Adults, even in their 30s and 40s, may raise their risk of stroke by six-fold every time they use cocaine, a recent U.S. study suggests.

Based on a comparison of younger victims of a first stroke, using cocaine in the 24 hours before the event raised the risk substantially – up to eight-fold when the drug was smoked in “crack” form, researchers found.

“Among other factors, we know that cocaine causes rapid increase in blood pressure and also can cause cardiac problems that can lead to stroke,” said senior author Dr. Steven J. Kittner of the University of Maryland School of Medicine and the Veterans Affairs Maryland Health Care System in Baltimore.

The researchers analyzed data from a study that took place between 1992 and 2008, identifying more than 1,000 cases of ischemic stroke in people ages 15 to 49 years from hospitals in the Baltimore/ Washington D.C. area. Ischemic stroke is caused by the blockage of a blood vessel in or leading to the brain, often by a blood clot, and is the most common kind of stroke.

The researchers matched these stroke cases to 1,152 similar people who had not suffered a stroke.

Participants were asked to recall whether they had ever used drugs, pills or medications for nonmedical or recreational reasons or to get high.

The stroke victims were more likely than the comparison group to be tobacco smokers and to have a history of diabetes and high blood pressure.

History of cocaine use was similar in both groups, with 28 percent of stroke victims and 26 percent of the comparison group saying they had used the drug at some time in their lives. A history of ever use was not linked to increased stroke risk, the researchers report in the journal Stroke.

People who said they had used cocaine over the previous day were more than six times as likely to have suffered a stroke as people who reported never having used cocaine. That result did not change much even after researchers adjusted for tobacco smoking and alcohol use.

Only 26 people reported cocaine use within 24 hours of their stroke, and 14 said they had used within six hours of the event, researchers note.

Roughly 10 to 20 young people per 100,000 suffer an ischemic stroke, and risk is much higher for African Americans than for Caucasian people, Kittner said.

No observational study like this one can “prove” causation, but a strong case can be made that using cocaine does cause stroke, based on the totality of evidence, he told Reuters Health by email.

But this study is very important for clinical practice, said Dr. Antonio Siniscalci of Annunziata Hospital in Cosenza, Italy, who was not part of the new study.

In particular, smoking crack cocaine seems to be associated with stroke, whereas cocaine hydrochloride causes mainly bleeding of the brain, Siniscalci told Reuters Health by email.

“It is reasonable to screen young patients, particularly men, for drug use when they present with cryptogenic stroke,” or stroke of unknown origin, he said.

“Unfortunately, this is not likely to be a deterrent for addicted users or even for most considering first use,” Kittner said. “However, it is possible that a small percent of potential users could be deterred.”