From Florey Institute of Neuroscience and Mental Health (Y.Y.L., J.E.B., A.M., C.F., C.L.M., P.M.), Parkville; Turner Institute for Brain and Mental Health (Y.Y.L., A.M.), School of Psychological Sciences, Monash University, Clayton; School of Computing and Information Systems (L.B.), The University of Melbourne, Parkville, Victoria; CSIRO Health and Biosecurity (J.F.), Australian e-Health Research Centre, Brisbane; Centre of Excellence for Alzheimer's Disease Research and Care (S.R.R.-S.), School of Medical Sciences, Edith Cowan University; Sir James McCusker Alzheimer's Disease Research Unit (Hollywood Private Hospital) (S.R.R.-S.), Perth; National Ageing Research Institute (D.A.), Parkville, Victoria; Academic Unit for Psychiatry of Old Age, Department of Psychiatry (D.A.), The University of Melbourne, St. George's Hospital, Kew; and Cogstate Ltd. (P.M.), Melbourne, Victoria, Australia.
Neurology. 2020 Nov 3;95(18):e2577-e2585. doi: 10.1212/WNL.0000000000010728. Epub 2020 Sep 4.
To determine the extent to which deficits in learning over 6 days are associated with β-amyloid-positive (Aβ+) and hippocampal volume in cognitively normal (CN) adults.
Eighty CN older adults who had undergone PET neuroimaging to determine Aβ status (n = 42 Aβ- and 38 Aβ+), MRI to determine hippocampal and ventricular volume, and repeated assessment of memory were recruited from the Australian Imaging, Biomarkers and Lifestyle (AIBL) study. Participants completed the Online Repeatable Cognitive Assessment-Language Learning Test (ORCA-LLT), which required they learn associations between 50 Chinese characters and their English language equivalents over 6 days. ORCA-LLT assessments were supervised on the first day and were completed remotely online for all remaining days.
Learning curves in the Aβ+ CN participants were significantly worse than those in matched Aβ- CN participants, with the magnitude of this difference very large ( [95% confidence interval (CI)] 2.22 [1.64-2.75], < 0.001), and greater than differences between these groups for memory decline since their enrollment in AIBL ( [95% CI] 0.52 [0.07-0.96], = 0.021), or memory impairment at their most recent visit. In Aβ+ CN adults, slower rates of learning were associated with smaller hippocampal and larger ventricular volumes.
These results suggest that in CN participants, Aβ+ is associated more strongly with a deficit in learning than any aspect of memory dysfunction. Slower rates of learning in Aβ+ CN participants were associated with hippocampal volume loss. Considered together, these data suggest that the primary cognitive consequence of Aβ+ is a failure to benefit from experience when exposed to novel stimuli, even over very short periods.
确定在认知正常（CN）成年人中，6 天以上的学习缺陷与β-淀粉样蛋白阳性（Aβ+）和海马体积之间的关联程度。
从澳大利亚成像、生物标志物和生活方式（AIBL）研究中招募了 80 名接受过 PET 神经影像学以确定 Aβ 状态（n = 42 Aβ-和 38 Aβ+）、MRI 以确定海马和脑室体积以及重复评估记忆的认知正常老年人。参与者完成了在线可重复认知评估-语言学习测试（ORCA-LLT），该测试要求他们在 6 天内学习 50 个汉字及其英语对应词之间的关联。ORCA-LLT 评估在第一天进行监督，其余所有天都在线远程完成。
Aβ+CN 参与者的学习曲线明显比匹配的 Aβ-CN 参与者差，差异幅度非常大（[95%置信区间（CI）]2.22[1.64-2.75]，<0.001），并且大于这些组之间的差异自他们加入 AIBL 以来的记忆下降（[95%CI]0.52[0.07-0.96]，=0.021），或最近一次就诊时的记忆障碍。在 Aβ+CN 成年人中，较慢的学习速度与海马体体积较小和脑室体积较大相关。
这些结果表明，在 CN 参与者中，Aβ+与学习缺陷的关联比任何记忆功能障碍方面都更为强烈。Aβ+CN 参与者较慢的学习速度与海马体体积丧失相关。综合考虑，这些数据表明，Aβ+的主要认知后果是即使在非常短的时间内，对新刺激也无法从经验中受益。
