Strokes can strike suddenly and often without any warning. It is the fifth leading cause of death in the United States and claims approximately 140,000 lives annually. Every year there are some 800,000 stroke cases among Americans. While it cannot always be avoided, there are many risk factors that increase the chance of developing a stroke. By taking action early, a stroke may be preventable in many instances.
What Happens in a Stroke?
Like any part of the body, the brain needs a constant supply of oxygen. However, brain tissue is highly oxygen-sensitive. Even a minor interruption in bloody supply to the brain can cause significant effects. Oxygen reaches the brain through blood in the arteries and usually the interruption in oxygen supply arises when there is a problem in one of these arteries.
Read more on brain stroke.
There are two problems which can affect the arteries and result ina stroke. The most common is where a blood clot blocks the artery and prevents blood flow to the brain. This is known as a thromboembolic stroke. Thrombus refers to a blood clot that forms in the artery while an embolus is a blood clot that breaks away and becomes lodged elsewhere.
Therefore the clot that blocks the artery to the brain may have originated from elsewhere in the body. A thromboembolic stroke accounts for 90% of all strokes. The other 10% are known as hemorrhagic strokes. In these strokes there is a break in the artery carrying blood to the brain. The oxygen-rich blood leaks out and does not reach the brain tissue.
Without sufficient oxygen, the brain tissue undergoes a type of injury known as ischemia. This damage can sometimes be reversed. If oxygen supply is not quickly restored then the affected portion of the brain tissue can die. This is known as an infarct. A stroke is where a portion of this brain tissue dies and the damage cannot be reversed.
What are the Risks for a Stroke?
Being a male, over the age of 55 years and having a family history of strokes are some of the non-modifiable risk factors. This means it cannot be changed. Risk factors are not a certainty that a stroke will occur. It can even occur in people who are considered to be low risk.
Modifiable risk factors can be changed and this is the key to preventing a stroke. Apart from dietary and lifestyle changes, it may also require proper treatment and management of various diseases as well as regular screening. Always consult with a doctor about these stroke risks.
Read more on signs of a stroke.
Overweight or Obese
Being overweight or obese is one of the leading risk factors in strokes. This means having a BMI (body mass index) over 25 which is considered overweight or over 30 which is classified as obesity. Abdominal circumference is another factor to consider.
However, even people with a healthy body weight and normal BMI can still be at risk of strokes. It is now known that deep visceral fat which surrounds organs is more dangerous that the visible fat like belly fat (subcutaneous fat).
It is important to note that a high calorie diet and physical inactivity which are the major contributors to obesity should also be considered as stroke risk factors.
High blood pressure (hypertension) is another leading cause of strokes. It increases the risk of arterial narrowing and the formation of a blood clot. Most of the time hypertension arises for unknown reasons and is considered to be primary hypertension.
Age, obesity, physical inactivity, family history and high sodium intake ar some of the contributing factors in primary hypertension. Sometimes high blood pressure may arise due to other medical conditions and this is known as secondary hypertension.
High blood lipids (hyperlipidemia) includes high cholesterol and high triglyceride levels in the blood These lipids (fats) can become deposited in the walls of arteries to form plaques. As the plaques grow it narrows the arteries (atherosclerosis). The arteries in the neck that carry blood to the brain are commonly affected. Diet is only one risk factor in hyperlipidemia. A lack of exercise, obesity, smoking and diabetes are other risk factors.
Tobacco, Alcohol and Other Substances
Cigarette smoking is a major risk factor for strokes. It also increases the risk of various diseases such as hypertension and diabetes which are in turn risk factors for stroke. Excessive alcohol consumption is also a problem, especially if the daily consumption surpasses the recommended allowance (not more than 2 units a day) or with binge drinking. Using illicit substances like cocaine may also increase the risk of a stroke even when consumed in small quantities.
Another condition that is a significant risk factor for strokes is diabetes. Type 2 diabetes is a major problem across the globe and is associated with a host of lifestyle factors such as obesity. When diabetes is poorly controlled over the long term, it can lead to a host of different conditions.
The elevated blood glucose levels causes various problems, such as hypertension (high blood pressure), high blood cholesterol levels and narrowed arteries (atherosclerosis). All of these conditions increases the risk of strokes.
Sleep apnea is another condition that is becoming more common and this may in part be due to the rise in obesity levels across the globe. In sleep apnea, breathing stops for short periods of time while sleeping. This causes a drop in oxygen levels. It also causes a host of other disturbances in the body. Various studies have shown that obetsructive sleep apnea, the more common type of sleep apnea, is associated with a higher risk of cardiovascular diseases such as strokes.
Strokes are also associated with certain types of heart disease. It is more likely to occur in heart diseases where disturbance in heart activity increases the risk of blood clots. These clots can then travel up in the arteries to the brain where it may then block the artery. The heart diseases where this is more likely to occur are arrhythmias, endocarditis, congenital heart defects, heart valve disease and heart failure.
Read more on ways to prevent a stroke.