Examining the Impact of Socioeconomic Position Across the Life Course on Cognitive Function and Brain Structure in Healthy Aging.

This study explores the relationship of life-course intergenerational social mobility with cognitive function and brain structure in older adults using Diagonal Reference Models. Data from the Irish Longitudinal Study on Ageing, a population-based cohort of adults aged 50 years and older (N = 4 620 participants; mean age: 66.1; standard deviation: 9.1; 55% female) was used for analysis. Brain magnetic resonance imaging data were available for 464 participants. Social mobility was characterized as the difference between childhood socioeconomic position (SEP; ie, father's occupation) and adulthood SEP (ie, own occupation). The Montreal Cognitive Assessment (MoCA), the Mini-Mental State Examination (MMSE), cortical thickness, and total gray matter volume (GMV) served as global cognitive and brain measures. Exploratory analyses included the volumes of the ventromedial prefrontal cortex (vmPFC), anterior cingulate (AC), hippocampus, and amygdala. A social gradient in cognitive function was observed among the intergenerationally stable; brain structure was not as clearly socially patterned. Adulthood SEP was significantly associated with MoCA (weight = 0.76; p < .001), MMSE (weight = 0.91; p < .001), GMV (weight = 0.77; p = .002), and AC volume (weight = 0.76; p < .001), whereas childhood SEP was associated with vmPFC volume (weight = 1.00; p = .003). There was no independent association of social mobility with any of the outcomes. Together our results suggest that both childhood and adulthood SEP are important in shaping later-life brain health, but that adulthood SEP predominates in terms of its influence. This is potentially an important insight as it suggests that brain health may be modifiable if socioeconomic circumstances change.

Life-course socioeconomic factors are associated with markers of epigenetic aging in a population-based study.

Adverse socioeconomic circumstances negatively affect the functioning of biological systems, but the underlying mechanisms remain only partially understood. Here, we explore the associations between life-course socioeconomic factors and four markers of epigenetic aging in a population-based setting. We included 684 participants (52 % women, mean age 52.6 ± 15.5 years) from a population and family-based Swiss study. We used nine life-course socioeconomic indicators as the main exposure variables, and four blood-derived, second generation markers of epigenetic aging as the outcome variables (Levine's DNAmPhenoAge, DunedinPoAm38, GrimAge epigenetic age acceleration (EAA), and the mortality risk score (MS)). First, we investigated the associations between socioeconomic indicators and markers of epigenetic aging via mixed-effect linear regression models, adjusting for age, sex, participant's recruitment center, familial structure (random-effect covariate), seasonality of blood sampling, and technical covariates. Second, we implemented counterfactual mediation analysis to investigate life-course and intermediate mechanisms underlying the socioeconomic gradient in epigenetic aging. Effect-size estimates were assessed using regression coefficients and counterfactual mediation parameters, along with their respective 95 % confidence intervals. Individuals reporting a low father's occupation, adverse financial conditions in childhood, a low income, having financial difficulties, or experiencing unfavorable socioeconomic trajectories were epigenetically older and had a higher mortality risk score than their more advantaged counterparts. Specifically, this corresponded to an average increase of 1.1-1.5 years for Levine's epigenetic age (ß and 95 %CI range, ß (minimum and maximum): 1.1-1.5 95 %CI[0.0-0.2; 2.3-3.0]), 1.1-1.5 additional years for GrimAge (ß: 1.1-1.5 95 %CI[0.2-0.6; 1.9-3.0]), a 1-3 % higher DunedinPoAm38 age acceleration (ß: 0.01-0.03 95 %CI[0.00; 0.03-0.04]), and a 10-50 % higher MS score (ß: 0.1-0.4 95 %CI[0.0-0.2; 0.3-0.4]) for the aforementioned socioeconomic indicators. By exploring the life-course mechanisms underlying the socioeconomic gradient in epigenetic aging, we found that both childhood and adulthood socioeconomic factors contributed to epigenetic aging, and that detrimental lifestyle factors mediated the relation between socioeconomic circumstances in adulthood and EAA (31-89 % mediated proportion). This study provides emerging evidence for an association between disadvantaged life-course socioeconomic circumstances and detrimental epigenetic aging patterns, supporting the "sensitive-period" life-course model. Counterfactual mediation analyses further indicated that the effect of socioeconomic factors in adulthood operates through detrimental lifestyle factors, whereas associations involving early-life socioeconomic factors were less clear.

