Two paths to one destination: Altered low-frequency oscillations of cerebral perfusion and oxygenation but not oxygen metabolism in mild cognitive impairment

Abstract

Cerebrovascular dysfunction, a risk factor for dementia, is challenging to detect in mild cognitive impairment (MCI). Herein, we used novel, light-based technology to investigate low-frequency hemodynamic oscillations (LFO; 0.02-0.16 Hz) in cerebral perfusion, oxygenation, and relative metabolic rate of oxygen (rCMRO₂) in MCI (n = 13; 74 ± 6 years) and cognitively-intact controls (CTL, n = 10; 69 ± 6 years). Relative cerebral microvascular perfusion and tissue oxygenation changes were recorded using a depth-enhanced optical monitoring system. Continuous wavelet transforms were used to compare average LFO power between groups (α = 0.025). Compared to controls, MCI had lower LFO power in microvascular perfusion, greater power in oxygenation (p ≤ 0.02), and no statistical difference in oscillatory power for rCMRO₂.Similar rCMRO₂ but opposing changes in oscillatory power for cerebral perfusion and oxygenation associated with MCI suggest an adaptation to maintain energy production.