轻度认知障碍和阿尔茨海默病的边缘系统氢质子磁共振波谱特点

目的探讨海马和扣带回后部氢质子磁共振波谱(’H-MRS)改变在轻度认知障碍(MCI)和阿尔茨海默病(AD)早期诊断中的作用。方法应用’H-MRS技术检测15名健康老年人、15例MCI患者及15例AD患者脑内边缘系统的代谢物水平,对检测的N-乙酰天门冬氨酸(NAA)、胆碱复合物(Cho)、肌酸复合物(Cr)和肌醇(mI)波谱数据进行比较分析。结果 AD组与健康对照组和MCI组相比,海马部位的mI/Cr均升高(均P0.05),NAA/mI降低(均P0.05);随病情进展,扣带回后部的mI/Cr呈递增趋势(P0.05),NAA/mI呈递减趋势(P0.05);AD组和MCI组扣带回后部的NAA/mI与健康对照组的差别程度大于海马部位(P=0.001,P=0.019)。结论扣带回后部的mI/Cr和NAA/mI有助于鉴别健康老人和AD患者;海马部位的NAA/mI有助于鉴别痴呆和非痴呆;MRS在诊断AD和MCI方面有一定辅助作用。     

阿尔茨海默病与轻度认知障碍弥散张量成像研究

目的:应用磁共振弥散张量成像技术(DTI)研究阿尔茨海默病(AD)与轻度认知障碍患者(MCI)脑白质损伤情况。方法:对21例AD患者、15例MCI患者和20名健康志愿者进行脑部DTI扫描后,测量双脑区感兴趣区的各向异性分数值(FA)且进行比较。结果:AD患者额叶、顶叶、颞叶和胼胝体的FA值与MCI组和对照组均存在显著性差异,MCI患者仅颞叶和胼胝体的FA值与对照组均存在显著性差异。结论:AD患者与MCI患者存在脑白质结构的差异,DTI技术能够在一定程度上提供MCI的早期诊断指标。     

轻度认知障碍和阿尔茨海默病患者认知功能和MRI对照研究

目的探讨轻度认知障碍（MCI）和阿尔茨海默病（AD）的认知功能及影像学特点。方法回顾性分析经临床确诊的21例MCI和24例AD患者的临床资料。所有实验对象均用简易智力量表（MMSE）和蒙特利尔认知评估（MoCA）测定。结果MCI与AD的认知功能损害相比较：除了MMSE的记忆力组间无统计学意义（P＝0．28）,其余均有统计学差异（P〈0．05）。MoCA比MMSE具有更好的敏感性。AD的MRI表现：脑萎缩,特别是海马存在不同程度的萎缩;老年性脑改变;MCI的MRI主要表现为脑白质脱髓鞘病变,少数提示轻度脑萎缩或未见明显异常。结论MCI和AD患者早期均表现为记忆力下降,对记忆力减退人群进行MMSE、MoCA量表筛查有助于AD的早期诊断。AD患者到中晚期治疗较困难,因此早期诊断及干预对延缓病程起积极作用。     

阿尔茨海默病和轻度认知障碍患者脑网络变化特点的研究进展

阿尔茨海默病(AD)是一种隐匿性进展的神经退行性疾病,而轻度认知障碍(MCI)是AD发病前一个重要的临床前阶段。静息态功能磁共振(rs-f MRI)能在疾病早期反映脑网络变化,可作为研究AD及MCI的有效手段。本文综述了以rs-f MRI研究为基础的AD及MCI患者默认网络,注意网络,执行控制网络等的变化特点,为AD的早期诊断及干预提供依据。     