Intergenerational Social Mobility and Allostatic Load in Midlife and Older Ages: A Diagonal Reference Modeling Approach.

OBJECTIVES: This study aims to understand the association of life-course intergenerational social mobility with allostatic load (AL) burden in midlife and older ages in Ireland. METHODS: The study involved biological data for 3,987 older adults participating in The Irish Longitudinal Study on Ageing (TILDA). Intergenerational social mobility was characterized using the cross-classification of origin socioeconomic position (SEP; i.e., father's occupation) and destination SEP (i.e., own occupation). AL was operationalized using 12 biomarkers tapping cardiovascular, metabolic, renal, and immune system dysregulation. Diagonal reference modeling (DRM) and ordinary least square regression techniques were applied to explore the effect of social mobility on AL burden. RESULTS: A total of 55.5% experienced intergenerational mobility: 37.5% were upwardly mobile, 18.0% were downwardly mobile. A social gradient in AL was observed among the socially non-mobile. Destination SEP (b = 0.74, 95% CI = 0.57, 0.92) predominated in influence over origin, although both life stages exerted significant influence on later-life AL. Social mobility in either direction was not associated with AL burden. Mobility coefficients were substantially small across a large variety of model specifications. DISCUSSION: Findings provide evidence for an accumulation model of social inequalities in which disparities in health are diluted rather than increased by social mobility (i.e., gradient constraint), with the socially mobile having an AL score that is intermediate between their origin class and destination class. This implies that the effects of origin SEP on health are not immutable, but are instead responsive to changing socioeconomic circumstances across the life course.

The Role of Epigenetic Clocks in Explaining Educational Inequalities in Mortality: A Multicohort Study and Meta-analysis.

Educational inequalities in all-cause mortality have been observed for decades. However, the underlying biological mechanisms are not well known. We aimed to assess the role of DNA methylation changes in blood captured by epigenetic clocks in explaining these inequalities. Data were from 8 prospective population-based cohort studies, representing 13 021 participants. First, educational inequalities and their portion explained by Horvath DNAmAge, Hannum DNAmAge, DNAmPhenoAge, and DNAmGrimAge epigenetic clocks were assessed in each cohort via counterfactual-based mediation models, on both absolute (hazard difference) and relative (hazard ratio) scales, and by sex. Second, estimates from each cohort were pooled through a random effect meta-analysis model. Men with low education had excess mortality from all causes of 57 deaths per 10 000 person-years (95% confidence interval [CI]: 38, 76) compared with their more advantaged counterparts. For women, the excess mortality was 4 deaths per 10 000 person-years (95% CI: -11, 19). On the relative scale, educational inequalities corresponded to hazard ratios of 1.33 (95% CI: 1.12, 1.57) for men and 1.15 (95% CI: 0.96, 1.37) for women. DNAmGrimAge accounted for the largest proportion, approximately 50%, of the educational inequalities for men, while the proportion was negligible for women. Most of this mediation was explained by differential effects of unhealthy lifestyles and morbidities of the World Health Organization (WHO) risk factors for premature mortality. These results support DNA methylation-based epigenetic aging as a signature of educational inequalities in life expectancy emphasizing the need for policies to address the unequal social distribution of these WHO risk factors.

Special Report: The Biology of Inequalities in Health: The Lifepath Consortium.

Funded by the European Commission Horizon 2020 programme, the Lifepath research consortium aimed to investigate the effects of socioeconomic inequalities on the biology of healthy aging. The main research questions included the impact of inequalities on health, the role of behavioral and other risk factors, the underlying biological mechanisms, the efficacy of selected policies, and the general implications of our findings for theories and policies. The project adopted a life-course and comparative approach, considering lifetime effects from childhood and adulthood, and pooled data on up to 1.7 million participants of longitudinal cohort studies from Europe, USA, and Australia. These data showed that socioeconomic circumstances predicted mortality and functional decline as strongly as established risk factors currently targeted by global prevention programmes. Analyses also looked at socioeconomically patterned biological markers, allostatic load, and DNA methylation using richly phenotyped cohorts, unraveling their association with aging processes across the life-course. Lifepath studies suggest that socioeconomic circumstances are embedded in our biology from the outset-i.e., disadvantage influences biological systems from molecules to organs. Our findings have important implications for policy, suggesting that (a) intervening on unfavorable socioeconomic conditions is complementary and as important as targeting well-known risk factors, such as tobacco and alcohol consumption, low fruit and vegetable intake, obesity and a sedentary lifestyle, and that (b) effects of preventive interventions in early life integrate interventions in adulthood. The report has an executive summary that refers to the different sections of the main paper.

