Adults who smoke, or are genetically predisposed to smoking behaviours, are more likely to experience a subarachnoid haemorrhage (SAH), new research has revealed.
The study found that while smokers are at a higher risk of SAH, that rises to over 60 per cent among those with genetic variants that predispose them to smoking.
The research, published in Stroke, a journal of the American Stroke Association, establishes a link between smoking and the risk of SAH for the first time.
While it has been proven in other types of stroke, this is pioneering research in its link with SAH – a type of stroke that occurs when a blood vessel on the surface of the brain ruptures and bleeds into the space between the brain and the skull.
Results of the study show:
- the relationship between smoking and SAH risk appeared to be linear, with those who smoked half a pack to 20 packs of cigarettes a year having a 27% increased risk;
- heavier smokers, those who smoked more than 40 packs of cigarettes a year, were nearly three times more at risk for SAH than those who did not smoke; and,
- people who were genetically predisposed to smoking behaviours were at a 63% greater risk for SAH.
Researchers also stated that while their findings suggest a more pronounced and harmful effect of smoking in women and adults with high blood pressure, they believe larger studies are needed to confirm these results.
“Previous studies have shown that smoking is associated with higher risks of SAH, yet it has been unclear if smoking or another confounding condition such as high blood pressure was a cause of the stroke,” says senior study author Guido Falcone, assistant professor of neurology at Yale School of Medicine.
“A definitive, causal relationship between smoking and the risk of SAH has not been previously established as it has been with other types of stroke.”
During the study, researchers analysed the genetic data of 408,609 people from the UK Biobank, aged 40 to 69 at time of recruitment (2006-2010).
Incidence of SAH was collected throughout the study, with a total of 904 SAHs occurring by the end of the study.
Researchers developed a genetic risk scoring system that included genetic markers associated with risk of smoking and tracked smoking behaviour data, which was collected at the time each participant was recruited.
“Our results provide justification for future studies to focus on evaluating whether information on genetic variants leading to smoking can be used to better identify people at high risk of having one of these types of brain haemorrhages,” said lead study author Julian N. Acosta, neurologist, postdoctoral research fellow at the Yale School of Medicine.
“These targeted populations might benefit from aggressive diagnostic interventions that could lead to early identification of the aneurysms that cause this serious type of bleeding stroke.”
