Regional cerebrovascular reactivity and cognitive performance among people with risk of cognitive decline

Abstract

AbstractBackgroundCerebrovascular reactivity (CVR) is an indicator of the compensatory dilatory capacity of blood vessel in the brain in response to vasoactive stimuli. BOLD MRI‐measured CVR showed that CVR is correlated with cognition. However, BOLD signal is a complex combination of multiple parameters such as cerebral blood flow (CBF), cerebral blood volume, and oxygen metabolism. In this study, we directly measured CBF using dynamic arterial spin labeling (ASL) during a hypercapnia challenge and tested if regional CVR or CBF is related to cognitive performance among people with risk of cognitive decline.MethodSeventy‐eight subjects (age: 69±7.18 years, M/F: 22/56; BMI: 27.29±5.12; years of education: 15.6 ±2.45; 12 Type 2 diabetes with 6 under treatment; 38 hypertension; 23 under treatment or 14 both; MMSE score: 28.41±1.43) enrolled in the Wake Forest Alzheimer’s Disease Research Center (ADRC) Clinical Core cohort underwent Pseudo‐continuous ASL during a 2‐minute baseline and a 2‐minute hypercapnic period with a RespirAct computer‐controlled gas blender, targeting 10mmHg higher end‐tidal CO2 level than the baseline while end‐tidal O2 level is maintained. Partial volume corrected voxel‐wise CVR was calculated (Figure 1). Multivariable linear regression analyses were performed to investigate the relationship between CBF or CVR and Mini‐Mental State Examination (MMSE) score in each ROI with adjustment for covariates: age, sex, race, BMI, years of education, hypertension/diabetic status, hypertension/diabetic medication status, and regional volume.ResultMultivariable linear regression analysis of CVR in the whole brain gray and white matter were positively associated with MMSE score (gray matter: =0.662, p=0.003, white matter: =0.474, p=0.027) (Figure 2‐a and b). Lower MMSE scores were significantly associated with lower CVR (corrected p<0.05) in 26 regions out of 122 gray matter ROIs (Figure 2‐c and 3). There was no significant relationship between regional white matter CVR and MMSE and between baseline CBF and MMSE score.ConclusionLower CVR in the whole brain gray and white matter and in the regional gray matter was related to lower MMSE score, while resting CBF showed no significant relationship with cognitive performance. Therefore, impaired CVR in the reported gray matter regions may be imaging biomarkers that predict cognitive performance.