Stress as a Potential Modifier of the Impact of Lead Levels on Blood Pressure: The Normative Aging Study Junenette L. Peters,1 Laura Kubzansky,2 Eileen McNeely,1 Joel Schwartz,1 Avron Spiro III,3 David Sparrow,3 Robert O. Wright,1,4 Huiling Nie,1,4 and Howard Hu1,4,5 1Department of Environmental Health, and 2Department of Society, Human Development, and Health, Harvard School of Public Health, Boston, Massachusetts, USA; 3Veterans Affairs Boston Healthcare System and Boston University Schools of Medicine and Public Health, Boston, Massachusetts, USA; 4The Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA; 5Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA Abstract Background: Lead exposure and psychological stress have been independently associated with hypertension in various populations, and animal studies suggest that when they co-occur, their effects may be exacerbated. Objectives: We examined whether psychological stress modifies the impact of cumulative lead exposure (measured as bone lead levels) on hypertension and blood pressure in Boston-area community–exposed men participating in the Normative Aging Study. Methods: We evaluated the modifying effect of stress on lead exposure on baseline hypertension status (513 participants) and on blood pressure in those without hypertension (237 participants) , cross-sectionally. In baseline nonhypertensives, we examined the same risk factors in relation to prospective risk of developing hypertension. Results: Cross-sectional analysis revealed a positive interaction between stress and tibia lead on systolic blood pressure, after adjusting for age, body mass index, family history of high blood pressure, education, smoking, alcohol consumption, physical activity, and nutritional factors. In prospective multivariate analyses, high stress also modified the effect of tibia lead and patella lead on the risk of developing hypertension. Those reporting high stress had 2.66 [95% confidence interval (CI) , 1.43–4.95] times the risk of developing hypertension per standard deviation increase in tibia lead and had 2.64 (95% CI, 1.42–4.92) times the risk per standard deviation increase in patella lead. Conclusion: To our knowledge, these are the first analyses to look at interactive effects of stress and lead on hypertension in humans. These results suggest that the effect of lead on hypertension is most pronounced among highly stressed individuals, independent of demographic and behavioral risk factors. Key words: blood pressure, bone lead, hypertension, psychosocial stress. Environ Health Perspect 115: 1154–1159 (2007) . doi:10.1289/ehp.10002 available via http://dx.doi.org/ [Online 19 March 2007] Address correspondence to J. Peters, Department of Environmental Health, Harvard School of Public Health, P.O. Box 15697, Landmark Ctr. East/Rm 3-111-23, 401 Park Dr., Boston, MA 02215 USA. Telephone: (617) 384-8647. Fax: (617) 384-8994. E-mail: jpeters@hsph.harvard.edu This research was supported by National Institutes of Health (NIH) grants R01-ES05257, P20-MD000501, P42-ES05947, and GCRC M01-RR02635. The Normative Aging Study is supported by the Cooperative Studies Program/Epidemiology Research and Information Center, U.S. Department of Veterans Affairs. The KXRF instrument used was developed by ABIOMED, Inc. (Danvers, MA) with NIH grant support (ES03918-02) . The authors declare they have no competing financial interests. Received 15 December 2006 ; accepted 19 March 2007. The full version of this article is available for free in HTML or PDF formats. |