Cerebrovascular reactivity (CVR) reflects the response of brain blood vessels to vasoactive stimuli, such as neural activity. The current research assessed age-related changes in regional CVR to 5% CO2 inhalation in younger (n = 30, range: 21-45 years) and older (n = 29, range: 55-75 years) adults, and the contribution of regional CVR to cognitive performance using blood-oxygen-level dependent contrast imaging (BOLD) functional magnetic resonance imaging (fMRI) at 3T field strength. CVR was measured by inducing hypercapnia using a block-design paradigm under physiological monitoring. Memory and attention were assessed with a comprehensive computerized aging battery. MRI data analysis was conducted using MATLAB® and SPM12. Memory and attention performance was positively associated with CVR in the temporal cortices. Temporal lobe CVR influenced memory performance independently of age, gender, and education level. When analyzing age groups separately, CVR in the hippocampus contributed significantly to memory score in the older group and was also related to subjective memory complaints. No associations between CVR and cognition were observed in younger adults. Vascular responsiveness in the brain has consequences for cognition in cognitively healthy people. These findings may inform other areas of research concerned with vaso-protective approaches for prevention or treatment of neurocognitive decline.
Keywords: Cerebrovascular reactivity; cognition; healthy aging; magnetic resonance imaging (MRI); memory.