childhood/adolescent stress and inflammation over the lifecourse. Furthermore, we addressed three unresolved conceptual questions: (a) Does the strength of this association change over the lifecourse? (b) Are different types of childhood/adolescent stressors differentially associated with inflammation? (c) And which components of the inflammatory response are involved? A systematic search identified 187 articles reporting 922 associations. Meta-analyses were conducted using a three-level multilevel approach and controlled for study quality, conversion confidence, and whether effect sizes were unadjusted or adjusted (n = 662, 72%). Results indicated a small but reliable overall adjusted association ( r ^ = .04 ) . The magnitude of the association strengthened across the lifecourse-effect sizes were smallest in studies that measured inflammation in childhoodr ^ = .02 and became progressively larger in studies of adolescencer ^ = .04 and adulthoodr ^ = .05 , suggesting the impact of early stress strengthens with time. By contrast, effect sizes did not vary by adversity type (socioeconomic disadvantage, maltreatment, other interpersonal stressors, and cumulative exposure across stressors), or component of inflammation (circulating biomarkers of low-grade inflammation vs. cytokine responses to microbial stimuli). Implications and future directions are discussed.

Timing, duration, and differential susceptibility to early life adversities and cardiovascular disease risk across the lifespan: Implications for future research

Early life adversities (ELA), include experiences such as child maltreatment, household dysfunction, bullying, exposure to crime, discrimination, bias, and victimization, and are recognized as social determinants of cardiovascular disease (CVD). Strong evidence shows exposure to ELA directly impacts cardiometabolic risk in adulthood and emerging evidence suggests there may be continuity in ELA's prediction of cardiometabolic risk over the life course. Extant research has primarily relied on a cumulative risk framework to evaluate the relationship between ELA and CVD. In this framework, risk is considered a function of the number of risk factors or adversities that an individual was exposed to across developmental periods. The cumulative risk exposure approach treats developmental periods and types of risk as equivalent and interchangeable. Moreover, cumulative risk models do not lend themselves to investigating the chronicity of adverse exposures or consider individual variation in susceptibility, differential contexts, or adaptive resilience processes, which may modify the impact of ELA on CVD risk. To date, however, alternative models have received comparatively little consideration. Overall, this paper will highlight existing gaps and offer recommendations to address these gaps that would extend our knowledge of the relationship between ELA and CVD development. We focus specifically on the roles of: 1) susceptibility and resilience, 2) timing and developmental context; and 3) variation in risk exposure. We propose to expand current conceptual models to incorporate these factors to better guide research that examines ELA and CVD risk across the life course.

Annual Research Review: Social relationships and the immune system during development

A child's social relationships serve critical functions during development. The interface between a child's social world and their immune system, particularly innate immunity, which helped children survive in the face of infections, nutritional scarcity, and violence throughout human history, is the focus of this Annual Research Review. This article reviews the state of research on social relationships and innate immune inflammation during childhood. Warmth and rejection in childhood social relationships, as well as physical trauma and unpredictable social environments, were not consistently related to circulating inflammatory markers such as interleukin-6 and C-reactive protein during childhood. Instead, links between social environments and inflammation were observed in studies that focus on children with greater background risk factors, such as low family socioeconomic status, family history of mood disorders, or presence of chronic interpersonal stressors combined with acute episodic stressors. In addition, studies on worse childhood social environments and greater inflammation in adulthood were more consistent. Warmth and rejection in the social environment may be related to sensitivity of immune cells to the anti-inflammatory actions of glucocorticoids, though this is primarily observed in adolescent women at risk for depression. Additional mechanistic evidence suggests that greater warmth and less rejection are related to processes that regulate inflammation, including greater expression of the glucocorticoid receptor gene and lower expression of genes that are responsive to the pro-inflammatory transcription factor NF-kappa B. The article concludes by discussing implications of the interface between a child's social relationships and inflammation for mental health and other recent (on evolutionary timescales) health threats, as well as recommendations for future research, and recommendations for researchers interested in integrating inflammatory measures in developmental research.

