遗忘型轻度认知功能障碍的执行功能损害

目的探讨遗忘型轻度认知功能障碍患者执行功能变化的特点。方法依据Miyake的执行功能三因素模型(工作记忆、任务转换、反应抑制),使用E-prime软件对这三种执行功能核心成分编写检测任务:利用2-back任务和Keep-track任务检测工作记忆,Stop-signal任务和Stroop任务检测反应抑制,More-odd shift-ing任务检测任务转换能力。在34例遗忘型轻度认知功能障碍(amnestic mild cognitive impairement,aMCI)患者和31例正常老年人中进行这些任务的检测,比较两组间执行功能差异的特点。结果 aMCI组的执行功能比对照组显著降低(Wilks′λ=0.567,P﹤0.01)。除Stroop任务的数据两组间没有明显差异之外,aMCI组的2-back任务、Keep-track任务、Stop-signal任务、More-odd shifting任务的成绩均显著低于对照组(P<0.05),但这4种任务成绩下降的程度彼此间没有显著差异。结论aMCI阶段已经出现了执行功能的全面损害,三种执行功能核心成分均有受损。     

遗忘型轻度认知障碍内隐记忆启动效应的研究

目的探讨遗忘型轻度认知障碍患者(aMCI)内隐记忆概念性启动和知觉性启动损害的特征。方法采用分类产生和图片辨别对35例aMCI患者和35名正常老年人的内隐记忆(概念性启动和知觉性启动)进行测试,同时进行外显记忆(即刻回忆、延时回忆、延时再认)和其他神经心理学背景测试,并进行组间比较和分析。结果与正常老年组相比,aMCI患者组即刻回忆、延时回忆、延时再认、概念性启动成绩均差于正常对照组(P0.01)。两组在知觉性启动成绩差异无统计学意义(P0.05)。患者组概念性启动成绩与词汇流畅性成绩呈正相关(r=0.74,P0.01)。结论aMCI患者外显记忆及内隐记忆的概念性启动存在损害,且其概念性启动损害可能与其额叶功能减退存在一定的相关性。     

Caregiver burden in mild cognitive impairment

Objectives: We aimed to compare the rates of burden amongst caregivers of participants with mild cognitive impairment (MCI), compared to a control group. We also aimed to identify factors in both the caregiver and patient that are associated with significant levels of burden.

Method: This was a cross-sectional study. Sixty-four participants with MCI, 36 control-participants and their respective caregivers/informants were recruited to a university research clinic. The proportion of those who showed clinically significant levels of burden was determined by a Zarit Burden Interview score of >21. The associations of burden in MCI-caregivers were calculated in the following categories; participant characteristics (including depressive symptoms, cognition and informant ratings of cognitive and behavioural change); caregiver characteristics; and the caregiving context. Multivariate analyses were performed to examine the relative contribution of individual variables to burden amongst MCI-caregivers.

Results: We found that 36% of MCI-caregivers reported clinically significant levels of burden, twice that of the control informant group. Participant behavioural problems contribute most to burden, with participant depression and possibly cognition also having a significant association.

Conclusion: Caregiver burden is a considerable problem in MCI and shares some of the same characteristics as caregiver burden in dementia, namely a strong association with challenging behaviours in the patient. This has implications for further research and intervention studies.     

Profile of memory impairment and gray matter loss in amnestic mild cognitive impairment

The present study assessed the patterns of cortical gray matter (GM) loss in patients with amnestic mild cognitive impairment (aMCI) with distinct profiles of memory impairment, i.e. aMCI patients failing on both recall and recognition memory vs. aMCI patients showing impaired recall but preserved recognition memory. This distinction is usually not taken into account in studies on aMCI and the aim of the present study was to assess whether this distinction is useful. Twenty-eight aMCI patients and 28 matched controls subjects were included. All aMCI patients failed a recall memory task (inclusion criteria). All underwent a visual recognition memory task (DMS48). However, 12 succeeded on this task while 16 failed. Relative gray matter (GM) loss was measured using voxel-based morphometry. When comparing aMCI patients to controls regardless of the profile of memory impairment, GM loss was found in temporal, parietal and frontal areas. However, in aMCI patients with preserved recognition (but impaired recall), GM loss was confined to frontal areas. This contrasted with GM loss in the right medial temporal lobe and bilateral temporo-parietal regions in aMCI patients with impaired recall and recognition memory, a pattern of GM loss usually described in early AD. We conclude that different profiles of memory impairment in aMCI patients are associated with distinct patterns of GM loss.     

