Antecedents of Hypertension: Role of Race and Stress

BACKGROUND: The theoretical rationale for the role of environmental stress factors in the development of essential hypertension has been outlined in several studies. Briefly, individuals at increased risk for essential hypertension are more likely than non-risk cohorts to exhibit exaggerated cardiovascular reactivity to environmental stressors. This may be especially true for Blacks compared to whites. Furthermore, individuals at risk for developing essential hypertension who are subjected to more frequent physical and/or sociopsychological stressors may experience frequent feelings of anger and hostility with concomitant exaggerated cardiovascular reactivity. Blacks may experience many of these stressors more frequently than whites. The exaggerated cardiovascular reactivity, in turn, is associated with complex neuroendocrine changes which result in pathophysiological alterations, eventually causing chronic elevated blood pressure. Although this rationale has received some empirical support in animal and human studies, definitive evidence to support an etiologic role of environmental stress factors is still lacking and needs to be tested in a prospective manner. DESIGN NARRATIVE: The study was cross-sectional and longitudinal. An estimated 1,523 children, 7 to 14 years old at baseline, whose families reported essential hypertension, participated in a blood pressure screening following medical verification of their family history of hypertension. Children whose systolic blood pressures were in the 5th to 25th percentiles or 75th to 95th percentiles were recruited. A sample of children was obtained with relatively equal distributions by race, age, gender, and blood pressure grouping. Environmental stress factors evaluated include: psychophysiological responses to physical and psychological stressors including physical exercise testing, video game, and mental arithmetic tests; sociopsychological variables including anger and hostility coping styles; and sociostructural variables including socioeconomic status and family stability. The environmental risk factors were assessed within the context of other hypertension risk factors such as cholesterol level, sodium and alcohol intake, tobacco usage, resting blood pressure, and body weight. Each child and his parents were followed annually. The study was renewed in 1994 and again in 1998 to continue follow-up for an additional four years. Follow-up continued of these adolescents and young adults who were 13 to 20 years old in 1998. The purpose was to index early markers of preclinical disease including resting blood pressure, left ventricular mass, and several new measures including plasma endothelin-1 (ET-1) and endothelium dependent arterial dilation (EDAD).