There are multiple, well-defined risk factors for stroke. Perhaps the most important risk factor is hypertension. Increasing age is also an important risk factor. It is estimated that the risk of stroke doubles for every decade after the age of fifty five. Nevertheless, stroke can be seen in young adults and even children, although the causes tend to be different than in the older age groups.
Heredity plays a role in stroke, especially if one or more parents suffered a stroke.
African-Americans have a higher risk of dying and being disabled by stroke than whites which probably, in large part, is related to a greater incidence of high blood pressure and diabetes. Diabetes mellitus is a clear risk factor for stroke, effecting both small and large blood vessels in the brain. Cigarette smoking is likewise an important risk factor for stroke. Someone who has had a prior stroke is at significant increased risk of having another stroke compared to individuals who have never had a stroke. High blood cholesterol and lipids can lead to both heart disease and stroke.