DTI评价轻度认知障碍及轻中度阿尔茨海默病脑白质微细结构损害的研究

目的应用磁共振弥散张量成像(DTI)技术研究轻度认知障碍(MCI)及轻中度阿尔茨海默病(AD)患者脑白质微细结构的改变。方法对MCI患者、轻中度AD患者各12例及健康老年人12名(对照组)行常规MRI及DTI检查,测量其胼胝体压部、额叶、顶叶、颞叶、枕叶、内囊前肢及内囊后肢白质区部分各向异性分数(FA)和平均弥散率(MD)。将3组的FA、MD值进行比较,并与MMSE评分、单词回忆及单词再认评分进行相关性分析。结果 (1)MCI患者顶叶白质FA值为0.489±0.079,与对照组(0.558±0.079)相比下降(P0.05)。(2)AD患者额叶、顶叶及颞叶FA值分别为0.405±0.072、0.454±0.069和0.363±0.056,与对照组(分别为0.499±0.081、0.558±0.079和0.440±0.061)比较差异均有统计学意义(P0.05)。AD患者胼胝体压部、额叶及顶叶MD值分别为0.978±0.082、0.920±0.054和0.81 7±0.045,均高于对照组(分别为0.801±0.093、0.820±0.084、0.712±0.096)(P0.05)。AD、MCI两组内囊前、后肢及枕叶FA及MD值分别与健康对照组比较均无统计学差异(P0.05)。(3)3组顶叶、颞叶FA值与MMSE、单词回忆及单词再认评分均有相关性(分别r=0.869、-0.621、-0.759,均P0.01;r=0.446、-0.486、-0.361,均P0.05),胼胝体压部FA值与单词再认评分有相关性(r=-0.343,P0.05);3组胼胝体压部及顶叶MD值与MMSE、单词回忆及单词再认评分均有相关性(分别r=-0.612、0.547、0.586,均P0.01;r=-0.576、0.499、0.519,均P0.01),内囊前肢MD值与MMSE评分相关(r=-0.340,P0.05)。结论 MCI及轻中度AD患者存在脑白质选择性微细结构损害,且该损害出现在与高级皮层功能相关的脑区,而与初级功能相关的区域未见明显受损。     

阿尔茨海默病和轻度认知障碍患者脑网络变化特点的研究进展

阿尔茨海默病（AD）是一种隐匿性进展的神经退行性疾病,而轻度认知障碍（MCI）是AD发病前一个重要的临床前阶段。静息态功能磁共振（rs-fMRI）能在疾病早期反映脑网络变化,可作为研究AD及MCI的有效手段。本文综述了以rs-fMRI研究为基础的AD及MCI患者默认网络,注意网络,执行控制网络等的变化特点,为AD的早期诊断及干预提供依据。     

轻度认知障碍和阿尔茨海默病静息态功能磁共振成像研究进展

随着功能磁共振研究的不断发展,大量的研究发现轻度认知障碍（MCI）和阿尔茨海默病（AD）患者的部分脑区自发活动发生改变.这种改变包括脑区相似性的改变和不同脑区之间功能连接的改变, 主要发生于大脑默认网络（DMN）的大部分区域中.本文将近年来在这方面的研究进展进行了综述.     

轻度认知障碍和阿尔茨海默病患者血清中兴奋性氨基酸的含量

目的 研究遗忘型轻度认知障碍(amnestic mild cognitive impairment,aMCI)及阿尔茨海默病(Alzheimer's disease,AD)患者血清中兴奋性氨基酸(EAAs)含量的变化,探讨EAAs在二者发病中的作用.方法 使用高效液相法对30例aMCI、32例AD患者以及34名健康对照者血清中EAAs[谷氨酸、天门冬氨酸(Asp)]及EAAs N-甲基-D-Asp(N-methyl-D-aspartate,NMDA)受体的协同激动剂甘氨酸、丝氨酸、丙氨酸含量进行测定和比较.结果 aMCI组血清中的谷氨酸[(39.6±22.1)μmol/L]和丙氨酸[(282.5±71.3)μmol/L]含量高于健康对照组[(30.0±11.6)μmol/L,P=0.044;(240.7±46.3)μmol/L,P=0.007].而AD组血清中谷氨酸[(42.2±21.8)μmol/L]、甘氨酸[(464.2±142.6)μmol/L]明显高于健康对照组[P=0.010;(395.6±88.8)μmol/L,P=0.010];但aMCI组和AD组之间差异无统计学意义.AD组血清中Asp(P=0.011)和谷氨酸(P=0.017)的含量与MMSE得分呈正相关,轻度AD患者血清中这两种氨基酸含量[(42.1±21.3)、(55.0±29.0)μmol/L]要高于中重度AD患者[(25.4±9.2)μmol/L,P=0.023;(34.6±11.1)μmol/L,P=0.036].结论 EAAs可能参与AD的发病,并且与AD的严重程度存在一定的相关性;aMCI患者也存在着EAAs代谢的紊乱,提示其可能和AD有着类似的发病机制.     

