Stress and body mass index each contributes independently to tumor necrosis factor-alpha production in prepubescent Latino children

The Relationship between Psychological Stress and Anthropometric, Biological Outcomes: A Systematic Review

Background and Objectives: Challenges and threats to global security and the growing demands of today's society lead to significantly increased exposure to stress. Stress can negatively affect numerous physiological processes, including metabolic changes. An unhealthy lifestyle might intensify this disruption. The aim of the systematic review was to establish the effect of psychological stress on metabolic and anthropometric factors in healthy individuals. Materials and Methods: The study was conducted according to the PRISMA guidelines; and the risk of bias (ROB) assessment was based on the Newcastle-Ottawa Scale (NOS). A literature search of the MEDLINE/PubMed database was conducted using specific search terms. Results: We identified 32 articles meeting the inclusion criteria for the review with the different experimental designs and aims. Most of the papers were at high ROB. The included studies were conducted in groups of adults and children/teenagers. The most-often-applied tool to measure stress severity was the Perceived Stress Scale (PSS). Twenty-two studies analyzed the connection between stress and body composition, and bioimpedance analysis (BIA) was the most often used method. For biological parameters, the most frequently analyzed was cortisol (n = 9). The other examined factors included glucose, insulin, parameters related to food intake regulation, carbohydrates, lipid metabolism, inflammation, and oxidative stress. The included studies were incompliance in relation to the assessment method and type of assessed biological fluids. Conclusions: The vast majority of studies do not support the effect of chronic distress on anthropometric measurements and biological markers levels. However, many of them suggest adverse, synergistic effects of unhealthy lifestyle patterns and the stress on the examined variables. Further experiments should implement a similar and repeatable methodology.

Measuring Adolescent Chronic Stress: A Review of Established Biomarkers and Psychometric Instruments

Adolescence is a period of stressful physiological and psychosocial changes. Exposure to chronic stress can cause specific structural and functional changes in an organism, which can be appraised objectively. Some of these alterations are an expected reaction of the body in its attempt to adapt to a stressful situation, while others are signs of possible disease development. The aim of this review was to present the most widely used methods of stress evaluation in adolescence research. Primary biomarkers associated with different biological systems, such as the stress hormones glucocorticoids, and catecholamines, as well as the available methods of extraction and assessment of each biomarker, are presented. This work also includes secondary outcomes, which can also provide an estimation of an individual's stress level. Also, most available psychometric instruments of stress, constructed to address specifically this period of life, are presented and discussed. In addition, this paper addresses possible confounding factors that may affect stress measurements, which should be taken under consideration when conducting stress research. To objectively evaluate stress, it is of great importance for a researcher to be familiar with the condition under examination and its representative stress indices. Adequate evaluation of adolescents with the selection of proper psychometric tests and biological markers can help design targeted interventions aiming to prevent or reverse the effects of physical and mental stressors that occur during adolescence, effects that can be carried into adulthood with detrimental consequences.

Molecular aspects of COVID-19 and its relationship with obesity and physical activity: a narrative review

BACKGROUND

Severe acute respiratory syndrome coronavirus 2 has several mechanisms of action related to inflammatory responses, especially in individuals diagnosed with obesity. This hyperinflammatory clinical profile resulting from the association between obesity and coronavirus disease 2019 (COVID-19) may be attenuated by regular physical activity.

OBJECTIVE

The aim of this study was to review the evidence on the consequences of physical inactivity and physical activity on COVID-19 in patients with obesity.

DESIGN AND SETTING

Narrative review at the Bahiana School of Medicine and Public Health in Salvador, Brazil.

METHODS

We searched evidence on the association of COVID-19 with physical activity and obesity using the following keywords: "covid-19," "physical activity," and "obesity". The databases used were MEDLINE (PubMed), ScienceDirect, and Virtual Health Library. Studies published from 2019 to 2021 and available in Portuguese, English, and Spanish were included. The final search was conducted on September 26, 2021.

RESULTS

We identified 661 studies in the database, among which 71 were considered for inclusion in the narrative review of the molecular aspects of COVID-19 and its relationship with physical activity and obesity.

CONCLUSION

This literature review enabled the perception of the relationship between the molecular mechanisms of COVID-19 and obesity. Regular physical activity had various benefits for the inflammatory condition of the studied population, highlighting moderate-intensity.

