The Key Laboratory of Biomedical Information Engineering of Ministry of Education, and Institute of Biomedical Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, 710049, China; National Engineering Research Center of Health Care and Medical Devices, Xi'an Jiaotong University Branch, Xi'an, 710049, China.
Department of Geriatric Neurology, National Clinical Research Center for Geriatric Diseases, Chinese PLA General Hospital, Beijing, 100853, China; Department of Neurology, The General Hospital of the PLA Rocket Force, Beijing, 100088, China.
Brain Res Bull. 2018 Oct;143:207-216. doi: 10.1016/j.brainresbull.2018.09.010. Epub 2018 Sep 18.
Alzheimer's disease (AD) is a worldwide progressive neurodegenerative disorder in the elderly. Previous research has indicated that Alzheimer's disease impairs white matter (WM) tracts. Anatomical and neuroimaging studies have indicated that WM tracts are associated with cognitive function. Whether the abnormal WM integrity in AD is associated with cognitive impairments and the clinical symptoms is still not clear. To this end, we investigated the relationship between the impairments in WM tracts and the decline of cognitive ability in AD. Diffusion tensor imaging (DTI) data were collected from 38 AD patients and 30 normal, cognitively healthy volunteers. The tract-based spatial statistics (TBSS) approach was used to compare the fractional anisotropy (FA) and mean diffusivity (MD) values between the two groups. WM tracts (cingulum, superior longitudinal fasciculus (SLF), uncinate fasciculus (UF), and inferior longitudinal fasciculus (ILF)) associated with cognition function were extracted for region of interest (ROI)-based analysis. Significantly decreased FA values and increased MD values of the cognition-related WM tracts were observed in the AD group compared with the normal cognition (NC) group. In addition, we further demonstrated that the decreased FA values and increased MD values of the cognition-related WM tracts were significantly correlated with MMSE scores. These results indicated that abnormal changes in WM integrity are observed following AD. Finally, we used support vector machine (SVM) with a repeated, stratified 10-fold cross-validated classifier to evaluate the ability of FA and MD values to discriminate disease. The accuracy of the SVM using cognition-related WM as classified features was higher than that using non-cognition-related tracts. Most importantly, our results showed the relationship between abnormal WM tracts and cognitive ability in AD. These findings further suggested that AD-related impairments in cognition-related WM tracts may influence the cognitive ability of AD patients.
阿尔茨海默病（AD）是一种全球性的老年人进行性神经退行性疾病。先前的研究表明，阿尔茨海默病会损害白质（WM）束。解剖和神经影像学研究表明，WM 束与认知功能有关。AD 中 WM 完整性的异常是否与认知障碍和临床症状有关尚不清楚。为此，我们研究了 AD 患者 WM 束损伤与认知能力下降之间的关系。从 38 名 AD 患者和 30 名正常认知健康志愿者中收集了弥散张量成像（DTI）数据。采用基于束的空间统计学（TBSS）方法比较两组的各向异性分数（FA）和平均弥散度（MD）值。为了进行基于感兴趣区（ROI）的分析，提取了与认知功能相关的 WM 束（扣带束、上纵束（SLF）、钩束（UF）和下纵束（ILF））。与正常认知（NC）组相比，AD 组与认知功能相关的 WM 束的 FA 值降低，MD 值升高。此外，我们进一步证明，与认知功能相关的 WM 束的 FA 值降低和 MD 值升高与 MMSE 评分显著相关。这些结果表明 AD 后 WM 完整性发生异常变化。最后，我们使用具有重复、分层 10 折交叉验证分类器的支持向量机（SVM）来评估 FA 和 MD 值区分疾病的能力。使用认知相关 WM 作为分类特征的 SVM 的准确率高于使用非认知相关束的准确率。最重要的是，我们的结果显示了 AD 中异常 WM 束与认知能力之间的关系。这些发现进一步表明，AD 相关的认知相关 WM 束损伤可能影响 AD 患者的认知能力。
