Uncontrollable factors:

• Age – Stroke becomes more common as a person ages. For each decade after 55, the chance of stroke doubles.
• Gender – Strokes happen to men slightly more often, while women make up over half of stroke fatalities.
• Race – African Americans are more likely to die from strokes, partially because of higher risk for hypertension, diabetes, and obesity.
• Family history – If someone in the immediate family has had a stroke or heart attack, particularly when young.
• Personal history – A previous stroke puts the person at a higher risk of having another one. The risk is also elevated for a prior ‘mini-stroke’, also known as a transient ischemic attack. This occurs when there is a temporary block to the brain’s blood supply and has symptoms of a full-blown stroke that pass within minutes to a few hours.
• Certain physical abnormalities – One strong risk factor is an aneurism within the skull, caused by an artery bulging due to weakened walls. Fibromuscular dysplasia, in which the arteries develop improperly, is another risk factor. Finally, there is patent foramen ovale, or a flap opening between the upper chambers of the heart, which allows blood clots to travel up into the brain.