Brain may hold key to cause of high blood pressure

The brain, rather than the heart, blood vessels, or the kidneys, may be where high blood pressure originates, a new research by Bristol University scientists suggests. The scientists isolated a protein, JAM-1, which seemed to trap white blood cells, impeding blood flow. This could result in inflammation and compromise the brain’s oxygen supply, triggering events that increase blood pressure. The study published in the journal, Hypertension in April 2007, could indicate new approaches to treating high blood pressure.

The study shows there is a link between JAM-1 and increased blood pressure in rats, although the precise mechanisms involved, and whether the same holds for the human brain are now the subjects of further investigations, which might confirm the potential in treating high blood pressure of drugs that reduce blood vessel inflammation and increase the brain’s blood flow.

This is not the first time scientists have suggested a link between the brain and hypertension. In 2005, researchers at the University of Oxford and Imperial College, London led by Neurosurgeon, Mr Alex Green noted that deep-brain electrical stimulation could control blood pressure in humans2. Incidentally, this technique, which typically entails stimulation of the brain’s periventricular/periaqueductal gray matter (PVG/PAG), has been in use for the treatment of intractable pain for over half a century3.

High blood pressure or hypertension is prevalent worldwide. Prehypertension (a systolic blood pressure (SBP) of 120 to 139mmHg or a diastolic blood pressure (DBP) of 80 to 89mmHg) and hypertension (SBP of 140 mm Hg or higher or DBP of 90 mm Hg or higher) affect 60% of adult Americans for example4. Furthermore, high blood pressure is a risk factor for kidney damage, heart attacks, and stroke. Although it might cause headaches, dizziness, and vision problems, it does not show any evident symptoms or signs in most persons, often until complications for example kidney damage, or even a catastrophic event such as stroke develops.

Despite its promise, researchers need to do more work to consolidate the findings of this latest study, hence the need to emphasize the benefits of the current medications, and a healthy lifestyle in controlling high blood pressure. Additionally, with research evidence indicating that despite the widespread promotion of prior guidelines by the Joint National Committee (JNC) on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure, hypertension awareness, treatment, and control even in developed countries as the US remains poor5, 6, 7, the need to intensify our efforts to increase public awareness of hypertension is doubtless, urgent.

References:

1. Hidefumi Waki, Beihui Liu, Masao Miyake, Kiyoaki Katahira, David Murphy, Sergey Kasparov, and Julian F.R. Paton. Junctional Adhesion Molecule-1 Is Upregulated in Spontaneously Hypertensive Rats. Evidence for a Prohypertensive Role Within the Brain Stem. Hypertension, Apr 2007; doi:10.1161/HYPERTENSIONAHA.106.085589

2. Green AL, Wang S, Owen SLF. Deep brain stimulation can regulate arterial blood pressure in awake humans. NeuroReport. 2005; 16:1741-1745.

3. Bittar RG, Kar-Purkayastha I, Owen SL, et al. Deep brain stimulation for pain relief: A meta-analysis. J Clin Neurosci. 2005; 12:515-519

4. Wang Y, Wang QJ. The Prevalence of Prehypertension and Hypertension Among US Adults According to the New Joint National Committee Guidelines. Arch Intern Med. 2004; 164:2126-2134

5. Burt VL, Cutler JA, Higgins M, et al. Trends in the prevalence, awareness, treatment, and control of hypertension in the adult US population. Data from the health examination surveys, 1960 to 1991. Hypertension. 1995; 26:60-69.

6. Joffres MR, Hamet P, MacLean DR, L’italien GJ, Fodor G. Distribution of blood pressure and hypertension in Canada and the United States. Am J Hypertens. 2001; 14:1099-1105.

7. Wolf-Maier K, Cooper RS, Banegas JR, et al. Hypertension prevalence and blood pressure levels in 6 European countries, Canada, and the United States. JAMA. 2003; 289:2363-2369.