Florey Department of Neurosciences & Mental Health, The University of Melbourne, Parkville, VIC, 3052, Australia.
Department of Molecular Imaging & Therapy, Austin Health, 145 Studley Rd, Heidelberg, VIC, 3084, Australia.
Alzheimers Res Ther. 2022 Apr 8;14(1):51. doi: 10.1186/s13195-022-00993-x.
Tau deposition in the mesial temporal lobe (MTL) in the absence of amyloid-β (Aβ-) occurs with aging. The tau PET tracer F-MK6240 has low non-specific background binding so is well suited to exploration of early-stage tau deposition. The aim of this study was to investigate the associations between MTL tau, age, hippocampal volume (HV), cognition, and neocortical tau in Aβ- cognitively unimpaired (CU) individuals.
One hundred and ninety-nine Aβ- participants (Centiloid < 25) who were CU underwent F-MK6240 PET at age 75 ± 5.2 years. Tau standardized uptake value ratio (SUVR) was estimated in mesial temporal (Me), temporoparietal (Te), and rest of the neocortex (R) regions and four Me sub-regions. Tau SUVR were analyzed as continuous variables and compared between high and low MTL SUVR groups.
In this cohort with a stable clinical classification of CU for a mean of 5.3 years prior to and at the time of tau PET, MTL tau was visually observed in 9% of the participants and was limited to Braak stages I-II. MTL tau was correlated with age (r = 0.24, p < 0.001). Age contributed to the variance in cognitive scores but MTL tau did not. MTL tau was not greater with subjective memory complaint, nor was there a correlation between MTL tau and Aβ Centiloid value, but high tau was associated with smaller HV. Participants with MTL tau had higher tau SUVR in the neocortex but this was driven by the cerebellar reference region and was not present when using white matter normalization.
In an Aβ- CU cohort, tau tracer binding in the mesial temporal lobe was age-related and associated with smaller hippocampi, but not with subjective or objective cognitive impairment.
在没有淀粉样蛋白-β（Aβ-）的情况下，内侧颞叶（MTL）中的 Tau 沉积随着年龄的增长而发生。 Tau PET 示踪剂 F-MK6240 具有较低的非特异性背景结合，因此非常适合探索早期 Tau 沉积。本研究旨在探讨 Aβ-认知正常（CU）个体中 MTL Tau 与年龄、海马体积（HV）、认知和皮质 Tau 之间的关系。
199 名 Aβ-参与者（Centiloid < 25）在 75 ± 5.2 岁时接受了 F-MK6240 PET 检查。在颞叶（Me）、颞顶叶（Te）和其余皮质（R）区域以及四个 Me 亚区估计 Tau 标准化摄取值比（SUVR）。Tau SUVR 作为连续变量进行分析，并比较高和低 MTL SUVR 组之间的差异。
在这项队列研究中，参与者在 tau PET 检查前和检查时的平均 5.3 年内保持了稳定的 CU 临床分类，9%的参与者出现了 MTL Tau，且仅限于 Braak 分期 I-II。MTL Tau 与年龄呈正相关（r = 0.24，p < 0.001）。年龄对认知评分的变化有贡献，但 MTL Tau 没有。MTL Tau 与主观记忆主诉无关，也与 Aβ Centiloid 值之间没有相关性，但高 Tau 与 HV 较小有关。MTL Tau 阳性的参与者皮质 Tau SUVR 较高，但这是由小脑参考区驱动的，当使用白质归一化时则不存在。
在 Aβ- CU 队列中，内侧颞叶的 Tau 示踪剂结合与年龄相关，与海马体较小有关，但与主观或客观认知障碍无关。
