Fitzgibbon-Collins Laura K, Borrie Michael, Peters Sue, Shoemaker J Kevin, Bhangu Jaspreet
Department of Medicine, Division of Geriatric Medicine, Schulich School of Medicine & Dentistry, University of Western Ontario, London, Ontario, Canada.
Department of Kinesiology, University of Western Ontario, London, Ontario, Canada.
J Cereb Blood Flow Metab. 2025 Jun 3:271678X251345361. doi: 10.1177/0271678X251345361.
Altered cerebrovascular hemodynamics and low cerebral perfusion contribute to the development and progression of dementia. Dynamic cerebral autoregulation (dCA), a measure of the cerebral vasculature's ability to buffer abrupt changes in mean arterial pressure and prevent hypoperfusion, such as during a supine-to-standing transition, have mixed results in people clinically diagnosed with mild cognitive impairment (MCI, people with objective cognitive impairment but maintained functional independence). Therefore, in 30 people with MCI, we tested the hypothesis that participants with a higher standing middle cerebral artery velocity (MCAv) at diastole (higher-velocity group) would have lower dCA values, to confer better cerebrovascular outcomes and enhanced cognitive function compared to participants with a lower MCAv at diastole (lower-velocity group). This study separated people with MCI into different diastolic MCAv groups. dCA was calculated as (MCAv-MCAv/MCAv)/(MAP-MAP/MAP). This work led to the identification of a dysregulated dCA in the higher-velocity group (p = 0.009) compared to the lower-velocity group despite having greater cognitive scores (p = 0.008). Elevated levels of cerebral oxygen tissue saturation (p = 0.039) and lower end-tidal carbon dioxide (p = 0.042) suggest that a favourable dCA value may be a compensatory mechanism in the neurodegenerative disease processes. The unexpected results highlight the importance of uncovering hemodynamic pathways in clinical populations.
脑血管血流动力学改变和脑灌注不足会促使痴呆症的发生和发展。动态脑自动调节（dCA）是衡量脑血管系统缓冲平均动脉压突然变化并预防低灌注（如在仰卧位到站立位转换期间）能力的指标，在临床诊断为轻度认知障碍（MCI，即有客观认知障碍但保持功能独立的人）的人群中，其结果不一。因此，在30名MCI患者中，我们检验了以下假设：与舒张期大脑中动脉速度（MCAv）较低的参与者（低速组）相比，舒张期MCAv较高的参与者（高速组）的dCA值会更低，从而带来更好的脑血管结局和增强的认知功能。本研究将MCI患者分为不同的舒张期MCAv组。dCA的计算方法为（MCAv - MCAv/MCAv）/（MAP - MAP/MAP）。尽管高速组的认知得分更高（p = 0.008），但与低速组相比，本研究发现高速组存在dCA失调（p = 0.009）。脑氧组织饱和度升高（p = 0.039）和呼气末二氧化碳降低（p = 0.042）表明，有利的dCA值可能是神经退行性疾病过程中的一种代偿机制。这些意外结果凸显了在临床人群中揭示血流动力学途径的重要性。
