Institute of Neuroscience, Newcastle University, Newcastle, United Kingdom.
Medicine of the Elderly, Western General Hospital, Edinburgh, United Kingdom.
Mov Disord. 2016 Jan;31(1):103-10. doi: 10.1002/mds.26312. Epub 2015 Jul 22.
The aim of this work was to investigate the cortical and white matter changes that underlie cognitive impairment in patients with incident Parkinson's disease (PD) disease using voxel-based morphometry and diffusion tensor imaging.
Newly diagnosed nondemented PD (n = 125) and control subjects (n = 50) were recruited from the Incidence of Cognitive Impairment in Cohorts with Longitudinal Evaluation in Parkinson's Disease Study and completed cognitive assessments and 3T structural and diffusion tensor MR imaging. Voxel-based morphometry was performed to investigate the relationship between gray matter volume and cognitive ability. Microstructural white matter changes were assessed with diffusion tensor imaging measures of fractional anisotropy and mean diffusivity using tract-based spatial statistics.
Increased mean diffusivity was observed bilaterally in subjects with PD, relative to controls (P = 0.019). Increased mean diffusivity was associated with performance on the semantic fluency and Tower of London tasks in frontal and parietal white matter tracts, including the cingulum, superior longitudinal fasciculus, inferior longitudinal fasciculus, and inferior fronto-occipital fasciculus. There was no difference in total gray matter volume between groups; however, bilateral reductions in frontal and parietal gray matter volume were associated with reduced performance on measures of executive function in PD subjects.
At the earliest stages of PD, regionally specific increases in central white matter mean diffusivity are present and suggest early axonal damage. Such changes are not accompanied by significant gray matter volume loss and are consistent with proposed models of pathological progression of the disease. Structural MRI, especially diffusion tensor imaging analysis, offers potential as a noninvasive biomarker reflecting cognitive impairment in PD.
本研究旨在通过基于体素的形态测量学和弥散张量成像技术，探讨初发帕金森病（PD）患者认知障碍的皮质和白质变化。
从帕金森病纵向评估中的认知障碍发生率研究中招募了新诊断的非痴呆 PD 患者（n=125）和对照组（n=50），并完成了认知评估和 3T 结构及弥散张量磁共振成像。通过基于体素的形态测量学来研究灰质体积与认知能力之间的关系。使用基于束的空间统计学方法评估弥散张量成像的各向异性分数和平均弥散系数来评估白质微观结构变化。
与对照组相比，PD 患者双侧白质的平均弥散系数增加（P=0.019）。在额顶叶白质束（包括扣带束、上纵束、下纵束和下额枕束）中，平均弥散系数的增加与语义流畅性和伦敦塔任务的表现相关。两组间总灰质体积无差异；然而，双侧额顶叶灰质体积减少与 PD 患者执行功能测量的表现下降有关。
在 PD 的最早阶段，存在局部中央白质平均弥散系数的增加，提示早期轴索损伤。这种变化不伴有明显的灰质体积丢失，与疾病的病理进展的假设模型一致。结构 MRI，尤其是弥散张量成像分析，有望成为反映 PD 认知障碍的非侵入性生物标志物。
