Food Security Status and Hair Cortisol among Low-income Mother-Child Dyads

Translational science approaches for food insecurity research

Food insecurity is a pervasive problem that impacts health and well-being across the lifespan. The human research linking food insecurity to poor metabolic and behavioral health outcomes is inherently correlational and suffers from a high degree of variability both between households and even within the same household over time. Further, food insecurity is impacted by societal and political factors that are largely out of the control of individuals, which narrows the range of intervention strategies. Animal models of food insecurity are being developed to address some of the barriers to mechanistic research. However, animal models are limited in their ability to consider some of the more complex societal elements of the human condition. We believe that understanding the role that food insecurity plays in ingestive behavior and chronic disease requires a truly translational approach, and that understanding the health impacts of this complex social phenomenon requires understanding both its psychological and physiological dimensions. This brief review will outline some key features of food insecurity, highlighting those that are amenable to investigation with controlled animal models and identifying areas where integrating animal and human studies can improve our understanding of the psychological burden and health impacts of food insecurity. In the interest of brevity, this review will largely focus on food insecurity in the United States, as the factors that contribute to food insecurity vary considerably across the globe.

Experimental biology can inform our understanding of food insecurity

Food insecurity is a major public health issue. Millions of households worldwide have intermittent and unpredictable access to food and this experience is associated with greater risk for a host of negative health outcomes. While food insecurity is a contemporary concern, we can understand its effects better if we acknowledge that there are ancient biological programs that evolved to respond to the experience of food scarcity and uncertainty, and they may be particularly sensitive to food insecurity during development. Support for this conjecture comes from common findings in several recent animal studies that have modeled insecurity by manipulating predictability of food access in various ways. Using different experimental paradigms in different species, these studies have shown that experience of insecure access to food can lead to changes in weight, motivation and cognition. Some of these studies account for changes in weight through changes in metabolism, while others observe increases in feeding and motivation to work for food. It has been proposed that weight gain is an adaptive response to the experience of food insecurity as 'insurance' in an uncertain future, while changes in motivation and cognition may reflect strategic adjustments in foraging behavior. Animal studies also offer the opportunity to make in-depth controlled studies of mechanisms and behavior. So far, there is evidence that the experience of food insecurity can impact metabolic efficiency, reproductive capacity and dopamine neuron synapses. Further work on behavior, the central and peripheral nervous system, the gut and liver, along with variation in age of exposure, will be needed to better understand the full body impacts of food insecurity at different stages of development.

Methods for Assessing Health Outcomes Associated with Food Insecurity in the United States College Student Population: A Narrative Review

In the United States, college students experience disproportionate food insecurity (FI) rates compared to the national prevalence. The experience of acute and chronic FI has been associated with negative physical and mental health outcomes in this population. This narrative review aims to summarize the current methodologies for assessing health outcomes associated with the experience of FI in college students in the United States. To date, assessing the health outcomes of FI has predominately consisted of subjective assessments, such as self-reported measures of dietary intake, perceived health status, stress, depression, anxiety, and sleep behaviors. This review, along with the emergence of FI as an international public health concern, establishes the need for novel, innovative, and objective biomarkers to evaluate the short- and long-term impacts of FI on physical and mental health outcomes in college students. The inclusion of objective biomarkers will further elucidate the relationship between FI and a multitude of health outcomes to better inform strategies for reducing the pervasiveness of FI in the United States college student population.

Food insecurity as a cause of adiposity: evolutionary and mechanistic hypotheses

Food insecurity (FI) is associated with obesity among women in high-income countries. This seemingly paradoxical association can be explained by the insurance hypothesis, which states that humans possess evolved mechanisms that increase fat storage to buffer against energy shortfall when access to food is unpredictable. The evolutionary logic underlying the insurance hypothesis is well established and experiments on animals confirm that exposure to unpredictable food causes weight gain, but the mechanisms involved are less clear. Drawing on data from humans and other vertebrates, we review a suite of behavioural and physiological mechanisms that could increase fat storage under FI. FI causes short-term hyperphagia, but evidence that it is associated with increased total energy intake is lacking. Experiments on animals suggest that unpredictable food causes increases in retained metabolizable energy and reductions in energy expenditure sufficient to fuel weight gain in the absence of increased food intake. Reducing energy expenditure by diverting energy from somatic maintenance into fat stores should improve short-term survival under FI, but the trade-offs potentially include increased disease risk and accelerated ageing. We conclude that exposure to FI plausibly causes increased adiposity, poor health and shorter lifespan. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part II)'.