Cytokine alterations in pediatric internalizing disorders: Systematic review and exploratory multi-variate meta-analysis

Pediatric internalizing disorders are prevalent and characterized by a maladaptive cognitive, emotional response to a perceived stressor. The hypothesized effect of this response is observable changes in behavior mediated by homeostatic inflammatory cytokines. The aim of this study was to synthesize the literature and analyze the effect of cytokines on pediatric internalizing disorders. Influential moderating variables, including mean body mass index, fasting status at blood collection, participant sex, cytokine type, mean age, percentage of sample medicated, and diagnosis, were also assessed. A systematic literature search was performed in electronic databases (Medline, PubMed, and PsycINFO) from January 1, 1980 to June 15, 2022. Case-control studies of pediatric internalizing disorders, specifically anxiety and depression, were reviewed for their association with peripheral cytokine levels. Meta-analyses were performed using a random effects multi-variate model and effect sizes were calculated using Hedge's g for IL-2, CRP, IL-6, TNF-α, IL-1β, IFN-γ, and IL-10. Thirty-three studies were reviewed and 28 studies were included in the meta-analysis (n = 1322 cases and n = 3617 controls). Peripheral cytokine levels were elevated in pediatric internalizing disorders compared to controls (Hedge's g = 0.19, p < 0.001). In the moderator analyses, depression diagnosis (Hedge's g = 0.18, p = 0.009) and non-fasting blood collection (Hedge's g = 0.20, p = 0.006) were significant. The meta-analytic findings are limited by methodological variation between studies, high heterogeneity, and low statistical power. Despite this, the findings suggest that elevated peripheral cytokine levels may play a role in the etiology and/or symptom maintenance of pediatric internalizing disorders.

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.

Childhood maltreatment correlates with higher concentration of transforming growth factor beta (TGF-β) in adult patients with major depressive disorder

Transforming growth factor beta (TGF-β), which has a role as a regulatory cytokine, has not been widely investigated in patients with major depressive disorder (MDD) who experienced childhood trauma. The aim of our study was to investigate the differences in circulating TGF-β levels between the patients with major depressive disorder (MDD) with and without child maltreatment (CM) history, and to compare them to the corresponding control subjects' groups (with or without CM). Blood samples were obtained from 55 patients, fulfilling DSM-IV-R criteria for a current MDD episode without psychotic symptoms, and 45 healthy controls, matched for age and gender. Participants were administered the Childhood Trauma Questionnaire (CTQ). Serum TGF-β concentration was determined by enzyme-linked immunosorbent assay. The concentration of TGF-β was significantly higher in patients with MDD with CM history, compared to MDD patients with no CM, as well as both control groups. Furthermore, we have shown that the combined effect of CM history and MDD affected TGF-β levels in adulthood, which was not observed in the control group with CM. These results indicate that MDD patients with the experience of CM have altered immune-regulatory response, and they may constitute a specific subtype within this heterogenic disorder (ecophenotype).

Integrating anthropometric and cardiometabolic health methods in stress, early experiences, and development (SEED) science

Within Stress, Early Experiences, and Development (SEED) science, there is a growing body of research demonstrating complex associations not only between stress, development, and psychopathology, but also with chronic disease risk factors. We argue that it is important for SEED researchers to consider including child anthropometric and physical health measures to more comprehensively capture processes of risk and resilience. Broader adoption of harmonized anthropometry and health measures in SEED research will facilitate collaborations, yielding larger datasets for research in high-risk populations, and greater opportunity to replicate existing findings. In this review, we identify optimal anthropometric and cardiometabolic health measurement methods used from infancy through adolescence, including those that are low-burden and inexpensive. Methods covered include: waist, hip, and head circumference, height, length, weight, pubertal development, body composition, blood pressure, arterial stiffness, carotid intima media thickness, and serum measures of cardiometabolic risk and inflammation. We provide resources for SEED researchers to integrate these methods into projects or to better understand these methods when reading the literature as well as where to find collaborators for more in-depth studies incorporating these measures. With broader integration of psychological and physical health measures in SEED research, we can better inform theory and interventions to promote health and resilience in individuals who have experienced early stress.

Adverse childhood experiences and biomarkers of inflammation in a diverse cohort of early school-aged children

Objective

The objective of this study was to evaluate the relationship between ACEs and inflammatory profiles (i.e., pro- and anti-) in early childhood and to examine whether patterns differ for racial/ethnic subgroups.

Study design

Using longitudinal data from the Multidimensional Assessment of Preschoolers Study (MAPS) (N = 122), we examined the relationship between adverse childhood experiences (ACEs) beginning at birth, C -reactive protein (CRP), and both pro-inflammatory (i.e., IL-1 β, IL-6, TNF, and CRP) and anti-inflammatory (i.e. IL-4 and IL-10) biomarkers during early school age (ages 6-8 years).

