Conceptual implicit memory impaired in amnestic mild cognitive impairment patient

Explicit memory has been well proven to be impaired in amnestic mild cognitive impairment (aMCI), and conceptual implicit memory is impaired in Alzheimer's disease. However, it is unclear whether implicit memory is affected in aMCI. In the present study, 35 patients with aMCI and 35 healthy elderly subjects were administered a neuropsychological battery of tests including conceptual and perceptual implicit memory tasks (category exemplar generation, image identification) as well as explicit memory tasks. Patients with aMCI exhibited impairment in explicit memory tasks and selective impairment in conceptual priming tasks, while the effect of perceptual priming was preserved. More importantly, category exemplar generation task priming, but not perceptual priming, was positively correlated with verbal fluency test performance in the aMCI group. The dissociation between the 2 components of implicit priming suggests that conceptual priming impairment in aMCI patients may be related to frontal lobe dysfunction.     

轻度认知功能障碍患者的语义记忆损害与神经调控

文题释义：轻度认知障碍：是介于正常衰老与痴呆的过渡状态,是相对于年龄与教育程度的记忆或其他认知功能减退,记忆力、语言功能、注意力、执行能力等不同认知领域的减退,以记忆力减退为最常见的临床表现。国际轻度认知功能障碍工作组在2003年制定了轻度认知障碍的诊断标准：①有认知主诉,本人或知情者提供的认知功能障碍线索;②有认知功能损害的客观证据,选用蒙特利尔认知评估量表进行评分,高中及以上文化程度者≤26分,初中及以下文化程度者≤25分,且主要表现为记忆项异常者;③日常生活能力正常或仅有复杂日常能力轻度减退;④简易认知状态量表≥24分,不符合精神疾病的诊断和统计手册第四版诊断为痴呆的标准。语义记忆：包括对词语的意义、概念与事实的记忆。语义记忆涉及概念和实际知识是储存。广义上语义记忆包括对世界的所有认识。严格意义上的语义记忆,则是根据命名、分类任务判定。语义记忆障碍的患者表现为对熟悉的物品命名障碍。轻度的可能表现为语义分类词生成的减少,而严重的语义记忆障碍则表现为告知物品用途也不能进行命名,或给予名称也不能说出物品的用途,严重者可能表现为常识的缺失。 背景：阿尔茨海默病是一种进行性神经系统退化疾病,以认知下降为主要特点。认知力下降会导致老年人逐渐失去自我照料的能力,影响日常生活和活动。轻度认知障碍作为阿尔茨海默病的前驱状态,尽早对轻度认知障碍进行诊断和治疗,对预防阿尔茨海默病发展有重大的意义。 目的：针对轻度认知障碍语义记忆障碍评估与治疗的发展及未来前景做一综述。 方法：应用计算机在PubMed、Web of Science和中国知网、万方等数据库检索轻度认知障碍语义记忆评估、治疗的相关研究,检索关键词为“mild cognitive impairment,semantic memory impairment,semantic memory deficit,语义记忆,轻度认知功能障碍,轻度认知损害”,检索时间为2009年1月至2019年11月。结果与结论：语义记忆障碍为轻度认知障碍的主要临床症状之一,有一定的特异性。目前有不同类型的记忆量表可作为轻度认知障碍语义记忆障碍的神经心理学测量,颞叶、额叶和前运动区可能参与语义记忆环路。针对性的语义记忆神经生理学及辅助检查,靶向进行语义记忆康复训练,可利于早期识别轻度认知障碍的发生与转化。 ORCID: 0000-0002-2121-1523(关汉添) 中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

阻塞性睡眠呼吸暂停综合征患者轻度认知功能障碍的MoCA评估

目的 探讨简易精神状态检查量表(MMSE)、蒙特列尔认知评估量表(MoCA)评估阻塞性睡眠呼吸暂停综合征(OSAS)患者轻度认知功能障碍(MCI)的可行性.方法 用便携式多导睡眠仪、MMSE及MoCA对51名OSAS患者和35名单纯鼾症者进行睡眠监测和认知功能的评价.结果 OSAS组MoCA评分结果为21.1 ±3.0,显著低于对照组的25.0 ±2.6(P＜0.01);MMSE评分结果在OSAS组与对照组中分别为27.8±1.8及28.1±1.7,无统计学意义.结论 MoCA对于OSAS患者MCI的早期诊断敏感性优于MMSE,对于MMSE测试结果正常但高度怀疑存在MCI者,MoCA是一种简便可行的筛查工具.     