Is economic hardship associated with young children's cortisol levels?

Economic hardship during childhood has been linked to poor physical and mental health. This study examines cross-sectional and longitudinal associations of a summed economic hardship score of poverty, food insecurity, and financial hardship with hair cortisol in young children. Data from 24-month (Time 1, mean age 5 years) and 36-month (Time 2, mean age 6 years) follow-up from the NET-Works obesity prevention trial (NET-Works, NCT0166891) were used. Hair cortisol measures obtained at each time point were log-transformed and regressed on economic hardship at Time 1 and a cumulative economic hardship from Time 1 to Time 2, using generalized linear regressions. All models were adjusted for child age, sex, race/ethnicity, and intervention (prevention vs. control) arm. The final analytic sample sizes ranged from 248 to 287. Longitudinal analyses indicated that for every 1-unit higher economic hardship score at Time 1, hair cortisol at Time 2 follow-up was on average 0.07 log-picograms per milligram (pg/mg) higher (95% confidence interval [CI]: 0.01, 0.13). For every 1-unit increase in the cumulative economic hardship score between Time 1 and 2, there was a 0.04 log-pg/mg (95% CI: 0.00, 0.07) average higher level of hair cortisol at Time 2 follow-up. Results show suggestive but limited evidence for an association between economic hardship and cortisol in young children.

Preschool-aged children's hair cortisol and parents' behavior, psychopathology, and stress

Parental factors, including parenting behavior, parent mental health, and parent stress, are associated with child stress. More recently, studies have shown that these parental factors may also be associated with children's hair cortisol concentration (HCC). HCC is a novel biomarker for chronic stress. HCC indexes cumulative cortisol exposure thereby reflecting longer-term stress reactivity. Although HCC is associated with a range of problems in adults such as depression, anxiety, appraisal of stressful events, and diabetes, studies investigating HCC in children have been inconsistent, with particularly little information about parental factors and HCC. As chronic stress may have long-term physiological and emotional effects on children, and parent-based interventions can reduce these effects, it is important to identify parental factors that relate to children's HCC. The aim of this study was to examine associations between preschool-aged children's physiological stress measured via HCC and mother- and father-reported parenting behavior, psychopathology, and stress. Participants included N = 140 children ages 3-5-years-old and their mothers (n = 140) and fathers (n = 98). Mothers and fathers completed questionnaire measures on their parenting behavior, depressive and anxiety symptoms, and perceived stress. Children's HCC was assessed by processing small hair samples. HCC levels were higher in boys compared to girls, and higher in children of color compared to white children. There was a significant association between children's HCC and fathers' authoritarian parenting. Children's HCC was positively associated with physical coercion, a specific facet of fathers' authoritarian parenting, even after accounting for sex of the child, race/ethnicity of the child, stressful life events, fathers' depression, fathers' anxiety, and fathers' perceived stress. In addition, there was a significant interaction between higher levels of both mothers' and fathers' authoritarian parenting and children's HCC. Children's HCC was not significantly related to mothers' and fathers' anxiety and depression or mothers' and fathers' perceived stress. These findings contribute to the large literature that links harsh and physical parenting practices with problematic outcomes in children.

Household Social Needs, Emotional Functioning, and Stress in Low-Income Latinx Children and their Mothers

Latinx families may be particularly vulnerable to emotional dysfunction, due to higher rates of economic hardship and complex social influences in this population. Little is known about the impact of environmental stressors such as unmet social needs and maternal stress on the emotional health of Latinx children from low-income families. We conducted secondary analyses using survey and biomarker data from 432 Latinx children and mothers collected in a separate study. We used binomial and multinomial logistic regression to test if household social needs, or maternal perceived stress or hair cortisol concentration (HCC), predicted child measures of emotional functioning or child HCC, independent of relevant sociodemographic factors. Approximately 40% of children in the sample had symptoms consistent with emotional dysfunction, and over 37% of households reported five or more social needs. High perceived maternal stress predicted higher odds of child emotional dysfunction (OR = 2.15; 95% CI [1.14, 4.04]; p = 0.01), and high maternal HCC was positively associated with high child HCC (OR = 10.60; 95% CI [4.20, 26.74]; p < 0.01). Most individual household social needs, as well as the level of household social need, were not independently associated with child emotional dysfunction or child HCC. Our findings begin to define a framework for understanding emotional health, stress, and resilience when caring for Latinx children and mothers living with high levels of social need, and the need for integrated mental health and social needs screening and interventions in settings that serve this population.

