Department of Nuclear Medicine, Austin Health, Melbourne, Australia.
Neurology. 2012 Feb 14;78(7):477-84. doi: 10.1212/WNL.0b013e318246d67a. Epub 2012 Feb 1.
Given the recent and growing interest in the concepts of prodromal and presymptomatic Alzheimer disease, it is crucial to determine whether the presence of β-amyloid (Aβ) in the brain of asymptomatic elderly individuals is a pathologic condition associated with accelerated neuronal and synaptic loss. The aim of the present study was to assess whether Aβ influences the rate of atrophy in cognitively normal elderly individuals.
Seventy-four healthy elderly individuals underwent an MRI scan and a 11C-Pittsburgh compound B (PiB) PET scan at baseline and a second MRI scan 18 months later. Voxel-wise analyses were performed using maps of annual rate of atrophy generated from the serial MRI scans, including comparison between individuals with high vs low neocortical PiB and correlation with baseline neocortical PiB.
The rate of atrophy was significantly higher in the normal elderly individuals with high PiB compared with those with low PiB and was significantly correlated with baseline neocortical PiB, with the highest significance in the temporal neocortex and the posterior cingulate cortex.
Our findings show that the presence of Aβ in the brain, known to occur in about one-third of asymptomatic elderly individuals, is actually a pathologic state associated with accelerated atrophy. They also suggest that therapy aimed to reduce the neurodegenerative process should be commenced in presymptomatic individuals with high PiB.
鉴于人们对前驱期和前症状期阿尔茨海默病概念的兴趣近来与日俱增，确定无症状老年个体大脑中β-淀粉样蛋白（Aβ）是否为与加速神经元和突触丢失相关的病理性状态至关重要。本研究旨在评估 Aβ 是否会影响认知正常的老年个体的萎缩速度。
74 名健康的老年个体在基线时接受 MRI 扫描和 11C-匹兹堡化合物 B（PiB）PET 扫描，18 个月后进行第二次 MRI 扫描。通过对来自连续 MRI 扫描的年度萎缩速度图进行体素分析，包括比较高与低新皮质 PiB 的个体，并与基线新皮质 PiB 进行相关性分析。
高 PiB 的正常老年个体的萎缩速度明显高于低 PiB 的个体，且与基线新皮质 PiB 显著相关，在颞叶新皮质和后扣带回皮质的相关性最高。
我们的研究结果表明，大脑中存在 Aβ（约三分之一的无症状老年个体存在）实际上是一种与加速萎缩相关的病理性状态。此外，这些结果还提示，针对减少神经退行性过程的治疗应该在高 PiB 的前驱期个体中开始。