Socioeconomic disadvantage and health in early childhood: a population-based birth cohort study from Portugal.

BACKGROUND: Measuring early socioeconomic inequalities in health provides evidence to understand the patterns of disease. Thus, our aim was to determine which children's health outcomes are patterned by socioeconomics and to what extent the magnitude/direction of the differences vary by socioeconomic measure and outcome. METHODS: Data on early childhood (4 years) health was obtained from Generation XXI birth cohort (n = 8647). A total of 27 health outcomes and 13 socioeconomic indicators at the individual level and neighbourhood level were used to calculate the relative index of inequality (RII). RESULTS: Socioeconomic inequalities were evident across 21 of the 27 health outcomes. Education, occupation and income more often captured inequalities, compared with neighbourhood deprivation or employment status. Using highest maternal education as reference category, we observed that seizures (RII = 8.64), obesity (2.94), abdominal obesity (2.66), urinary tract infection (2.26), language/speech problems (2.24), hypertension (2.08) and insulin resistance (1.33) were heavily socially patterned, much more common in disadvantaged children. Contrastingly, eczema (0.26) and rhinitis (0.26) were more common among more advantaged children. CONCLUSIONS: Socioeconomic inequalities were evident for almost every health outcome assessed, although with varying magnitude/direction according to the socioeconomic indicator and outcome. Our results reinforce that the social gradient in health manifests early in childhood.

Socioeconomic Position and Incidence of Glomerular Diseases.

BACKGROUND AND OBJECTIVES: Social deprivation is a recognized risk factor for undifferentiated CKD; however, its association with glomerular disease is less well understood. We sought to investigate the relationship between socioeconomic position and the population-level incidence of biopsy-proven glomerular diseases. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In this retrospective cohort study, a provincial kidney pathology database (2000-2012) was used to capture all incident cases of membranous nephropathy (n=392), IgA nephropathy (n=818), FSGS (n=375), ANCA-related GN (ANCA-GN, n=387), and lupus nephritis (n=389) in British Columbia, Canada. Quintiles of area-level household income were used as a proxy for socioeconomic position, accounting for regional differences in living costs. Incidence rates were direct standardized to the provincial population using census data for age and sex and were used to generate standardized rate ratios. For lupus nephritis, age standardization was performed separately in men and women. RESULTS: A graded increase in standardized incidence with lower income was observed for lupus nephritis (P<0.001 for trend in both sexes) and ANCA-GN (P=0.04 for trend). For example, compared with the highest quintile, the lowest income quintile had a standardized rate ratio of 1.7 (95% confidence interval, 1.19 to 2.42) in women with lupus nephritis and a standardized rate ratio of 1.5 (95% confidence interval, 1.09 to 2.06) in ANCA-GN. The association between income and FSGS was less consistent, in that only the lowest income quintile was associated with a higher incidence of disease (standardized rate ratio, 1.55; 95% confidence interval, 1.13 to 2.13). No significant associations were demonstrated for IgA nephropathy or membranous nephropathy. CONCLUSIONS: Using population-level data and a centralized pathology database, we observed an inverse association between socioeconomic position and the standardized incidence of lupus nephritis and ANCA-GN.

Health inequalities: Embodied evidence across biological layers.

RATIONALE: Socioeconomic disparities have been documented in major non-communicable diseases and in their risk factors, such as obesity, hypertension, diabetes, smoking, physical inactivity, unhealthful diet and heavy drinking. However, a key research question has remained unanswered: is there a separate biological embodiment of socio-economic conditions underlying health disparities, additional and independent of those risk factors? As lifelong socioeconomic circumstances cannot be randomised, one way forward is the examination of different biological layers of evidence, including molecular changes. METHOD: In this methodological paper we report the association of socio-economic disadvantage with (a) long-term health outcomes, before and after taking risk factors into account; (b) biological intermediaries that increase susceptibility to disease, such as childhood obesity; (c) intermediate circulating biomarkers and omic measurements (transcriptomics, DNA methylation, inflammatory proteins, allostatic load); and (d) immunity. In our Lifepath consortium, these analyses have been performed in several cohort studies, countries and contexts, and at different stages of the life course in up to 1.7 million subjects. The main goal is to test the assumption that each layer (death, functional outcomes, DNA, RNA, proteins, infections) is characterized by different types of bias and confounding, and that consistency across layers reinforces causality assessment. RESULTS: The findings show consistent associations of social disparities with unfavourable health outcomes spanning inflammatory biomarkers, DNA or RNA-based markers, infection, indicators of physical functioning and mortality. Although each of these associations has a different set of confounders, a dose-response relationship is nevertheless consistently observed, thus showing the power of our multi-layered approach. CONCLUSIONS: This new evidence supports biological embodiment of social disadvantage, in addition to the impact of known (mainly behavioural) risk factors for disease.