Unmet Social Needs and Patterns of Hair Cortisol Concentration in Mother-Child Dyads

Background

Mothers and their children demonstrate dyadic synchrony of hypothalamic-pituitary-adrenal (HPA) axis function, likely influenced by shared genetic or environmental factors. Although evidence has shown that chronic stress exposure has physiologic consequences for individuals-including on the HPA axis-minimal research has explored how unmet social needs such as food and housing instability may be associated with chronic stress and HPA axis synchrony in mother-child dyads.

Methods

We conducted a secondary analysis of data from 364 mother-child dyads with low-income recruited during a randomized trial conducted in an urban pediatric clinic. We used latent profile analysis (LPA) to identify subgroups based on naturally occurring patterns of within-dyad hair cortisol concentration (HCC). A logistic regression model predicted dyadic HCC profile membership as a function of summative count of survey-reported unmet social needs, controlling for demographic and health covariates.

Results

LPA of HCC data from dyads revealed a 2-profile model as the best fit. Comparisons of log HCC for mothers and children in each profile group resulted in significantly "higher dyadic HCC" versus "lower dyadic HCC" profiles (median log HCC for mothers: 4.64 vs 1.58; children: 5.92 vs 2.79, respectively; P < .001). In the fully adjusted model, each one-unit increase in number of unmet social needs predicted significantly higher odds of membership in the higher dyadic HCC profile when compared to the lower dyadic HCC profile (odds ratio  =  1.13; 95% confidence interval [1.04-1.23]; P  =  .01).

Conclusion

Mother-child dyads experience synchronous patterns of physiologic stress, and an increasing number of unmet social needs is associated with a profile of higher dyadic HCC. Interventions aimed at decreasing family-level unmet social needs or maternal stress are, therefore, likely to affect pediatric stress and related health inequities; efforts to address pediatric stress similarly may affect maternal stress and related health inequities. Future research should explore the measures and methods needed to understand the impact of unmet social needs and stress on family dyads.

Stress Concepts and Applications in Various Matrices with a Focus on Hair Cortisol and Analytical Methods

When studying stress in animals, it is important to understand the types of stress and their classification, and how to assess the stress levels in different animal species using different matrices accurately and precisely. The classification of stress types helps to distinguish between good stress (eustress) and bad stress (distress). Hence, first, it is crucial to assess the animal's level of stress in a non-intrusive manner and second to identify the type of stress that is best suited to its environment. Third, it is also important to analyze the obtained samples using a suitable method to increase the validity of stress hormone measurements. Therefore, in this review, we aim to: (1) explain the classification of stress, (2) discuss the wide range of body matrices (e.g., saliva, milk, hair, urine, feces, sweat, fins, etc.) that can be used as samples to evaluate stress levels, as well as their comparisons and limitations, and present the reliable matrices for measuring stress hormones with special emphasis on hair, (3) compare the analytical methods for measuring stress hormones after sample preparation. Despite some literature that does not include hair as a reliable matrix for evaluating stress levels, hair is one of the matrices for measuring long-term stress hormone accumulations. This review discusses some factors that influence the level of stress hormones in the hair. By understanding these issues, the scientific community will not only be able to improve the understanding of stress and biomarker evaluation but also suggest how to deal with the consequences of stress in future research.

Race/ethnicity and age associations with hair cortisol concentrations among children studied longitudinally from early through middle childhood

A total of 513 children were included in this secondary analysis of data from the NET-Works trial of low income children at risk for obesity. The purpose of the analysis was to examine HCC longitudinally over 5 assessments from early through middle childhood with the goal of i) determining if there were racial/ethnic differences in HCC, and if so, how early in childhood these differences could be observed; and (ii) whether racial/ethnic differences in HCC reflected structural and family-level indicators of disadvantage. The sample consisted of children from diverse racial/ethnic backgrounds: Black, including Hispanic Black (N = 156), non-Hispanic White (N = 67) and Non-Black Hispanic (N = 290) children. As the largest group, the last group was used as the reference group in analyses. Structural and family-level indicators of disadvantage, including the neighborhood child opportunity index (COI), family income, and parent perceived neighborhood safety, were collected at each assessment. The results showed higher HCC among Black children beginning as early as 2-4 years of age than non-Black Hispanic children who did not differ from non-Hispanic White children. Although family income and COI were lower for children from minoritized racial-ethnic backgrounds, entering these measures as covariates did not reduce the difference in HCC between Black children and the other two groups. The results also showed that HCC initially decreased with age and then plateaued, with no evidence that this pattern differed by race/ethnicity. Because of the potential health risks of chronically elevated cortisol concentrations, these data argue for increased attention to the myriad of factors (oppressive structures, systems, and interpersonal experiences) that likely contribute to elevated cortisol levels among Black children.

