Neuroendocrine biomarkers, social relations, and the cumulative costs of stress in Taiwan

Allostatic load (AL) is thought to represent the physiological toll that builds up over the life course as a consequence of the body's response to stress. An important aim of this paper is to test this widely held-but little investigated-understanding of what AL represents. More specifically, using the Social Environment and Biomarkers of Aging Study (SEBAS), a nationally representative survey of Taiwan conducted in year 2000, this paper scrutinizes the connection between stressful life histories and neuroendocrine allostatic load (NAL). Stressful life histories are operationalized through the use of two sets of indicators: one set makes use of respondents' subjective interpretations of various life domains and the other makes use of non-subjective data about conditions that are expected to be stressful (e.g., widowhood, living alone, and low education). NAL is an index of four neuroendocrine biomarkers (cortisol, dehydroepiandrosterone sulfate (DHEAS), epinephrine, and norepinephrine) collected in blood and urine samples under resting, basal states. The major findings of this paper are twofold. First, there is little evidence to support the hypothesis that baseline levels of the neuroendocrine markers stem from stressful life histories. Second, report of current stress (among women only) is positively correlated with higher NAL levels. Taken together, these findings question whether the neuroendocrine markers of the AL construct reflect long-term processes over the life course. Indeed, evidence here suggests that the neuroendocrine markers may reflect the exact opposite-a transient state at the time of the study. (c) 2007 Elsevier Ltd. All rights reserved.