Maternal educational inequalities in measured body mass index trajectories in three European countries.

BACKGROUND: Social inequalities in the prevalence of childhood overweight and obesity are well-established, but less is known about when the social gradient first emerges and how it evolves across childhood and adolescence. OBJECTIVE: This study examines maternal education differentials in children's body mass trajectories in infancy, childhood and adolescence using data from four contemporary European child cohorts. METHODS: Prospective data on children's body mass index (BMI) were obtained from four cohort studies-Generation XXI (G21-Portugal), Growing Up in Ireland (GUI) infant and child cohorts, and the Millennium Cohort Study (MCS-UK)-involving a total sample of 41,399 children and 120,140 observations. Children's BMI trajectories were modelled by maternal education level using mixed-effect models. RESULTS: Maternal educational inequalities in children's BMI were evident as early as three years of age. Children from lower maternal educational backgrounds were characterised by accelerated BMI growth, and the extent of the disparity was such that boys from primary-educated backgrounds measured 0.42 kg/m2 (95% CI 0.24, 0.60) heavier at 7 years of age in G21, 0.90 kg/m2 (95% CI 0.60, 1.19) heavier at 13 years of age in GUI and 0.75 kg/m2 (95% CI 0.52, 0.97) heavier in MCS at 14 years of age. The corresponding figures for girls were 0.71 kg/m2 (95% CI 0.50, 0.91), 1.31 kg/m2 (95% CI 1.00, 1.62) and 0.76 kg/m2 (95% CI 0.53, 1.00) in G21, GUI and MCS, respectively. CONCLUSIONS: Maternal education is a strong predictor of BMI across European nations. Socio-economic differentials emerge early and widen across childhood, highlighting the need for early intervention.

Decomposing the social gradient in children's vocabulary skills at 3 years of age: A mediation analysis using data from a large representative cohort study.

Disparities in children's expressive language by socio-economic status are evident early in childhood and impact children's development and educational attainment. This study investigated the processes by which maternal education, as a powerful indicator for socio-economic status, affects early expressive language. A nationally representative cohort study of 8,062 children resident in the Republic of Ireland were assessed on the British Ability Scales (BAS) Naming Vocabulary Test at 36 months. A significant difference of almost six points was found between the mean vocabulary test scores of children whose mothers had completed the minimum level of educational attainment compared with children whose mothers had a degree-level qualification. Mediation analysis revealed that 78% of the difference was explained by mediating variables, with differences in household income, parental practice, and material resources accounting for most of the variation. The findings support interventions which redress gaps in maternal education, income, and caregiving.

Socioeconomic position, lifestyle habits and biomarkers of epigenetic aging: a multi-cohort analysis.

Differences in health status by socioeconomic position (SEP) tend to be more evident at older ages, suggesting the involvement of a biological mechanism responsive to the accumulation of deleterious exposures across the lifespan. DNA methylation (DNAm) has been proposed as a biomarker of biological aging that conserves memory of endogenous and exogenous stress during life.We examined the association of education level, as an indicator of SEP, and lifestyle-related variables with four biomarkers of age-dependent DNAm dysregulation: the total number of stochastic epigenetic mutations (SEMs) and three epigenetic clocks (Horvath, Hannum and Levine), in 18 cohorts spanning 12 countries.The four biological aging biomarkers were associated with education and different sets of risk factors independently, and the magnitude of the effects differed depending on the biomarker and the predictor. On average, the effect of low education on epigenetic aging was comparable with those of other lifestyle-related risk factors (obesity, alcohol intake), with the exception of smoking, which had a significantly stronger effect.Our study shows that low education is an independent predictor of accelerated biological (epigenetic) aging and that epigenetic clocks appear to be good candidates for disentangling the biological pathways underlying social inequalities in healthy aging and longevity.

