Publications | Schreier Lab

Publications — No Comments
15
Sep 15

Mercury and psychosocial stress exposure interact to predict maternal ambulatory cortisol during pregnancy

Background: Disrupted maternal prenatal cortisol production influences offspring development. Factors influencing the hypothalamic-pituitary-adrenal axis include social (e.g., stressful life events) and physical/chemical (e.g., toxic metals) pollutants. Mercury (Hg) is a common contaminant of fish and exposure is widespread in the US. No prior study has examined the joint associations of stress and mercury with maternal cortisol profiles in pregnancy. Objectives: To investigate potential synergistic influences of prenatal stress and Hg exposures on diurnal cortisol in pregnant women. Methods: Analyses included 732 women (aged 27.4 ± 5.6 years) from a Mexico City pregnancy cohort. Participants collected saliva samples on two consecutive days (mean 19.52 ± 3.00 weeks gestation) and reported life stressors over the past 6 months. Hg was assessed in toe nail clippings collected during pregnancy. Results: There were no main effects of Hg or psychosocial stress exposure on diurnal cortisol (ps > .20) but strong evidence of interaction effects on cortisol slope (interaction B = .006, SE = .003, p = .034) and cortisol at times 1 and 2 (interaction B = -.071, SE = .028, p = .013; B = -.078, SE = .032, p = .014). Women above the median for Hg and psychosocial stress exposure experienced a blunted morning cortisol response compared to women exposed to higher stress but lower Hg levels. Conclusions: Social and physical environmental factors interact to alter aspects of maternal diurnal cortisol during pregnancy. Research focusing solely on either domain may miss synergistic influences with potentially important consequences to the offspring.

CITATION: Schreier, H. M. C., Hsu, H.-H., Amarasiriwardena, C., Coull, B. A., Schnaas, L., Tellez-Rojo, M. M., Tamayo y Ortiz, M., Wright, R. J., & Wright, R. O. (2015). Mercury and psychosocial stress exposure interact to predict maternal ambulatory cortisol during pregnancy. Environmental Health, 14(28).

Childhood abuse is associated with increased hair cortisol levels among urban pregnant women

Background Hypothalamic–pituitary–adrenal (HPA) axis activity is known to be altered following events such as childhood abuse. However, despite potential adverse consequences for the offspring of women who have experienced abuse, very little is known about altered HPA axis activity during pregnancy. Methods During pregnancy, 180 women from diverse racial/ethnic backgrounds reported on their exposure to emotional, physical and/or sexual abuse before the age of 11, and general post-traumatic stress symptoms (ie, not limited to childhood years or abuse experiences). Around delivery, they provided hair samples for the assessment of cortisol levels during pregnancy. Hair cortisol was assessed for each pregnancy trimester. The effect of childhood abuse on hair cortisol was assessed using mixed-effects analyses of covariance models allowing for within-subject correlated observations, and were first performed in the entire sample and subsequently stratified by race/ethnicity. Results Controlling for post-traumatic stress symptoms, hair cortisol levels varied by history of child abuse, F(2,166)=3.66, p=0.028. Childhood physical and/or sexual abuse was associated with greater hair cortisol levels, t(166)=2.65, p=0.009, compared with no history of abuse. Because childhood rates of abuse and hair cortisol levels varied by race/ethnicity, analyses were stratified by race/ethnicity. The associations between history of abuse and cortisol levels were only significant among black women, F(2,23)=5.37, p=0.012. Conclusions Childhood abuse, especially physical and/ or sexual abuse, is associated with differences in cortisol production during pregnancy, particularly among black women. Future research should investigate how these differences impact physical and mental health outcomes among offspring of affected women.

CITATION: Schreier, H. M. C., Bosquet Enlow, M., Ritz, T., Gennings, C., & Wright, R. J. (2015). Childhood abuse is associated with increased hair cortisol levels among urban pregnant women. Journal of Epidemiology and Community Health, 69(12), 1169-1174.

