From the article:
After taking account of influential factors, such as salt intake, working hours, weight and family history of diabetes, smokers were almost three times as likely to have a brain bleed as non-smokers.
The impact of smoking was cumulative: the longer and more heavily a person had smoked, the greater was their risk of a brain bleed.
Quitting smoking cut the risk of a ruptured aneurysm by 59% after five or more years – bringing it down to the level of non-smokers. But this was not the case among heavy smokers.
Those who had smoked 20 or more cigarettes a day were still more than twice as likely to have a ruptured aneurysm as those who had never smoked. […]
In the short term, smoking thickens blood and drives up blood pressure, both of which can increase the risk of a brain bleed. These effects can be reversed by stopping smoking. But smoking also induces permanent changes in the structure of artery walls, say the authors. These changes may be greater in heavy smokers, they say.