How does socio-economic position (SEP) get biologically embedded? A comparison of allostatic load and the epigenetic clock(s).

Individuals of lower socio-economic position (SEP) carry a heavier burden of disease and morbidity and live shorter lives on average compared with their more advantaged counterparts. This has sparked research interest in the processes and mechanisms via which social adversity gets biologically embedded. The present study directly compares the empirical worth of two candidate mechanisms: Allostatic Load (AL) and the Epigenetic Clock(s) for advancing our understanding of embodiment using a sub-sample of 490 individuals from the Irish Longitudinal Study (TILDA) who were explicitly selected for this purpose based on their inter-generational life course social class trajectory. A battery of 14 biomarkers representing the activity of 4 different physiological systems: Immunological, Cardiovascular, Metabolic, and Renal was used to construct the AL score. Biomarkers were dichotomised into high and low risk groups according to sex-specific quartiles of risk and summed to create a count ranging from 0-14. Three measures of epigenetic age acceleration were computed according to three sets of age-associated Cytosine-phosphate-Guanine (CpG) sites described by Horvath, Hannum and Levine. AL was strongly socially patterned across a number of measures of SEP, while the epigenetic clocks were not. AL partially mediated the association between measures of SEP and an objective measure of physiological functioning: performance on the Timed Up and Go (TUG test). We conclude that AL may represent the more promising candidate for understanding the pervasive link between SEP and health.

A Comparative Analysis of the Status Anxiety Hypothesis of Socio-economic Inequalities in Health Based on 18,349 individuals in Four Countries and Five Cohort Studies.

The status anxiety hypothesis proposes that systematic inflammation as a consequence of chronic psycho-social stress is a possible pathway linking socio-economic position (SEP) to premature ageing and is a possible explanation for cross-national variation in patterns of health and well-being. Harmonised data from the LIFEPATH consortium on 18,349 individuals aged 50 to 75 and 30,632 observations are used to measure variation in the association between inflammation measured as C-reactive protein and SEP across four countries (Britain, Ireland, Portugal and Switzerland) and five studies (ELSA, Whitehall II, TILDA, EPIPorto and SKIPOGH). Adjusting for population composition, mean concentrations of CRP are highest in Portugal, the country with the highest income inequality and lowest in Switzerland, a lower income inequality country. Across all of the studies, lower SEP groups have higher mean concentrations of CRP and, as predicted by the theory, absolute differentials between SEP groups reflect the pattern of societal income inequality. Adjustment for lifestyle indicators reduces SEP differentials by between 45% and 52% but cannot account for country variation in mean inflammation.

Fiscal crises and personal troubles: the great recession in Ireland and family processes.

BACKGROUND: Social disadvantage is often associated with worse child psychological adjustment which itself is implicated in educational failure and poor adult social position. The family stress model holds that the association between social disadvantage and psychological adjustment stems from the impact of economic pressure on parental mental health mediated through the parent/child relationship. METHODS: We take advantage of a natural experiment offered by the 'great recession' in Ireland between 2008 and 2012. Structural equation models using causal modelling and Longitudinal data from the Growing Up in Ireland cohort study are used to test whether the experience of recession in families impacts on children's psychological adjustment and whether this occurs directly or is mediated by the processes identified in the family stress model. RESULTS: More than 70% of families experienced a reduction in income between 2008 and 2011 and 26% reported cutting back on basics such as clothing and food. Family experience of recession was significantly associated with negative change in all of the components of the family stress model, particularly parental mental health. However, less than half of the effect of recession was mediated by the processes of the family stress model. Tests showed that a model with a direct effect of recession on child psychological adjustment provided a better fit to the data. CONCLUSIONS: Recession and economic pressure had a significant effect on child psychological adjustment, but only a minority of this effect was indirect via the mental health of parents and parent/child relationship. The family stress model only offers a partial account of the mechanisms through which economic hardship impacts on families and children.

Kidney Disease in Women is Associated with Disadvantaged Childhood Socioeconomic Position.