Depressive symptoms in amnesic mild cognitive impairment: an FDG-PET/CT study

IntroductionThe detection in mild cognitive impairment (MCI) of metabolic alterations suggestive of depression and/or of evolution to dementia.MethodsSixty-nine MCI patients underwent clinical and imaging evaluation including position emission tomography/computed tomography with fluorodeoxy-glucose (FDG-PET/CT).ResultsThe metabolism mean values in parietal, temporal and pre-cuneus areas were lower in subjects who evolved to dementia, and in frontal and in anterior cingulate areas in depressed subjects. Abnormal metabolism values were higher in the frontal and parietal lobes, and in the precuneus in subjects who evolved to dementia independently from depression.ConclusionsIn MCI FDG-PET/CT abnormality patterns suggest the presence of depression or the evolution to dementia.     

Prognosis of mild cognitive impairment syndrome: Data from a two-year clinical follow-up study

The psychopathological structure and prognostic significance of mild cognitive impairment syndrome (MCI) were studied in a two-year prospective study of randomized cohorts of elderly subjects whose mental state corresponded to the criteria for MCI. A total of 40 patients aged from 50 to 80 years were studied. Patients underwent clinical history-taking, neuropsychological, psychometric, and genetic investigations (genotyping for ApoE), as well as brain imaging studies. The psychopathological structure and psychometric characteristics of MCI syndrome are presented. Clinical and genetic factors with prognostic significance are identified. __________ Translated from Zhurnal Nevrologii i Psikhiatrii imeni S. S. Korsakova, Vol. 107, No. 1, pp. 4–10, January, 2007.     

基于纹理分析的阿尔茨海默症及轻度认知功能障碍的分类研究

目的 利用脑MR图像中胼胝体的三维纹理特征对阿尔茨海默症患者（Alzheimer disease,AD）及轻度认知功能障碍（mild cognitive impairment,MCI）患者进行分类识别,以探索AD早期诊断新途径.方法 选取AD患者、MCI患者及健康对照者各l8例,采用灰度共生矩阵和游程长矩阵提取每位受试者胼胝体部位的三维纹理特征.通过筛选得到的纹理特征参量,利用BP神经网络建立识别模型,对AD患者、MCI患者和健康对照者进行分类识别,并对采用主成分分析、线性判别分析和非线性判别分析3种方法得到的识别结果进行比较.结果 使用神经网络模型的非线性判别分析的分类识别正确率最高.结论 利用三维纹理特征的神经网络模型可分类识别早期AD患者及MCI患者.     

Conversion from mild cognitive impairment to Alzheimer's disease is predicted by sources and coherence of brain electroencephalography rhythms

Objective. Can quantitative electroencephalography (EEG) predict the conversion from mild cognitive impairment (MCI) to Alzheimer’s disease (AD)?     

EEG network connectivity changes in mild cognitive impairment — Preliminary results

Resting state EEGs were compared between patients with amnestic subtype of mild cognitive impairment (aMCI) and matched elderly controls at two times over a one year period. The study aimed at investigating the role of functional connectivity between and within different brain regions in relation to the progression of cognitive deficit in MCI. The EEG was recorded in two sessions during eyes closed and eyes open resting conditions. Functional brain connectivity was investigated based on the measurement of phase synchronization in different frequency bands. Delta and theta synchronization characteristics indicated decreased level of local and large-scale connectivity in the patients within the frontal, between the frontal and temporal, and frontal and parietal brain areas which was more pronounced 1 year later. As a consequence of opening the eyes connectivity in the alpha1 band within the parietal lobe decreased compared to the eyes closed condition but only in the control group. The lack of alpha1 band reactivity following eye opening could reliably differentiate patients from controls. Our preliminary results support the notion that the functional disconnection between distant brain areas is a characteristic feature of MCI, and may prove to be predictive in terms of the progression of this condition.     

