Psychology Service, VA Boston Healthcare System, Boston, MA, USA.
J Int Neuropsychol Soc. 2013 Sep;19(8):925-37. doi: 10.1017/S1355617713000660. Epub 2013 Jul 1.
Improved understanding of the pattern of white matter changes in early and prodromal Alzheimer’s disease (AD) states such as mild cognitive impairment (MCI) is necessary to support earlier preclinical detection of AD, and debate remains whether white matter changes in MCI are secondary to gray matter changes. We applied neuropsychologically based MCI criteria to a sample of normally aging older adults; 32 participants met criteria for MCI and 81 participants were classified as normal control (NC) subjects. Whole-head high resolution T1 and diffusion tensor imaging scans were completed. Tract-Based Spatial Statistics was applied and a priori selected regions of interest were extracted. Hippocampal volume and cortical thickness averaged across regions with known vulnerability to AD were derived. Controlling for corticalthic kness, the MCI group showed decreased average fractional anisotropy (FA) and decreased FA in parietal white matter and in white matter underlying the entorhinal and posterior cingulate cortices relative to the NC group. Statistically controlling for cortical thickness, medial temporal FA was related to memory and parietal FA was related to executive functioning. These results provide further support for the potential role of white matter integrity as an early biomarker for individuals at risk for AD and highlight that changes in white matter may be independent of gray matter changes.
为了支持更早地在临床前阶段检测阿尔茨海默病（AD），有必要深入了解早期和前驱 AD 状态（如轻度认知障碍，MCI）的白质变化模式，目前仍存在争议，即 MCI 中的白质变化是否继发于灰质变化。我们根据神经心理学的 MCI 标准，对一组正常衰老的老年人进行了研究；32 名参与者符合 MCI 标准，81 名参与者被归类为正常对照组（NC）。完成了全脑高分辨率 T1 和弥散张量成像扫描。应用基于轨迹的空间统计学，并提取了预先选择的感兴趣区域。提取了具有 AD 易感性的已知区域的平均海马体积和皮质厚度。在控制皮质厚度的情况下，与 NC 组相比，MCI 组的平均各向异性分数（FA）和顶叶白质及内嗅皮质和后扣带回皮质下白质的 FA 降低。统计学上控制皮质厚度后，内侧颞叶 FA 与记忆有关，顶叶 FA 与执行功能有关。这些结果进一步支持了白质完整性作为 AD 风险个体的早期生物标志物的潜在作用，并强调了白质变化可能独立于灰质变化。