BACKGROUND: Socioeconomic position (SEP) is an important determinant of health and it is dynamic across the entire lifespan. We sought to investigate the relationship between life-course SEP and chronic kidney disease (CKD) using 3 conceptual models: critical period, pathway and accumulation. METHODS: Cross-sectional analysis of 4,996 participants from The Irish Longitudinal Study on Ageing, a nationally representative cohort of community-dwelling adults aged ≥50 years. We defined childhood and adulthood SEP according to father's and respondent's occupation respectively. SEP was categorised as high (reference), intermediate, low and never worked. CKD was defined as a glomerular filtration rate < 60 mL/min/1.73 m2 estimated from the combination of creatinine and cystatin C. We used logistic regression to estimate the age-adjusted association between SEP and CKD separately in men and women. RESULTS: Low childhood SEP was strongly associated with CKD in women, after adjusting for adulthood SEP (OR 1.90 [95% CI 1.24-2.92]), supporting the critical period hypothesis. This association was not explained by traditional CKD risk factors. Women who experienced low childhood SEP and whose circumstances improved in adulthood also had increased odds of CKD, further supporting a critical period effect in childhood. There was comparatively less evidence in support of the pathway or accumulation models. We did not observe a statistically significant association between SEP and CKD in men. CONCLUSIONS: Our findings suggest that women exposed to disadvantaged SEP in childhood represent an at-risk group in whom there may be opportunities for identification of CKD and facilitation of health-promoting behaviours from an early age.

Socioeconomic status, non-communicable disease risk factors, and walking speed in older adults: multi-cohort population based study.

OBJECTIVE: To assess the association of low socioeconomic status and risk factors for non-communicable diseases (diabetes, high alcohol intake, high blood pressure, obesity, physical inactivity, smoking) with loss of physical functioning at older ages. DESIGN: Multi-cohort population based study. SETTING: 37 cohort studies from 24 countries in Europe, the United States, Latin America, Africa, and Asia, 1990-2017. PARTICIPANTS: 109 107 men and women aged 45-90 years. MAIN OUTCOME MEASURE: Physical functioning assessed using the walking speed test, a valid index of overall functional capacity. Years of functioning lost was computed as a metric to quantify the difference in walking speed between those exposed and unexposed to low socioeconomic status and risk factors. RESULTS: According to mixed model estimations, men aged 60 and of low socioeconomic status had the same walking speed as men aged 66.6 of high socioeconomic status (years of functioning lost 6.6 years, 95% confidence interval 5.0 to 9.4). The years of functioning lost for women were 4.6 (3.6 to 6.2). In men and women, respectively, 5.7 (4.4 to 8.1) and 5.4 (4.3 to 7.3) years of functioning were lost by age 60 due to insufficient physical activity, 5.1 (3.9 to 7.0) and 7.5 (6.1 to 9.5) due to obesity, 2.3 (1.6 to 3.4) and 3.0 (2.3 to 4.0) due to hypertension, 5.6 (4.2 to 8.0) and 6.3 (4.9 to 8.4) due to diabetes, and 3.0 (2.2 to 4.3) and 0.7 (0.1 to 1.5) due to tobacco use. In analyses restricted to high income countries, the number of years of functioning lost attributable to low socioeconomic status by age 60 was 8.0 (5.7 to 13.1) for men and 5.4 (4.0 to 8.0) for women, whereas in low and middle income countries it was 2.6 (0.2 to 6.8) for men and 2.7 (1.0 to 5.5) for women. Within high income countries, the number of years of functioning lost attributable to low socioeconomic status by age 60 was greater in the United States than in Europe. Physical functioning continued to decline as a function of unfavourable risk factors between ages 60 and 85. Years of functioning lost were greater than years of life lost due to low socioeconomic status and non-communicable disease risk factors. CONCLUSIONS: The independent association between socioeconomic status and physical functioning in old age is comparable in strength and consistency with those for established non-communicable disease risk factors. The results of this study suggest that tackling all these risk factors might substantially increase life years spent in good physical functioning.

The Great Recession and the Health of Young Children: A Fixed-Effects Analysis in Ireland.

Economic recessions have been linked to adult health, but few studies have examined how recessions influence the health of young children. This study examined the impact of life transitions linked to the recent financial crisis on the health of young children in Ireland. Data came from the Growing Up in Ireland Infant Cohort Study (n = 11,134), which assessed children before (2008), during (2011), and after (2013) the Great Recession that followed the financial crisis of 2008 and incorporated questions on the impacts of the financial crisis on families. Using fixed-effects models to control for confounding, we found that a reduction in welfare benefits during the recession was associated with a significant increase in the risks of asthma (ß = 0.014, 95% confidence interval (95% CI): 0.004, 0.023) and atopy (ß = 0.014, 95% CI: 0.001, 0.027). While parental job loss was not associated with child health, a reduction in working hours was associated with increased reports of child health problems (ß = 0.024, 95% CI: 0.004, 0.043), as were difficulties affording basic necessities (ß = 0.019, 95% CI: 0.001, 0.038). Results suggest that failing to protect vulnerable families and children during economic recessions may have long-lasting implications for child health.

