Individuals with mild cognitive impairment that have high dual-task gait cost (≥20% slowing in gait speed while performing a cognitive brain demanding task), are three-fold more likely to progress to dementia. However, the cortical regions that may explain this association are unknown, which may identify potentially treatable areas. The aim of the current study is to investigate whether brain grey matter volume loss and motor cortex metabolite levels explain the association between dual-task cost and incident dementia in individuals with mild cognitive impairment. We included participants with mild cognitive impairment from the Gait&Brain Study Cohort, who had a baseline MRI and were followed-up for 9 years with cognitive and gait assessments every 6 months. Gait performance was investigated under four conditions: usual gait, counting backwards by ones, naming animals and subtracting serial sevens. Dual-task cost was calculated as the percentage change in gait speed under dual-task conditions relative to usual gait speed. Data were collected from July 2007 to June 2023. From the 139 individuals with mild cognitive impairment included at baseline (mean [SD] age, 73[6] years, 62 (44%) women), and 33 (24%) progressed to dementia. Baseline high dual-task cost (≥20%) under counting backwards by ones and naming animals conditions were associated with smaller grey matter volume in several brain structures. A higher ratio of choline to creatine in the primary motor cortex was associated with higher serial sevens DTC. High dual-task cost while counting backwards by ones and naming animals was associated with a three-fold risk of incident dementia (P=0.02). Mediation analyses revealed that grey matter volume clusters localized in the right anterior and middle cingulate cortices mediated the association between counting backwards by ones dual-task cost and incident dementia (effect: 48%, P=0.045) with no mediation observed in grey matter loss in other brain regions or through motor cortex metabolite levels. Smaller grey matter volume of the right anterior and middle cingulate cortices explained the association between high dual-task cost and incident dementia in mild cognitive impairment. This result sheds light on the neural mechanisms of cognitive-motor interaction linked with cognitive decline and dementia in mild cognitive impairment and support the use of gait under dual-tasking as a motor biomarker of dementia.

中文翻译：

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较小的扣带回灰质介导双重任务步态与新发痴呆之间的关联


患有轻度认知障碍的个体具有较高的双重任务步态成本（在执行认知大脑要求高的任务时步态速度减慢 ≥20%），进展为 痴呆 的可能性要高出三倍。然而，可能解释这种关联的皮质区域是未知的，这可能会确定潜在的可治疗区域。本研究的目的是调查脑灰质体积损失和运动皮层代谢物水平是否解释了轻度认知障碍个体的双重任务成本与事件痴呆之间的关联。我们纳入了来自 Gait&Brain 研究队列的轻度认知障碍参与者，他们进行了基线 MRI 检查，并每 6 个月接受一次认知和步态评估随访 9 年。在四种条件下调查步态表现：正常步态、向后数 1、命名动物和减去序列 7。双任务成本计算为双任务条件下步态速度相对于通常步态速度的百分比变化。数据收集时间为 2007 年 7 月至 2023 年 6 月。在基线纳入的 139 名轻度认知障碍个体中 （平均 [SD] 年龄，73[6] 岁，62 名 （44%） 女性） 和 33 名 （24%） 进展为痴呆。在按 1 倒数和命名动物条件下，基线高双重任务成本 （≥20%） 与多个大脑结构中较小的灰质体积相关。初级运动皮层中胆碱与肌酸的较高比率与较高的序列 7 DTC 相关。高双重任务成本，同时以 1 倒数和命名动物与发生痴呆的风险增加 3 倍相关 （P=0.02）。 中介分析显示，位于右侧前和中扣带回皮层的灰质体积簇介导了按双重任务成本向后计数与事件痴呆之间的关联 （效应：48%，P = 0.045），在其他大脑区域的灰质丢失或通过运动皮层代谢物水平未观察到中介。右侧前扣带回皮层和中扣带皮层的灰质体积较小解释了高双重任务成本与轻度认知障碍患者痴呆之间的关联。这一结果揭示了与轻度认知障碍中的认知衰退和痴呆相关的认知 - 运动相互作用的神经机制，并支持在双重任务下使用步态作为痴呆的运动生物标志物。