Bastin Christine, Giacomelli Fabrice, Miévis Frédéric, Lemaire Christian, Guillaume Bénédicte, Salmon Eric
GIGA-Cyclotron Research Center-in vivo Imaging, University of Liège, Liège, Belgium.
F.R.S.-Fonds National de la Recherche Scientifique, Bruxelles, Belgium.
Front Psychiatry. 2021 Mar 31;12:631518. doi: 10.3389/fpsyt.2021.631518. eCollection 2021.
While anosognosia is often present in Alzheimer's disease, the degree of awareness of cognitive difficulties in the earlier stages, such as Mild Cognitive Impairment (MCI), is less clear. Using a questionnaire and Feeling-of-Knowing tasks, the aims of this study were (1) to test the hypothesis that anosognosia is present specifically in prodromal AD stage in patients that, owing to a more severe AD neuropathology, will rapidly progress to overt dementia and (2) to assess the neural bases of self-awareness for memory functioning. A group of 44 patients with amnestic MCI and a group of 29 healthy older participants (CTRL) performed two Feeling-of-Knowing tasks (episodic and semantic FOK) and responded to the Functional Memory Scale (MARS), also completed by one of their relatives. They underwent FDG-PET and structural MRI. The participants were followed clinically for 4 years. At the end of follow-up, 23 patients with MCI developed Alzheimer's disease (converters) and 21 patients still presented symptoms of MCI without progression (non-converters). The analyses focused on the data from inclusion stratified according to clinical status 4 years later (converters, non-converters, CTRL). On the episodic FOK task, converters patients overestimated their ability to later recognize unrecalled words and they showed prediction accuracy (Hamann coefficient) at the level of chance. No difficulty was observed in any group with the semantic FOK task. On the MARS, converters patients had a higher anosognosia score than non-converters patients and CTRL, which did not differ from each other. Correlations between self-awareness scores and neuroimaging data using small volume correction analyses in a priori regions of interest in converters indicated that inaccurate episodic FOK judgments was related to changes in brain areas that might support interpretation of retrieved content for judging the likelihood of recognition. For the MARS, the association between anosognosia and decreased gray matter density of the left inferior prefrontal cortex in converters might indicate poor inhibition over outdated personal knowledge. In amnestic MCI, anosognosia could be an early sign of neurodegeneration in brain areas that would support control mechanisms over memory representations.
虽然失认症在阿尔茨海默病中经常出现，但在早期阶段，如轻度认知障碍（MCI）时，对认知困难的认知程度尚不清楚。本研究采用问卷调查和知晓感任务，目的是：（1）检验以下假设，即失认症特别存在于前驱期AD阶段，这类患者由于更严重的AD神经病理学特征，将迅速发展为明显的痴呆；（2）评估记忆功能自我意识的神经基础。一组44例遗忘型MCI患者和一组29例健康老年参与者（对照组）完成了两项知晓感任务（情景性和语义性知晓感），并对功能记忆量表（MARS）做出回应，其亲属也完成了该量表。他们接受了氟代脱氧葡萄糖正电子发射断层扫描（FDG-PET）和结构磁共振成像（MRI）检查。对参与者进行了4年的临床随访。随访结束时，23例MCI患者发展为阿尔茨海默病（转化者），21例患者仍有MCI症状但未进展（未转化者）。分析聚焦于根据4年后临床状态分层纳入的数据（转化者、未转化者、对照组）。在情景性知晓感任务中，转化者患者高估了自己随后识别未回忆起单词的能力，且其预测准确性（哈曼系数）处于随机水平。在语义性知晓感任务中，任何组均未观察到困难。在MARS量表上，转化者患者的失认症得分高于未转化者患者和对照组，而后两者之间无差异。在转化者中，使用小体积校正分析在先验感兴趣区域对自我意识得分与神经影像学数据之间的相关性表明，情景性知晓感判断不准确与可能支持对检索内容进行解释以判断识别可能性的脑区变化有关。对于MARS量表，转化者中失认症与左下前额叶皮质灰质密度降低之间的关联可能表明对过时个人知识的抑制不足。在遗忘型MCI中，失认症可能是大脑区域神经退行性变的早期迹象，这些区域支持对记忆表征的控制机制。
