Smokers with a Familial History of Stroke are Likelier To Suffer Stroke

A new study shows that people who are smokers and have a family history of aneurysmal subarachnoid hemorrhage (aSAH) appear to be six times more likely to suffer a stroke resulting from an aSAH themselves.

Researchers at the University of Cincinnati (UC; OH, USA) reviewed 339 people prospectively recruited from 17 hospitals in the UC area, and additional control subjects were selected by random telephone digit dialing. A total of 1,016 controls were matched to cases of aSAH by age (±5 years), race, and sex. Current smokers made up half of the group that had a stroke, while the other half had never smoked or had smoked in the past.

Researchers found people who smoked and had a family history of stroke were more than six times more likely to suffer a stroke than those who did not smoke and did not have a family history of stroke or brain aneurysm. The study also found that people with a family history of stroke could cut their risk by more than half by quitting smoking. The results were the same regardless of high blood pressure, diabetes, alcohol use, body mass index (BMI) and education level. The researchers therefore concluded that the evidence of a gene-environment interaction with smoking existed for aSAH, and stressed that this finding is important when counseling family members of stroke victims and for screening of intracranial aneurysm (IA), as well as the design and interpretation of genetic epidemiology of IA studies. The study was published in the January 6, 2009, issue of Neurology.

"While all people should be advised to quit smoking, our findings suggest that there is an interaction, so that if you smoke and you have a family history of aneurysms, you are at an extremely high risk of suffering a stroke from a ruptured brain aneurysm,” said study author Daniel Woo, M.D., an associate professor in the department of neurology at UC.

In recent years, several studies have shown cigarette smoking to be an important risk factor for stroke; the nicotine and carbon monoxide (CO) in cigarette smoke damage the cardiovascular system by disrupting the cells lining the blood vessels, increasing blood fibrogen levels, increasing the stickiness of platelets, and decreasing the body's natural clot-dissolving mechanism. The use of oral contraceptives combined with cigarette smoking also greatly increases stroke risk.

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