轻度阿尔茨海默病及轻度认知障碍患者汉语双字词判断反应时研究

目的探索轻度阿尔茨海默病(AD)和轻度认知障碍(MCI)患者在汉语词汇认知加工过程中语义和语音时间进程及模式的改变特点。方法对32例轻度AD(AD组)和39例MCI患者(MCI组)以及40名健康对照(NC组)进行汉语双字词判断任务,采用语义、同音、变调和无关对照四种启动类型,设立长短两种刺激呈现间隔(SOA),被试对目标词进行真假词判断,分别记录被试的反应时和错误率,判断是否出现语义或语音启动效应,通过方差分析和t检验方法对实验数据进行统计分析。结果轻度AD和MCI患者各启动类型的平均反应时较NC分别延长411ms和234ms(P<0.01),NC组在长SOA时的反应时较短SOA时快53ms(P=0.002),而轻度AD组和MCI组长SOA时的反应时分别较短SOA时延长95ms和74ms(分别为P=0.005,P=0.011);各组均出现了语义和语音启动效应,轻度AD和MCI组假词判断的错误率(20.0%和14.4%)明显高于NC组(9.0%,P<0.01)。结论轻度AD及MCI患者汉语词汇加工速度减慢;轻度AD患者的语音提取过程受损,轻度AD及MCI患者语义编码过程可能受损。MCI患者语音加工过程可能正常。     

轻度认知功能障碍和阿尔茨海默病的视神经视网膜退行性变

目的 采用光学相干断层扫描仪(optical coherence tomography,OCT)测量阿尔茨海默病(Alzheimer's disease,AD)和轻度认知功能障碍(Mild cognitive impairment,MCI)患者的视网膜神经纤维层厚度,根据厚度变化判断AD和MCI患者是否存在视神经视网膜退行性变以及与病情的相关性.方法 选择2010年2～12月就诊于首都医科大学宣武医院神经内科诊断为轻度AD患者10例、中度AD患者10例、重度AD患者7例、MCI患者12例.并招募年龄、性别匹配的正常志愿者30例作为对照组.利用OCT测量各种的视盘周围上、下、鼻、颞象限和总神经纤维层厚度.结果 AD和MCI患者上方象限和总神经纤维层厚度变薄,差异有统计学意义(P＜0.05).下方、鼻侧和颞侧象限神经纤维层厚度无明显变化,差异无统计学意义(P＞0.05).结论 AD和MCI患者存在视神经视网膜退行性变,而且神经纤维层厚度变薄的程度随着病情进展逐渐增加.     

Retinal thickness in patients with mild cognitive impairment and Alzheimer's disease

Objectives

Mild cognitive impairment (MCI) may represent a transition to early Alzheimer's disease (AD). The retinal nerve fiber layer (RNFL) is composed of axons originating in retinal ganglion cells that eventually form the optic nerves. Previous studies have shown that degenerative changes occur in optic nerve fibers and manifested as thinning of RNFL in patients with AD. The objective of this study was to assess the relationship between MCI, AD and loss of RNFL.

Patients and methods

In this study, patients fulfilling diagnostic criteria for MCI (n = 24), AD (n = 30) and cognitively normal age-matched controls (n = 24) have undergone neuro-ophthalmologic and optical coherence tomography (OCT) examinations to measure RNFL thickness.

Results

There was a significant decrease in RNFL thickness in both study groups (AD and MCI) compared to the control group, particularly in the inferior quadrants of the optic nerve head, while the superior quadrants were significantly thinner only in AD. Although AD patients may have more severe changes than MCI cases, the differences were statistically nonsignificant. Furthermore among AD patients, there was no relation to the severity of the dementia.

Conclusions

Our data confirm the retinal involvement in AD, as reflected by loss of axons in the optic nerves.     

Abnormal visual search in mild cognitive impairment and Alzheimer's disease

Our aim was to further characterize the clinical concept of mild cognitive impairment (MCI). We examined the status of visual attention-related processing in such patients in relation to healthy older adults and patients with Alzheimer's disease (AD) by measuring performance on a computer-based visual search task. We tested 20 older adult control participants, 13 patients with amnestic mild cognitive impairment and 12 patients with AD. Patients with AD and with MCI exhibited a significant detriment in visual search performance compared to the older adult controls. The deficit in visual search was greater for the patients with AD than the patients with MCI. The pattern of results displayed by the MCI group indicates that patients who appear clinically to suffer only from a deficit in memory also display a deficit in visual attention-related processing, which although not as severe as those with AD, represents a significant detriment in such performance compared to that seen in healthy ageing.     

Regularity changes of the retinal nerve fiber layer and macular ganglion cell complex in patients with the amnestic mild cognitive impairment

Purpose/aim: We investigated the regularity changes of the retinal nerve fiber layer (RNFL) and macular ganglion cell complex (mGCC) of the amnestic mild cognitive impairment (aMCI) patients in this prospective cohort study.