Increased risk of preterm delivery with high cortisol during pregnancy is modified by fetal sex: a cohort study

Background

Previous studies show an association between maternal plasma and salivary cortisol and preterm birth but have been primarily conducted in high-income countries. It is unknown whether salivary cortisol is a risk factor for preterm birth in Ghana. Our objective was to determine whether maternal salivary cortisol during pregnancy was associated with pregnancy duration and preterm delivery in Ghana.

Methods

We conducted a cohort study of 783 pregnant women in Ghana. We measured salivary cortisol at baseline (mean 16 wk), 28 wk., and 36 wk. gestation. Pregnancy duration was determined primarily by ultrasound. We used adjusted linear regression models to examine the association between cortisol and pregnancy duration and Poisson regression models to determine the risk of preterm delivery among women with high cortisol at baseline or 28 wk. gestation.

Results

Mean pregnancy duration was 39.4 ± 1.8 wk. and 6.6% had a preterm delivery. Mean maternal cortisol increased throughout pregnancy, from 4.9 ± 2.7 nmol/L at baseline (16 wk) to 6.4 ± 3.2 nmol/L at 28 wk. and 7.9 ± 3.0 nmol/L at 36 wk. gestation. In adjusted analyses, higher cortisol concentrations at baseline (β = − 0.39, p = .002) and 28 wk. (β = − 0.49, p = .001), but not 36 wk. (β = − 0.23, p = .084) were associated with a shorter pregnancy duration. Women with high cortisol at baseline (> 6.3 nmol/L) had an increased relative risk of preterm delivery (RR (95% CI): 1.96 (1.13, 3.40)), but the association between high cortisol at 28 wk. and preterm delivery was not significant. There was a significant interaction with fetal sex (p-for-interaction = 0.037): among women carrying male fetuses, high cortisol at baseline increased the risk of preterm delivery threefold (3.18 (1.51, 6.71)) while there was no association (1.17 (0.50, 2.74)) among women carrying female fetuses.

Conclusion

Higher maternal cortisol is associated with a shorter pregnancy duration and an increased risk of preterm delivery. Subgroup analysis by fetal sex revealed that this association is evident primarily among women carrying male fetuses. Future studies of cortisol and preterm delivery should include consideration of fetal sex as a potential effect modifier.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-022-05061-8.

Low income and schizophrenia risk: a narrative review

Despite decades of research, the precise etiology of schizophrenia is not fully understood. Ample evidence indicates that the disorder derives from a complex interplay of genetic and environmental factors during vulnerable stages of brain maturation. Among the plethora of risk factors investigated, stress, pre- and perinatal insults, and cannabis use have been repeatedly highlighted as crucial environmental risk factors for schizophrenia. Compelling findings from population-based longitudinal studies suggest low income as an additional risk factor for future schizophrenia diagnosis, but underlying mechanisms remain unclear. In this narrative review, we 1) summarize the literature in support of a relationship between low (parental) income and schizophrenia risk, and 2) explore the mediating role of chronic stress, pre- and perinatal factors, and cannabis use as established risk factors for schizophrenia. Our review describes how low income facilitates the occurrence and severity of these established risk factors and thus contributes to schizophrenia liability. The broadest influence of low income was identified for stress, as low income was found to be associated with exposure to a multitude of severe psychological and physiological stressors. This narrative review adds to the growing literature reporting a close relationship between income and mental health.

Hair cortisol concentration as a marker of long-term stress: sex and body temperature are major determinants in wild-living Alpine marmots

Hair cortisol concentration (HCC) has recently gained popularity as an easy-to-measure biomarker of long-term stress in wild and domestic animals. Hair integrates cortisol over long time periods within a single sample and it can be collected non-invasively, which makes its use particularly interesting for wildlife studies. Interpreting HCC values, however, is challenging, because they are determined by the interplay of multiple factors. Here, were explore potential determinants of HCC in the Alpine marmot Marmota marmota. We tested the relationship of sex, age class, physical condition and body temperature with the hair cortisol concentration of free-ranging marmots. We found marked sex difference in HCC, with higher levels in females. This might be related to sex-specific variation in social stress or resulting from physiological difference, e.g., in baseline and stress-induced levels of cortisol secretion. Interestingly, body temperature was also positively related to HCC, possibly hinting at individual short- and long-term stress reactivity as part of coping styles. Although further work is needed to entangle possible mechanisms underlying the neuro-endocrinological modulation on HCC, our results emphasize that determinants such as sex and body temperature in Alpine marmots should be accounted for, when using HCC as marker of chronic stress.

