Tian Qu, Resnick Susan M, Landman Bennett A, Huo Yuankai, Venkatraman Vijay K, Gonzalez Christopher E, Simonsick Eleanor M, Shardell Michelle D, Ferrucci Luigi, Studenski Stephanie A
Longitudinal Studies Section, Translational Gerontology Branch, National Institute on Aging, Baltimore, MD 21224, USA.
Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, MD 21224, USA.
Exp Gerontol. 2016 May;77:46-51. doi: 10.1016/j.exger.2016.02.009. Epub 2016 Feb 17.
Lower integrity of cerebral gray matter is associated with higher gait variability. It is not known whether gray matter integrity is associated with higher lap time variation (LTV), a clinically accessible measure of gait variability, high levels of which have been associated with mortality. This study examines the cross-sectional association between gray matter mean diffusivity (MD) and LTV in community-dwelling older adults.
Study participants consisted of 449 high-functioning adults aged 50 and older (56.8% female) in the Baltimore Longitudinal Study of Aging, free of overt neurological disease. The magnitude of MD in the gray matter, a measure of impaired tissue integrity, was assessed by diffusion tensor imaging in 16 regions of interest (ROIs) involved with executive function, sensorimotor function, and memory. LTV was assessed as variability in lap time based on individual trajectories over ten 40-m laps. Age, sex, height, and weight were covariates. The model additionally adjusted for mean lap time and health conditions that may affect LTV.
Higher levels of average MD across 16 ROIs were significantly associated with higher LTV after adjustment for covariates. Specifically, higher MD in the precuneus and the anterior and middle cingulate cortices was strongly associated with higher LTV, as compared to other ROIs. The association persisted after adjustment for mean lap time, hypertension, and diabetes.
Lower gray matter integrity in selected areas may underlie greater LTV in high-functioning community-dwelling older adults. Longitudinal studies are warranted to examine whether changes in gray matter integrity precede more variable gait.
脑灰质完整性较低与较高的步态变异性相关。目前尚不清楚灰质完整性是否与较高的圈时变化（LTV）相关，LTV是一种临床上可获取的步态变异性测量指标，高水平的LTV与死亡率相关。本研究调查了社区居住的老年人中灰质平均扩散率（MD）与LTV之间的横断面关联。
研究参与者包括巴尔的摩纵向衰老研究中449名50岁及以上的高功能成年人（56.8%为女性），他们没有明显的神经系统疾病。通过扩散张量成像在涉及执行功能、感觉运动功能和记忆的16个感兴趣区域（ROI）评估灰质中MD的大小，MD是组织完整性受损的一个指标。LTV根据十个40米圈的个体轨迹评估圈时的变异性。年龄、性别、身高和体重作为协变量。该模型还对平均圈时和可能影响LTV的健康状况进行了调整。
在对协变量进行调整后，16个ROI的平均MD水平较高与较高的LTV显著相关。具体而言，与其他ROI相比，楔前叶以及前扣带回和中扣带回皮质中较高的MD与较高的LTV密切相关。在对平均圈时、高血压和糖尿病进行调整后，这种关联仍然存在。
在功能良好的社区居住老年人中，特定区域较低的灰质完整性可能是LTV增加的基础。有必要进行纵向研究，以检查灰质完整性的变化是否先于步态变异性增加。
