Hostility and adiposity mediate disparities in insulin resistance among adolescents and young adults

Association between leukocyte telomere length and hostility in US army service members

Hostility is a common form of emotionally charged anger which can lead to maladaptive and unhealthy behaviors. Significant association between shortened telomeres and greater levels of hostility has been observed in civilian populations, but has not yet been comprehensively studied in military populations. Our study investigates the relationship between hostility, post-traumatic stress disorder (PTSD), and leukocyte telomere length (LTL) in a sample of United States Army Special Operations personnel (n = 474) who deployed to Iraq and/or Afghanistan as part of combat operations. Hostility was measured with five items from the Brief Symptom Inventory (BSI). PTSD was determined using the PTSD Checklist (PCL) total score. The LTL was assessed using quantitative polymerase chain reaction methods and regression analyses were conducted to determine the association of hostility and telomere length. PTSD subjects reported higher hostility scores compared with those without PTSD. Among the participants with PTSD, those with medium or high level of hostility had shorter LTL than those with low level hostility (P < 0.01). Stepwise regression indicated that hostility level and age, but not gender and PTSD, were negatively correlated with LTL. Univariate regression showed that total hostility score was negatively associated with LTL (CI= -0.06 to -0.002, Beta= -0.095, p < 0.039) as well as a significant correlation between LTL and hostility impulses (HI) (CI= -0.108 to -0.009, Beta= -0.106, p < 0.021) and hostility controlling (HC) (CI= -0.071 to -0.002, Beta= -0.095, p < 0.004). Multiple regression analyses revealed that, while HC has no significant association with LTL, HI was still negatively correlated with LTL (p = 0.021). Our data indicates that LTL is associated with HI levels. Prevention and treatment efforts designed to reduce hostility may help mitigate risk for LTL shortening, a process of cellular aging, and thus slow accelerated aged-related health outcomes.

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.

Socio-economic differences in cardiometabolic risk markers are mediated by diet and body fatness in 8- to 11-year-old Danish children: a cross-sectional study

OBJECTIVE

To explore whether socio-economic differences exist in cardiometabolic risk markers in children and whether lifestyle-related factors potentially mediate these differences.

DESIGN

Cross-sectional study including measurements of fasting blood lipids, glucose, homeostasis model assessment of insulin resistance (HOMA-IR), blood pressure and heart rate. Potential mediators examined were fat mass index (FMI); intakes of fruit, vegetables, dietary fibre and added sugar; whole-blood n-3 long-chain PUFA (LCPUFA) as a biomarker of fish intake; and physical activity and sedentary time.

SETTING

Nine primary schools in Denmark.

SUBJECTS

Children aged 8-11 years (n 715).

RESULTS

Children of parents with the shortest compared with longest education had higher TAG by 0·12 (95 % CI 0·04, 0·21) mmol/l and HOMA-IR by 0·36 (0·10, 0·62), whereas children of parents with a vocational education had higher total cholesterol by 0·14 (0·02, 0·27) mmol/l and LDL cholesterol by 0·14 (0·03, 0·25) mmol/l compared with children of parents with the longest education; all P<0·05. FMI explained 25 % of the difference in TAG, 64 % of the difference in HOMA-IR and 21-29 % of the differences in cholesterols. FMI and whole-blood n-3 LCPUFA combined explained 42 % of the difference in TAG, whereas FMI, whole-blood n-3 LCPUFA and dietary fibre explained 89 % of the difference in HOMA-IR.

CONCLUSIONS

Socio-economic differences were present in blood lipids and insulin resistance among 8- to 11-year-olds and were mediated by body fatness, whole-blood n-3 LCPUFA and dietary fibre. These lifestyle factors may be targets in public initiatives to reduce socio-economic differences. Confirmation in longitudinal studies and trials is warranted.

Race differences in the relation of vitamins A, C, E, and β-carotene to metabolic and inflammatory biomarkers

Using archival data, we conducted a secondary analysis to examine race differences in the relation of serum vitamins A, C, E and β-carotene to insulin resistance (IR), fasting insulin and glucose, high sensitivity C-reactive protein (hs-CRP), and leukocyte count in 176 non-smoking, healthy, white, and African American (AA) adults aged 18 to 65 years (48% women, 33% AA). We hypothesized that micronutrient concentrations would be associated with early risk markers of cardiometabolic diseases in a race-dependent manner. Fasting blood samples were analyzed for micronutrients, insulin, glucose, hs-CRP, and leukocyte count. Insulin resistance was estimated using the homeostatic model assessment. After adjusting for age, body mass index, gender, educational level, use of vitamin supplements, alcohol intake, leisure time physical activity, menopausal status, and total cholesterol, we observed that β-carotene was significantly associated with insulin resistance and fasting insulin in a race-dependent manner. Among AA, lower β-carotene levels were associated with higher estimates of insulin resistance and fasting insulin; whereas, these same associations were not significant for whites. Race also significantly moderated the relation of vitamin C to leukocyte count, with lower vitamin C being associated with higher leukocyte count only in AA but not whites. For all subjects, lower β-carotene was associated with higher hs-CRP. In AA, but not whites, lower levels of β-carotene and vitamin C were significantly associated with early risk markers implicated in cardiometabolic conditions and cancer. Whether or not lower levels of micronutrients contribute uniquely to racial health disparities is a worthwhile aim for future research.

