A multi-measurement approach to investigate the concept of allostatic load

Abstract

Allostatic load (AL) is a measure of cumulative, multisystemic chronic stress-related burden. Although widely associated with physical and mental health outcomes, AL has not yet been validated by data-driven techniques. To this end we used Covariance Based Structural Equation Models (SEM), Partial Least Squares SEM and Network analysis to investigate AL in three cohorts: the English Longitudinal Study of Ageing (ELSA) - Wave 6 (N= 2,695), the Midlife in the United States (MIDUS 2) Biomarker Project - Wave 2 (N= 1,255), and the Survey of Midlife in Japan (MIDJA) Biomarker Project - Wave 1 (N= 328). Three concepts of AL were tested: unifactorial (based on the AL index), two- (primary mediators- secondary outcomes) and four-interrelated systems (neuroendocrine, metabolic, cardiovascular, immune), with continuous and dichotomized (quartiles) data. Only 7 of the 48 possible models reached acceptable fit. We discuss the need to revisit the construct and choice of biomarkers of AL.