Looking for a reason to stop smoking? How about brain bleeds? A recent study found that cigarette smoking is linked to death from the extremely serious bleeding stroke called subarachnoid hemorrhage (SAH).
Researchers in Finland followed 16,282 twin pairs for over 40 years. They found that for both men and women smoking was strongly linked to death from a subarachnoid hemorrhage, and was more important than any genetic factors (which had a "modest link" to only a few deaths). They also did not find a link with high blood pressure, or levels of physical activity.
A subarachnoid hemorrhage is a type of stroke that results from bleeding in the space between the brain and the thin membrane that covers it (subarachnoid space). A SAH occurs in about 5 to 6% of all strokes. It is a medical emergency that frequently leads to death.
Excerpts from Science Daily: Smoking linked to bleeding in the brain in large, long-term study of twins
An investigation of the Finnish Twin Cohort reaffirmed 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 new study by researchers in Finland is published today in Stroke, a journal of the American Stroke Association, a division of the American Heart Association.
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 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. This study utilized 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. Researchers identified 120 fatal bleeding stroke events among the twins, and the strongest link for a fatal brain bleed was found among smokers.
"Our study provides further evidence about the link between smoking and bleeding in the brain," said corresponding researcher Ilari Rautalin, B.M., a sixth-year medical and Ph.D. student at the University of Helsinki in Finland.
Participants were separated into two groups: smokers (occasional or current) or non-smokers (never and former). Current smokers were classified according to the number of cigarettes smoked per day: light, less than 10; moderate, 10-19; heavy, 20 or more.
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.
Median age at the fatal brain bleed was 61.4 years.
Risk factors such as high blood pressure, lower physical activity rates and being female were not found to be significant influences in this investigation, unlike prior studies. Smoking was associated with 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 SAH.