FIGURE 2.

This image displays cerebrovascular reactivity (CVR) to hypercapnia in young and older adults. (A) Global CVR in young and older adults. (B) CVR in each intracranial vessel of interest [basilar artery, left (L) and right (R) internal carotid arteries (ICA), and L and R middle cerebral arteries (MCA)]. CVR was calculated as the linear relationship between cerebrovascular conductance (CVC) (flow/mean arterial pressure × 100) and end-tidal carbon dioxide during 4 and 6% CO₂ inhalation. Young adults are shown in black and older adults are shown in gray. Data are mean ± standard error. ^∗p < 0.05. Global CVR was significantly lower in older adults compared with young adults. These results persisted in each vessel of interest (basilar artery, ICAs, and MCAs).