Primary and secondary allostatic processes in the context of high-stress work: A multigroup moderation from the English longitudinal study of ageing

Evidence suggests that chronic cortisol excess may precede the development of an allostatic load, and that this association may be influenced by the level of work stress. This study aims to investigate the associations between hair cortisol concentration and the development of systemic allostatic load cross-sectionally and at a lag of four years, stratified by level of effort-reward imbalance. The sample consisted of respondents from the English Longitudinal Study of Ageing (ELSA) who were in employment with hair cortisol measurements at baseline (wave 6), and allostatic load markers at baseline and follow-up (wave 8; n=411; 64 % female). Hair cortisol was used as a measure of total cortisol expression over the preceding two months. Allostatic load was modelled as a count-based index using nine markers; three per system, across the immune, metabolic and cardiovascular systems. This model was then grouped by a median-cut effort reward-imbalance scale (0.83) and regression pathways were compared between groups using a series of Chi-Squared tests of difference. Results provide evidence that higher hair cortisol concentrations predict an increase in immune and cardiovascular allostatic load cross-sectionally, and a metabolic allostatic load at a lag of four years. These pathways were found in the high effort-reward imbalance group, but not in the low effort-reward imbalance group. There were also significant differences found between groups for hair cortisol concentration as a predictor of concurrent immune and cardiovascular allostatic load Findings may indicate a novel temporality to the accumulation of an allostatic load, and that the "tipping point" between allostasis and allostatic load may lie within the ability of the HPA axis to regulate the cardiovascular system concurrently, with longitudinal consequences for metabolic syndrome indicators.