Genes Don't Explain Hypertension in Blacks

Genes probably don’t deserve the blame for high blood pressure in African-Americans (search).

Studies have consistently shown that in the U.S., African-Americans tend to have higher rates of high blood pressure than whites. However, the same isn’t true of blacks overseas.

According to the researchers, conventional wisdom has led to the belief that genes predispose blacks to high blood pressure.

Yet based on this new study, it’s unlikely that genes account for America’s black-white blood pressure gap. If genetics were at work, the trend should hold around the globe. But that’s not what new research shows.

Richard S. Cooper, MD, of Loyola University’s Stricht School of Medicine, worked on the study, which appears in BMC Medicine. Cooper partnered with colleagues from Nigeria, Spain, Jamaica, Italy, Finland, Canada, Germany, Sweden, and the U.K.

Their mission: Find and analyze high-quality, international data on high blood pressure among blacks and whites. They reviewed surveys from Africa, the Caribbean, Canada, the U.S., and Europe.

For consistency, data were limited to adults aged 35-74. High blood pressure was defined as being at least 140/90 or current use of high blood pressure medicines. High blood pressure is a major risk factor for serious health concerns including heart disease and stroke.

Cooper’s team didn’t find any surprises in the U.S., where high blood pressure affects 44 percent of African-Americans. That’s 50 percent higher than the prevalence rate among U.S. whites. It’s also the highest prevalence rate of any group of blacks in the international study.

But blacks in the Caribbean (search) and Africa didn’t have the same high blood pressure problems. The gap was smaller in the U.K., and in Nigeria, only 14 percent of blacks had high blood pressure.

In fact, the world’s worst high blood pressure prevalence wasn’t seen in a black population. Instead, it was middle-aged German men of European origin, 60 percent of whom had high blood pressure.

The researchers say their data demonstrate a wide variation in the rates of high blood pressure in both racial groups: 27-55 percent in whites and 14-44 percent in blacks. It suggests that the impact of environmental factors has been underestimated.

Science -- and people around the world -- might be better off focusing on curbing the preventable causes of high blood pressure instead of hunting for racial differences, say the researchers.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Cooper, R. BMC Medicine, Jan. 4, 2005. News release, BioMed Central.