Mediating pathways between parental socio-economic position and allostatic load in mid-life: Findings from the 1958 British birth cohort
Introduction
Redressing the social stratification of ill health is a major concern in public health research. Classic determinants of non-communicable disease, which are mainly behavioral, are insufficient for explaining the large disparities observed in morbidity and mortality (Gallo et al., 2012). The concept of embodiment (Krieger, 2005) and biological embedding (Hertzman, 2012) are similar, and may be useful tools for formulating hypotheses on how health inequalities are produced over the lifecourse. In both concepts, how human environments affect our health by penetrating the cells, organs and physiological systems of our bodies, is a key tenet. We conceptualize embodiment as a dynamic process that summarizes how we become altered by our past experiences and are responding to the present, from how well we feel, down to the molecular modifications in our bodily structures. The process of embodiment being socially stratified (Hertzman and Boyce, 2010) may contribute to explaining the production of social gradients in health.
Growing evidence supports the idea that exposure to stressful conditions over life contributes to physiological dysregulation, subsequently translated into disease, through prolonged activation of stress response systems (McEwen and Stellar, 1993). Allostasis is the process where our body adapts to environmental challenges or stressful conditions in order to maintain physiological stability. The repeated activation of compensatory physiological mechanisms as a response to chronic stress can lead to a physiological wear-and-tear, known as allostatic load (AL) (Juster et al., 2010, McEwen and Stellar, 1993). AL has been strongly correlated with subclinical conditions, cardiovascular events, physical and functioning decline and mortality (Juster et al., 2010, Karlamangla et al., 2002, Karlamangla et al., 2006). As a composite measure, AL performs as a better predictor of subsequent morbidity and mortality over and above each constituent biomarker when analyzed individually (Karlamangla et al., 2002). These findings suggest that AL could represent a global physiological state and perhaps even a proxy for an outcome of the embodiment process.
Growing evidence suggests that early life socioeconomic position (SEP) is a distal determinant of AL (Gruenewald et al., 2012), suggesting that poor socioeconomic circumstances early in life could set different population subgroups on life trajectories that are unfavorable for health, increasing their probability of being exposed to unhealthy environmental stressors and lifestyles. Early SEP is often measured using parental education and occupation at birth or in childhood, both of these measures being generally available in birth cohort studies. Education and occupation may operate through both similar and unique mechanisms to influence offspring health. In the current analysis, measures of parental education were limited to maternal education (ME), and occupation to paternal occupation (PO), due to variables availability and due to the historical context in which measures were assessed. Literature suggests that education and occupation do not impact health through the same pathways and should be analyzed separately (Galobardes et al., 2006, Galobardes et al., 2007). PO may affect health through: i) material resources (that determine material leaving standards), ii) work privileges (i.e. social security), iii) social standing (determining work control/autonomy and work based stress), and iv) toxic occupational exposures (Bartley et al., 1996, Galobardes et al., 2006). ME could affect health through: i) higher score of knowledge/skills and thus cultural capital, ii) material resources, iii) increasing the odds of acquiring better positions in occupation and higher income (Galobardes et al., 2006).
The lifecourse pathways linking early SEP to AL deserve to be disentangled, in particular the specific pathways involving ME and PO respectively. We aim to address this question by exploring four pathways through which ME and PO may be differentially embodied during childhood, adolescence and early adulthood leading to physiological wear-and-tear, as measured by AL. (a) A material/financial pathway: we hypothesize that living in poor material/financial circumstances could increase the risk of exposure to stressful and harmful situations relate to housing, work conditions, neighborhood, etc. (toxins, allergens, overcrowding) (Gustafsson et al., 2012, Lannero et al., 2002, Robertson et al., 2015). (b) A psychosocial/psychological pathway: parental SEP could influence parenting and the creation of a secure social environment buffering toxic stress responses, as well as the set-up of stress responses systems (Repetti et al., 2002, Shonkoff et al., 2012). (c) An educational pathway: higher parental SEP may influence educational outcomes in childhood, impact cognitive functions (Dubow et al., 2009, Kaplan et al., 2001) and later adult SEP (d) a health behaviors & BMI pathway: the accumulation of social disadvantage over life could contribute to adopt risky behaviors, impacting physiological functioning (Adler and Stewart, 2010, Stringhini et al., 2011).
We selected these four pathways based on epidemiological evidence and on empirical studies suggesting a link between SEP and each path. Lynch et al. (Lynch et al., 2000) suggested that health is the result of an accumulation of experiences and exposures due to the material world. Biological (viruses, bacteria) and chemical hazards, are more likely in more deprived homes and neighborhoods, and in some occupational statuses. An inverse relation between SEP and risky health behaviors has been largely demonstrated in empirical research (Stringhini et al., 2011). The adoption of health behaviors may be explained by complex psychological processes (e.g. self-regulation, self-efficacy, locus of control) (Bandura, 1991). Other explanations relate to social norms, tradition, and customs since lifestyle depends on social characteristics established by community social standards (Bartley, 2003). Concerning the psychosocial path, previous research (Marmot and Wilkinson, 1999) suggests that SEP may relate to health through the perception individuals have of their position in a social hierarchy. These perceptions may produce negative emotions resulting in poorer health, through psycho-neuroendocrine mechanisms (Brunner and Marmot, 1999) linked to stress responses (and/or stress-related behaviors such as smoking). Regarding the educational path, Hackman & Farah, showed in a recent review that SEP is linked with neurocognitive performance, such as language and executive function. Cognitive ability appears to be affected by poverty, especially during childhood. Different mechanisms have been suggested (e.g. cognitive stimulation, nutrition, parenting styles).
