Cocaine and amphetamine users face double or more the risk of having a stroke compared to nonusers, according to new research from the University of Texas Southwestern Medical Center.

Reuters reported April 2 that researcher Arthur Westover and colleagues found that cocaine users had double the risk of ischemic and hemorrhagic stroke, while amphetamine users increased their risk of hemorrhagic stroke fivefold. Risk of ischemic strokes -- in which a blockage cuts off blood flow to the brain -- did not increase for amphetamine users, however.

The drugs are believed to cause strokes by raising blood pressure and causing spasms in blood-vessel walls.

The study was published in the April 2007 issue of the Archives of General Psychiatry.