脑白质病变相关性轻度认知功能障碍患者神经心理学特征分析

目的观察脑白质病变(WML)对轻度认知功能损害(mild cognitive impairment,MCI)患者神经心理学的影响。方法 WML-MCI患者和健康对照者进行常规核磁共振及神经心理学检查,观察WML对MCI患者神经心理学的影响,并对其机制进行探讨。结果 WML-MCI组与对照组相比,高血压、糖尿病和冠心病比例明显增高;词语流畅性测验、积木测验和画钟测验评分均明显降低(P<0.05);而2组间MMSE、数字广度测验和词语延迟回忆测验评分无明显差异。结论 WML影响MCI患者的认知功能,主要表现为视空间及执行功能。血管危险因素是MCI发病的危险因素。     

多领域认知训练对社区轻度认知障碍老年人影响的随机对照研究

目的 探索多领域认知训练对社区轻度认知障碍(MCI)老年人的干预效果.方法 将120例研究对象按照区组随机化方法分为干预组(60例)和对照组(60例),干预组进行12周多领域认知训练,2次/周,60 min/次;干预前后采用可重复的成套神经心理状态测量(RBANS)、视觉匹配与推理测验、stroop字色干扰测验(CWST)、彩色数字连线测验(TMT)评定2组的认知功能并进行比较.结果 (1)干预前:干预组RBANS注意力因子分[(81.3±15.5)分]与对照组[(74.3±12.1)分]比较,差异有统计学意义(t=-2.37,P=0.02);其他测评指标2组比较差异均无统计学意义.(2)干预后:干预组与对照组RBANS总分[(86.4±12.6)分:(78.6±9.3)分;t=3.07,P=0.00]、即刻记忆[(83.4±14.1)分:(74.6±11.5)分;t=3.03,P=0.00]、空间结构[(95.7±14.3)分:(89.1±12.9)分;t=2.16,P=0.03]、延迟记忆等因子分[(91.8±17.4)分:(83.7±13.0)分;t=2.32,P=0.02],视觉匹配与推理[(5.2±1.9)分:(3.9±1.9)分;t=3.11,P=0.00],TMT测验1完成时间[(110.0±44.4)s:(130.5±45.1)s;t=-2.07,P=0.04]比较,差异有统计学意义.结论 多领域认知训练干预效果明显,依从性好,对社区MCI老年人的认知功能具有促进或保持作用.     

Alteration of autobiographical memory in amnestic mild cognitive impairment

The concept of amnestic mild cognitive impairment (aMCI) concerns a population of older individuals at high risk of developing probable Alzheimer's disease. Although anterograde memory deficits have been largely documented in patients with aMCI, little is known about the integrity of their autobiographical memory (AuM). This study aimed at evaluating AuM in aMCI individuals and at investigating whether their ability to retrieve AuMs varied as a function of whether the tests used required recognition or effortful retrieval processes. Fourteen aMCI patients and 14 matched controls underwent a standard neuropsychological evaluation and an extensive autobiographical assessment. AuM was explored using verbal material, the Autobiographical Memory Interview, and a visual task of personal photographs. Together, these tests tapped the semantic and episodic components of AuM and different cognitive processes involved in retrieval (recall and recognition). Results indicate that AuM is altered in aMCI patients. This impairment affects both episodic and semantic components of AuM, and is characterized by a general difficulty in recollecting personal episodes covering the entire lifespan, along with a loss of recognition of recently experienced episodes. Furthermore, recollection of personal episodes was correlated with scores on tests requiring retrieval abilities, while recognition of familiar photographs was correlated with scores on tests assessing encoding/storage of new information. Results suggest that the AuM deficit in aMCI patients may result from the combination of two mechanisms, an anterograde memory impairment impeding the storage of newly experienced events, and a global alteration of recollection affecting the recall of AuM covering all periods of life. Alteration of these processes may possibly be related to the progression and distribution of the neuropathological lesions in medial temporal and frontal lobe structures found in Alzheimer's disease.     

Cognitive reserve modulates task-induced activations and deactivations in healthy elders, amnestic mild cognitive impairment and mild Alzheimer's disease

Introduction

Cognitive reserve (CR) reflects the capacity of the brain to endure neuropathology in order to minimize clinical manifestations. Previous studies showed that CR modulates the patterns of brain activity in both healthy and clinical populations. In the present study we sought to determine whether reorganizations of functional brain resources linked to CR could already be observed in amnestic mild cognitive impairment (a-MCI) and mild Alzheimer's disease (AD) patients when performing a task corresponding to an unaffected cognitive domain. We further investigated if activity in regions showing task-induced deactivations, usually identified as pertaining to the default-mode network (DMN), was also influenced by CR.

