UC Irvine

A multi-systemic biological risk index (MSBR), a proxy for allostatic load, is a composite index of biomarkers that represents dysregulation due to responses to chronic external stress. Research suggests that long term stressful conditions take a toll on one's health, providing the basis for a model that ties external stressors with bio-physiological responses, which in turn influences incidence and prognosis of disease.

This dissertation examined three aims that addressed a few gaps in the literature. For one, no previous study has accounted for major sources of chronic stress such as low social support and multiple dimensions of discrimination, which could potentially confound the allostatic load-mortality association. To address this gap we examined the association of MSBR with all-cause mortality in an African-American cohort. Next, while a few previous studies have linked a biological measure of multi-systemic stress with obesity, diabetes, and cardiovascular disease, there is no research that has examined an objective biological measure of multi-systemic stress with cancer outcomes. Lastly, we examined if exposure to discrimination, as measured by a comprehensive discrimination instrument, was associated with multi-systemic biological risk. This dissertation provides new evidence for the strong association between an index of MSBR, (a proxy for allostatic load), and cancer mortality in the NHANES III population. This was particularly evident amongst those who were overweight and obese, and the association was mainly driven by the immune and cardiovascular domains. In the Jackson Heart Study, we found that the MSBR index was positively associated with risk for mortality within an African-American cohort, and the association was higher amongst those of a younger age. This was independent of socioeconomic position, lifestyle risk factors and experiences of discrimination. Lastly, in the CARDIA study we found no association between discrimination or changes in discrimination and the MSBR index. This study provided novel data on the topic of discrimination and objectively measured health risk factors, particularly because we were able to examine change in discrimination with MSBR.