High Blood Pressure Linked to Inflammation

Image for hypertension article Data from the Womens Health Study, published in Circulation in 1998, indicated that women with the most inflammation in their blood had a seven-fold increased risk of heart attack or stroke . Research has recently expanded still further. For the first time, Harvard Medical School researchers have now clearly shown that inflammation may trigger high blood pressure . This is a major issue since the condition will afflict nine out of ten Americans during their lives, yet scientists still dont know what causes it.

Groundbreaking Study

Researchers from Brigham and Womens Hospital and Harvard Medical School, in Boston, Massachusetts, published their results in the December 10, 2003 issue of the Journal of the American Medical Association. Lead researcher Dr. Howard Sesso and his colleagues studied 21,000 women health professionals aged 45 years or older for an average period of eight years. All the women were participants in the larger Womens Health Study who were initially free of high blood pressure and other cardiovascular disease.

For each woman, Dr. Sesso and his colleagues recorded a baseline blood level of C-reactive protein, a marker of inflammation in the body. During the study period, about one-fourth of the women went on to develop hypertension. Researchers then correlated each womans initial blood level of C-reactive protein with her risk of later developing high blood pressure. In the analysis, they corrected for other cardiovascular risk factors such as older age, obesity, inactivity, smoking, heavy alcohol intake, family history of premature heart disease, high cholesterol, diabetes, and use of hormone replacement therapy.

The researchers found that C-reactive protein levels are significantly and independently associated with the future development of hypertension. After correcting for other coronary risk factors, women in the study with the highest levels at baseline were about 50% more likely to develop high blood pressure than those with the lowest levels. This result held true, Dr. Sesso says, even for women with no coronary risk factors and those with very low levels of baseline blood pressure. These data provide evidence that inflammation may be an important mechanism through which hypertension develops, the researchers conclude. Explaining the Connection Although the current data provide evidence for a critical role of inflammation in the development of hypertension, Dr. Sesso notes, the mechanisms of this effect are uncertain and require further evaluation. In an accompanying editorial, Scott Grundy, MD, professor at the Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, says that metabolic factors may explain the connection. For example, excess body fata known risk factor for high blood pressurestimulates the release of inflammatory substances from fat cells. Other factors such as high LDL (bad cholesterol), low HDL (good cholesterol), insulin resistance, and diabetes can further injure arterial walls and elicit an inflammatory response, he says. Clustering of these factors in what is known as metabolic syndrome is associated with increased inflammation in the body as well as heart disease and hypertension.
Other explanations for the connection also exist. Dr. Grundy says smoking can trigger both inflammatory changes and high blood pressure. Dr. Sessos research suggests that having an elevated blood level of C-reactive protein, in itself, may contribute to complex processes (such as arterial narrowing, plaque formation, and blood clotting) that can lead to high blood pressure and heart disease. Applying the Results Othr researchers have continued to explore the intriguing connection between inflammation and hypertension. In the meantime, says Dr. Sesso, Identification of individuals at risk for hypertension remains a high priority. Blood tests for C-reactive protein are available and increasingly used to look for evidence of increased cardiovascular risk. The vast majority of persons will eventually develop high blood pressure needing some kind of treatment. C-reactive protein measurements may help predict those persons with the highest risk of developing a variety of heart and circulatory disorders. If youre at risk for high blood pressure, consult your doctor about the best ways to monitor your risk and reduce your chance of getting high blood pressure. RESOURCES: American Heart Association
http://www.americanheart.org National Heart, Lung, and Blood Institute http://www.nhlbi.nih.gov/ References: Chobanian AV, Bakris GL, Black HR, et al. The seventh report of the Joint National Committee on prevention, detection, evaluation, and treatment of high blood pressure. JAMA. 2003;289:2560-2572. Grundy SM. Inflammation, hypertension, and the metabolic syndrome. JAMA. 2003;290:3000-3001. Ridker PM, Cushman M, Stampfer MJ, et al. Inflammation, aspirin and the risk of cardiovascular disease in apparently healthy men. New Engl J Med. 1997;336:973-979. Ridker, PM, Buring JF, Shih J, et al. Prospective study of C-reactive protein and risk of future cardiovascular events among apparently healthy women. Circulation . 1998;98:731-733. Sesso HD, Buring JE, Rifai N, Blake GJ, Gaziano JM, Ridker PM. C-reactive protein and the risk of developing hypertension. JAMA. 2003;290:2945-2951. Vasan RS, Beiser A, Seshadri, S, et al. Residual lifetime risk for developing hypertension in middle-aged women and men. JAMA. 2002;287:1003-1010.
Bautista LE, Atwood JE, O'Malley PG, Taylor AJ. Association between C-reactive protein and hypertension in healthy middle-aged men and women. Coron Artery Dis. 2004;15(6):331-6. Last reviewed September 2006 by Lawrence Frisch, MD, MPH Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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