BackgroundBoth Alzheimer's disease (AD) and cerebral small vessel disease (CSVD) manifest in cognitive impairment and gait disorders. The precise similarities and differences in gait characteristics and underlying neuroimaging mechanisms remain unclear.MethodsA total of 399 participants were enrolled: 132 with probable AD, including 98 with mild cognitive impairment due to AD (AD‐MCI) and 34 with AD dementia, and 185 with CSVD and 82 healthy controls. CSVD patients with cognitive impairment, including subcortical vascular mild cognitive impairment (svMCI) and subcortical vascular dementia, were grouped as subcortical vascular cognitive impairment (SVCI). Voxel‐based morphology analysis assessed grey matter volume (GMV), while cerebral blood flow (CBF) was derived from 3D‐arterial spin labelling data. Gait metrics included the timed up and go (TUG) test, dual‐task TUG (DTUG) test, Berg balance scale (BBS), dual‐task cost (DTC), step length, gait speed, cadence and coefficient of variation of gait. The relationships among structural and perfusion variations, gait metrics and cognitive function were examined.ResultsSVCI patients exhibited greater gait impairments and variability than those with AD, while AD patients experienced higher DTC (p < 0.05). These differences were most evident in the MCI stage. In AD, gait speed correlated with GMV in the left middle occipital gyrus (F = 6.149), middle temporal gyrus (F = 4.595), right precuneus (F = 5.174) and other regions (all p < 0.025). In SVCI, gait speed was linked to thalamic GMV (F = 6.004, p < 0.025). Altered CBF in the parietal lobe and precuneus was associated with DTUG (F = 5.672), gait speed (F = 4.347) and BBS (F = 4.153) in AD, while cerebellar CBF related to TUG (F = 6.042), DTUG (F = 4.857) and BBS (F = 7.097) in SVCI (all p < 0.025). In AD‐MCI, memory mediated the effect of hippocampal volume on DTC (indirect effect: −2.432, 95% CI [−5.503, −0.438]), while executive function (indirect effect: −2.920, 95% CI [−7.227, −0.695]) and processing speed (indirect effect: −2.286, 95% CI [−5.174, −0.484]) mediated the effect on DTUG. In svMCI, executive function mediated the effect of thalamic volume on step length (indirect effect: 2.309, 95% CI [0.486, 4.685]) and gait speed (indirect effect: 2.029, 95% CI [0.142, 4.588]), while processing speed mediated the effect on step length (indirect effect: 1.777, 95% CI [0.311, 4.021]).ConclusionsDifferent gait disorder characteristics and mechanisms were observed in AD and CSVD patients. In AD, gait is associated with volume/perfusion in posterior brain regions, whereas in SVCI, it relates to thalamic volume and cerebellar perfusion. Cognitive impairment mediates the effect of hippocampal and thalamic volumes on gait in AD‐MCI and svMCI, respectively.

中文翻译：

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阿尔茨海默病和脑小血管病中独特的步态变化和神经影像学相关性


背景阿尔茨海默病 （AD） 和脑小血管病 （CSVD） 都表现为认知障碍和步态障碍。步态特征和潜在神经影像学机制的确切相似和不同之处仍不清楚。方法共纳入 399 名参与者： 132 名可能患有 AD，包括 98 名因 AD 引起的轻度认知障碍 （AD-MCI） 和 34 名 AD 痴呆，以及 185 名 CSVD 和 82 名健康对照。患有认知障碍的 CSVD 患者，包括皮质下血管轻度认知障碍 （svMCI） 和皮质下血管痴呆，被归类为皮质下血管认知障碍 （SVCI）。基于体素的形态学分析评估了灰质体积 （GMV），而脑血流 （CBF） 来自 3D 动脉自旋标记数据。步态指标包括计时和开始 （TUG） 测试、双任务 TUG （DTUG） 测试、Berg 平衡量表 （BBS）、双任务成本 （DTC）、步长、步态速度、步频和步态变异系数。检查了结构和灌注变化、步态指标和认知功能之间的关系。结果SVCI 患者表现出比 AD 患者更大的步态障碍和变异性，而 AD 患者的 DTC 更高 （p < 0.05）。这些差异在 MCI 阶段最为明显。在 AD 中，步态速度与左枕中回 （F = 6.149）、颞中回 （F = 4.595）、右楔前叶 （F = 5.174） 和其他区域 （均 p < 0.025） 的步态速度相关。在 SVCI 中，步态速度与丘脑 GMV 有关 （F = 6.004，p < 0.025）。顶叶和楔前叶 CBF 改变与 AD 中的 DTUG （F = 5.672）、步态速度 （F = 4.347） 和 BBS （F = 4.153） 相关，而小脑 CBF 与 TUG （F = 6.042）、DTUG （F = 4.857） 和 BBS （F = 7.097） 在 SVCI 中 （均 p < 0.025）。在 AD-MCI 中，记忆介导了海马体积对 DTC 的影响（间接效应：-2.432， 95% CI [-5.503， -0.438]），而执行功能（间接效应：-2.920， 95% CI [-7.227， -0.695]）和处理速度（间接效应：-2.286， 95% CI [-5.174， -0.484]）介导了对 DTUG 的影响。在svMCI中，执行功能介导丘脑体积对步长（间接效应：2.309， 95% CI [0.486， 4.685]）和步态速度（间接效应：2.029， 95% CI [0.142， 4.588]）的影响，而处理速度介导对步长的影响（间接效应：1.777， 95% CI [0.311， 4.021]）。结论AD 和 CSVD 患者步态障碍特征和机制不同。在 AD 中，步态与后脑区域的体积/灌注有关，而在 SVCI 中，它与丘脑体积和小脑灌注有关。认知障碍分别介导海马体和丘脑体积对 AD-MCI 和 svMCI 步态的影响。