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This study found that genetic predisposition to smoking initiation causally increases the risk of ischemic stroke, especially large artery and small vessel types. Smoking does not appear to cause intracerebral hemorrhage.

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Area of Science:

  • Neurology
  • Genetics
  • Epidemiology

Background:

  • Smoking is a known risk factor for stroke.
  • The causal relationship between smoking and specific stroke subtypes remains under investigation.
  • Mendelian randomization offers a method to infer causality using genetic variants.

Purpose of the Study:

  • To investigate the potential causal association between smoking initiation and ischemic stroke (IS) and intracerebral hemorrhage (ICH).
  • To differentiate the effects of smoking on various stroke subtypes using genetic data.

Main Methods:

  • Employed a Mendelian randomization design.
  • Utilized summary statistics data from large-scale genome-wide association studies.
  • Investigated genetic predisposition to smoking initiation (ever smoking regularly) using up to 372 single-nucleotide polymorphisms (SNPs).

Main Results:

  • Genetic predisposition to smoking initiation was significantly associated with an increased risk of any ischemic stroke, large artery stroke, and small vessel stroke.
  • No significant association was found between genetic predisposition to smoking and cardioembolic stroke or intracerebral hemorrhage.
  • The findings provide strong genetic evidence supporting a causal link between smoking and ischemic stroke.

Conclusions:

  • Smoking initiation has a causal effect on the development of ischemic stroke.
  • The causal association is particularly evident for large artery and small vessel stroke subtypes.
  • This research strengthens the evidence for smoking cessation as a critical stroke prevention strategy.