Slowed information processing speed is among the earliest markers of cognitive impairment in multiple sclerosis (MS) and has been associated with white matter (WM) structural integrity. Localization of WM tracts associated with slowing, but not significant impairment, on specific cognitive tasks in pediatric and young age onset MS can facilitate early and effective therapeutic intervention. Diffusion tensor imaging data were collected on 25 MS patients and 24 controls who also underwent the Symbol Digit Modalities Test (SDMT) and the computer-based Cogstate simple and choice reaction time tests. Fractional anisotropy (FA), mean (MD), radial (RD) and axial (AD) diffusivities were correlated voxel-wise with processing speed measures. All DTI metrics of several white matter tracts were significantly different between groups (p < 0.05). Notably, higher MD, RD, and AD, but not FA, in the corpus callosum correlated with lower scores on both SDMT and simple reaction time. Additionally, all diffusivity metrics in the left corticospinal tract correlated negatively with SDMT scores, whereas only MD in the right superior fronto-occipital fasciculus correlated with simple reaction time. In conclusion, subtle slowing of processing speed is correlated with WM damage in the visual-motor processing pathways in patients with young age of MS onset.

信息处理速度减慢是多发性硬化症（MS）认知障碍的最早标志之一，并且与白质（WM）结构完整性有关。与减慢但无明显损害的WM束的定位有关，在小儿和青年发病的MS中，其特定的认知任务可以促进早期有效的治疗干预。收集了25位MS患者和24位对照的扩散张量成像数据，这些患者还接受了符号数字模态测试（SDMT）和基于计算机的Cogstate简单反应和选择反应时间测试。分数各向异性（FA），平均值（MD），径向（RD）和轴向（AD）扩散与体素相关具有处理速度的措施。各个白质区的所有DTI指标在各组之间均存在显着差异（p <0.05）。值得注意的是，call体中较高的MD，RD和AD，而不是FA与SDMT和简单反应时间均较低。此外，左皮质脊髓束中的所有扩散率指标均与SDMT得分呈负相关，而仅右上额枕筋膜中的MD与简单反应时间相关。总之，在MS发病年龄较小的患者中，加工速度的细微减慢与视觉运动加工通路中的WM损伤有关。