Methods

Fifteen healthy elders, 15 a-MCI and 15 AD patients underwent functional magnetic resonance imaging (fMRI) during a speech comprehension task. Differences in the regression of slopes between CR proxies and blood-oxygen-level dependent (BOLD) signals across clinical groups were investigated for activation and deactivation areas. Correlations between significant fMRI results and a language comprehension test were also computed.

Results

Among a-MCI and AD we observed positive correlations between CR measures and BOLD signals in task-induced activation areas directly processing speech, as well as greater deactivations in regions of the DMN. These relationships were inverted in healthy elders. We found no evidence that these results were mediated by gray matter volumes. Increased activity in left frontal areas and decreased activity in the anterior cingulate were related to better language comprehension in clinical evaluations.

Conclusions

The present findings provide evidence that the neurofunctional reorganizations related to CR among a-MCI and AD patients can be seen even when considering a preserved cognitive domain, being independent of gray matter atrophy. Areas showing both task-induced activations and deactivations are modulated by CR in an opposite manner when considering healthy elders versus patients. Brain reorganizations facilitated by CR may reflect behavioral compensatory mechanisms.     

Caregiving burden and psychiatric morbidity in spouses of persons with mild cognitive impairment

BACKGROUND: While the deleterious psychosocial and mental health effects of dementia caregiving are firmly established, very little is known about the burdens or psychiatric outcomes of providing care to a spouse with less severe cognitive impairment, such as mild cognitive impairment (MCI). We characterized the nature and level of caregiver burden and psychiatric morbidity in spouses of persons diagnosed with MCI. METHODS: Interview assessments were completed on a cohort of 27 spouses of persons with a recent diagnosis of MCI. Patient medical records were reviewed to collect information regarding the MCI patient's medical history. RESULTS: Respondents endorsed elevated levels of both task-related responsibilities and subjective caregiver burden. Depression and anxiety symptom levels also showed some elevations. Measures of caregiver burden were significantly associated with depression and anxiety levels. In particular, even after controlling for demographic risk factors for distress, nursing task burden was correlated with elevated depressive symptoms, and greater lifestyle constraints were correlated with higher anxiety levels. CONCLUSIONS: Although caregiver burden and psychiatric morbidity levels were lower than those typically observed in family dementia caregiving samples, our findings suggest that MCI caregivers have already begun to experience distress in association with elevated caregiving burden. These individuals may be ideal targets for selective preventive interventions to maximize their psychological well-being as caregiving burdens related to their spouses' cognitive impairment increase.     

Dynamic working memory performance in individuals with single-domain amnestic mild cognitive impairment

Previous studies have observed poorer working memory performance in individuals with amnestic mild cognitive impairment than in healthy older adults. It is unclear, however, whether these difficulties are true only of the multiple-domain clinical subtype in whom poorer executive functioning is common. The current study examined working memory, as measured by the self-ordered pointing task (SOPT) and an n-back task, in healthy older adults and adults with single-domain amnestic mild cognitive impairment (aMCI). Individuals with single-domain aMCI committed more errors and required longer to develop an organizational strategy on the SOPT. The single-domain aMCI group did not differ from healthy older adults on the 1-back or 2-back, but had poorer discrimination on the 3-back task. This is, to our knowledge, the first characterization of dynamic working memory performance in a single-domain aMCI group. These results lend support for the idea that clinical amnestic MCI subtypes may reflect different stages on a continuum of progression to dementia and question whether standardized measures of working memory (span tasks) are sensitive enough to capture subtle changes in performance.     

遗忘型轻度认知损害的神经影像与神经心理特点

目的 了解aMCI脑结构改变和相关认知损害特点,探讨准确诊断aMCI的神经影像和神经心理生物指标。方法 3-DMRI采集35例aMCI患者和35名健康对照者脑结构信息,LEAP软件计算左右侧和均侧海马、杏仁核和颞角体积,MoCA测评认知功能。结果两组被试年龄、性别差异无统计学意义（P〉0．05）,受教育年限差异有统计学意义（P〈0．01）。aMCI的左、右侧及均侧海马萎缩和右侧颞角扩大（P〈0．05）,MoCA总评分和注意力、重复句子、抽象能力、延迟回忆、定向力等亚项得分减低（P〈0．05）,MoCA与右、均侧海马及右侧杏仁核呈正相关（P〈0．05）。ROC分析显示Mo—cA总评分、左、右及均侧海马、左、右及均侧杏仁核等指标诊断aMCI准确性高（P〈0．01）。单独认知指标MoCA总评分和重复句子（wilks’Lambda=0．299,X^2=80．905,df=2,P〈0．01）区分aMCI和NC的准确性为88．6％,单独脑结构指标均侧海马和杏仁核（wilks’Lambda=0．515,X^244．509,df=2,P〈0．01）的准确性为81．4％,认知和脑结构综合指标MoCA总评分、均侧海马和左侧杏仁核（Wilks’Lambda=0．261,X^2=89．228,df=3,P〈0．01）的准确性为95．7％。结论 aMCI期已出现特异的海马、杏仁核萎缩和弥漫性认知损害,在AD非痴呆期联合应用认知测试和神经影像指标更有助于AD早期准确诊断。     

