Disparities in allostatic load, telomere length and chronic stress burden among African American adults: A systematic review.

BACKGROUND The chronic disease burden among African Americans has continued to rise. Although racial disparities in chronic disease risk are well documented, the role of chronic stress in risk disparities among racial and ethnic minorities is not well understood. This systematic review of studies reporting on the relationship between chronic stress, education, and/or income, and biomarkers of chronic stress (allostatic load and telomere length) longitudinally among African Americans, seeks to contribute to this knowledge gap. OBJECTIVE To use the existing literature to both examine the strength of two objective biomarkers--telomere length and allostatic load--as measures of the overactivation of physiological stress processes in African American adults; and determine if existing studies used these two biomarkers to assess the relationship between chronic stress, income and level of educational attainment among African Americans longitudinally. METHODS In order to identify English-language articles published prior to October 11, 2021, a comprehensive search strategy was developed using five databases: PubMed/Medline, EMBASE, Web of Science Plus, Global Health (Ovid), and PsycINFO. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method was used to record progress on the comprehensive search for studies reporting on allostatic load and/or telomere length biomarkers longitudinally within all bodily fluids and chronic stress among African American adults. RESULTS In total, 7 studies met the search criteria; 902 were excluded. Thus, less than 1% of all studies reporting on biomarkers of chronic stress longitudinally included African Americans. Each of the 7 studies described the relationship between telomere length and/or allostatic load among African Americans and chronic stress, education, and/or income. Higher chronic stress levels and experiences of racial discrimination were associated with telomere shortening while lower income and higher chronic stress levels were associated with an increase in allostatic load among African Americans. DISCUSSION Given the limited number of studies reporting on the association between allostatic load, telomere length, and/or the relationship between both in assessing chronic stress severity longitudinally among African American populations, it is impossible to determine whether one biomarker has greater predictive value than the other. However, based on the literature included in this review, higher chronic stress levels and experiences of racial discrimination were associated with shorter telomere length, while lower income and higher chronic stress levels are associated with an increase in allostatic load among African Americans. CONCLUSION These data illustrate a gap in the literature on the relationship between the biomarkers of telomere length and allostatic load combined as a potential measure for chronic stress among African Americans. To our knowledge, none the current literature describes the relationship between telomere length and allostatic load longitudinally among African American adults. As the field strives to develop a "gold standard" for measuring chronic stress, the combination of these biomarkers needs to be the subject of scientific inquiry and thus, fully examined. Future longitudinal studies among African Americans are needed to better understand which biomarker, or combination of biomarkers will provide the most accurate measure of physiological stress processes.