Gender Minority Stress, Support, and Inflammation in Transgender and Gender-Nonconforming Youth

Purpose: Transgender and gender-nonconforming (TGNC) youth often report higher rates of chronic social stressors such as victimization, discrimination, and rejection. Some of these gender-based stressors may have long-range physical health consequences through inflammation pathways. This study evaluates the feasibility and acceptability of adding biological measures of inflammation to an ongoing prospective clinical study of TGNC youth (ages 9-20 years), initiating affirming medical therapy at a large, urban children's hospital (N=56). We also examine the relationship between gender-based sources of stress and support with inflammation. This is the first study to explore how gender identity, social stressors, and social supports may contribute to poorer health in TGNC youth through inflammation and immune dysregulation pathways. Methods: Between October 2016 and August 2018, the study team collected dried blood spot (DBS) samples and health measures during clinical visits. Participants also completed computer-assisted surveys assessing gender minority stress and support during these visits. We used regression analysis to evaluate differences in C-reactive protein (CRP) controlling for demographics, health, gender-based stress, and supports. Results: The results from this study indicate that adding DBS samples to assess inflammation was feasible and acceptable in a clinical sample of TGNC youth seeking affirming-medical interventions. We found an association between greater inflammation and the composite score for greater gender-based stressors and lower gender-based supports using the Gender Minority Stress and Resilience Tool (GMSR); however, we did not find statistically significant differences in CRP associated with any of the individual GMSR subscales assessing various types of gender-based supports or stressors. Conclusion: More research is necessary to evaluate how different sources of gender-based support and stress relate to inflammation with larger sample sizes.

Peripheral immune correlates of childhood and adolescent peer relationships: A systematic review

The objective of this review was to comprehensively evaluate the literature investigating associations between peripheral immune correlates and youth peer relationship dimensions. We aimed to identify potential aspects of peer relationships in childhood and adolescence that may be associated with immune profiles and to identify gaps in the field to provide suggestions for future research in this area. We conducted a systematic electronic search in health-related databases from the earliest records to December 2020. Search terms included domains related to youth, immune correlates, and peers. We summarized studies by the time between the peer measurement and the immune outcome. In the 17 included studies, associations between peer dimensions and immune outcomes varied substantially. Peer victimization in youth demonstrated the most consistent negative associations with immune health across development, including within 1 week of measurement, 1-3 years later, and 10 or more years later. This review indicated that that peer relationships during youth may have important associations with immune processes; however, there are several gaps in the literature regarding the operationalization of peer relationships, the timing of the immune measurement, and the type of immune outcome to be addressed by future research.

Discrimination and systemic inflammation: A critical review and synthesis

Exposure to discrimination or unfair treatment has emerged as an important risk factor for illness and disease that disproportionately affects racial and ethnic minorities. Discriminatory experiences may operate like other stressors in that they activate physiological responses that adversely affect the maintenance of homeostasis. Research suggests that inflammation plays a critical role in the pathophysiology of stress-related diseases. Recent findings on discrimination and inflammation are discussed. We highlight limitations in the current evidence and provide recommendations for future studies that seek to examine the association between discrimination and inflammation.

Future Directions in Peer Relations Research

Peer relationships among youth have been examined as predictors of mental health outcomes for at least fifty years, revealing dozens of discrete peer constructs that each are associated with adjustment in childhood, adolescence, and later in adulthood. Future research may benefit by examining a range of new outcomes and psychological processes that have been discussed recently in related literatures. This paper reviews recent research on interpersonal determinants of physical health outcomes, and opportunities for greater examination of 1) peer influence processes toward health risk behaviors; 2) neural correlates of peer adversity; 3) adverse peer experiences that may affect physiological markers of stress response; and 4) immune system markers of peer adversity. Additional future directions include the study of differences in the forms and functions of peer interactions within the digital age.

Differences in Febrile and Respiratory Illnesses in Minority Children: The Sociodemographic Context of Restrictive Parenting

OBJECTIVE

To examine the moderating role of restrictive parenting on the relation of socioeconomic status (SES) to febrile illnesses (FIs) and upper respiratory illnesses (URIs) among ethnic minority and non-minority children.

METHODS

Children from diverse ethnic backgrounds (Caucasian, African American, Asian, Latino, other, or multiethnic) were followed across the course of the kindergarten year. Parents reported on SES and parenting. A nurse completed 13 physical exams per child over the year to assess FIs and URIs.

RESULTS

During the school year, 28% of children (n = 199, 56% ethnic minority) exhibited one or more FIs (range, 0-6) and 90% exhibited one or more URIs (range, 0-10). No main or moderating effects of SES or restrictive parenting on FIs or URIs were found among Caucasian children; however, among ethnic minority children, the relation of SES to FIs was conditional upon restrictive parenting (β = .66; P = .02), as the fewest FIs were found for lower SES minority children whose parents reported more restrictive practices. Additionally, among minority children, more restrictive parenting was marginally associated with fewer URIs (β = -.21; P = .05).

CONCLUSIONS

Unexpectedly, among minority children the fewest illnesses occurred among lower SES children whose parents endorsed more restrictive parenting. This may be due to unique appraisals of this rearing style among minority children in lower SES environments and its potential to influence immune functioning. Results suggest variability in the effects of parenting on offspring health and support context-specific evaluations of parenting in efforts to ameliorate early health disparities.

