What is the primary risk factor for ischemic stroke?

Hypertension, or high blood pressure, is recognized as the primary risk factor for ischemic stroke. It contributes to stroke risk through several mechanisms. High blood pressure can lead to the thickening and hardening of arteries (a process known as atherosclerosis), which narrows the arteries and reduces blood flow to the brain. It can also cause small vessel disease, where small vessels become damaged, increasing the risk of lacunar strokes.

Moreover, elevated blood pressure can cause damage to the blood vessel linings, making them more susceptible to forming clots. When a clot forms in the arteries supplying blood to the brain, it can block blood flow, leading to an ischemic stroke.

Other factors such as high cholesterol, smoking, and obesity are also significant risk factors for ischemic stroke, but they often have secondary roles compared to hypertension. For example, high cholesterol can contribute to atherosclerosis, smoking damages blood vessels, and obesity is associated with increasing blood pressure and cholesterol levels. However, managing hypertension is crucial as its control directly impacts the reduction of stroke risk, making it the most critical factor in preventing ischemic strokes.