Neurite orientation dispersion and density imaging (NODDI) is a technique providing more detailed information on the microstructural bases of white matter. Given the previously reported white matter contributions to chronic pain, the present study aims to investigate pain-specific differences in NODDI measures across white matter tracts in a sample of community-dwelling older adults with (n = 29) and without (n = 18) chronic musculoskeletal pain. We further aimed to investigate associations between NODDI measures and clinical and experimental pain measures. As part of the Nepal study, a subset of older adults (>60 years old), underwent multiple laboratory sessions providing self-reported and experimental pain measures and a diffusion weighted neuroimaging sequence. Older adults with chronic musculoskeletal pain had a lower neurite density with less geometric complexity across a number of white matter tracts compared to older pain-free controls (corrected p's < 0.05). Lower neurite density was associated with greater self-reported pain intensity and anatomical pain sites, as well as greater experimental pain sensitivity (p's < 0.05). There were also significant pain-by-sex differences in neurite density and geometric complexity across multiple white matter tracts mainly around the hippocampus (corrected p's < 0.05). Finally, there were no pain differences with respect to extra-cellular water diffusion (corrected p's > 0.05). Our study demonstrates less geometric complexity in neurite density and architecture in chronic musculoskeletal pain, partly in a sex-dependent manner. An increased understanding of neurobiological mechanisms such as those measured by NODDI may contribute to the potential targeting of interventions in our older population suffering from chronic pain.

神经突定向分散和密度成像 (NODDI) 是一种提供有关白质微结构基础的更详细信息的技术。鉴于先前报道的白质对慢性疼痛的贡献，本研究旨在调查社区居住的老年人（n = 29）和没有（n = 18）样本中白质束 NODDI 测量的疼痛特异性差异慢性肌肉骨骼疼痛。我们进一步旨在调查 NODDI 措施与临床和实验性疼痛措施之间的关联。作为尼泊尔研究的一部分，一部分老年人（> 60 岁）接受了多个实验室课程，提供自我报告和实验性疼痛测量以及扩散加权神经影像序列。与老年无疼痛对照组相比，患有慢性肌肉骨骼疼痛的老年人神经突密度较低，许多白质束的几何复杂性较低（校正后的 p < 0.05）。较低的神经突密度与更大的自我报告的疼痛强度和解剖疼痛部位以及更大的实验疼痛敏感性相关（p < 0.05）。在主要围绕海马体的多个白质束中，神经突密度和几何复杂性也存在显着的性别差异（校正后的 p < 0.05）。最后，在细胞外水扩散方面没有疼痛差异（校正后的 p > 0.05）。我们的研究表明，慢性肌肉骨骼疼痛中神经突密度和结构的几何复杂性较低，部分与性别相关。