Department of Psychiatry (HTK, DLT, AC, HJA), University of Pittsburgh, Pittsburgh, PA.
Department of Psychiatry (HTK, DLT, AC, HJA), University of Pittsburgh, Pittsburgh, PA; Department of Internal Medicine (DLT), University of Pittsburgh, Pittsburgh, PA; Department of Biostatistics (DLT), University of Pittsburgh, Pittsburgh, PA.
Am J Geriatr Psychiatry. 2019 Dec;27(12):1360-1371. doi: 10.1016/j.jagp.2019.07.008. Epub 2019 Jul 19.
In cognitively healthy older adults, amyloid-beta (Aβ) burden is associated with greater activity on task-based functional magnetic resonance imaging. Higher levels of functional activation are associated with other factors along with amyloid and the authors investigated these relationships as well as how they relate to Aβ in cognitively healthy older adults.
The authors recruited cognitive healthy older adults (N = 50) from the Pittsburgh community that underwent extensive cognitive batteries, activation during a working memory (digit symbol substitution task, DSST), positron emission tomography scan for Pittsburgh Compound B (PiB, measuring amyloid), and other demographic measures. The authors tested the association between DSST activation and global PiB, neurocognitive batteries, and education.
The authors found that the DSST robustly activated expected structures involved in working memory. The authors found that greater global Aβ deposition was associated with greater DSST activation in the right calcarine, precuneus, middle temporal as well as the left insula and inferior frontal gyrus. The authors also found that greater education was associated with lower DSST activation - however this was not significant after adjusting for Aβ.
Greater amyloid was associated with greater activation, which may represent compensatory activation. Greater education was associated with lower activation, which may represent more efficient activation (i.e., less activation for the same task). After adjusting for amyloid, education was not significantly associated with activation suggesting that during the preclinical stage amyloid is the primary determinant of activation. Further, activation was not associated with cognitive function. Compensatory activation in the preclinical stage may help maintain cognitive function.
在认知健康的老年人中，淀粉样蛋白（Aβ）负担与任务相关的功能磁共振成像（fMRI）上的更高活动水平相关。更高水平的功能激活与 Aβ 以及其他因素有关，作者研究了这些关系以及它们与认知健康老年人中的 Aβ 的关系。
作者从匹兹堡社区招募了认知健康的老年人（N=50），他们接受了广泛的认知测试、工作记忆（数字符号替代任务，DSST）期间的激活、正电子发射断层扫描（PiB，测量淀粉样蛋白）以及其他人口统计学测量。作者测试了 DSST 激活与全球 PiB、神经认知测试和教育之间的关系。
作者发现 DSST 强烈激活了预期的工作记忆相关结构。作者发现，更大的全局 Aβ 沉积与右距状回、楔前叶、中颞叶以及左岛叶和额下回的 DSST 激活增加有关。作者还发现，更高的教育程度与 DSST 激活较低有关-但在调整 Aβ 后这并不显著。
更多的淀粉样蛋白与更高的激活有关，这可能代表代偿性激活。更高的教育程度与较低的激活有关，这可能代表更有效的激活（即，相同任务的激活较少）。在调整 Aβ 后，教育程度与激活不再显著相关，这表明在临床前阶段，Aβ 是激活的主要决定因素。此外，激活与认知功能无关。在临床前阶段的代偿性激活可能有助于维持认知功能。
