UC Irvine

INTRODUCTION: Older adults with mild cognitive impairment (MCI) exhibit deficits in cerebrovascular reactivity (CVR), suggesting CVR is a biomarker for vascular contributions to MCI. This study examined if spontaneous CVR is associated with MCI and memory impairment. METHODS: One hundred sixty-one older adults free of dementia or major neurological/psychiatric disorders were recruited. Participants underwent clinical interviews, cognitive testing, venipuncture for Alzheimers disease (AD) biomarkers, and brain magnetic resonance imaging. Spontaneous CVR was quantified during 5 minutes of rest. Respiratory gases analyzed through nasal cannula to quantify end-tidal carbon dioxide (ETCO2) levels were used to estimate CVR. RESULTS: Whole brain CVR was negatively associated with age, but not MCI. Lower CVR in the parahippocampal gyrus (PHG) was found in participants with MCI and was linked to worse memory performance on memory tests. Results remained significant after adjusting for AD biomarkers and vascular risk factors. DISCUSSION: Spontaneous CVR deficits in the PHG are observed in older adults with MCI and memory impairment, suggesting medial temporal microvascular dysfunction is observed in cognitive decline. HIGHLIGHTS: Aging is associated with decline in whole brain spontaneous cerebrovascular reactivity (CVR). Older adults with mild cognitive impairment exhibit deficits in spontaneous CVR in the parahippocampal gyrus (PHG). Memory impairment is correlated with reduced spontaneous CVR in the PHG.