Section snippets
Study population
The National Child Development Study (NCDS) is a birth cohort that includes all children born during one week in 1958 (N = 18,558) in Great Britain. Subsequent data collection was carried out on cohort members between 7y and 50y. At age 44-45y a biomedical survey was conducted including a self-reported questionnaire, physical measurements, blood and saliva samples (Power and Elliott, 2006). The sample used for this study is described in Fig. S1. Details about ethics and data are given in
Results
Descriptive statistics of the nonimputed sample are presented in Table 1 for the subsample (n = 3782 for men; n = 3791 for women). Fig. 2, Fig. 3 represent the path analyses results, showing only the mediating variables explaining >5% of the total effect for men and women respectively, first between ME and AL, and second between PO and AL. The sum of all pathways are not equal to 1 due to other small or negative pathways not presented in the figures (Tables S5 and S6).
The path analyses for ME
Discussion
Lower maternal education and manual paternal occupation were associated with a higher allostatic load at 44 years, mainly via the educational, material/financial, and health behaviors pathways for both men and women. For the relationship between ME and AL, more than 60% of the link in women and 45% in men, remained unexplained by the mediators. Around 50–60% of the relationship between PO and AL remained unexplained by the mediators in men and in women. In both relationships these pathways may
Acknowledgments
C.B.S. is supported by the University of Costa Rica and funded by the European Commission (Horizon 2020 grant no 633666). The present work is part of the Incorporation Biologique et Inégalités Sociales de Santé (IBISS) project supported by funds from Agence Nationale de la Recherche (ANR-12-DSSA-0004).
References (77)
- et al.
Assessing salivary cortisol in large-scale, epidemiological research
Psychoneuroendocrinology
(2009) Social cognitive theory of self-regulation
Organ. Behav. Hum. Decis. Process.
(1991)Fetal programming of coronary heart disease
Trends Endocrinol. Metab.
(2002)- et al.
The impact of parental educational trajectories on their adult offspring's overweight/obesity status: a study of three generations of Swedish men and women
Soc. Sci. Med.
(2014) - et al.
Increased educational attainment and its effect on child mortality in 175 countries between 1970 and 2009: a systematic analysis
Lancet
(2010) - et al.
History of socioeconomic disadvantage and allostatic load in later life
Soc. Sci. Med.
(2012) - et al.
Allostatic load biomarkers of chronic stress and impact on health and cognition
Neurosci. Biobehav. Rev.
(2010) - et al.
Allostatic load as a predictor of functional decline MacArthur studies of successful aging
J. Clin. Epidemiol.
(2002) - et al.
Social differences in insulin-like growth factor-1: findings from a British birth cohort
Ann. Epidemiol.
(2008) - et al.
Gender and C-reactive protein: data from the Multiethnic Study of Atherosclerosis (MESA) cohort
Am. Heart J.
(2006)
Allostasis and allostatic load: implications for neuropsychopharmacology
Neuropsychopharmacology
Inequalities in self-rated health: explanations from different stages of life
Lancet
Smoking during pregnancy was up to 70% more common in the most deprived municipalities – a multilevel analysis of all singleton births during 2005-2010 in Finland
Prev. Med.
The role of material, psychosocial and behavioral factors in mediating the association between socioeconomic position and allostatic load (measured by cardiovascular, metabolic and inflammatory markers)
Brain Behav. Immun.
Health disparities across the lifespan: meaning, methods, and mechanisms
Loss and representativeness in a biomedical survey at age 45 years: 1958 British birth cohort
J. Epidemiol. Community Health
Adverse childhood experiences and physiological wear-and-tear in midlife: findings from the 1958 British birth cohort
Proc. Natl. Acad. Sci. U. S. A.
Fetal and infant origins of adult disease
Monatsschrift Kinderheilkd.
Breastfeeding, maternal education and cognitive function: a prospective study in twins
Behav. Genet.
Health Inequality: an Introduction to Theories, Concepts and Methods
Measuring inequalities in health: an analysis of mortality patterns using two social classifications
Sociol. Health Illn.
A systematic review of allostatic load, health, and health disparities
Biol. Res. Nurs.
The influence of education and home environment on the cognitive outcomes of preschool children in Germany
Child Dev. Res.
Social relationships and allostatic load in the MIDUS study
Health Psychol.
Social organization, stress, and health
C-reactive protein, obesity, atopy and asthma symptoms in middle-aged adults
Eur. Respir. J.
Childhood abuse, parental warmth, and adult multisystem biological risk in the Coronary Artery Risk Development in Young Adults study
Proc. Natl. Acad. Sci. U. S. A.
Sleep and multisystem biological risk: a population-based study
PLoS One
Evolution of reporting P values in the biomedical literature, 1990–2015
Jama J. Am. Med. Assoc.
Parental obesity and risk factors for cardiovascular disease among their offspring in mid-life: findings from the 1958 British Birth Cohort Study
Int. J. Obes.
Mother's education and the intergenerational transmission of human capital: evidence from college openings
Q. J. Econ.
Long-term effects of parents' education on children's educational and occupational success mediation by family interactions, child aggression, and teenage aspirations
Merrill-Palmer Quart. J. Dev. Psychol.
User Guide to the Biomedical Survey 2002–2004 Dataset
Social inequalities and mortality in Europe – results from a large multi-national cohort
PLoS One
Measuring socioeconomic position in health research
Br. Med. Bull.
Indicators of socioeconomic position (part 1)
J. Epidemiol. Community Health
Maternal early life risk factors for offspring birth weight: findings from the add health study
Prev. Sci.
Sex differentials in biological risk factors for chronic disease: estimates from population-based surveys
J. Womens Health
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