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Adults who smoke or are genetically predisposed to smoking are more likely to have a severe type of stroke called subarachnoid hemorrhage (SAH). This is according to a new study published today in Stroke, a journal of the American Stroke Association, a division of the American Heart Association. The results of this study provide important evidence that there is a causal relationship between smoking and the risk of SAH.

SAH is a type of stroke that occurs when a blood vessel on the surface of the brain bursts and bleeds into the space between the brain and the skull. It mainly affects middle-aged adults and has a high rate of complications and death.

“Previous studies have shown that smoking is associated with a higher risk of SAH. However, it was unclear whether smoking or some other confusing condition like high blood pressure was a cause of the stroke,” said lead author of the study, Guido Falcone, MD. Sc.D., MPH, Assistant Professor of Neurology at the Yale School of Medicine in New Haven, Connecticut. “A definitive, causal relationship between smoking and the risk of SAH has not been established as with other types of stroke.”

To determine whether smoking and SAH had a causal effect, the researchers analyzed the genetic data of 408,609 people in the UK biobank, ages 40 to 69, at the time of discontinuation (2006-2010). The incidence of SAH was collected throughout the study, with a total of 904 SAH occurring by the end of the study. Researchers developed a genetic risk assessment system that included genetic markers of smoking risk and tracked smoking behavior data collected at the time each participant was recruited.

The researchers found that:

  • The relationship between smoking and SAH risk appeared to be linear, with those who smoked half a pack for 20 packs of cigarettes per year had a 27% increased risk;
  • Heavy smokers, those who smoked more than 40 packs of cigarettes a year, were almost three times as likely to SAH as those who did not smoke. and,
  • People who were genetically predisposed to smoking were 63% more likely to develop SAH.

“Our results provide justification for future studies to focus on assessing whether information about genetic variants that lead to smoking can be used to better identify people at high risk for any of these types of brain haemorrhage,” said Dr . Julian N. Acosta, neurologist, postdoctoral fellow at the Yale School of Medicine, and lead study author. “These audiences could benefit from aggressive diagnostic interventions that could lead to the early detection of the aneurysms that are causing this severe type of bleeding stroke.”

The researchers say that while their results indicate stronger and more harmful effects of smoking in women and adults with high blood pressure, they believe that larger studies are needed to confirm these results. Their analysis is also limited by the type of data used in the UK biobank, which, like all major sources of information, is based on standardized treatment codes from medical charts, while smaller studies focus on more detailed health records and information for each individual.

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More information:
Stroke (2021). DOI: 10.1161 / STROKEAHA.120.031622 Provided by the American Heart Association

Quote: Smoking directly linked to a higher risk of subarachnoid hemorrhage (2021 January 14), accessed January 14, 2021 from https://medicalxpress.com/news/2021-01-linked-higher-subarachnoid-hemorrhage. html

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