Sparto Patrick J, Aizenstein Howard J, Vanswearingen Jessie M, Rosano Caterina, Perera Subashan, Studenski Stephanie A, Furman Joseph M, Redfern Mark S
Department of Physical Therapy, University of Pittsburgh, 6035 Forbes Tower, Pittsburgh, PA 15260, USA.
Exp Brain Res. 2008 Jul;188(4):633-40. doi: 10.1007/s00221-008-1443-4. Epub 2008 Jun 11.
An increased volume of white matter hyperintensities (WMH) on MRI has been associated with mobility impairments in older adults. The objective of this preliminary study was to investigate the relationship between the volume of WMH and the delays in auditory-cued step initiation. Eight subjects aged 75-83 years participated. The WMH volume in the corticospinal tracts and anterior thalamic radiations were summed. Subjects performed an auditory-cued stepping task that included two simple reaction time (SRT) trials and three choice reaction time (CRT) trials. SRT trials required subjects to step as quickly as possible with the right foot from a symmetric standing position to a single target position in response to an auditory stimulus. For the CRT trials, subjects stepped as quickly as possible to one of two possible locations, depending on the auditory stimulus. The time from the stimulus onset to the reaction time of the anticipatory postural adjustment (APA(RT)) and liftoff (LO) of the right foot was computed for each stimulus. The mean APA(RT) and LO were greater for the CRT steps compared with the SRT steps to the same location. Increases in WMH were significantly associated with larger APA(RT) and LO during both SRT and CRT for both target locations. These data suggest that increased volume of WMH is associated with greater central processing time during voluntary step initiation, and highlight a possible mechanism that can help to explain how damage to white matter tracts affects mobility in older adults.
磁共振成像（MRI）显示，老年人脑白质高信号（WMH）体积增加与行动能力受损有关。这项初步研究的目的是调查WMH体积与听觉提示下起步延迟之间的关系。8名年龄在75至83岁之间的受试者参与了研究。计算皮质脊髓束和丘脑前辐射中的WMH体积总和。受试者进行了一项听觉提示的踏步任务，包括两次简单反应时间（SRT）试验和三次选择反应时间（CRT）试验。SRT试验要求受试者在听到听觉刺激后，尽可能快地从对称站立姿势用右脚迈向单个目标位置。对于CRT试验，受试者根据听觉刺激尽可能快地迈向两个可能位置之一。计算每次刺激从刺激开始到右脚预期姿势调整（APA(RT)）和离地（LO）反应时间。与相同位置的SRT步相比，CRT步的平均APA(RT)和LO更大。在两个目标位置的SRT和CRT过程中，WMH增加均与更大的APA(RT)和LO显著相关。这些数据表明，WMH体积增加与自愿起步过程中更长的中枢处理时间有关，并突出了一种可能的机制，有助于解释白质束损伤如何影响老年人的行动能力。
