Do chronic stressors lead to physiological dysregulation? Testing the theory of allostatic load.

OBJECTIVES To explore three questions: 1) Do chronic stressors predict physiological dysregulation? 2) Is that relationship moderated by characteristics of the individual and his or her social environment? and 3) Do perceived levels of stress mediate the relationship between stressors and dysregulation? METHODS Data come from a nationally representative, longitudinal study of older Taiwanese (n = 916). Regression models are used to examine the relationship between the number of life challenges (i.e., stressors) during 1996 to 2000 and physiological dysregulation (in 2000) based on 16 biomarkers that reflect neuroendocrine function, immune system, cardiovascular function, and metabolic pathways. We include interaction terms to test whether psychosocial vulnerability moderates the impact of stressors. Additional models evaluate the mediating effects of perceived stress. RESULTS We find a positive association between the number of stressors and physiological dysregulation. The results indicate that this relationship is stronger for persons with greater psychosocial vulnerability, but even so, the magnitude of the effect remains modest. We find some evidence that the level of perceived stress mediates the relationship between chronic stressors and physiological dysregulation. CONCLUSIONS Our results provide some support for the theory of allostatic load, although the relationship between life challenges and physiological dysregulation is weak. The evidence also supports the stress-buffering hypothesis: the combination of low social position, weak social networks, and poor coping ability is associated with greater physiological consequences of life challenges.