Effect of conceptual and lexical errorless versus trial-and-error learning in amnestic mild cognitive impairment

Errorless learning (EL), involving presenting the target information during encoding, is generally considered effective for teaching information to memory-impaired populations. However, evidence suggests that trial-and-error learning (TEL) can benefit healthy older adults’ memory when guesses are conceptually related to the target. To determine whether TEL can benefit persons with mild cognitive impairment (aMCI), 24 participants with aMCI were given cues associated with nine target words. Half the sample received Conceptual cues (e.g., “beverage”) and the other half received Lexical cues (e.g., SC_______). All underwent an EL study phase, in which the target was presented immediately after the cue, and a TEL phase, in which they made guesses from the cue before the target was presented. Cued recall was tested immediately and 24?h later. At immediate but not 24-h delayed recall, EL targets were better remembered than TEL targets in both conditions. Verbal memory performance appeared to explain why certain individuals benefited more from EL relative to TEL, while semantic memory performance appeared to explain why some people benefited more from conceptual than lexical errors. Thus, EL-based memory intervention for aMCI is likely to be more effective than TEL, particularly to the extent that semantic or episodic memory is affected.     

中文版MoCA和MMSE在诊断遗忘型轻度认知功能障碍中的应用

目的 研究中文版蒙特利尔认知评估量表(MoCA)在遗忘型轻度认知障碍(aMCI)诊断筛查中的作用. 方法 以2009-05-2010-03在卫生部北京医院神经内科门诊就诊的患者为检查对象,筛选出aMCI患者31例及健康对照者30名,分别进行简易精神状态量表(MMSE)、MoCA等量表检测,计算两量表诊断aMCI的敏感性和特异性并进行比较,分析MoCA在诊断aMCI中的作用和特点. 结果 以26分作为分界值时,MMSE和MoCA诊断aMCI的敏感性分别为9.68%和87.10%,特异性分别为93.33%和73.33%.MoCA的敏感性显著高于MMSE. 结论与MMSE 相比,MoCA以其较高的敏感性在筛查aMCI中具有较大作用,而且可对多个认知领域的功能进行检测,有望在多个认知损害类型的研究中起到重要作用.     

Global brain hypoperfusion and oxygenation in amnestic mild cognitive impairment

BackgroundTo determine if global brain hypoperfusion and oxygen hypometabolism occur in patients with amnestic mild cognitive impairment (aMCI).MethodsThirty-two aMCI and 21 normal subjects participated. Total cerebral blood flow (TCBF), cerebral metabolic rate of oxygen (CMRO₂), and brain tissue volume were measured using color-coded duplex ultrasonography (CDUS), near-infrared spectroscopy (NIRS), and MRI. TCBF was normalized by total brain tissue volume (TBV) for group comparisons (nTCBF). Cerebrovascular resistance (CVR) was calculated as mean arterial pressure divided by TCBF.ResultsReductions in nTCBF by 9%, CMRO₂ by 11%, and an increase in CVR by 13% were observed in aMCI relative to normal subjects. No group differences in TBV were observed. nTCBF was correlated with CMRO₂ in normal controls, but not in aMCI.ConclusionsGlobal brain hypoperfusion, oxygen hypometabolism, and neurovascular decoupling observed in aMCI suggest that changes in cerebral hemodynamics occur early at a prodromal stage of Alzheimer's disease, which can be assessed using low-cost and bedside-available CDUS and NIRS technology.     