Increased plasma levels of heat shock protein 70 in patients with vascular mild cognitive impairment

Heat shock proteins (Hsps) have been regarded as cytoprotectants that protect brain cells from damage encountered following cerebral ischemia or during the progression of neurodegenerative diseases. In this study, we assessed the plasma Hsp70 and Hsp27 levels in not cognitively impaired (NCI) subjects and in patients with mild cognitive impairment (MCI), vascular mild cognitive impairment (VMCI), and probable Alzheimer's disease (AD). Comparison of the plasma Hsp70 and Hsp27 levels of the 4 groups revealed that only the plasma Hsp70 level of VMCI patients (14.11 ng/ml) was significantly higher than that of NCI subjects (11.32 ng/ml), MCI patients (10.16 ng/ml), and patients with probable AD (10.16 ng/ml) after adjustment of age, sex, and education (F=4.231, d.f.=3, p=0.008). Furthermore, there was no difference in plasma Hsp27 levels among the 4 groups. These findings suggest that the plasma Hsp70 level may be related to vascular factors or inflammation.     

Differences in and correlations between cognitive abilities and brain volumes in healthy control,mild cognitive impairment,and Alzheimer disease groups

The purpose of this study is to investigate differences in and correlations between cognitive abilities and brain volumes in healthy control (HC), mild cognitive impairment (MCI), and Alzheimer's disease (AD) groups. The Korean Version of the Consortium to Establish a Registry for Alzheimer's Disease (CERAD‐K), which is used to diagnose AD, was used to measure the cognitive abilities of the study subjects, and the volumes of typical brain components related to AD diagnosis—cerebrospinal fluid (CSF), gray matter (GM), and white matter (WM)—were acquired. Of the CERAD‐K subtests, the Boston Naming Test distinguished significantly among the HC, MCI, and AD groups. GM and WM volumes differed significantly among the three groups. There was a significant positive correlation between Boston Naming Test scores and GM and WM volumes. In conclusion, the Boston Naming Test and GM and WM brain volumes differentiated the three tested groups accurately, and there were strong correlations between Boston Naming Test scores and GM and WM volumes. These results will help to establish a test method that differentiates the three groups accurately and is economically feasible. Clin. Anat. 29:473–480, 2016. © 2016 Wiley Periodicals, Inc.     

轻度认知障碍神经炎症机制的作用靶点

背景:临床上,轻度认知障碍是正常衰老认知下降与阿尔茨海默症早期之间的过渡状态,被认为是预防或改变阿尔茨海默症退行性变的最佳阶段.近年来,越来越多的研究表明,神经炎症是轻度认知障碍的核心发病机制和主要早期病理特征之一.目的:综述国内外神经炎症导致轻度认知障碍的机制研究进展.方法:英文检索词为neuroinflammat...     

Executive dysfunction and gray matter atrophy in amnestic mild cognitive impairment

Recent studies have shown that impairment in executive function (EF) is common in patients with amnestic mild cognitive impairment (aMCI). However, the neuroanatomic basis of executive impairment in patients with aMCI remains unclear. In this study, multiple regression voxel-based morphometry analyses were used to examine the relationship between regional gray matter volumes and EF performance in 50 patients with aMCI and 48 healthy age-matched controls. The core EF components (response inhibition, working memory and task switching, based on the EF model of Miyake et al) were accessed with computerized tasks. Atrophic brain areas related to decreases in the three EF components in patients with aMCI were located in the frontal and temporal cortices. Within the frontal cortex, the brain region related to response inhibition was identified in the right inferior frontal gyrus. Brain regions related to working memory were located in the left anterior cingulate gyrus, left premotor cortex, and right inferior frontal gyrus, and brain regions related to task shifting were distributed in the bilateral frontal cortex. Atrophy in the right inferior frontal gyrus was most closely associated with a decrease in all three EF components in patients with aMCI. Our data, from the perspective of brain morphology, contribute to a better understanding of the role of these brain areas in the neural network of EF.     