Chronic experience with unpredictable food availability promotes food reward, overeating, and weight gain in a novel animal model of food insecurity

Ubiquitous, easy access to food is thought to promote obesity in the modern environment. However, people coping with food insecurity have limited, unpredictable food access and are also prone to obesity. Causal factors linking food insecurity and obesity are not understood. In this study we describe an animal model to investigate biopsychological impacts of the chronic unpredictability inherent in food insecurity. Female rats were maintained on a 'secure' schedule of highly predictable 4x/day feedings of uniform size, or an 'insecure' schedule delivering the same total food over time but frequently unpredictable regarding how much, if any, food would arrive at each scheduled feeding. Subgroups of secure and insecure rats were fed ordinary chow or high-fat/high-sugar (HFHS) chow to identify separate and combined effects of insecurity and diet quality. Insecure chow-fed rats, relative to secure chow-fed rats, were hyperactive and consumed more when provided a palatable liquid diet. Insecure HFHS-fed rats additionally had higher progressive ratio breakpoints for sucrose, increased meal size, and subsequently gained more weight during 8 days of ad libitum HFHS access. Insecurity appeared to maintain a heightened attraction to palatable food that habituated in rats with secure HFHS access. In a second experiment, rats fed ordinary chow on the insecure schedule subsequently gained more weight when provided ad libitum chow, showing that prior insecurity per se promoted short-term weight gain in the absence of HFHS food. We propose this to be a potentially useful animal model for mechanistic research on biopsychological impacts of insecurity, demonstrating that chronic food uncertainty is a factor promoting obesity.

Food Insecurity and Mental Well-Being Among Low-Income Families During COVID-19 Pandemic

Purpose

To examine the interaction effects of adult and child food insecurity on parents’ and children’s mental well-being.

Design

An online survey study was conducted.

Setting

Two Head Start organizations and the Qualtrics Panel.

Subjects

Four hundred and eight parents under poverty level and having a child aged 3–5 years participated.

Measures

Food insecurity was assessed by the U.S. Household Food Security Survey Module. Parents’ stress, anxiety and depression; and children’s sadness, fear, anger, and positive affect were measured using instruments from HealthMeasures.

Analysis

Multivariate general linear models were performed in SPSS.

Results

Mean age was 31 years, 17% Hispanic, 21% Black. About 51% parents and 37% children were food insecure. After adjusting for demographics and child food insecurity, parents with adult food insecurity had higher stress (B = 2.65, p = .002), anxiety (B = 3.02, p = .001), and depression (B = 3.66, p = .001); and fear in their children (B = 5.03, p = .002) than those without adult food insecurity. Similarly, parents reporting child food insecurity had greater depression than those having no child food insecurity (B = 4.61, p = .020). Black parents had lower stress (B = −1.91, p = .018), anxiety (B = −2.26, p = .012), and depression (B = −4.17, p < .001) than their White counterparts.

Conclusions

The study’s results underscore the importance of reducing food insecurity in both parents and children as a whole family system to promote mental well-being of low-income families.

Pathways from Food and Housing Insecurity to Adolescent Behavior Problems: The Mediating Role of Parenting Stress

Unmet basic needs in childhood predict a range of behavior problems, but long-term pathways from childhood food and housing insecurity to adolescent behavior problems are not well understood. Applications of the Family Stress Model suggest parenting stress may mediate this relationship in the transition to adolescence. The present study tested whether the links from childhood food and housing insecurity to adolescent aggressive and depressive behaviors were mediated by parenting stress over 10 years. The analytic sample included 2454 mother-child dyads and skewed socioeconomically disadvantaged. The majority (78%) of mothers were nonwhite, half had not received beyond a high school education, and 60% were single. The first wave of data for the present study occurred when children (48% female) were approximately five years old, with follow-ups at age nine and 15. Structural equation modeling with latent variables showed direct associations from housing insecurity to both behavioral outcomes, and indirect associated from food insecurity to both outcomes via parenting stress. The findings point to the need for screening and supports for food and housing problems in order to prevent long-term mental health consequences.

Food insecurity, type 2 diabetes, and hyperglycaemia: A systematic review and meta-analysis

AIMS

Food insecurity (FIS) is a major public health issue with possible implications for type 2 diabetes mellitus (T2DM) risk. We conducted a systematic review and meta-analysis to explore the association between FIS and T2DM.

