Madureira João, Castro Pedro, Azevedo Elsa
Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, Porto, Portugal.
Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, Porto, Portugal; Department of Neurology, Hospital Center São João, Porto, Portugal.
J Stroke Cerebrovasc Dis. 2017 Mar;26(3):500-508. doi: 10.1016/j.jstrokecerebrovasdis.2016.12.003. Epub 2016 Dec 27.
A competent cerebrovascular regulation maintains an adequate cerebral blood flow by 3 major mechanisms: cerebral autoregulation (CA), vasomotor reactivity (VMR), namely to CO, and neurovascular coupling (NVC). However, most studies generalize their results based on a response to a single parameter. Using a full battery of neurovascular stress tests, our study aims to evaluate the relationships among grades of CA, VMR, and NVC, and how their interplay is influenced by demographic and systemic hemodynamic factors.
Fifty-eight healthy adults were recruited to fit each decade age stratum from 20 to 80 years old with similar sex ratio. Arterial blood pressure (Finometer), cerebral blood flow velocity in the middle cerebral arteries (transcranial Doppler), electrocardiogram, and end-tidal CO were monitored. We assessed CA by transfer function analysis, VMR at hypocapnia and hypercapnia (carbogen 5%), and NVC response during the N-Back Task. The Montreal Cognitive Assessment scores were recorded.
Neurovascular stress tests were not affected by age or gender, and no correlation was found between their outputs (P > .05). Systemic hemodynamic parameters during tasks as well as cognitive scores had no correlation with cerebrovascular measurements (P > .05).
Age and gender do not have major influence on the 3 major cerebrovascular regulation mechanisms. Our results also pinpoint the fact that neurovascular stress tests measure different aspects of cerebrovascular control, and that their outputs are uncorrelated and cannot be used interchangeability. Being independent of age and cognitive status, neurovascular stress tests seem adequate for studying several cerebrovascular conditions affecting the aging brain.
有效的脑血管调节通过三种主要机制维持充足的脑血流量：脑自动调节（CA）、血管运动反应性（VMR），即对二氧化碳（CO）的反应，以及神经血管耦合（NVC）。然而，大多数研究基于对单一参数的反应来概括其结果。通过一系列全面的神经血管应激测试，我们的研究旨在评估CA、VMR和NVC分级之间的关系，以及它们的相互作用如何受到人口统计学和全身血流动力学因素的影响。
招募了58名健康成年人，年龄从20岁到80岁，每个十年年龄层各有合适数量且性别比例相似的参与者。监测动脉血压（Finometer）、大脑中动脉的脑血流速度（经颅多普勒）、心电图和呼气末二氧化碳。我们通过传递函数分析评估CA，通过低碳酸血症和高碳酸血症（5%的混合气）时的VMR以及在N-回溯任务期间的NVC反应。记录蒙特利尔认知评估分数。
神经血管应激测试不受年龄或性别的影响，并且在它们的输出之间未发现相关性（P > 0.05）。任务期间的全身血流动力学参数以及认知分数与脑血管测量值之间没有相关性（P > 0.05）。
年龄和性别对三种主要的脑血管调节机制没有重大影响。我们的结果还明确了这样一个事实，即神经血管应激测试测量脑血管控制的不同方面，并且它们的输出不相关，不能互换使用。独立于年龄和认知状态，神经血管应激测试似乎适用于研究影响衰老大脑的几种脑血管状况。