The effects of childhood maltreatment on epigenetic regulation of stress-response associated genes: an intergenerational approach

While biological alterations associated with childhood maltreatment (CM) have been found in affected individuals, it remains unknown to what degree these alterations are biologically transmitted to the next generation. We investigated intergenerational effects of maternal CM on DNA methylation and gene expression in N = 113 mother-infant dyads shortly after parturition, additionally accounting for the role of the FKBP5 rs1360780 genotype. Using mass array spectrometry, we assessed the DNA methylation of selected stress-response-associated genes (FK506 binding protein 51 [FKBP5], glucocorticoid receptor [NR3C1], corticotropin-releasing hormone receptor 1 [CRHR1]) in isolated immune cells from maternal blood and neonatal umbilical cord blood. In mothers, CM was associated with decreased levels of DNA methylation of FKBP5 and CRHR1 and increased NR3C1 methylation, but not with changes in gene expression profiles. Rs1360780 moderated the FKBP5 epigenetic CM-associated regulation profiles in a gene × environment interaction. In newborns, we found no evidence for any intergenerational transmission of CM-related methylation profiles for any of the investigated epigenetic sites. These findings support the hypothesis of a long-lasting impact of CM on the biological epigenetic regulation of stress-response mediators and suggest for the first time that these specific epigenetic patterns might not be directly transmitted to the next generation.

The body remembers: Adolescent conflict struggles predict adult interleukin-6 levels

Struggles managing conflict and hostility in adolescent social relationships were examined as long-term predictors of immune-mediated inflammation in adulthood that has been linked to long-term health outcomes. Circulating levels of interleukin-6 (IL-6), a marker of immune system dysfunction when chronically elevated, were assessed at age 28 in a community sample of 127 individuals followed via multiple methods and reporters from ages 13 to 28. Adult serum IL-6 levels were predicted across periods as long as 15 years by adolescents' inability to defuse peer aggression and poor peer-rated conflict resolution skills, and by independently observed romantic partner hostility in late adolescence. Adult relationship difficulties also predicted higher IL-6 levels but did not mediate predictions from adolescent-era conflict struggles. Predictions were also not mediated by adult trait hostility or aggressive behavior, suggesting the unique role of struggles with conflict and hostility from others during adolescence. The implications for understanding the import of adolescent peer relationships for life span physical health outcomes are considered.

When inflammation and depression go together: The longitudinal effects of parent-child relationships

Parent-child relationships have long-term effects on health, particularly later inflammation and depression. We hypothesized that these effects would be mediated by later romantic partner relationships and elevated stressors in young adulthood, helping promote chronic, low grade, inflammation as well as depressive symptoms, and driving their covariation. It has been proposed recently that youth experiencing harsher parenting may also develop a stronger association between inflammation and depressive symptoms in adulthood and altered effects of stressors on outcomes. In the current investigation, we test these ideas using an 18-year longitudinal study of N = 413 African American youth that provides assessment of the parent-child relationship (at age 10), pro-inflammatory cytokine profile and depressive symptoms (at age 28), and potential mediators in early young adulthood (assessed at ages 21 and 24). As predicted, the effect of harsher parent-child relationships (age 10) on pro-inflammatory state and increased depressive symptoms at age 28 were fully mediated through young adult stress and romantic partner relationships. In addition, beyond these mediated effects, parent-child relationships at age 10 moderated the concurrent association between inflammation and depressive symptoms, as well as the prospective association between romantic partner relationships and inflammation, and resulted in substantially different patterns of indirect effects from young adult mediators to outcomes. The results support theorizing that the association of depression and inflammation in young adulthood is conditional on earlier parenting, and suggest incorporating this perspective into models predicting long-term health outcomes.

Rethinking IL-6 and CRP: Why they are more than inflammatory biomarkers, and why it matters

Behavioral researchers have increasingly become interested in the idea that chronic, low-grade inflammation is a pathway through which social and behavioral variables exert long-term effects on health. Much research in the area employs putative inflammatory biomarkers to infer an underlying state of inflammation. Interleukin 6 (IL-6) and C-reactive protein (CRP, whose production is stimulated by IL-6) are arguably the two most commonly assayed biomarkers. Yet, in contrast with near-universal assumptions in the field, discoveries in immunology over the past two decades show that neither IL-6 nor CRP are unambiguous inflammatory markers. IL-6 operates through two distinct signaling pathways, only one of which is specifically upregulated during inflammation; both pathways have a complex range of effects and influence multiple physiological processes even in absence of inflammation. Similarly, CRP has two isoforms, one of which is produced locally in inflamed or damaged tissues. The other isoform is routinely produced in absence of inflammation and may have net anti-inflammatory effects. We propose a functional framework to account for the multiple actions of IL-6 and CRP. Specifically, we argue that both molecules participate in somatic maintenance efforts; hence elevated levels indicate that an organism is investing in protection, preservation, and/or repair of somatic tissue. Depending on the state of the organism, maintenance may be channeled into resistance against pathogens (including inflammation), pathogen tolerance and harm reduction, or tissue repair. The findings and framework we present have a range of potential implications for the interpretation of empirical findings in this area-a point we illustrate with alternative interpretations of research on socioeconomic status, stress, and depression.