METHODS

We performed a systematic search in PubMed, Embase, Scopus, and Web of Science. All cross-sectional, peer-reviewed studies investigating the link between FIS and T2DM were included. Population characteristics, study sizes, covariates, T2DM diagnoses, and diabetes-related clinical measures such as fasting blood glucose (FBG) and HbA1c were extracted from each study. Outcomes were compared between food insecure and food secure individuals. Effect sizes were combined across studies using the random effect model.

RESULTS

Forty-nine peer-reviewed studies investigating the link between FIS and T2DM were identified (n = 258,250). Results of meta-analyses showed no association between FIS and clinically determined T2DM either through FBG or HbA1c: OR = 1.22 [95%CI: 0.96, 1.55], Q(df = 5) = 12.5, I2  = 60% and OR = 1.21 [95%CI: 0.95, 1.54], Q(df = 5) = 14; I2  = 71% respectively. Standardized mean difference (SMD) meta-analyses yielded no association between FIS and FBG or HbA1c: g = 0.06 [95%CI: -0.06, 0.17], Q(df = 5) = 15.8, I2  = 68%; g = 0.11 [95% CI: -0.02, 0.25], Q(df = 7) = 26.8, I2  = 74% respectively. For children, no association was found between FIS and HbA1c: g = 0.06 [95%CI: 0.00, 0.17], Q(df = 2) = 5.7, I2  = 65%.

CONCLUSIONS

Despite multiple proposed mechanisms linking FIS to T2DM, integration of the available literature suggests FIS is not associated with clinically determined T2DM or increases in FBG or HbA1c among adult patients.

Salivary biomarkers of stress and inflammation in first graders in Côte d'Ivoire: Effects of a probiotic food intervention

This semi-randomized controlled trial examined the effects of a probiotic food supplement on cortisol and C-reactive protein (CRP) in a sample of 262 four-to seven-year-old children (56% girls) in two economically-disadvantaged schools in an urban setting in Côte d'Ivoire. For one semester, children in one school were randomized to receive a probiotic (N = 79) or placebo (N = 85) fermented dairy food each day they attended school; one child (due to medical reasons) and all children in the other school (N = 98) continued their diets as usual. Children provided two saliva samples at 11:30 on consecutive days at the end of the study. Analyses revealed that the probiotic group had lower cortisol than the placebo or diet-as-usual groups (p = .015); CRP levels were comparable across groups (p = .549). Exploratory analyses suggested that dose and regularity of consumption may impact the biomarkers as well. This study provides the first evidence that a probiotic milk product may lower cortisol in a sample of young, economically-disadvantaged children.

Associations between social adversity and young children's hair cortisol: A systematic review

Psychosocial and socioeconomic adversity in early childhood (termed 'social adversity') can have lifelong detrimental effects on health and development. Physiological stress is one proposed mechanism by which social adversity 'gets under the skin'. There is substantial research interest in whether hair cortisol, a biomarker proposed to measure the cumulative physiological stress response over time, can illustrate this mechanism. As a result, a growing number of studies have tested for associations between indicators of social adversity and child hair cortisol. The aim of this paper is to conduct a comprehensive, systematic review of the evidence for associations between indicators of social adversity and hair cortisol, specifically in young children (birth to 8 years) published any time up to 31 December 2019. The literature search identified 44 published studies that met inclusion criteria. The studies examined associations between one or more indicators of social adversity and child hair cortisol across 35 independent cohorts comprising 8370 children. Indicators of adversity examined in the identified literature included socioeconomic factors (e.g. low parental education, low income and unemployment), psychosocial factors (e.g. parent stress, poor mental health and family violence), and children's direct exposure to maltreatment, abuse and stressful events. Across all indicators of adversity, a total of 142 associations with hair cortisol were examined. Evidence of associations was limited and inconsistent; 34/142 (24%) showed evidence of a positive association between adversity and higher hair cortisol, 8/142 (6%) showed a negative association, and more than two thirds (100/142, 70%) of all examined associations were null. The collective evidence appears insufficient to conclude that there is a relationship between social adversity and hair cortisol, as a measure of physiological stress response, in young children.

Toxic stress, health and nutrition among Brazilian children in shelters

Background

Living in a shelter is an adverse experience that generates toxic stress. This situation can cause the dysregulation of the hypothalamic-pituitary-adrenal axis and exert a negative impact on health.The aim of the present study was to determine the association between toxic stress and social, clinical and nutritional characteristics in children at welfare institutions in a city of northeastern of Brazil.

