The disproportionately high rates of hypertension among African Americans (approximately 43 percent of men and 45 percent of women) have often been attributed to genetic factors, such as the theory that people from certain parts of Africa have higher levels of sensitivity to salt than people from other parts of the world. Other researchers have also considered environmental issues, such as poverty or stress, “but with the continuous availability of genetic information, biomedical researchers are increasingly seeking genetic explanations for hypertension and other racial disparities in health,” says Amy Non, PhD, a 2010-2012 Robert Wood Johnson Foundation (RWJF) Health & Society Scholar at Harvard University.
While genetics certainly play a role in many health issues, Non points out that the sheer complexity of an illness like hypertension suggests that many issues are in play. “For this reason, our study examined genetic and environmental factors simultaneously and found that African American ancestry did not correlate with high blood pressure,” says Non, who is a biological anthropologist.
The Critical Role of Education
Using data from the Family Blood Pressure Program (a large, federal study of genetics and hypertension in multicultural groups), Non and her team analyzed 3,690 Black and White Americans. There was a broad age range (13 to 80), but the mean age was 45. In addition, 55 percent of the participants were women.
The results, were published in “Education, Genetic Ancestry, and Blood Pressure in African Americans and Whites,” in the June 14, 2012 online issue of American Journal of Public Health. “We found that systolic blood pressure dropped 0.5 points for each additional year of education,” Non says. “This means that a two point decrease in blood pressure is predicted after just four years of additional education, such as a college degree. Though it may sound small at an individual level, this decrease in blood pressure is predicted to result in a significant reduction of 17 percent of blood pressure-related mortality in the total population.
These results show that education may be especially important for reducing racial disparities in health, as hypertension contributes more to racial inequalities in life expectancy than any other cause of death.”
The study population came from urban areas in ten states that included Alabama, Michigan, Massachusetts, Illinois and North Carolina. Researchers measured education in three ways: as a continuous measure from no school to one or more years of graduate school; as a two-category variable of less than or equal to a high school diploma versus more than a high school degree; and also as a five-category variable of less than a high school diploma, a high school diploma, some vocational or technical school, some college, or some graduate school.
A New Way to Cut Health Care Costs
In 2010, hypertension was estimated to cost the United States $93.5 billion in direct and related health costs, according to the Centers for Disease Control and Prevention. That fact underscores the importance of the discovery of a critical link between education and hypertension and the value of public investment in providing access to education. “Education leads to increased social support, better jobs, income, health benefits and most likely improved health behaviors,” Non says. But this work suggests it may also reduce disparities in health.
Non also hopes to encourage researchers to take a more careful look at the complex interactions between genetics and the social environment when considering racial inequalities in health and disease. “In my latest work, I am focusing on epigenetics—changes to the genome that affect how a person’s genes are expressed—and stress. I believe that psychological and social stressors may change gene expression, especially in early childhood, and may contribute to racial disparities in health. I am currently analyzing modifications to DNA in cord blood of children born to mothers with depression. I am interested in the biological mechanisms beyond genetics that may explain disease,” she says.
In addition to the fact that genetic differences cannot be broken down along racial lines, a gene is just one measure that may contribute to health. “We need to be cautious about interpreting the ancestry and disease association. Potentially important social factors need to be included in this work, so that we can identify the true causes behind racial disparities in health, and be sure to address them when formulating solutions to health problems.”
The Robert Wood Johnson Foundation Health & Society Scholars program is based on the principle that progress in the field of population health depends upon multidisciplinary collaboration and exchange. Its goal is to improve health by training scholars to rigorously investigate the connections among biological, genetic, behavioral, environmental, economic and social determinants of health; and develop and disseminate knowledge and interventions that will improve health. The program is intended to produce leaders who will change the questions asked, the methods employed to analyze problems, and the range of solutions to reduce population health disparities.