Smoking May Cause Brain Bleeds

Smoking is a known risk for heart disease, COPD, and cancer. Now, research directly links smoking to subarachnoid hemorrhages — life-threatening brain bleeds.

There’s no doubt smoking is a danger to health. In fact, smoking harms almost every organ system in the body and is the leading cause of preventable death in the U.S., according to the Centers for Disease Control and Prevention (CDC).

The list of smoking risks is long. It causes most lung cancer and raises the chance of developing bladder, esophageal, throat, and other cancers. Smoking is the primary cause of chronic obstructive pulmonary disease (COPD), too, and a major cause of cardiovascular disease (CVD) — resulting in one of every four deaths from CVD. Now another often deadly medical problem, subarachnoid hemorrhage (SAH), has been directly tied, for the first time, to smoking.

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Why subarachnoid hemorrhages are extremely serious

Smoking has long been known to be a factor in the most common type of strokes, which are caused by cardiovascular disease, the CDC explains. That’s because smoking makes blood sticky and more likely to clot, damages and narrows blood vessels, and raises levels of cholesterol and triglycerides (the “bad” fats) — all factors that can clog arteries. And when blood supply to the brain is blocked, an ischemic stroke occurs.

But subarachnoid hemorrhages are different. Also known as brain bleeds, subarachnoid hemorrhages are the most dangerous type of stroke. They result when a blood vessel on the surface of the brain ruptures and bleeds into the space between the brain and the surrounding membrane (the subarachnoid space). These brain bleeds, most often occurring in middle-aged adults, have high rates of complications and death.

A subarachnoid hemorrhage is a life-threatening medical emergency that needs immediate treatment. For those who survive, recovery from a subarachnoid hemorrhage is slow, if there is any improvement at all. About 50 percent of people who survive a subarachnoid hemorrhage will have neurological disabilities for many months or even permanently.

Doctors have previously noticed people who smoke have an increased risk for a subarachnoid hemorrhage (SAH). but it was not known if the SAH and smoking link was due to health problems a smoker might have, rather than specifically being the result of cigarettes.

A Yale University research team, however, has now found evidence smoking is a direct SAH cause. What’s more, the risk of brain bleeds is extremely elevated for people with a specific genetic make-up linked to smoking, according to their study, published in Stroke.

What the research shows about smoking and brain bleeds

"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," said Guido Falcone, MD, ScD, Yale School of Medicine assistant professor of neurology and senior author of the study. "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."

To search for causal effect of smoking and brain bleeds, Falcone and his colleagues analyzed the genetic data of 408,609 people, all between the ages of 40 to 69, from the UK Biobank (a large long-term study in the United Kingdom that is investigating how genetic predisposition and environmental exposure contributes to the development of different diseases).

The UK Biobank collects information on research subjects in the study who experience subarachnoid hemorrhages, and the Yale team zeroed in on 904 of these people who experienced these brain bleeds over the course of four years, looking at who smoked and how much, and if any genetic markers associated with the risk of smoking played a role in who developed SAH.

The results showed a clear and dramatic relationship between smoking and SAH risk. Those who smoked from half a pack to 20 packs of cigarettes a year, had a 27 percent increased risk in a brain bleed, and the heaviest smokers — those who smoked more than 40 packs of cigarettes a year — had about three times the risk for SAH than non-smokers. What’s more, people who were genetically predisposed to smoking where at 63 percent more likely to have a brain bleed stroke than non-smokers.

Preventing brain bleeds is another reason to not smoke

The researchers are continuing to look for ways to identify smokers at highest risk for SAH, so hopefully they can be encouraged to quit.

“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 hemorrhages," said Yale neurologist Julian N. Acosta, MD, a lead author of the study.

Bottom line? The list of serious and life-threatening dangers of smokers continues to grow. If you are having difficulty with smoking cessation, talk to your doctor about tools, ranging from counseling to medication, that can help. Visit the CDC website for information on how to quit smoking and where to get help.

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