Neuroimaging Laboratory, Santa Lucia Foundation, IRCCS, Rome, Italy.
J Alzheimers Dis. 2010;19(1):147-59. doi: 10.3233/JAD-2010-1223.
This study investigates abnormalities of grey (GM) and white matter (WM) in Alzheimer's disease (AD), by modeling the AD pathological process as a continuous course between normal aging and fully developed dementia, with amnesic mild cognitive impairment (aMCI) as an intermediate stage. All subjects (9 AD, 16 aMCI patients, and 13 healthy controls) underwent a full neuropsychological assessment and an MRI examination at 3 Tesla, including a volumetric scan and diffusion tensor (DT)-MRI. The volumes were processed to perform a voxel-based morphometric analysis of GM and WM volume, while DT-MRI data were analyzed using tract based spatial statistics, to estimate changes in fractional anisotropy and mean diffusivity data. GM and WM volume and mean diffusivity and fractional anisotropy were compared across the three groups, and their correlation with cognitive functions was investigated. While AD presented a pattern of widespread GM atrophy, tissue loss was more subtle in patients with aMCI. WM atrophy was mainly located in the temporal lobe, but evidence of WM microscopic damage, assessed by DT-MRI, was also observable in the thalamic radiations and in the corpus callosum. Memory and executive functions correlated with either GM volume or fractional anisotropy in fronto-temporal areas. In conclusion, this study shows a comprehensive assessment of the brain tissue damage across AD evolution, providing insights on different pathophysiological mechanisms (GM atrophy, Wallerian degeneration, and brain disconnection) and their possible association with clinical aspects of cognitive decline.
本研究通过将阿尔茨海默病（AD）的病理过程建模为正常衰老和完全发展为痴呆之间的连续过程，以研究 AD 中灰质（GM）和白质（WM）的异常，其中遗忘型轻度认知障碍（aMCI）为中间阶段。所有受试者（9 名 AD 患者、16 名 aMCI 患者和 13 名健康对照者）均在 3 Tesla 磁共振扫描仪上接受了全面的神经心理学评估和 MRI 检查，包括容积扫描和弥散张量（DT）-MRI。对体积进行处理，以对 GM 和 WM 体积进行基于体素的形态计量学分析，而使用基于束的空间统计学分析 DT-MRI 数据，以估计各向异性分数和平均弥散度数据的变化。比较了三组之间的 GM 和 WM 体积、平均弥散度和各向异性分数，并研究了它们与认知功能的相关性。AD 表现出广泛的 GM 萎缩模式，而 aMCI 患者的组织损失则更为微妙。WM 萎缩主要位于颞叶，但通过 DT-MRI 评估的 WM 微观损伤也可在丘脑辐射和胼胝体中观察到。记忆和执行功能与额颞区的 GM 体积或各向异性分数相关。总之，本研究全面评估了 AD 演变过程中的脑组织损伤，深入了解了不同的病理生理机制（GM 萎缩、瓦勒氏变性和脑连接中断）及其与认知功能下降的临床方面的可能关联。
