Atherosclerosis is the process by which fat is laid down on the walls of blood vessels. Fat-laden blood vessel walls have lose their natural elasticity, and increase a person's risk of stroke. The so called "atherogenic" or atherosclerosis-causing risk factors include:
High Blood Pressure: Besides being one of the strongest risk factors for heart disease, high blood pressure, also known as hypertension, is the most potent risk factor for stroke. Here are two ways by which high blood pressure increases the risk of stroke:
- If high blood pressure is chronic, it can cause the walls of blood vessels to become stiff. This process makes blood vessels weaker, and more likely to rupture and to cause a hemorrhagic stroke.
- Even if a person has normal blood pressure they can still have transient moments of elevated blood pressure. When these transient elevations in blood pressure are sudden and extreme, they can lead to bleeding inside the brain. Of course, these transient extreme elevations in blood pressure are even more dangerous in someone who has atherosclerotic blood vessels.
- Blood vessels affected by atherosclerosis induce blood clot formation.
- Blood clots growing inside the brain increase the risk of small thrombotic strokes, which are also known as lacunar strokes
- Blood clots and small fragments of fat deposits along the walls of blood vessels are likely to break off and to become trapped inside narrow atherosclerotic blood vessels inside the brain, causing embolic strokes
High Cholesterol: Blood cholesterol levels, especially the bad kind, or low density lipoprotein (LDL), cause fat to be laid along the walls of the major blood vessels that bring blood to brain (e.g., the carotid arteries). When these important blood vessels become narrowed by this process it leads to a condition known as carotid stenosis by which blood flow to the brain is significantly impaired. When people develop symptoms of stroke, they must undergo surgery to reestablish normal blood flow to the brain and prevent stroke.
High cholesterol can lead to stroke through the following cascade of events:
Diabetes: This is a disease that affects the body’s ability to transport sugar from the bloodstream into the cells that make up the body's organs. People with diabetes maintain very high levels of blood sugar, which causes damage to the walls of blood vessels in a similar way to high blood pressure and high cholesterol. Unfortunately, most people with diabetes also suffer from high blood pressure and high cholesterol, which magnifies their risk of stroke. Diabetes is second only to high blood pressure as a risk factor for stroke.
Obesity: Defined as a body mass index (BMI) of 30 or more, obesity alone is a risk factor for stroke, independent of whether a person has other risk factors such as high blood pressure, or diabetes.
Source:
Bradley G Walter, Daroff B Robert, Fenichel M Gerald, Jancovic, Joseph Neurology in clinical practice, principles of diagnosis and management. Fourth Edition, Philadelphia Elsevier, 2004.
