What is the Origin of Cerebrovascular Reactivity?

The concept is rooted in neurophysiology and clinical neurology, developed as a diagnostic tool to assess the reserve capacity of the cerebral vasculature. Its measurement has evolved from invasive techniques to non-invasive neuroimaging modalities, such as transcranial Doppler ultrasound and functional magnetic resonance imaging. CVR is increasingly recognized as a key biomarker for vascular contributions to cognitive impairment.

What is the Mechanism of Cerebrovascular Reactivity?

The underlying mechanism involves the vascular smooth muscle cells in the cerebral arterioles responding to local metabolic cues, primarily changes in partial pressure of carbon dioxide. A healthy response involves nitric oxide release and other vasoactive mediators that cause vasodilation, increasing blood flow to active brain regions. Hormonal factors, particularly estrogens, can exert a protective effect on endothelial function, thereby supporting optimal cerebrovascular reactivity.

Cerebrovascular Reactivity ∞ Area

Cerebrovascular Reactivity

Meaning

Cerebrovascular reactivity (CVR) is a physiological measure of the capacity of the cerebral blood vessels to dilate or constrict in response to a vasoactive stimulus, typically carbon dioxide or a pharmacological agent. This metric reflects the health and flexibility of the brain’s circulatory system, indicating its ability to appropriately adjust blood flow to meet metabolic demands. Diminished CVR is a clinical sign of impaired cerebral vascular health and can precede cognitive decline.