Results

No children in the sample were reported to have experienced 0 ACES, 7% had 1 ACE, 51% had 2-3 ACEs, and 42% had 4 or more ACEs accumulated by the early school-age wave (ESA). There were no significant associations between cumulative ACEs and inflammatory markers. However, parental substance abuse, a specific ACE, was positively correlated with a pro-inflammatory profile at early school age (r = 0.18, p<.05). Specifically, substance abuse as an ACE was associated with higher levels of pro-inflammatory markers such as IL-1 β and IL-6. Additionally, Hispanics with ACEs had higher levels of CRP than Black and white individuals.

Conclusions

Children with histories of ACEs, especially those with parental substance abuse, may have higher levels of inflammation. Better understanding the role of inflammation in the development of chronic diseases for individuals with ACEs may allow earlier identification and prevention of disease during childhood for those at the highest risk.

The Consequences of Foster Care Versus Institutional Care in Early Childhood on Adolescent Cardiometabolic and Immune Markers: Results From a Randomized Controlled Trial

OBJECTIVE

Children exposed to institutional rearing often exhibit problems across a broad array of developmental domains. We compared the consequences of long-term, high-quality foster care versus standard institution-based care, which began in early childhood on cardiometabolic and immune markers assessed at the time of adolescence.

METHODS

The Bucharest Early Intervention Project is a longitudinal investigation of children institutionalized during early childhood (ages 6 to 30 months at baseline) who were subsequently randomized to either high-quality foster care or continued institutional care. At the age of 16 years, 127 respondents participated in a biomarker collection protocol, including 44 institutionalized children randomly assigned to receive care as usual, 41 institutionalized children randomized to be removed from institutional care and placed in high-quality foster care in infancy, and a control group of 42 demographically matched children raised in biological families. Outcomes included body mass index (BMI), systolic and diastolic blood pressure, C-reactive protein, interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor α, glycosylated hemoglobin A1c, and Epstein-Barr virus antibody titers.

RESULTS

Early institutional rearing was not associated with differences in cardiometabolic or immune markers. Randomization to foster care and age of placement into foster care were also unrelated to these markers, with the exception of BMI z-score, where children assigned to care as usual had lower BMI z-scores relative to children assigned to foster care (-0.23 versus 0.08, p = .06), and older age at placement was associated with lower BMI (β = -0.07, p = .03).

CONCLUSIONS

The impact of institutional rearing on measures of cardiometabolic health and immune system functioning is either absent or not evident until later in development. These findings provide new insights into the biological embedding of adversity and how it varies developmentally and across regulatory systems and adversity type.

CLINICAL TRIAL REGISTRATION

NCT00747396.

Psychosocial stress and C-reactive protein from mid-adolescence to young adulthood

OBJECTIVE

Cardiovascular disease (CVD) is one of the most prevalent chronic conditions and leading causes of death. Although CVD clinically manifests in adulthood, underlying processes of CVD begin in the earlier decades of life. Inflammation has been shown to play a key role, but relatively little is understood about how inflammation changes over time among young individuals. Additionally, how psychosocial factors like stress may influence changes in inflammation earlier in the lifespan is not entirely clear. Thus, the current three-wave longitudinal study examined the developmental trajectory of CRP, a marker of systemic inflammation, over a 4-year period from mid-adolescence into young adulthood. Between- and within-person differences in stress in relation to changes in CRP were also examined.

METHOD

A sample of 350 individuals was recruited during mid-adolescence and participated in 1 to 3 assessments, 2 years apart. At each assessment, participants provided dried blood spots for the assessment of CRP and reported on recent major life events, perceived stress, and daily interpersonal stress.

RESULTS

Multilevel modeling indicated that CRP increased with age, and within-person increases in perceived stress, but not life events or daily stress, were associated with higher CRP. Between-person differences in average levels of stress from mid-adolescence into young adulthood were not associated with changes in CRP.