轻度认知功能障碍老年人的睡眠实验研究

目的探讨轻度认知功能障碍（MCI）老年人多导睡眠图（PSG）变化特点。方法应用多导睡眠生理仪,采用眼电图和下颌肌电图及脑电图技术,对19例MCI老年人（MCI组）的PSG进行全夜监测,并与20名正常老年人（NC组）对照。结果与NC组比较,MCI组睡眠总时间减少[NC组（381±37）min,MCI组（313±67）min,P〈0.01],觉醒时间增加[NC组（30±10）min,MCI组（53±17）min,P〈0.01],睡眠维持率下降[NC组（94±10）%,MCI组（85±13）%,P〈0.05],第1阶段睡眠增加[NC组（14±2）%,MCI组（28±10）%,P〈0.01],第2阶段睡眠降低[NC组（60±4）%,MCI组（51±18）%,P〈0.05]和第3阶段睡眠降低[NC组（9±5）%,MCI组（4±3）%,P〈0.01],REM强度增强[NC组（21±4）%,MCI组（40±22）%,P〈0.01]。结论PSG中的浅睡眠增多,慢波睡眠S3减少可能是MCI病人所具有的电生理学指标之一。     

轻度认知功能障碍患者的神经心理学研究

目的 探讨轻度认知功能障碍(MCI)患者神经心理学的特点. 方法 对42例MCI患者和55例健康对照者进行多项神经心理学检查,包括简易精神状态检查量表(MMSE)、蒙特利尔认知评估量表(MoCA)、临床痴呆评定量表(CDR)、语言流畅性测验(RVR)、韦氏智力测验(WAIS-RC)[包括数字广度测验(DS)、积木测验(BD)、相似性测验]、韦氏记忆测验(WMS-R)(包括逻辑记忆、联想学习、视觉再认、图片回忆)、日常生活能力量表(ADL),比较2组患者上述量表评分和MMSE、MoCA量表各亚项评分的差异.结果 与对照者比较,MCI患者MMSE、MoCA总分和RVR、WAIS-RC、WMS-R分测验,MoCA量表各亚项(地点定向力除外),MMSE量表中计算与注意、延迟回忆两亚项评分较低,差异均有统计学意义(P<0.05).结论 MCI患者不仅记忆受损,其计算与注意力、命名、视空间结构能力、执行功能也可受损,尤以延迟回忆、计算与注意力受损明显.MoCA涵盖了重要的认知领域,能较全面评估MCI患者的认知功能,值的临床推广应用.     

Self-awareness of cognitive efficiency: Differences between healthy elderly and patients with mild cognitive impairment (MCI)

Introduction: Self-estimation of performance implies the ability to understand one’s own performance with relatively objective terms. Up to date, few studies have addressed this topic in mild cognitive impairment (MCI) patients. The aim of the present study was to compare objective measures of performance with subjective perception of specific performance on cognitive tests and investigate differences in assessment between MCI patients and healthy elderly. Method: Thirty-five participants diagnosed with MCI (women = 16, men = 19, mean age = 65.09 years ±SD = 7.81, mean education = 12.83 years ±SD = 4.32) and 35 control subjects similar in terms of age and education (women = 20, men = 15, mean age = 62.46 years ± SD = 9.35, mean education = 14.26 ± SD = 2.84) were examined with an extended battery of neuropsychological tests. After every test they were asked to self-evaluate their performance by comparing it to what they considered as average for people of their age and educational level. This self-evaluation was reported on a scale ranging from –100 to +100. Results: Significant differences were found in the self-assessment patterns of the two groups in memory measures of verbal and visual delayed recall, visuospatial perception, and tests of attention. MCI patients overestimated their performance on every cognitive domain while control participants underestimated their performance on measures of verbal memory. Conclusions: The present results indicate that accuracy of self-report is not uniform across groups and functional areas. The discrepancies in the MCI patients indicate unawareness of their memory deficits, which is contradictory to subjective memory complaints as being an important component for clinical diagnosis.     

An fMRI study of verbal episodic memory encoding in amnestic mild cognitive impairment

Amnestic mild cognitive impairment (aMCI) is a high-risk and often prodromal state for the development of Alzheimer's disease (AD) and is characterised by isolated episodic memory impairment. Functional neuroimaging studies in healthy subjects consistently report left prefrontal cortex (PFC) activation during verbal episodic memory encoding. The PFC activation at encoding is related to semantic processing which enhances memory. The purpose of this study was to ascertain whether impaired verbal episodic memory in aMCI is related to PFC dysfunction. Using functional magnetic resonance imaging (fMRI) we compared 10 aMCI patients with 10 elderly controls during verbal encoding. The encoding task was sensitive to the effects of semantic processing. Subsequent recognition was tested to measure encoding success. Behavioural results revealed impaired recognition and a lower false recognition rate for semantically related distracters (lures) in aMCI, which suggest impaired semantic processing at encoding. Both groups activated left hemispheric PFC, insula, premotor cortex and cerebellum, but group comparisons revealed decreased activation in left ventrolateral PFC in the aMCI group. The magnitude of activation in left ventrolateral PFC during encoding was positively correlated with recognition accuracy in the control group but not in the aMCI group. We propose that verbal episodic memory impairment in aMCI is related to PFC dysfunction which affects semantic processing at encoding.