High blood pressure is the leading modifiable risk factor in ischemic and hemorrhagic strokes. In fact, in more than three-fourths of first strokes, patients have blood pressure higher than 140/90.

So what exactly is a stroke?

A stroke occurs when blood flow to an area in the brain is cut off. As a result, the brain cells are deprived of the oxygen and glucose that they need to survive and they die.  If this is not caught early, permanent brain damage can result.

People who have high blood pressure are 4 to 6 times more likely to have a stroke.  If you have hypertension, this leads to atherosclerosis and hardening of the large arteries, which in turn leads to blockage and weakening of the walls of the small blood vessels in the brain, causing them to balloon and burst.  Therefore, the risk of stroke is directly related to how high the blood pressure is.

There are two types of stroke, ischemic and hemorrhagic.  However, about 80% of most strokes are ischemic.

Ischemic stroke is similar to a heart attack, except it occurs in the blood vessels of the brain.  Blood clots can form either in the brain’s blood vessels, in blood vessels leading to the brain, or even blood vessels elsewhere in the body which then travel to the brain.  These clots are dangerous, as they block blood flow to the brain’s cells.

An ischemic stroke can also occur when too much plaque, fatty deposits and cholesterol clog the brain’s blood vessels.

A hemorrhagic stroke occurs when a blood vessel in the brain breaks or ruptures.  This causes blood to seep into the brain tissue, causing damage to brain cells.  The most common causes of hemorrhagic stroke are high blood pressure and brain aneurysms.  An aneurysm is a weakness or thinness in the blood vessel wall that causes it to balloon outward.

To prevent a stroke, it is very important to take measures to lower blood pressure and cholesterol if they are elevated, control diabetes, quit smoking, exercise, and maintain a healthy weight.

Individuals at risk for stroke and heart attack may also be treated with aspirin or similar medications, which can prevent blood clots from forming. There are also procedures to remove plaque from the arteries or widen the arteries to improve blood flow, if that is the problem.  As described above, a stroke may be preventable if you maintain overall good health.