Methods

An analytical, cross-sectional study was conducted with male and female children up to 60 months of age who live in shelters. Hair cortisol was used for the assessment of stress (immunoassay). The anthropometric data collected were height for age, body mass index for age, arm circumference for age, and head circumference for age (expressed in z-scores). We also evaluated food intake using markers proposed by the Brazilian Dietary and Nutritional Vigilance Surveillance System as well as the occurrence of dental caries and anemia.

Results

Sixty-three children one to 60 months of age participated in the present study. Asthma was the most frequent disease (11.1%). The prevalence of short stature, anemia and dental caries in the sample was 22.2, 22.2 and 9.4%, respectively. Cortisol levels ranged from 0.93 pg/mg to 391.29 pg/mg (median: 6.17 pg/mg). Higher cortisol levels were found in children with illnesses (p = 0.012) and those who had been hospitalized after being admitted to the institutions (p = 0.001).

Conclusions

The majority of children had unhealthy eating behavior. The cortisol concentrations found in the present study were suggestive of dysregulation of the hypothalamic-pituitary-adrenal axis. Hypercortisolism was associated with illness and hospitalization.

Cortisol and socioeconomic status in early childhood: A multidimensional assessment

The hypothalamic-pituitary-adrenal (HPA) axis is sensitive to early life stress, with enduring consequences for biological stress vulnerability and health (Gunnar & Talge, 2008). Low socioeconomic status (SES) is associated with dysregulation of the stress hormone cortisol in early childhood. However, a mechanistic understanding of this association is lacking. Multidimensional assessment of both SES and cortisol is needed to characterize the intricate relations between SES and cortisol function in early childhood. We assessed parent-reported family income, parent education, occupational prestige, neighborhood risk, food insecurity, and household chaos for 12-month-old infants (N = 90) and 3.5-year-old children (N = 91). Hair cortisol concentration (HCC) was obtained from parent and child, indexing chronic biological stress, and diurnal salivary cortisol was measured in the children. Controlling for parent HCC, parent education uniquely predicted infant and child HCC and, in addition, neighborhood risk uniquely predicted infant HCC. Household chaos predicted bedtime salivary cortisol concentration (SCC) for both infants and children, and infant daily cortisol output. Food insecurity was associated with flattened cortisol slope in 3.5-year-old children. Parental sensitivity did not mediate relations between SES and cortisol. Results highlight the utility of SES measures that index unpredictable and unsafe contexts, such as neighborhood risk, food insecurity, and household chaos.

Food insecurity and hypertension: A systematic review and meta-analysis

Background

Food insecurity (FIS) is an important public health issue associated with cardiovascular risk. Given the association of FIS with diets of poorer nutritional quality and higher salt intake as well as chronic stress, numerous studies have explored the link between FIS and hypertension. However, no systematic review or meta-analysis has yet to integrate or analyze the existing literature.

Methods

We performed a wide and inclusive search of peer-reviewed quantitative data exploring FIS and hypertension. A broad-terms, systematic search of the literature was conducted in PubMed, Embase, Scopus, and Web of Science for all English-language, human studies containing primary data on the relationship between FIS and hypertension. Patient population characteristics, study size, and method to explore hypertension were extracted from each study. Effect sizes including odds ratios and standardized mean differences were extracted or calculated based on studies’ primary data. Comparable studies were combined by the random effects model for meta-analyses along with assessment of heterogeneity and publication bias.

Results

A total of 36 studies were included in the final analyses. The studies were combined into different subgroups for meta-analyses as there were important differences in patient population characteristics, methodology to assess hypertension, and choice of effect size reporting (or calculability from primary data). For adults, there were no significantly increased odds of elevated blood pressures for food insecure individuals in studies where researchers measured the blood pressures: OR = 0.91 [95%CI: 0.79, 1.04; n = 29,781; Q(df = 6) = 7.6; I² = 21%]. This remained true upon analysis of studies which adjusted for subject BMI. Similarly, in studies for which the standardized mean difference was calculable, there was no significant difference in measured blood pressures between food secure and FIS individuals: g = 0.00 [95%CI: -0.04, 0.05; n = 12,122; Q(df = 4) = 3.6; I² = 0%]. As for retrospective studies that inspected medical records for diagnosis of hypertension, there were no significantly increased odds of hypertension in food insecure adults: OR = 1.11 [95%CI: 0.86, 1.42; n = 2,887; Q(df = 2) = 0.7; I² = 0%]. In contrast, there was a significant association between food insecurity and self-reports of previous diagnoses of hypertension: 1.46 [95%CI: 1.13, 1.88; n = 127,467; Q(df = 7) = 235; I² = 97%]. Only five pediatric studies were identified which together showed a significant association between FIS and hypertension: OR = 1.44 [95%CI: 1.16, 1.79; n = 19,038; Q(df = 4) = 5.7; I² = 30%]. However, the small number of pediatric studies were not sufficient for subgroup meta-analyses based on individual study methodologies.

