Age and Sex Differences in Cerebral Hemodynamics

Abstract

Background and Purpose-Hemodynamic factors seem to play an important role in the pathogenesis of cerebral ischemic events. The aim of this study was to evaluate whether changes in cerebrovascular reactivity occur in women after menopause. Methods-Using transcranial Doppler ultrasonography, we studied the changes of flow velocity after hypercapnia in the middle cerebral arteries of 45 healthy premenopausal women (mean age, 32.3 years; range, 20 to 47 years) and 40 postmenopausal women (mean age, 54.4 years; range, 48 to 64 years). The same measurements were recorded in two groups of healthy male subjects age matched with premenopausal (45 subjects) and postmenopausal women (40 subjects). Moreover, a subgroup of postmenopausal women aged 48 to 53 years (15 subjects) were compared with a group of 15 premenopausal women of the same age. We obtained hypercapnia with breath holding and evaluated cerebrovascular reactivity with the breath-holding index (BHI). Results-BHI was significantly lower in postmenopausal women (0.89Ϯ0.3) than in premenopausal women (1.59Ϯ0.3;PϽ0.0001) and in young (1.34Ϯ0.5; PϽ0.001) and old men (1.20Ϯ0.4; PϽ0.04). In the latter group, BHI was significantly lower than in premenopausal women (PϽ.0001). BHI values were also significantly lower in postmenopausal than in premenopausal women of the same age (0.81Ϯ0.1 versus 1.34Ϯ0.1; PϽ0.0001). Conclusions-These findings suggest that the large reduction of cerebrovascular reactivity in postmenopausal women cannot be considered a simple factor related to aging but is probably influenced by hormonal changes. The alteration in cerebrovascular regulation could be involved in the increase of cerebrovascular disease in postmenopausal women.(Stroke. 1998;29:963-967.)

Age, aerobic fitness, and cerebral perfusion during exercise: role of carbon dioxide

“…However, since none of the subjects were predominantly engaged in resistance training this is likely not to have influenced the study outcome. Since only male volunteers were examined this also implies that the obtained data may not necessarily be valid for female although differences are not apparent (30). The PaCO 2 values reported in the present study are derived from PETCO 2 ; however, there are studies reporting good correlations between the two.…”

Hemodynamics and brain blood flow during posture change in younger women and postmenopausal women compared with age-matched men

“…It is also possible that regulation of brain blood flow could affect orthostatic tolerance, as women have a greater cerebrovascular reactivity to changes in carbon dioxide (29) (i.e., cerebrovascular vasodilatory response to higher arterial CO 2 ), yet better autoregulatory responses than men (8) (i.e., the brain's inherent ability to control flow over a wide range of perfusion pressures). Higher cerebrovascular reactivity to carbon dioxide and better autoregulatory responses in elderly women were also observed compared with that in elderly men (Ͼ70 yr old) (9); however, cerebrovascular reactivity was reported to be reduced in postmenopausal compared with younger women (39).…”

The Effects of Endogenous Sex Hormones and Acute Hypoxia on Vasoconstriction in Isolated Rat Pulmonary Artery Rings

“…Both testosterone and estrogen have been shown to acutely affect vasoreactivity in various vascular beds [11,12]. Acute administration of estrogen or testosterone to pulmonary arteries causes vasorelaxation under normoxic conditions [13].…”