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Research report
Early-life inequalities and biological ageing: a multisystem Biological Health Score approach in U nderstanding S ociety
  1. Maryam Karimi1,2,
  2. Raphaële Castagné3,
  3. Cyrille Delpierre3,
  4. Gaëlle Albertus3,
  5. Eloïse Berger3,
  6. Paolo Vineis1,2,4,
  7. Meena Kumari5,
  8. Michelle Kelly-Irving3,
  9. Marc Chadeau-Hyam1,2
  1. 1 Department of Epidemiology and Biostatistics, School of Public Health, Imperial College London, London, UK
  2. 2 MRC-PHE Centre for Environment and Health, Imperial College London, London, UK
  3. 3 UMR1027, Université de Toulouse, UPS, Inserm, Toulouse, France
  4. 4 Italian Institute for Genomic Medicine IIGM, Torino, Italy
  5. 5 Institute for Social and Economic Research, University of Essex, Colchester, UK
  1. Correspondence to Dr Marc Chadeau-Hyam, School of Public Health, Imperial College, London W2 1 PG, UK; m.chadeau{at}imperial.ac.uk

Abstract

Social position is known to play a role in the quality of ageing, notably through the stimulation/dysregulation of key physiological systems in response to external stresses. Using data from one wave of Understanding Society including 9088 participants, we defined, as an extension of the allostatic load, a synthetic Biological Health Score (BHS) capturing the wear-and-tear of four physiological systems (endocrine, inflammatory, cardiovascular and metabolic systems) and two organs (liver and kidney). We used 16 established blood-derived biomarkers of these systems to calculate the BHS and explored the relative contribution of socioeconomic position to the BHS and its main components across age groups. We identified a systematic decreasing education-related gradient of the BHS (p<0.001) leading to lower biological risk in participants with longer education. Education-related differences in the BHS were detected early in life, and were not attributable to lifestyle and behavioural factors. We found a consistent contribution of the inflammatory and metabolic systems to the overall score throughout from early adulthood onwards, while the contribution of the other four systems seems to vary across age groups and gender. Our findings highlight the social-to-biological processes ultimately leading to health inequalities, and suggest that such disparities can already be detected in the 20–40 years old age group and cannot be fully explained by lifestyle and behavioural factors. This may define early adulthood social condition as a precursor to accelerated biological ageing and as an important target for public health policies.

  • biomarkers
  • biological ageing
  • social epidemiology

This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See: https://creativecommons.org/licenses/by/4.0/.

https://doi.org/10.1136/jech-2018-212010

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    Footnotes

    • Contributors MKa and RC contributed equally to the study. MK-I and MC-H are joint last authors. MK-I, MC-H and CD conceived the study. MKa and RC performed the statistical analyses. GA and EB contributed to the analyses and to results interpretation. MKu provided the data, contributed to the results interpretation and to manuscript drafting. All authors revised the manuscript for important intellectual content. They have seen and approved the submission of the manuscript. MC-H had full access to the data and takes responsibility for the integrity of the data and the accuracy of the data analysis and for the decision to submit for publication.

    • Funding This study was supported by the European Commission (Horizon 2020 grant no 633666 to PV). The Centre for Environment and Health is supported by the Medical Research Council and Public Health England (MR/L01341X/1). Biological measures in Understanding Society were funded through an enhancement to Economic and Social Research Council (ESRC) grant ES/N00812X/1. MKu is supported by the University of Essex and ESRC (grants RES-596-28-0001 and ES/M008592/1). MK-I is supported by the Medical Research Council (MR/R024227/1) and the National Institute on Aging (NIA), US (R01AG056477). The funders had no role in the design and conduct of the study; collection, management, analysis and interpretation of the data; and preparation, review or approval of this manuscript.

    • Competing interests None declared.

    • Patient consent for publication Not required.

    • Ethics approval Ethical approval for the nurse visit was obtained from the National Research Ethics Service (Reference: 10/H0604/2). Participants gave written consent for blood sampling.29

    • Provenance and peer review Commissioned; externally peer reviewed.