Smoking is associated with SAH in nearly half of cases and increases the risk of SAH by 2-10 times, with a dose-related effect. The SAH risk decreases with the number of years since giving up smoking, with the excess risk largely disappearing 2-4 years after cessation of smoking.
Hypertension is a common comorbid condition and, as a result, there is conflicting evidence regarding the role it plays as an independent risk factor for SAH. Some authors have found that hypertension is not a risk factor for SAH, with no notable excess over an age- and sex-matched control autopsy population, whilst others have found that hypertension does appear to be related to an increased risk of SAH.
Hypertension and smoking act as synergistic risk factors. The risk of SAH in hypertensive individuals who smoke is nearly 15 times that in the non-smoking, non-hypertensive population, although smoking poses a greater risk than hypertension to the population as a whole.
There is a strong temporal association between cocaine use and both ischemic and hemorrhagic cerebrovascular events. The use of sympathomimetic drugs, such as cocaine or metamphetamine, tends to increase the incidence and decrease the age at which rupture occurs in patients harboring aneurysms; aneurysmal size at rupture also tends to be smaller.
Many authors have suggested that hormonal status may have a role to play in the formation of IAs, given the female preponderance in most series of SAH. Use of the combined oral contraceptive (COC) may increase the risk of SAH, particularly in hypertensive smokers. More recent studies have failed to show any significant increased risk with new low-dose COC in individuals less than 35-40 years old, although, again, there may be an increased relative risk of 2.5 in older individuals.
The role of pregnancy as a risk factor for SAH remains unclear. Older studies have shown a 1 in 10,000 pregnancies risk of SAH - a fivefold increase over the expected incidence in a population based study. This may be as a result of growth of cerebral aneurysms caused by increased laxity of vascular walls during pregnancy, although changes in blood pressure, stroke volume and blood volume may also have a role. More recent studies, however, show no significantly increased risk of SAH during pregnancy, although, as maternal mortality from other causes decreases, intracranial hemorrhage may become a more common cause of maternal mortality. Ruptured aneurysms are currently responsible for approximately 5% of maternal deaths. Mortality and morbidity of aneurysmal SAH in pregnancy are high: maternal mortality is 13-35%, whilst that of the fetus is 7-25%.
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Among the evils which a vitiated appetite has fastened upon mankind, those that arise from the use of Tobacco hold a prominent place, and call loudly for reform. We pity the poor Chinese, who stupifies body and mind with opium, and the wretched Hindoo, who is under a similar slavery to his favorite plant, the Betel but we present the humiliating spectacle of an enlightened and christian nation, wasting annually more than twenty-five millions of dollars, and destroying the health and the lives of thousands, by a practice not at all less degrading than that of the Chinese or Hindoo.