Estrogen and Stroke

Although middle-aged women have a lower incidence of stroke than men, their risk significantly increase by as much as 50% in the decade after menopause. [457] This may be due to the fact that estrogen deficiency during the postmenopausal period leads to obesity and increases in blood pressure, cholesterol and blood sugar levels – all of which are major risk factors of stroke. Interestingly, there is robust clinical evidence that ERT may actually protect against different types of stroke:
1. In postmenopausal women, ERT use is associated with a decrease in the incidence of stroke, suggesting that the treatment is safe and effective. [458]
2. In middle-aged and older women, researchers found that ERT decreases risk of total stroke during 10.5 years follow-up. [459]
3. In younger postmenopausal women, ERT is associated with lower prevalence of stroke. [460]
4. Studies indicate a reduced risk of stroke and its consequent mortality among estrogen users. [461]
5. In younger postmenopausal women with normal blood pressure (50-59 years), there is a reduced risk of stroke associated with ERT use, particularly when lower doses are prescribed soon after menopause. [462]
6. In women aged 50-79 years, transdermal ERT reduces stroke risk by 25%. [463]
7. In users of low-dose ERT, the treatment significantly reduces the risk of stroke without any adverse side effects. [464]
8. In postmenopausal women without personal history of cardiovascular disease or contraindication to hormone therapy, short-term ERT use is associated with lower risk of stroke and is considered safe. [465]
9. In postmenopausal women, ERT protects against stroke by increasing membrane fluidity of red blood cells and improving the rigidity of cell membranes via activation of nitric oxide. [466]
10. Experimental evidence suggests that estradiol can protect the brain from stroke and that surgical removal of the ovaries removes this neuroprotective effect. [467-468]
11. In animals, estradiol administration decreases infarct size (extent of tissue injury) in the brain. [469]
12. In male adult rats, higher blood estradiol protects against ischemic injury. [470]
13. In rats, administration of estrogen protects against stroke by reducing the levels of inflammatory substances. [471-490]