Adolescents / Family Influences / Inflammation / Publications / Socioeconomic Status — 1 Comment
09
Sep 15

Family chaos and adolescent inflammatory profiles: the moderating role of socioeconomic status

Objective: To test whether family chaos influences adolescents’ inflammatory profiles and whether adolescents from low socio- economic status (SES) environments are at higher risk for experiencing adverse inflammatory profiles from living in chaotic family environments. Methods: A total of 244 families with an adolescent aged 13 to 16 years participated. Parents completed measures of family SES and family chaos. Both systemic inflammation and stimulated proinflammatory cytokine production in response to bacterial challenge were assessed in adolescents. Results: Our results suggest that SES moderates the detrimental effect of family chaos on systemic inflammation and interleukin-6 (B = -0.010, standard error [SE] = 0.004, p = .026), but not C-reactive protein (B = 0.009, SE = 0.006, p = .11), and on stimulated proinflammatory cytokine production (B = -0.098, SE = 0.044, p = .026) in adolescents, such that a chaotic family environment is positively associated with greater systemic inflammation and greater stimulated proinflammatory cytokine production in adolescents as family SES declines. Conclusions: These findings indicate that living in chaotic family environments places youth who may be vulnerable based on socioeconomic factors at a potentially higher risk for inflammation-related diseases. Key words: inflammation, family chaos, adolescents, socioeconomic status.

CITATION: Schreier, H. M. C., Roy, L. B., Frimer, L., & Chen, E. (2014). Family chaos and adolescent inflammatory profiles: the moderating role of socioeconomic status. Psychosomatic Medicine, 76(6), 460-467.

Family Influences / Publications — No Comments
09
Sep 15

Maternal sensitivity and infant autonomic and endocrine stress response

Background: Early environmental exposures may help shape the development of the autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal (HPA) axis, influencing vulnerability for health problems across the lifespan. Little is known about the role of maternal sensitivity in influencing the development of the ANS in early life. Aims: To examine associations among maternal sensitivity and infant behavioral distress and ANS and HPA axis reactivity to the Repeated Still-Face Paradigm (SFP-R), a dyadic stress task. Study Design: Observational repeated measures study. Subjects: Thirty-five urban, sociodemographically diverse mothers and their 6-month-old infants. Outcome Measures: Changes in infant affective distress, heart rate, respiratory sinus arrhythmia (RSA), and T-wave amplitude (TWA) across episodes of the SFP-R were assessed. A measure of cortisol output (area under the curve) in the hour following cessation of the SFP-R was also obtained. Results: Greater maternal insensitivity was associated with greater infant sympathetic activation (TWA) during periods of stress and tended to be associated with greater cortisol output following the SFP-R. There was also evidence for greater affective distress and less parasympathetic activation (RSA) during the SFP-R among infants of predominantly insensitive mothers. Conslusions: Caregiving quality in early life may influence the responsiveness of the sympathetic and parasympathetic branches of the ANS as well as the HPA axis. Consideration of the ANS and HPA axis systems together provides a fuller representation of adaptive versus maladaptive stress responses. The findings highlight the importance of supporting high quality caregiving in the early years of life, which is likely to promote later health.

CITATION: Bosquet Enlow, M., King, L., Schreier, H. M. C., Howard, J. M., Rosenfield, D., Ritz, T., & Wright, R. J. (2014). Maternal sensitivity and infant autonomic and endocrine stress response. Early Human Development, 90(7), 377-385.

Chronic Illnesses / Publications / Socioeconomic Status — No Comments
09
Sep 15

Socioeconomic status and the health of youth: A multi-level, multi-domain approach to conceptualizing pathways