Socioeconomic and other social stressors and biomarkers of cardiometabolic risk in youth: a systematic review of less studied risk factors

Background

Socioeconomic disadvantage and other social stressors in childhood have been linked with cardiometabolic diseases in adulthood; however the mechanisms underlying these observed associations and the timing of their emergence are unclear. The aim of this review was to evaluate research that examined relationships between socioeconomic disadvantage and other social stressors in relation to less-studied cardiometabolic risk factors among youth, including carbohydrate metabolism-related factors, lipids, and central adiposity.

Methods

We searched PubMed and ISI Web of Science to identify relevant publications between 2001 and 2013.Studies were selected based on 4 criteria: (1) the study examined an association between at least one social or economic stressor and one relevant outcome prior to age 21; (2) the sample originated from a high-income country; (3) the sample was not selected based on a health condition; and (4) a central aim was to evaluate the effect of the social or economic stressor on at least one relevant outcome. Abstracts were screened and relevant publications were obtained and evaluated for inclusion criteria. We abstracted data from selected articles, summarized them by exposures and outcomes, and assigned an evidence grade.

Results

Our search identified 37 publications from 31 studies. Socioeconomic disadvantage was consistently associated with greater central adiposity. Research to date does not provide clear evidence of an association between childhood stressors and lipids or carbohydrate metabolism-related factors.

Conclusions

This review demonstrates a paucity of research on the relationship of socioeconomic disadvantage and other social stressors to lipid and carbohydrate metabolism-related factors in youth. Accordingly, it is not possible to form strong conclusions, particularly with regard to stressors other than socioeconomic disadvantage. Findings are used to inform priorities for future research. An improved understanding of these pathways is critical for identifying novel prevention targets and intervention opportunities to protect the long-term health of children and adolescents.

Association of optimism with cardiometabolic risk in adolescents

PURPOSE

Dispositional optimism is a psychological trait associated with cardiovascular disease outcomes in adults. However, it is not known whether these associations are present in adolescents. We attempted to determine whether an association exits between optimism and 9 biomarkers of cardiometabolic risk during adolescence. Because cardiometabolic risk differs by race and ethnicity, we also explored whether race and ethnicity moderated the optimism-cardiometabolic risk relationship.

METHODS

This was a cross-sectional study of 529 non-Hispanic white and 421 non-Hispanic black seventh through 12th graders living in greater Cincinnati in 2001-2002. We measured dispositional optimism with the Life-Orientation Test-Revised as a single continuum and as separate optimism and pessimism dimensions. Multivariable regression analyses tested for associations between optimism and nine biomarkers of risk (interleukin-6, tumor necrosis factor-α, lipids, insulin, glucose, and fibrinogen), adjusting for age, gender, parent education, body mass index, smoking, and pubertal stage.

RESULTS

Dispositional optimism with the Life-Orientation Test-Revised as a single continuum was inversely associated with two risks (interleukin-6, β = -.03, p = .02; insulin, β = -.02, p = .01), but only among blacks. Optimism and pessimism were inversely related (R = -.27, p < .001) and both were higher in blacks than whites (p < .001). Optimism was directly associated with high-density lipoprotein among all subjects (β = .42, p = .03), and among blacks (β = .74, p = .02) but not whites. Among blacks, optimism was also inversely associated with interleukin-6 (β = -.07, p = .001) and triglycerides (β = -.02, p = .04). Pessimism was inversely associated with glucose, but only in whites (β = -.38, p = .03).

CONCLUSIONS

Associations between dispositional optimism and cardiometabolic risks are present in adolescence and vary by race and ethnicity. A better understanding of the natural history of these associations over the lifespan may help decrease disparities and prevent cardiometabolic disease.

Relationship of insulin resistance to psychobehavioral characteristics of overweight and obese African American children

OBJECTIVES

The objective of this study was to evaluate the relationships of insulin resistance to positive as well as negative dimensions of the child's emotions, behavior and personality (hereafter referred to as "psychobehavioral characteristics") in a convenience sample of inner-city, overweight and obese, African American children.

METHODS

A secondary analysis was performed on a sample of 127 children ages 9-12 yr old who were participating in a community-based, Type 2 diabetes prevention program. Psychobehavioral characteristics of children were assessed using both child and parent ratings derived from the Behavioral Assessment for Children, 2nd edition (BASC-2). Body fatness was evaluated using anthropometric techniques, and insulin resistance (HOMA-IR) was calculated from fasting glucose and insulin concentrations. Hierarchical multiple linear regression models were employed with BASC scales as dependent variables and HOMA-IR as the independent variable of interest.

RESULTS

After adjusting for child age, pubertal stage, gender, family socioeconomic index, and intervention group assignment, child HOMA-IR was related at p<0.05 to less favorable scores for parent-report of behavioral symptoms and externalizing problems composites, and to content scales for bullying and negative emotionality. Additionally, child HOMA-IR was related at p<0.01 to less favorable scores for child-report inattention/hyperactivity composite. Body fatness suppressed the unfavorable relationship between HOMA-IR and these and other psychobehavioral characteristics as the degree of significance was higher following adjustment for body fatness in this cohort.

CONCLUSION

More than one psychobehavioral characteristic were associated with body fatness and insulin resistance in the overweight children of this study. Whether the associations are due to several, or only one, of these psychobehavioral characteristics could not be determined. A much larger and future study will be needed to determine which, if any, of these psychobehavioral characteristics are independently associated with insulin resistance in overweight children.