Developmental psychoneuroendocrine and psychoneuroimmune pathways from childhood adversity to disease

Childhood adversity has been repeatedly and robustly linked to physical and mental illness across the lifespan. Yet, the biological pathways through which this occurs remain unclear. Functioning of the inflammatory arm of the immune system and the hypothalamic-pituitary-adrenal (HPA)-axis are both hypothesized pathways through which childhood adversity leads to disease. This review provides a novel developmental framework for examining the role of adversity type and timing in inflammatory and HPA-axis functioning. In particular, we identify elements of childhood adversity that are salient to the developing organism: physical threat, disrupted caregiving, and unpredictable environmental conditions. We propose that existing, well-characterized animal models may be useful in differentiating the effects of these adversity elements and review both the animal and human literature that supports these ideas. To support these hypotheses, we also provide a detailed description of the development and structure of both the HPA-axis and the inflammatory arm of the immune system, as well as recent methodological advances in their measurement. Recommendations for future basic, developmental, translational, and clinical research are discussed.

From the Cradle to the Grave: The Effect of Adverse Caregiving Environments on Attachment and Relationships Throughout the Lifespan

This paper reviews research examining the effects of adverse early caregiving on relationships throughout the lifespan. Central attachment constructs are summarized and integrated into a review of research on the long-term effects of institutional rearing and child maltreatment. Findings are interpreted within the organizational perspective on development, which conceptualizes attachment as a stage-salient task of infancy that influences the reorganization of adaptive/maladaptive functioning around subsequent stage-salient tasks. Children who experience adverse early caregiving are more likely to exhibit aberrant attachment behaviors, deficits in social-emotional competencies, and persisting difficulties in social functioning and relationship outcomes. Disorganized attachment behavior stemming from adverse early caregiving has been a major focus of this work. Intervention efforts that target mental representations related to attachment relationships can facilitate improved social functioning. Clinical implications of this work are discussed.

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.

The impact of stress at different life stages on physical health and the buffering effects of maternal sensitivity

OBJECTIVE

Many studies indicate that early life stress leads to negative health outcomes in adulthood, and some suggest that high-quality parenting might buffer these effects. Most prior research, however, has relied on cross-sectional retrospective reports of stress and parenting. Our study tests how coder-rated stress and parenting quality assessed at different life stages predict adult health outcomes in a prospective, longitudinal study.

METHOD

Participants were 163 individuals in the Minnesota Longitudinal Study of Risk and Adaptation studied since birth. Physical health was assessed at age 32 with body mass index, self-reports of symptoms and illnesses experienced, and self-ratings of overall physical health. Stress was assessed by coder-rated interviews involving participants or their mothers at 16 time points partitioned into 5 life stages: early childhood, middle childhood, adolescence, young adulthood, and at age 32 (when health was assessed). Parenting quality was measured by coder ratings of each mother's provision of sensitive, responsive support at 7 time points between birth and age 13.

RESULTS

Early childhood, adolescent, and concurrent stress predicted adult health outcomes at age 32. Early childhood and adolescent stress, and adolescent and concurrent stress, both showed a "dual-risk" pattern, such that experiencing higher stress at both of these life stages predicted the worst health outcomes. Higher maternal sensitivity, however, buffered these deleterious effects.

CONCLUSION

Our prospective data reveal that early childhood and adolescence are important developmental periods during which stress is influential for adult physical health. However, parenting interventions that promote greater sensitivity may help children in high-stress environments avoid negative adult health outcomes. (PsycINFO Database Record

Effects of relationship functioning on the biological experience of stress and physical health

In this paper, we outline how relationship functioning affects the biological experience of stress and its consequences for physical health. Negative relationship perceptions and processes, such as attachment insecurity, hostility, and frequent conflict, tend to heighten stress responses and generate worse health over time, whereas positive relationship perceptions and processes, such as responsiveness, support, and intimacy, are generally associated with reduced or buffered stress responses and improved health (with some caveats). Future research should focus on the mechanisms behind these effects, the extent to which they can be changed or reversed, incorporating developmental perspectives, and effects of individual differences on these processes.