CONCLUSION

These findings suggest that the link between stress and systemic inflammation between mid-adolescence and young adulthood may be most affected by contemporaneous experiences of perceived stress. There was little evidence to suggest that CRP trajectories varied by between-person differences in overall average levels of perceived stress, life events, and daily stress. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Early life stress, air pollution, inflammation, and disease: An integrative review and immunologic model of social-environmental adversity and lifespan health

Socially disadvantaged individuals are at greater risk for simultaneously being exposed to adverse social and environmental conditions. Although the mechanisms underlying joint effects remain unclear, one hypothesis is that toxic social and environmental exposures have synergistic effects on inflammatory processes that underlie the development of chronic diseases, including cardiovascular disease, diabetes, depression, and certain types of cancer. In the present review, we examine how exposure to two risk factors that commonly occur with social disadvantage-early life stress and air pollution-affect health. Specifically, we identify neuroimmunologic pathways that could link early life stress, inflammation, air pollution, and poor health, and use this information to propose an integrated, multi-level model that describes how these factors may interact and cause health disparity across individuals based on social disadvantage. This model highlights the importance of interdisciplinary research considering multiple exposures across domains and the potential for synergistic, cross-domain effects on health, and may help identify factors that could potentially be targeted to reduce disease risk and improve lifespan health.

Chronic Stress in Children and Adolescents: A Review of Biomarkers for Use in Pediatric Research

PROBLEM

Incorporating biomarkers of chronic stress into pediatric research studies may help to explicate the links between exposure to adversity and lifelong health, but there are currently very few parameters to guide nurse researchers in choosing appropriate biomarkers of chronic stress for use in research with children and adolescents.

METHODS

Biomarkers of chronic stress are described, including primary mediators (glucocorticoids, catecholamines, and cytokines) and secondary outcomes (neurologic, immune, metabolic, cardiovascular, respiratory, and anthropometric) of the chronic stress response.

RESULTS

Evidence of the use of each biomarker in pediatric research studies is reviewed. Recommendations for pediatric researchers, including selection of appropriate biomarkers, measurement considerations, potential moderators, and future directions for research, are presented.

DISCUSSION

A wide range of biomarkers is available for use in research studies with children. While primary mediators of chronic stress have been frequently measured in studies of children, measurement of secondary outcomes, particularly immune and metabolic biomarkers, has been limited. With thoughtful and theoretically based approaches to selection and measurement, these biomarkers present an important opportunity to further explore the physiologic pathways linking exposure to chronic stress with later health and disease.

CONCLUSION

The incorporation of chronic stress biomarkers into pediatric research studies may provide valuable insight into the mechanisms through which stressful environments "get under the skin" and ultimately inform efforts to promote health and reduce inequities among children exposed to adversity.

Accumulation of adverse childhood events and overweight in children: A systematic review and meta-analysis

OBJECTIVE

This study systematically summarizes the evidence of all observational studies investigating the relation between accumulation of adverse life events and measures of overweight in children <18 years.

METHODS

MEDLINE, Embase, PsycINFO, and CINAHL were systematically searched (last search date 18 February 2015). The Newcastle-Ottawa Scale was used for methodological quality assessment. Study estimates were pooled using a random-effects model, and sources of heterogeneity were explored (PROSPERO registration number CRD42014014927).

RESULTS

Eighteen articles were included, containing five longitudinal (n = 6,361) and fourteen cross-sectional and case-control study results (n = 52,318). The pooled estimate of the longitudinal studies showed that accumulation of adverse life events is positively related to childhood overweight measures (OR [95% CI] = 1.12 [1.01-1.25]). Cross-sectional and case-control study results were heterogeneous. Subgroup analyses showed that cross-sectional and case-control studies using a continuous adverse events measure, studies using a continuous overweight measure, and studies in children >6-12 years also generated positive pooled estimates, while the pooled estimate of studies assessing recent adverse events (past 2 years) was indicative of no relation with overweight.

CONCLUSIONS

Accumulation of adverse life events and childhood overweight measures are positively associated. However, increases in overweight measures in response to adverse childhood events do not seem to occur instantaneously.

The Longitudinal Relation Between Accumulation of Adverse Life Events and Body Mass Index From Early Adolescence to Young Adulthood

OBJECTIVE

Stressors, such as adverse life events, can cause weight changes through behavioral and biological mechanisms. Whether the accumulation of adverse life events is related to body mass index (BMI) across multiple time points from early adolescence to young adulthood has not been investigated to date.

METHODS

Data are from 2188 children participating at T1 (10-12 years), T3 (14-18 years), and/or T5 (21-23 years) of the prospective Tracking Adolescents' Individual Lives Survey cohort study. Adverse events before T1 and between T1, T3, and T5 were measured with a parent interview at T1 and a semistructured interview (Event History Calendar) with the adolescent at T3 and T5. An adverse events score was calculated per wave. Body mass index z-scores were determined from objectively measured height and weight using the LMS (skewness, median, and coefficient of variation) reference curves of the International Obesity Task Force for children 18 years or younger. Data were analyzed using a modified bivariate autoregressive cross-lagged structural equation model.

