Hypertension, defined as blood pressure >140/90 mmHg for an extended period, is the most important modifiable risk factor for stroke. Hypertension increases the risk of stroke by two to more than four times, independent of other risk factors. Elevation of either systolic or diastolic pressure is associated with greater risk. Successful, long-term treatment of hypertension can reduce the risk of stroke by as much as 33%.

Populations at special risk
It is estimated that up to 40% of adult African Americans have hypertension, compared to 20% of adult non-Hispanic whites. Furthermore, African Americans develop hypertension earlier in life, and their average blood pressures are much higher compared to most other populations. Finally, regardless of race or gender, more than 60% of all seniors over 60 years of age are hypertensive.

Relationship to stroke pathogenesis
Atherosclerotic plaque development in the carotid and vertebrobasilar system is a slowly progressive process that apparently begins in the teenage years. Vessels that are continuously subjected to high pressures are more likely to develop plaque, and it is more likely that the endothelial surface of the vessel will be damaged, promoting plaque rupture and the formation of thrombi. A thrombus can occlude the vessel locally or can break off and embolize the brain. Hypertension also increases the likelihood that small thin-walled penetrating vessels will rupture, producing an intracerebral hemorrhage.

A little about control and treatment
Recommended blood pressure is <140/90 mmHg, or <135/85 mmHg if the patient has heart failure, renal insufficiency or diabetes. For a small number of patients, treatment of kidney, adrenal or thyroid disease can reverse hypertension.  However for most patients, the physician's challenge is to create a management plan that will enable the patient to maintain the recommended blood pressure levels over an extended period. This plan usually combines lifestyle changes (smoking cessation, increased physical activity, weight loss, alcohol moderation, more fruits/vegetables and lower fat in diet) and medications. Adhering to such a regimen is difficult for many patients. One troubling statistic suggests that only about half of those who have prescribed medications actually take them consistently.