Increased fMRI responses during encoding in mild cognitive impairment

Structural and functional magnetic resonance imaging (fMRI) was performed on 21 healthy elderly controls, 14 subjects with mild cognitive impairment (MCI) and 15 patients with mild Alzheimer's disease (AD) to investigate changes in fMRI activation in relation to underlying structural atrophy. The fMRI paradigm consisted of associative encoding of novel picture-word pairs. Structural analysis of the brain was performed using voxel-based morphometry (VBM) and hippocampal volumetry. Compared to controls, the MCI subjects exhibited increased fMRI responses in the posterior hippocampal, parahippocampal and fusiform regions, while VBM revealed more atrophy in MCI in the anterior parts of the left hippocampus. Furthermore, the hippocampal volume and parahippocampal activation were negatively correlated in MCI, but not in controls or in AD. We suggest that the increased fMRI activation in MCI in the posterior medial temporal and closely connected fusiform regions is compensatory due to the incipient atrophy in the anterior medial temporal lobe.     

Abnormal white matter independent of hippocampal atrophy in amnestic type mild cognitive impairment

Hippocampal atrophy is the key marker in the pathogenesis of Alzheimer's disease (AD), which is associated with white matter (WM) disruption. This type of WM disruption could partly explain AD-related pathology. However, relatively little attention has been directed toward WM disruption which may be independent of these fundamental gray matter (GM) changes in amnestic mild cognitive impairment (aMCI) which is associated with high risk of AD. To evaluate the differences of WM integrity between aMCI patients (N = 32) and healthy controls (N = 31), whole-brain voxel-based methods were applied to diffusion tensor imaging. To explore the possible independence of WM changes from GM loss, an index of hippocampal atrophy was used to partial out GM effects. aMCI patients showed WM disruption in frontal lobe, temporal lobe, internal capsule, cingulate gyrus and precuneus. The findings supported the evidence of independent patterns of degeneration in WM tracts which may co-act in the WM pathological process of aMCI patients. As aMCI is a putatively prodromal syndrome to AD, these data may assist with a better understanding of WM pathological change associated with the development of AD.     

The nature of memory failure in mild cognitive impairment: examining association with neurobiological markers and effect of progression

The main goal of this study was to assess vulnerability to proactive interference and memory binding capacity, the ability to combine different information into a single coherent memory event, in persons with mild cognitive impairment (MCI). We also examined whether hippocampal atrophy and vascular burden were differentially related to these memory capacities in MCI. We further assessed whether memory performance and brain changes differ as a function of later development (or not) of dementia and whether they can predict progression to dementia. The study included 77 participants, 49 meeting the criteria for MCI and 28 healthy older adults. Results showed binding deficits and greater vulnerability to proactive interference in persons with MCI compared with healthy older adults. Hippocampal volume was associated with binding capacity, whereas vascular burden was associated with resistance to interference in persons with MCI. Follow-up analyses indicated that binding deficits predict progression from MCI to dementia. In conclusion, binding deficits and vulnerability to proactive interference are present in persons with MCI and are associated with different brain markers. However, only binding deficits predict progression to dementia.     

轻度认知功能损害多维识别体系及在社区筛查中的运用(综述)

轻度认知功能损害(MCI)是介于正常老化和老年期痴呆之间的过渡阶段,其识别是预防和延缓老年期痴呆的一个突破口.本文首先回顾了近年来研究人员从临床问诊、神经心理测查、影像分析以及生化标记4个维度开展的MCI识别工作,对单维识别各自的优势和劣势进行了分析,指出有效的MCI诊断模型需要将多种技术和手段相结合.进而提出多维识别的核心理念,旨在强调指标的有效性、可获取性以及互不重叠的原则.最后提出基于社区的MCI筛查理想模型,包含大样本初筛、疑似人群细筛及诊断后的监控和干预3部分.     