RESULTS

Adverse events before T1 and between T3 and T5 were related to BMI at T5 (β = 0.06, p = .001 and β = -0.04, p = .04, respectively). Specifically, health events before T1 were associated with a higher BMI at T5, and events related to relationships and victimhood events between T3 and T5 were associated with a lower BMI at T5.

CONCLUSIONS

Adverse relationship and victimhood events in their recent past were related to a lower BMI in young adults, whereas adverse health events during childhood were related to a higher BMI in young adults. No relationships were found between adverse life events with BMI in children and adolescents.

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.

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.

Trajectories of relationship stress and inflammatory processes in adolescence

Researchers have identified cross-sectional links between interpersonal stress and inflammation. Little is known, however, about how these dynamics unfold over time, what underlying immune pathways might exist, or whether moderators such as race could alter the strength of the connection between interpersonal stress and inflammatory processes. We examined whether adolescent girls whose relationship trajectories were characterized by chronic stress would exhibit a proinflammatory phenotype marked by systemic inflammation, heightened cytokine responses to bacterial challenges, and resistance to the anti-inflammatory properties of cortisol. Significant Stress × Race interactions revealed that family stress trajectories predicted glucocorticoid sensitivity and peer stress trajectories predicted cytokine production for White but not Asian girls. Relationship stress trajectories were not associated with systemic inflammation, however. These findings suggest that particular subgroups of adolescent girls who face chronic and elevated stress in their close relationships may be at risk for disruptions to the immune system.

Proinflammatory and anti-inflammatory cytokine profile in pediatric patients with irritable bowel syndrome

BACKGROUND AND OBJECTIVES

There is evidence that patients with irritable bowel syndrome (IBS) have a low degree of inflammation in the intestinal mucosa. The aim of the study was to evaluate the profile of pro- and anti-inflammatory cytokines in plasma in Mexican pediatric patients with IBS.

PATIENTS AND METHODS

Fifteen patients with IBS according to Rome III criteria for childhood and 15 healthy children, matched by age and sex, were included in the study. Plasma levels of tumoral necrosis factor alpha (TNF-α), interleukins 10 and 12 (IL-10, IL-12) and transforming growth factor beta (TGF-β) were quantified and compared between groups.

RESULTS

Plasma levels of IL-10 were lower in patients with IBS (86.07+21.3 pg/mL vs. 118.71+58.62 pg/mL: P=.045) and IL-12 levels were higher in patients with IBS compared to the control group of healthy children (1,204.2±585.9 pg/mL vs. 655.04±557.80 pg/mL; P=.011). The IL-10/IL-12 index was lower in patients with IBS (0.097±0.07 vs. 0.295±0.336; P=.025). Plasma concentration of TGF-β was higher in patients with IBS (545.67±337.69 pg/mL vs. 208.48±142.21 pg/mL; P=.001). There was no difference in plasma levels of TNF-α between groups.

CONCLUSIONS

This study suggests that children with IBS have a state of altered immune regulation. This is consistent with the theory of low-grade inflammatory state in these patients. Further studies are needed to elucidate the role played by these cytokines, specifically TGF-β in the pathogenesis of IBS.

Research review: the role of cytokines in depression in adolescents: a systematic review

BACKGROUND

While cytokines have been implicated in the pathophysiology of depression in adults, the potential role in younger age groups such as adolescents is less clear. This article therefore reviews the literature (a) to explore the relationship between cytokines and depression in adolescents, and (b) to examine how cytokines may be related to adolescent depression in the context of other neurobiological theories of depression.

METHOD

A systematic review of the scientific literature on the subject was conducted in February 2013, searching the Web of Knowledge, PubMed (Medline), PsycInfo and Cochrane electronic databases.

RESULTS

Eighteen studies were identified measuring both depression or depressive symptoms and cytokines or immune markers in adolescents. Adolescents with depression show age-specific characteristics of the immune and inflammatory system, specifically in NK cell activity and in pro-inflammatory cytokines (such as IL-1β and TNF-α). In addition, the role of cytokines in adolescent depression is influenced by neurodevelopment, hormonal changes, stress and trauma.

CONCLUSIONS

There may be differences in the neurobiology of adolescent major depressive disorder (MDD) compared with adult MDD. Increased understanding of the role of cytokines in adolescent MDD may lead to improved outcomes in the treatment of adolescent depression.

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.

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.