AbstractBackgroundAllostatic load (AL) is a measure of cumulative physiological dysregulation that is posited to capture the `wear and tear` on the body resulting from exposure to chronic stress. AL has been shown to predict disease, morbidity and mortality. Multiple studies have shown an inverse relationship between AL and SEP, but few have examined the life course social patterning of AL.MethodsUsing baseline data from The Irish Longitudinal Study on Ageing (TILDA), an AL index was calculated by summing the number of biomarkers for which respondents fell within high risk quartiles. 17 biomarkers were examined, representing cardiovascular, immune, metabolic and parasympathetic nervous systems. SEP and life course trajectories were determined using father`s occupation (at age 14) and current occupation, which were aggregated to create four categories of social mobility; stable high, downwardly mobile, upwardly mobile and stable low. Negative binomial regression models were fitted for each of the life course models of critical period, accumulation and social mobility, to examine the associations between SEP and AL (n=3,282).ResultsHigher SEP was associated with lower AL. A significant association between origin SEP and later life remained after controlling for destination SEP. The `stable high` across the life course had the lowest AL burden, the `stable low` had the highest burden, and the mobile groups ranked intermediate.ConclusionFindings suggest childhood to be a sensitive period for the embedding of early life disadvantage. The accumulation hypothesis suggests that those who spend more time disadvantaged fair worse in terms of health. This study supports this hypothesis, as those who were stable low / stable high were in the worst / best health respectively.