Jor'dan Azizah J, Poole Victoria N, Iloputaife Ikechukwu, Milberg William, Manor Brad, Esterman Michael, Lipsitz Lewis A
Institute for Aging Research, Hebrew SeniorLife, Boston, Massachusetts.
Department of Medicine, Harvard Medical School, Boston, Massachusetts.
J Gerontol A Biol Sci Med Sci. 2017 Nov 9;72(12):1669-1675. doi: 10.1093/gerona/glx063.
Changes in cerebral blood flow velocity (CBF) in response to a cognitive task (task-related ΔCBF) have been shown by Transcranial Doppler ultrasonography (TCD) to be reduced in slow walkers. However, it is unknown whether reduced task-related ΔCBF is associated with reduced neural activity in specific brain regions, as measured by blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI).
We assessed the regional changes in neural activity associated with reduced middle cerebral artery (MCA) task-related ΔCBF to an executive task and slow walking speed in 67 community-dwelling older adults from the MOBILIZE Boston Study. Participants underwent walking assessments and TCD ultrasonography measures of MCA ΔCBF during the n-back task of executive function. A subset of participants (n = 27) completed the same task during fMRI. Individual BOLD activation maps for the n-back task were correlated with TCD measures and network-level averages were associated with TCD and preferred walking speed.
Participants with diminished task-related ΔCBF walked more slowly (β = .39, p = .001). fMRI revealed significant associations between task-related ΔCBF and regional BOLD activation in several brain regions/networks supplied by the MCA. Of these regions and networks, those within the executive network were most strongly associated with walking speed (β = .36, p = .01).
Task-related ΔCBF during an executive function task is related to activation in several neural networks and impairment in the ability to recruit the executive network in particular is associated with slow walking speed in older adults.
经颅多普勒超声检查（TCD）显示，慢行者对认知任务的脑血流速度变化（与任务相关的ΔCBF）有所降低。然而，尚不清楚与任务相关的ΔCBF降低是否与特定脑区神经活动的减少有关，这可通过血氧水平依赖性功能磁共振成像（BOLD-fMRI）来测量。
我们评估了来自波士顿MOBILIZE研究的67名社区居住老年人中，与大脑中动脉（MCA）执行任务相关的ΔCBF降低以及步行速度减慢相关的神经活动区域变化。参与者在执行功能的n-back任务期间接受了步行评估和MCA ΔCBF的TCD超声测量。一部分参与者（n = 27）在功能磁共振成像期间完成了相同任务。n-back任务的个体BOLD激活图与TCD测量值相关，网络水平平均值与TCD和首选步行速度相关。
与任务相关的ΔCBF降低的参与者步行速度较慢（β = 0.39，p = 0.001）。功能磁共振成像显示，在MCA供应的几个脑区/网络中，与任务相关的ΔCBF和区域BOLD激活之间存在显著关联。在这些区域和网络中，执行网络内的区域与步行速度的关联最为强烈（β = 0.36，p = 0.01）。
执行功能任务期间与任务相关的ΔCBF与几个神经网络的激活有关，特别是招募执行网络的能力受损与老年人步行速度减慢有关。