Materials and methods: Twenty-four aMCI patients and 30 health controls, who are more than 60 years old, were recruited into the study. The RNFL and the mGCC average thickness were measured with Fourier-domain optical coherence tomography (FD-OCT).

Results: Compared with that in the controls, the intraocular pressure (IOP) was significantly lower in the aMCI patients. A significant decrease in RNFL thickness in superior temporal, temporal upper (TU), and temporal upper and lower (TL) (TU+TL) quadrants was found in the aMCI patients than in the controls. The average thickness of the mGCC was also significantly thinner in the aMCI patients than in the controls.

Conclusions: Retinal degeneration in the aMCI patients detected by OCT together with lower IOP may indicate disease pathological progression.     

Alzheimer's disease and mild cognitive impairment

As our society ages, age-related diseases assume increasing prominence as both personal and public health concerns. Disorders of cognition are particularly important in both regards, and Alzheimer's disease is by far the most common cause of dementia of aging. In 2000, the prevalence of Alzheimer's disease in the United States was estimated to be 4.5 million individuals, and this number has been projected to increase to 14 million by 2050. Although not an inevitable consequence of aging, these numbers speak to the dramatic scope of its impact. This article focuses on Alzheimer's disease and the milder degrees of cognitive impairment that may precede the clinical diagnosis of probable Alzheimer's disease, such as mild cognitive impairment.     

Abnormal spatial and non-spatial cueing effects in mild cognitive impairment and Alzheimer's disease

Our aim was to further characterize the clinical concept of mild cognitive impairment (MCI). We examined visual attention-related processing in 12 patients with amnestic MCI, 16 healthy older adults and 16 patients with Alzheimer's disease (AD) by measuring performance on computer-based tests of attentional disengagement, alerting ability, and inhibition of return. Unlike the healthy older controls, the patients with AD and the patients with amnestic MCI exhibited a significant detriment in both the ability to disengage attention from an incorrectly cued location and the ability to use a visual cue to produce an alerting effect. The pattern of results displayed by the MCI group indicates that patients who only appear clinically to suffer from a deficit in memory also display a deficit in specific aspects of visual attention-related processing, which closely resemble the magnitude seen in AD.     

Reduction in retinal nerve fiber layer thickness in migraine patients

Migraine is a common disorder and its pathogenesis remains still unclear. Several hypotheses about the mechanisms involved in the pathogenesis of migraine have been proposed, but the issue is still far from being fully clarified. Neurovascular system remains one of the most important mechanisms involved in the pathogenesis of migraine and it could be possible that hypoperfusion might involve other areas besides brain, including the retina. This is, for example, of particular interest in a form of migraine, the retinal migraine, which has been associated with hypoperfusion and vasoconstriction of the retinal vasculature. Although vasoconstriction of cerebral and retinal blood vessels is a transient phenomenon, the chronic nature of the migraine might cause permanent structural abnormalities of the brain and also of the retina. On this basis, a few studies have evaluated whether retina is involved in migraine patients: Tan et al. have not found differences in retinal nerve fiber layer (RNFL) thickness between migraine patients and healthy subjects, while Martinez et al. have shown that RNFL in the temporal retinic quadrant of migraineurs is thinner than in normal people. The aim of our study was to analyze if there are differences in retinal nerve fiber layer thickness between migraine patients and normal subjects by studying 24 consecutive migraine patients who presented at the Headache Center of our Neurological Department. Migraine diagnosis has been made according to the International Classification of Headache disorder (ICHD-II). Patients have been recruited according to strict inclusion criteria; then patients have undergone a complete ophthalmological examination at the Ophthalmological Department. All patients and controls who met the ophthalmological criteria have been examined with ocular coherence tomography spectral domain (OCT-SD) after pupillary dilation. OCT-SD is an optical system designed to acquire the retinal layer images simultaneously with fundus confocal images. The statistical analysis has been performed using the Statistical Package for Social Sciences program. The Student’s t test has been used to compare numeric variables between migraine and control groups. p value >0.05 has been considered not significant. We have analyzed 40 female subjects, 24 included in the study group and 16 included in the control group. Two migraine patients have been excluded. No differences have been found in the visual acuity between the two groups. Comparing RNFLs of a single eye per person in the two groups, we have found that migraine patients showed significant reduction in the superior quadrants (p < 0.005). Also evaluating both eyes per person there was a significant difference in the same quadrant between the two groups (p < 0.05). The result of this present study show that migraine patients have RNFL thickness reduction in the superior retinal quadrant compared with normal subjects. It is important to underline that RNFL thickness measurement could be a new interesting technique to evaluate the evolution of migraine and perhaps to study if prophylactic treatment could reduce retinal abnormalities seen in migraine patients. OCT-SD is a simple exam that could be repeated and then used for evaluation of headache progression during the time. Our study shows that RNFLs thickness does not depend on illness duration and frequency.     