Previous research has clearly established associations between low socioeconomic status (SES) and poor youth physical health outcomes. This article provides an overview of the main pathways through which low SES environments come to influence youth health. We focus on 2 prevalent chronic health problems in youth today, asthma and obesity. We review and propose a model that encompasses (a) multiple levels of influence, including the neighborhood, family and person level; (b) both social and physical domains in the environment; and finally (c) dynamic relationships between these factors. A synthesis of existing research and our proposed model draw attention to the notion of adverse physical and social exposures in youth’s neighborhood environments altering family characteristics and youth psychosocial and behavioral profiles, thereby increasing youth’s risk for health problems. We also note the importance of acknowledging reciprocal influences across levels and domains (e.g., between family and child) that create self-perpetuating patterns of influence that further accentuate the impact of these factors on youth health. Finally, we document that factors across levels can interact (e.g., environmental pollution levels with child stress) to create unique, synergistic effects on youth health. Our model stresses the importance of evaluating influences on youth’s physical health not in isolation but in the context of the broader social and physical environments in which youth live. Understanding the complex relationships between the factors that link low SES to youth’s long-term health trajectories is necessary for the creation and implementation of successful interventions and policies to ultimately reduce health disparities.

CITATION: Schreier, H. M. C. & Chen, E. (2013). Socioeconomic status and the health of youth: A multi-level, multi-domain approach to conceptualizing pathways. Psychological Bulletin, 139(3), 606-654.

Adolescents / Inflammation / Intervention / Publications / Volunteering — No Comments
08
Sep 15

Effect of volunteering on cardiovascular risk in adolescents

Importance The idea that individuals who help others incur health benefits themselves suggests a novel approach to improving health while simultaneously promoting greater civic orientation in our society. The present study is the first experimental trial, to our knowledge, of whether regular volunteering can reduce cardiovascular risk factors in adolescents. Objective To test a novel intervention that assigned adolescents to volunteer with elementary school–aged children as a means of improving adolescents’ cardiovascular risk profiles. Design Randomized controlled trial, with measurements taken at baseline and 4 months later (postintervention). Setting Urban public high school in western Canada. Participants One hundred six 10th-grade high school students who were fluent in English and free of chronic illnesses. Intervention Weekly volunteering with elementary school–aged children for 2 months vs wait-list control group. Main Outcome Measures Cardiovascular risk markers of C-reactive protein level, interleukin 6 level, total cholesterol level, and body mass index. Results No statistically significant group differences were found at baseline. Postintervention, adolescents in the intervention group showed significantly lower interleukin 6 levels (log₁₀ mean difference, 0.13; 95% CI, 0.004 to 0.251), cholesterol levels (log₁₀ mean difference, 0.03; 95% CI, 0.003 to 0.059), and body mass index (mean difference, 0.39; 95% CI, 0.07 to 0.71) compared with adolescents in the control group. Effects for C-reactive protein level were marginal (log₁₀ mean difference, 0.13; 95% CI, −0.011 to 0.275). Preliminary analyses within the intervention group suggest that those who increased the most in empathy and altruistic behaviors, and who decreased the most in negative mood, also showed the greatest decreases in cardiovascular risk over time. Conclusions and Relevance Adolescents who volunteer to help others also benefit themselves, suggesting a novel way to improve health.

CITATION: Schreier, H. M. C., Schonert-Reichl, K. A., & Chen, E. (2013). Effect of volunteering on cardiovascular risk in adolescents. JAMA – Pediatrics, 167(4), 327-332.

Inflammation / Publications — No Comments
08
Sep 15

Stress and food allergy: mechanistic considerations

Recent years have seen a marked increase in food allergy prevalence among children, particularly in Western countries, that cannot be explained by genetic factors alone. This has resulted in an increased effort to identify environmental risk factors underlying food allergies and to understand how these factors may be modified through interventions. Food allergy is an immune-mediated adverse reaction to food. Consequently, considerations of candidate risk factors have begun to focus on environmental influences that perturb the healthy development of the emerging immune system during critical periods of development (eg, prenatally and during early childhood), particularly in the gut. Given that psychosocial stress is known to play an important role in other allergic and inflammatory diseases, such as asthma, its potential role in food allergy is a growing area of research. However, research to date has largely focused on animal studies. This review synthesizes relevant animal research and epidemiological data, providing proof of concept for moderating influences of psychological stress on food allergy outcomes in humans. Pathways that may underlie associations between psychosocial stress and the expression of food allergy are discussed.

CITATION: Schreier, H. M. C. & Wright, R. J. (2013). Stress and food allergy: mechanistic considerations. Annals of Allergy, Asthma, & Immunology, 112(4), 296-301.

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