A stroke is caused by either a blood clot (ischemic stroke) or a bleed (hemorrhagic stroke) inside the brain. Many conditions can increase the risk of stroke over time, especially if they are not properly treated. While the main condition that increases the risk for stroke is uncontrolled high blood pressure, conditions such as diabetes, heart disease, obesity, and atrial fibrillation (irregular heart beat) also increase risk. Other risk factors for stroke include smoking, past history of stroke or transient ischemic attack, elderly age, African American race, substance use, unhealthy diet, and insufficient exercise.[1]
What causes a stroke?
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•Last Updated: May 16, 2025
A stroke can be caused by a blood clot (ischemic stroke) or a bleed (hemorrhagic stroke) in the brain. Various conditions can increase the risk of stroke over time, particularly uncontrolled high blood pressure, along with factors like diabetes, heart disease, obesity, and lifestyle choices.