Modifiable Lifestyle Risk Factors

Cigarette smoking is the most powerful modifiable stroke risk factor. Smoking almost doubles a person's risk for ischemic stroke, independent of other risk factors, and it increases a person's risk for subarachnoid hemorrhage by up to 3.5 percent. Smoking is directly responsible for a greater percentage of the total number of strokes in young adults than in older adults. Risk factors other than smoking - like hypertension, heart disease, and diabetes - account for more of the total number of strokes in older adults.

Heavy smokers are at greater risk for stroke than light smokers. The relative risk of stroke decreases immediately after quitting smoking, with a major reduction of risk seen after 2 to 4 years. Unfortunately, it may take several decades for a former smoker's risk to drop to the level of someone who never smoked.

Smoking increases the risk of stroke by promoting atherosclerosis and increasing the levels of blood-clotting factors, such as fibrinogen. In addition to promoting conditions linked to stroke, smoking also increases the damage that results from stroke by weakening the endothelial wall of the cerebrovascular system. This leads to greater damage to the brain from events that occur in the secondary stage of stroke. (The secondary effects of stroke are discussed in greater detail in the Appendix.)

High alcohol consumption is another modifiable risk factor for stroke. Generally, an increase in alcohol consumption leads to an increase in blood pressure. While scientists agree that heavy drinking is a risk for both hemorrhagic and ischemic stroke, in several research studies daily consumption of smaller amounts of alcohol has been found to provide a protective influence against ischemic stroke, perhaps because alcohol decreases the clotting ability of platelets in the blood. Moderate alcohol consumption may act in the same way as aspirin to decrease blood clotting and prevent ischemic stroke. Heavy alcohol consumption, though, may seriously deplete platelet numbers and compromise blood clotting and blood viscosity, leading to hemorrhage. In addition, heavy drinking or binge drinking can lead to a rebound effect after the alcohol is purged from the body. The consequences of this rebound effect are that blood viscosity (thickness) and platelet levels skyrocket after heavy drinking, increasing the risk for ischemic stroke.

The use of illicit drugs, such as cocaine and crack cocaine, can cause stroke. Cocaine may act on other risk factors, such as hypertension, heart disease, and vascular disease, to trigger a stroke. It decreases relative cerebrovascular blood flow by up to 30 percent, causes vascular constriction, and inhibits vascular relaxation, leading to narrowing of the arteries. Cocaine also affects the heart, causing arrhythmias and rapid heart rate that can lead to the formation of blood clots.

Marijuana smoking may also be a risk factor for stroke. Marijuana decreases blood pressure and may interact with other risk factors, such as hypertension and cigarette smoking, to cause rapidly fluctuating blood pressure levels, damaging blood vessels.

Other drugs of abuse, such as amphetamines, heroin, and anabolic steroids (and even some common, legal drugs, such as caffeine and L-asparaginase and pseudoephedrine found in over-the-counter decongestants), have been suspected of increasing stroke risk. Many of these drugs are vasoconstrictors, meaning that they cause blood vessels to constrict and blood pressure to rise.

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