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Neuro rehab research

Smoking and stroke: will it make recovery worse?

“By examining gene variants that increase a person’s risk of smoking, we found that smoking does cause worse stroke outcomes.”



According to a new study, risk of worse recovery from an ischemic stroke is increased by a genetic predisposition for smoking.

Study author, Xinfeng Liu says: “Stroke recovery can vary widely among people, from full recovery to serious disability or death.

“While previous studies have found links between smoking and worse stroke recovery, it has been unclear if smoking is a cause. 

“By examining gene variants that increase a person’s risk of smoking, we found that smoking does cause worse stroke outcomes.”

In order to evaluate the genetic relationship between smoking and stroke recovery, researchers analysed the results of a meta-analysis of 12 studies from Europe, Australia and the United States, focusing on genetics and stroke recovery.

Studies included 6,021 individuals of genetic ancestry who had an ischemic stroke. 

Recovery levels were measured three months after stroke.

Recovery was defined in two ways, good and poor.

Those determined to have a good recovery, had either fully recovered or had slight disability, but required no assistance from others. 

Being determined to have a poor recovery meant that they either had moderate disability that requires assistance all the way up to death.

A total of 3,741 individuals had a good recovery, whilst 2,280 had poor recovery.

The study design used by the researchers was called Mendelian randomisation. 

This was used to determine if there was a case and effect between 373 genetic variations called single nucleotide polymorphisms (SNPs) which are known to be linked to an increased risk of smoking and poor recovery from stroke.

SNPs are common and can act as biological markers, which help to locate genes that are associated with disease.

After researchers adjusted for age, sex and stroke severity, they discovered that individuals who were genetically predisposed to smoke had a 48% greater risk of worse stroke recovery than those who were not genetically predisposed.

The results also stayed the same when researchers made further adjustments for genetically predicted alcohol consumption.

Liu says: “Our results provide genetic support for the theory that smoking causes poor recovery after ischemic stroke.

“These findings have important implications for stroke recovery. Not only should doctors encourage all people to not smoke, people who have had a stroke should be encouraged to quit smoking.”

A limitation of this study, however, is that the participants were of European ancestry, meaning larger studies are needed in other ethnic populations.