Black–White Blood Pressure Disparities: Depressive Symptoms and Differential Vulnerability to Blood Lead

Margaret T. Hicken,¹ Gilbert C. Gee,² Cathleen Connell,³ Rachel C. Snow,³ Jeffrey Morenoff,⁴ and Howard Hu⁵


¹Department of Epidemiology, University of Michigan, Ann Arbor, Michigan, USA; ²Department of Community Health Sciences, University of California, Los Angeles, Los Angeles, California, USA; ³Department of Health Behavior and Health Education, and ⁴Department of Sociology, University of Michigan, Ann Arbor, Michigan, USA; ⁵Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada


Abstract

Background: Blacks have higher hypertension rates than whites, but the reasons for these disparities are unknown. Differential vulnerability, through which stress alters vulnerability to the effects of environmental hazards, is an emergent notion in environmental health that may contribute to these disparities.


Objectives: We examined whether blacks and whites exhibit different associations between blood lead (BPb) and blood pressure (BP) and whether depressive symptoms may play a role.


Methods: Using the National Health and Nutrition Examination Survey 2005–2008, we regressed BP on the three-way interaction among race/ethnicity, BPb, and depressive symptoms in blacks and whites ≥ 20 years of age.


Results: Blacks but not whites showed a positive association between BPb and systolic blood pressure (SBP). The disparity in this association between blacks and whites appeared to be specific to the high depressive symptoms group. In the low depressive symptoms group, there was no significant black–white disparity (β_interaction = 0.9 mmHg; 95% CI: –0.9, 2.7). However, of those with high depressive symptoms, blacks and whites had 5.6 mmHg (95% CI: 2.0, 9.2) and 1.2 mmHg (95% CI: –0.5, 2.9) increases in SBP, respectively, in association with each doubling of BPb (β_interaction = 4.4 mmHg; 95% CI: 0.5, 8.3). The pattern of results was similar for diastolic blood pressure.


Conclusions: Our results suggest that depressive symptoms may contribute to the black–white disparity in the association between BPb and BP. Depressive symptoms may result, in part, from psychosocial stress. Our results support the notion that stress increases vulnerability to the health effects of environmental hazards and suggest that stress-related vulnerability may be an important determinant of racial/ethnic health disparities.


Key words: African Americans, depressive symptoms, health status disparities, hypertension, lead, psychosocial stress. 


Environ Health Perspect 121:205–209 (2013). http://dx.doi.org/10.1289/ehp.1104517 [Online 25 October 2012]


Address correspondence to M.T. Hicken, Department of Epidemiology, School of Public Health, University of Michigan, 3436 SPH Tower, 1416 Washington Heights, Ann Arbor, MI 48109-2029 USA. Telephone: (734) 615-9205. E-mail: mhicken@umich.edu


We thank S.K. Park for helpful suggestions on earlier drafts of this paper. 


This research was financially supported by a National Institutes of Health/National Institute on Aging training grant to the Population Studies Center at the University of Michigan, T32 AG000221 (M.T.H.) and by the Robert Wood Johnson Foundation Health and Society Scholars Program (M.T.H.). 


The authors declare they have no actual or potential competing financial interests.


Received 20 September 2012; Accepted 25 October 2012; Online 25 October 2012.