Arterial Stiffness, Theta Oscillations In Resting State Eeg, And Neurovascular Coupling In Young Adults

The delivery of cerebral blood flow to meet neuronal metabolic demand is termed neurovascular coupling (NVC). For younger adults, blood flow delivery during a cognitive task is less pulsatile, which is optimal for NVC. An important vascular contributor to NVC is arterial stiffness; elastic arteries minimize cerebral pulsatility. There is currently a knowledge gap on whether arterial stiffness also impacts neural activity. PURPOSE: To evaluate the association between arterial stiffness, NVC, and brain neural activity in young adults. METHODS: 49 participants (ages 18-23) underwent measures of resting state electroencephalography (rsEEG) with a low-density 20-channel system. Theta wave power was extracted from the power spectral densities within the 4-7 Hz bandwidth, with higher values signifying lower neurocognitive function. Carotid beta stiffness was calculated from distension changes measured with a 7-12 MHz linear array ultrasound probe and calibrated to carotid blood pressure (BP). Cerebral blood velocity in the left middle cerebral artery was acquired using transcranial Doppler to record Pulsatility Index (PI) at rest and during two cognitive tasks Stop Signal Task (SST) and Sustained Attention Task (SAT). NVC was defined as the change in PI, with higher values signifying lower NVC. RESULTS: Although there was no association found between carotid stiffness and theta power (r = 0.13, p>0.05), rsEEG theta power was associated with NVC PI during the SST (r = 0.41, p<0.05) and SAT (r = 0.40, p< 0.05). Carotid stiffness was also associated with NVC PI during both the SAT (r = 0.46, p<0.05) and SST (r = 0.35, p<0.05). According to results from linear regression, after adjusting for age, sex, and carotid BP, predictors of SAT NVC included carotid stiffness (unstandardized β= 0.06, 95% CI [0.02, 0.08]) and theta power (unstandardized β=0.26, 95% CI [0.03, 0.49]); predictors of SST NVC also included carotid stiffness (unstandardized β= 0.04, 95% CI [0.003, 0.07]) and theta power (unstandardized β=0.25, 95% CI [0.04, 0.45]), explaining 34% and 27% of the variance, respectively. CONCLUSION: Higher carotid stiffness and theta power are associated with lower NVC (higher PI during cognitive tasks) in a young adult population.