Smoking, particularly heavy smoking, is linked to some unexplained strokes in younger adults, mainly in male individuals and in people ages 45 to 49, according to a study published in the February 19,

Smoking more than doubles the risk of unexplained strokes among younger adults, a new study warns. And heavy smoking is even worse, with stroke risk more than quadrupled among adults who smoke more than a pack of cigarettes every day for 20 years compared to people who don’t smoke,

Researchers say the risk of an unexplained stroke is higher in younger adults who smoke, especially males and people ages 45 to 49. People who smoke the equivalent of 20 packs or more per year have even higher stroke risks.