In a new study, researchers confirmed a link between smoking and subarachnoid hemorrhage (SAH), a type of bleeding stroke that occurs under the membrane that covers the brain and is frequently fatal.
The research was conducted by a team at the University of Helsinki in Finland.
In a 2010 study of nearly 80,000 twins from Denmark, Finland and Sweden, results suggested that SAH had more to do with external risk factors and very little to do with genetic influence.
Twins share either all or half their genes (identical vs. fraternal) so they are valuable for studies designed to evaluate the role of genetics versus environmental factors in disease development.
In this new study, researchers sought to clarify the factors involved when only one twin suffered from fatal bleeding in the brain and hypothesized that smoking – the most important environmental risk factor – could play a significant role.
They used health care data from the Finnish Twin Cohort, a national database of 32,564 individuals (16,282 same-sex, twin pairs in Finland) who were born before 1958 and alive in 1974, and followed for over 42 years between 1976 and 2018.
The team identified 120 fatal bleeding stroke events among the twins, and the strongest link for a fatal brain bleed was found among smokers.
Heavy and moderate smokers had 3 times the risk of fatal bleeding in the brain, while light smokers had slightly less at 2.8 times the risk.
The median age at the fatal brain bleed was 61.4 years.
The findings provide further evidence about the link between smoking and bleeding in the brain.
Risk factors such as high blood pressure, lower physical activity rates and being female were not found to be big influences in this study, unlike prior studies.
Smoking was linked to fatal bleeding in the brain consistently in both men and women and with bleeding stroke deaths within twin pairs where only one of the twins died from a bleeding stroke.
Researchers say that not smoking or quitting if you’ve already started, is an essential component of primary prevention of bleeding strokes.
One author of the study is researcher Ilari Rautalin, B.M.
The study is published in Stroke.
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