Age differences in spontaneous cerebrovascular reactivity at rest.

Deficits in cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) may indicate vulnerability to vascular dysfunction and cognitive impairment. Prior findings on age-related change in CVR are mixed, and no studies to date have investigated age group differences in spontaneous CVR (sCVR) at rest. The present study compared whole brain and regional sCVR at rest between 24 healthy younger adults (ages 18-34) and 163 cognitively unimpaired older adults (ages 55-87). Relative to younger adults, older adults had deficits in both whole brain and regional sCVR at rest. Among the regions examined, medial temporal lobe areas showed the largest age differences in sCVR at rest. Age differences in sCVR and CBF variability were larger than age differences in mean CBF. Results show age-related deficits in sCVR are present even in cognitively unimpaired older adults, suggesting sCVR may be indicative of cerebrovascular aging. Further research should investigate sCVR as a means for early detection of age-related vascular dysfunction that may predate irreversible vascular brain injury.