For people who carry common gene variants, cigarette smoking greatly increases the risk that a blood vessel in the brain will weaken and balloon out called an aneurysm which could be life-threatening if it ruptures, according to research presented at the American Stroke Association's International Stroke Conference 2010.
Researchers reported on two new studies from the Familial Intracranial Aneurysm (FIA) project, a multinational collaboration funded by the National Institutes of Neurological Disorders and Stroke to study genetic and other risk factors in families with at least two members affected by intracranial aneurysm.
In one study (Broderick, abstract 156), researchers found that the chance of an intracranial aneurysm increased between 37 percent and 48 percent for people who carried one copy of an identified risky gene variation. However, when the gene variant was combined with smoking the equivalent of one pack a day for 20 years, the risk increased more than five-fold. People with two copies of the gene variant were at even higher risk.
"Like putting a match to kindling, smoking greatly increases the likelihood of a ruptured aneurysm in people with a genetic susceptibility," said Joseph P. Broderick, M.D., study author and professor and chair of the neurology department at the University of Cincinnati Neuroscience Institute.
Cigarette smoking is the leading environmental cause of intracranial aneurysm. An estimated 70 percent to 80 percent of people who experience aneurysms are current or former smokers, he said. In the study, 82.5 percent of participants were smokers at some point. Intracranial aneurysms also occur in multiple members of certain susceptible families.
A ruptured intracranial aneurysm can create a subarachnoid hemorrhage. When that occurs, 40 percent of patients die, and most others experience major disability from the brain injury caused by the rapid bleeding.
By comparing the frequency in 40
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American Heart Association