Gait speed is a robust health biomarker in older adults, correlating with the risk of physical and cognitive impairments, including dementia. Myelination plays a crucial role in neurotransmission and consequently affects various functions, yet the connection between myelination and motor functions such as gait speed is not well understood. Understanding this link could offer insights into diagnosing and treating neurodegenerative diseases that impair mobility. This study analyzed 437 longitudinal observations from 138 cognitively unimpaired adults, aged 22 to 94 years, to investigate the relationship between myelin content and changes in gait speed over an average of 6.42 years. Myelin content was quantified using a novel multicomponent magnetic resonance relaxometry method, and both usual and rapid gait speeds (UGS, RGS) were measured following standard protocols. Adjusting for covariates, we found a significant fixed effect of myelin content on UGS and RGS. Longitudinally, lower myelin content was linked to a greater decline in UGS, particularly in brain regions associated with motor planning. These results suggest that changes in UGS may serve as a reliable marker of neurodegeneration, particularly in cognitively unimpaired adults. Interestingly, the relationship between myelin content and changes in RGS was only observed in a limited number of brain regions, although the reason for such local susceptibility remains unknown. These findings enhance our understanding of the critical role of myelination in gait performance in unimpaired adults and provide evidence of the interconnection between myelin content and motor function impairment.

步态速度是老年人中强大的健康生物标志物，与身体和认知障碍（包括痴呆）的风险相关。髓鞘形成在神经传递中起着至关重要的作用，因此会影响各种功能，但髓鞘形成与步态速度等运动功能之间的联系尚不清楚。了解这种联系可以为诊断和治疗损害活动能力的神经退行性疾病提供见解。本研究分析了 437 名年龄在 22 至 94 岁之间的认知未受损成年人的 138 次纵向观察，以调查髓鞘含量与平均 6.42 岁步态速度变化之间的关系。使用一种新的多组分磁共振弛豫测量法对髓鞘含量进行量化，并按照标准方案测量正常和快速步态速度 （UGS、RGS）。调整协变量，我们发现髓鞘含量对 UGS 和 RGS 有显著的固定效应。纵向上，较低的髓鞘含量与 UGS 的更大下降有关，尤其是在与运动规划相关的大脑区域。这些结果表明，UGS 的变化可能是神经退行性变的可靠标志物，尤其是在认知未受损的成年人中。有趣的是，髓鞘含量与 RGS 变化之间的关系仅在有限数量的大脑区域观察到，尽管这种局部易感性的原因仍然未知。这些发现增强了我们对髓鞘形成在未受损成人步态表现中的关键作用的理解，并为髓鞘含量与运动功能障碍之间的相互联系提供了证据。