Abnormal verbal event related potentials in mild cognitive impairment and incipient Alzheimer's disease

BACKGROUND: It has been reported that patients with amnesia have a reduced effect of word repetition upon the late positive component of the event related potential (ERP), which peaks at around 600 ms after word onset. OBJECTIVE: To study a word repetition ERP paradigm in subjects with mild cognitive impairment. SUBJECTS: 14 patients with mild cognitive impairment (mean mini-mental state examination score = 27); 14 normal elderly controls. METHODS: Auditory category statements were each followed by a single visual target word (50% "congruous" category exemplars, 50% "incongruous") while ERPs were recorded. N400 (an ERP component elicited by semantically "incongruous" words) and LPC amplitude data were submitted to analysis of variance. RESULTS: The latency of the N400 was slower in mild cognitive impairment. In normal controls, the ERPs to "congruous" targets showed a late positive component to new words, which was greatly diminished with repetition. This repetition effect in normal subjects started before 300 ms at right frontal sites, and peaked at approximately 600 ms post-stimulus over posterior sites. In contrast, the group with mild cognitive impairment had a reduced repetition effect (p < 0.02), which started around 500 ms, with a more central distribution. Further comparisons within the cognitive impairment group showed no appreciable congruous word repetition effect among seven individuals who subsequently converted to probable Alzheimer's disease. The congruous word repetition effect in the group with mild cognitive impairment was almost entirely accounted for by the non-converters. The amplitude of the congruous late positive component word repetition effect was significantly correlated (0.38 < or = r < or = 0.73) with several verbal memory measures. CONCLUSIONS: The congruous word repetition ERP effect appears sensitive to the memory impairment in mild cognitive impairment and could have value in predicting incipient Alzheimer's disease.     

Cortical thickness in frontotemporal dementia, mild cognitive impairment, and Alzheimer's disease

Cortical thickness analysis has been proposed as a potential diagnostic measure in memory disorders. In this retrospective study, we compared the cortical thickness values of 24 patients with frontotemporal dementia (FTD) to those of 25 healthy controls, 45 symptomatic subjects with stable mild cognitive impairment (S-MCI), 15 subjects with progressive mild cognitive impairment (P-MCI), and 36 patients with Alzheimer's disease (AD). The patterns of regions of thinning in FTD when compared to controls and also S-MCI patients showed similar trends; thinning of the bilateral frontal poles and bilateral medial temporal lobe structures, especially the anterior part of the gingulum, the uncus, and parahippocampal gyri. Cortical thinning in FTD was also found on the boundary regions of parietal and occipital lobes. In the P-MCI group compared to FTD, the trend of thinning in small distinct areas of the parietal and occipital lobes was observed. The FTD and AD groups did not differ statistically, but we found trends toward thinning in FTD of the left cingulate gyrus, and the left occipitotemporal gyri, and in AD of the inferior parietal, occipitoparietal, and the pericalcarine regions, more in the right hemisphere. In FTD, increased slowness in the executive test (Trail-Making A) correlated with the thinner cortex, whereas the language tests showed the lower scores, the thinner cortex in the left hemisphere. Cortical thickness might be a tool for detecting subtle changes in brain atrophy in screening of dementia prior to the development of diffuse or lobar atrophies.     

Gender-specificities in Alzheimer's disease and mild cognitive impairment

Background Amnestic Mild Cognitive Impairment (MCI) is a condition with an increased risk for developing Alzheimer's disease (AD). Presently, gender differences are neglected in the assessment of MCI and AD. Methods We examined verbal and visuospatial episodic memory in 143 subjects diagnosed as healthy controls (HC; N = 48, Mini-Mental State Examination (MMSE) 29.2 ± 1.0 (mean ± standard deviation)), MCI (N = 43,MMSE 28.5 ± 1.4), and AD (N = 49, MMSE 25.1 ± 2.2). Findings Female HC and MCI subjects performed better on verbal episodic memory tasks than males. In contrast, visuospatial episodic memory was better in male than female AD patients. Conclusions We interpret the results in light of a genderspecific cognitive reserve and conclude that the gender-specificity of neuropsychological performance needs to be accounted for in clinical diagnosis of Alzheimer’s disease.