Discussion

In this systematic review and meta-analysis, an association was found between adult FIS and self-reported hypertension, but not with hypertension determined by blood pressure measurement or chart review. Further, while there is evidence of an association between FIS and hypertension among pediatric subjects, the limited number of studies precluded a deeper analysis of this association. These data highlight the need for more rigorous and longitudinal investigations of the relationship between FIS and hypertension in adult and pediatric populations.

A systematic review examining the relationship between food insecurity and early childhood physiological health outcomes

Food insecurity, or limited access to nutritious foods, is a significant public health concern especially among vulnerable populations including infants and young children in low-income households. While literature to date has thoroughly examined the psychological and behavioral impacts of food insecurity on children, no known study to date has specifically synthesized the literature exploring the relationship between food insecurity and physiological health outcomes during early childhood. The purpose of this study was to review the literature on physiological health outcomes associated with food insecurity during early childhood among children aged 0-5 years in developed countries. Our literature search sources included PubMed, PsycInfo, CINAHL, and Embase databases. A total of 657 articles published up to September 2019 were reviewed for eligibility by two coders, with a third reviewer in cases of disagreement. Eighty-three articles remained after screening by abstract, with a final 27 studies ultimately included in the final synthesis. This review is registered with PROSPERO and adhered to PRISMA guidelines. In total, 20 articles (74%) noted significant relationships between food insecurity and physiological health outcomes in young children. Findings included an association with overweight or obesity (n = 9), anemia (n = 3), poor child health (n = 3), low birth weight (n = 3), chronic illness (n = 1), special health care needs (n = 1), and increased cortisol (n = 1), in young children who experience food insecurity. Identifying relationships between food insecurity and health outcomes during early childhood has the potential to inform future prevention interventions to reduce health disparities in these vulnerable populations.

Using syndemic theory to understand food insecurity and diet-related chronic diseases

Syndemic Theory (ST) provides a framework to examine mutually enhancing diseases/health issues under conditions of social inequality and inequity. ST has been used in multiple disciplines to address interacting infectious diseases, noncommunicable diseases, and mental health conditions. The theory has been critiqued for its inability to measure disease interactions and their individual and combined health outcomes. This article reviews literature that strongly suggests a syndemic between food insecurity (FI) and diet-related chronic diseases (DRCDs), and proposes a model to measure the extent of such interaction. The article seeks to: (1) examine the potential syndemic between FI and DRCDs; (2) illustrate how the incorporation of Life History Theory (LHT), into a syndemic framework can help to highlight critical lifeperiods when FI-DRCD interactions result in adverse health outcomes; (3) discuss the use of mixed methods to identify and measure syndemics to enhance the precision and predictive power of ST; and (4) propose an analytical model for the examination of the FI-DRCD syndemic through the life course. The proposed model is more relevant now given the significant increase in FI globally as a result of the ongoing COVID-19 pandemic. The differential impact that the pandemic appears to have among various age groups and by other demographic factors (e.g., race, gender, income) offers an opportunity to examine the potential FI-DRCD syndemic under the lens of LHT.

Biological sensitivity to context in Pakistani preschoolers: Hair cortisol and family wealth are interactively associated with girls' cognitive skills

Many young children in low- and middle-income countries (LMICs) face heightened risk for experiencing environmental adversity, which is linked with poorer developmental outcomes. Children's stress physiology can shed light on why children are differentially susceptible to adversity. However, no known studies have examined whether links between adversity and children's development are moderated by children's stress physiology in LMICs. The present study revealed significant interactive effects of hair cortisol concentrations, an index of chronic physiological stress regulation, and family wealth on preschoolers' cognitive skills in rural Pakistan. In a sample of 535 4-year-old children (n = 342 girls), we found significant associations between family wealth and direct assessments of verbal intelligence, pre-academic skills, and executive functions only in girls with lower hair cortisol concentrations. Specifically, girls with lower cortisol concentrations displayed greater cognitive skills if they came from relatively wealthier families, but lower cognitive skills if they came from very poor families. There were no significant associations among boys. Results provide evidence of biological sensitivity to context among young girls in a LMIC, perhaps reflecting, in part, sex differences in daily experiences of environmental adversity.