A randomized controlled trial of estrogen treatment in men with mild cognitive impairment

This randomized, placebo-controlled, cross-over study investigated whether estrogen treatment would have a beneficial effect on tests of verbal memory in men with mild cognitive impairment (MCI). Forty-three men newly diagnosed with MCI were administered a battery of neuropsychological tests before randomly receiving 12 weeks of treatment with estrogen or placebo followed by a 12 week cross-over treatment. A significant improvement in the total score, and in two subscale scores of the Buschke Selective Reminding Test occurred following estrogen treatment compared to both pretreatment and post-placebo scores (p < 0.05). However, benefit occurred only in the men who had received estrogen for 12 weeks following 12 weeks of placebo. Although these findings tentatively suggest that treatment with estrogen may improve verbal memory in men with MCI, the fact that the improvement occurred only in the group that received estrogen following 12 weeks of placebo and the absence of improvement on every test of verbal memory administered suggests that these findings need to be replicated using a larger sample size.     

Brain perfusion SPECT with an automated quantitative tool can identify prodromal Alzheimer's disease among patients with mild cognitive impairment

Objective

To improve diagnosis of early Alzheimer's disease (AD), i.e., prodromal AD, by an automated quantitative tool combining brain perfusion single-photon emission computed tomography (SPECT) images and memory tests scores in order to be applied in clinical practice.

Patients and methods

In this prospective, longitudinal, multi-centric study, a baseline ^99mTc-ECD perfusion SPECT was performed in 83 patients with memory complaint and mild cognitive impairment (MCI). After a 3-year follow-up, 11 patients progressed to Alzheimer's disease (MCI-AD group), and 72 patients remained stable (MCI-S group), including 1 patient who developed mild vascular cognitive impairment. After comparison between the MCI-S and MCI-AD groups with a voxel-based approach, region masks were extracted from the statistically significant clusters and used alone or in combination with Free and Cued Selective Reminding Test (FCSRT) scores for the subject's categorization using linear discriminant analysis. Results were validated using the leave-one-out cross-validation method.

Results

Right parietal and hippocampal perfusion was significantly (p < 0.05, corrected) decreased in the MCI-AD group as compared to the MCI-S group. The patients’ classification in the MCI group using the mean activity in right and left parietal cortex and hippocampus yielded a sensitivity, specificity, and accuracy of 82%, 90%, and 89%, respectively. Combination of SPECT results and FCSRT free recall scores increased specificity to 93%.

Conclusion

The combination of an automated quantitative tool for brain perfusion SPECT images and memory test scores was able to distinguish, in a group of amnestic MCI, patients at an early stage of AD from patients with stable MCI.     

Neural correlates of delayed episodic memory in patients with mild cognitive impairment—A FDG PET study

Mild cognitive impairment (MCI) is characterized by cognitive deficits which do not yet reach the threshold of dementia but represent a putative preclinical state of Alzheimer's disease (AD). Little is known about the neural correlates of delayed episodic memory which is among the earliest signs of cognitive decline in patients at risk of developing AD. We performed resting state positron emission tomography (PET) with ¹⁸Fluorodeoxyglucose (FDG) in patients with MCI, and hypothesized a correlation between delayed episodic memory performance and frontal glucose metabolism since the latter is relatively spared in the preclinical phase of the disease. 43 patients (age: 69.7 ± 7.9 years; 24 male, 19 female) with MCI were investigated by FDG PET. Significant positive correlations with delayed episodic memory performance were calculated by statistical parametric mapping. To our knowledge the present study is the first to demonstrate by FDG PET the neural correlates of delayed episodic memory in patients with MCI. Our study revealed a pattern of cerebral glucose metabolism including bifrontal regions which may contribute to the delayed episodic memory performance of patients with MCI. Since not all patients with MCI will further deteriorate, AD specific mechanism may not be concluded from the present study but warrant longitudinal investigations.