Socioeconomic position across the lifecourse &amp; allostatic load: data from the West of Scotland Twenty-07 cohort study

Tony Robertson,Frank Popham,Michaela Benzeval

doi:10.1186/1471-2458-14-184

Abstract

BackgroundWe examined how socioeconomic position (SEP) across the lifecourse (three critical periods, social mobility and accumulated over time) is associated with allostatic load (a measure of cumulative physiological burden).MethodsData are from the West of Scotland Twenty-07 Study, with respondents aged 35 (n = 740), 55 (n = 817) and 75 (n = 483). SEP measures representing childhood, the transition to adulthood and adulthood SEP were used. Allostatic load was produced by summing nine binary biomarker scores (1 = in the highest-risk quartile). Linear regressions were used for each of the lifecourse models; with model fits compared using partial F-tests.ResultsFor those aged 35 and 55, higher SEP was associated with lower allostatic load (no association in the 75-year-olds). The accumulation model (more time spent with higher SEP) had the best model fit in those aged 35 (b = −0.50, 95%CI = −0.68, −0.32, P = 0.002) and 55 (b = −0.31, 95%CI = −0.49, −0.12, P < 0.001). However, the relative contributions of each life-stage differed, with adulthood SEP less strongly associated with allostatic load.ConclusionsLong-term, accumulated higher SEP has been shown to be associated with lower allostatic load (less physiological burden). However, the transition to adulthood may represent a particularly sensitive period for SEP to impact on allostatic load.

Highlights

We examined how socioeconomic position (SEP) across the lifecourse is associated with allostatic load
A longer time spent in a higher SEP was associated with lower allostatic load, but the association was only significant in childhood for the measure (b = −0.51, 95% CI = −0.90, −0.13, P = 0.01) and the transition to adulthood (b = −0.84, 95% CI = −1.63, −0.05, P = 0.04), but not in adulthood (b = −0.33, 95% CI = −0.83, 0.17, P = 0.19)
Findings in relation to other studies a small number of studies have tested for associations between SEP and allostatic load, there has been limited attention given to differences in the association across the lifecourse and no studies have compared the different lifecourse models directly using a structured modelling approach

Summary

Introduction

We examined how socioeconomic position (SEP) across the lifecourse (three critical periods, social mobility and accumulated over time) is associated with allostatic load (a measure of cumulative physiological burden). The most widely used construct of allostatic load has been developed by Seeman and colleagues, who have conceptualised it using biomarker measures across an array of systems including the cardiovascular, metabolic and inflammatory systems [7] This summary measure of allostatic load has been shown to predict the risk of major health outcomes including heart disease and allcause mortality [7,8,9,10,11]. Not all of the individual components of allostatic load are risk predictors for these same health outcomes Assessing these biomarkers together as allostatic load helps us to understand the synergistic nature of the physiological burden on the body imposed by exposure to damaging environmental stressors. This could make allostatic load an important, early predictor of disease risk

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