Social adversity and epigenetic aging: a multi-cohort study on socioeconomic differences in peripheral blood DNA methylation.

Low socioeconomic status (SES) is associated with earlier onset of age-related chronic conditions and reduced life-expectancy, but the underlying biomolecular mechanisms remain unclear. Evidence of DNA-methylation differences by SES suggests a possible association of SES with epigenetic age acceleration (AA). We investigated the association of SES with AA in more than 5,000 individuals belonging to three independent prospective cohorts from Italy, Australia, and Ireland. Low SES was associated with greater AA (ß = 0.99 years; 95% CI 0.39,1.59; p = 0.002; comparing extreme categories). The results were consistent across different SES indicators. The associations were only partially modulated by the unhealthy lifestyle habits of individuals with lower SES. Individuals who experienced life-course SES improvement had intermediate AA compared to extreme SES categories, suggesting reversibility of the effect and supporting the relative importance of the early childhood social environment. Socioeconomic adversity is associated with accelerated epigenetic aging, implicating biomolecular mechanisms that may link SES to age-related diseases and longevity.

Socioeconomic differences in children's growth trajectories from infancy to early adulthood: evidence from four European countries.

BACKGROUND: Height is regarded as a marker of early-life illness, adversity, nutrition and psychosocial stress, but the extent to which differences in height are determined by early-life socioeconomic circumstances, particularly in contemporary populations, is unclear. This study examined socioeconomic differences in children's height trajectories from birth through to 21 years of age in four European countries. METHODS: Data were from six prospective cohort studies-Generation XXI, Growing Up in Ireland (infant and child cohorts), Millennium Cohort Study, EPITeen and Cardiovascular Risk in Young Finns Study-comprising a total of 49 492 children with growth measured repeatedly from 1980 to 2014. We modelled differences in children's growth trajectories over time by maternal educational level using hierarchical models with fixed and random components for each cohort study. RESULTS: Across most cohorts at practically all ages, children from lower educated mothers were shorter on average. The gradient in height was consistently observed at 3 years of age with the difference in expected height between maternal education groups ranging between -0.55 and -1.53 cm for boys and -0.42 to -1.50 cm for girls across the different studies and widening across childhood. The height deficit persists into adolescence and early adulthood. By age 21, boys from primary educated maternal backgrounds lag the tertiary educated by -0.67 cm (Portugal) and -2.15 cm (Finland). The comparable figures for girls were -2.49 cm (Portugal) and -2.93 cm (Finland). CONCLUSIONS: Significant differences in children's height by maternal education persist in modern child populations in Europe.

Socioeconomic indicators in epidemiologic research: A practical example from the LIFEPATH study.

BACKGROUND: Several social indicators have been used in epidemiological research to describe socioeconomic position (SEP) of people in societies. Among SEP indicators, those more frequently used are education, occupational class and income. Differences in the incidence of several health outcomes have been reported consistently, independently from the indicator employed. Main objectives of the study were to present the socioeconomic classifications of the social indicators which will be employed throughout the LIFEPATH project and to compare social gradients in all-cause mortality observed in the participating adult cohorts using the different SEP indicators. METHODS: Information on the available social indicators (education, own and father's occupational class, income) from eleven adult cohorts participating in LIFEPATH was collected and harmonized. Mortality by SEP for each indicator was estimated by Poisson regression on each cohort and then evaluated using a meta-analytical approach. RESULTS: In the meta-analysis, among men mortality was significantly inversely associated with both occupational class and education, but not with father's occupational class; among women, the increase in mortality in lower social strata was smaller than among men and, except for a slight increase in the lowest education category, no significant differences were found. CONCLUSIONS: Among men, the proposed three-level classifications of occupational class and education were found to predict differences in mortality which is consistent with previous research. Results on women suggest that classifying them through their sole SEP, without considering that of their partners, may imply a misclassification of their social position leading to attenuation of mortality differences.