|摘要||背景:阿尔茨海默病患者早期即可出现视空间定位异常.而大多数阿尔茨海默病患者是由轻度认知障碍患者演变而来.目的:了解轻度认知障碍患者是否也存在与阿尔茨海默病患者类似的视空间障碍,利用功能磁共振对轻度认知障碍患者和正常人的脑激活情况进行比较.设计:病例-对照观察.单位:北京大学第一医院神经内科.对象:调查对象为2000-04/2003-03于北京大学第一医院神经科门诊就诊的轻度认知障碍患者9例,并选择年龄、性别和受教育程度与之相匹配的正常人9例.方法:受试者进行辨别钟面指针位置异同的任务.被试根据计算机生成的视觉信号对不同的认知任务分别用左手或右手拇指按键做出相应的反应.采用组块设计,刺激组块与基线组块交替出现.基线组块播放位于画面中心的"+",持续停留21 s.刺激组块连续播放的10幅图.一幅图的3个钟面中有两个钟面的指针位置相同.同一个刺激组块中的每幅图上的相异两钟面指针旋转角度绝对值相同.6个随机排布的刺激组块指针旋转角度分别为30°,45°,180°.要求被试做出相同的两个钟面.数据的采集和分析在1.5T GEMRTWIN实时成像全身磁共振扫描仪上进行.应用Excel统计软件对轻度阿尔茨海默病患者与正常人的正确反应时间和正确率进行t检验.脑功能成像数据采用国际上通用的AFNI软件包对数据进行预处理和统计分析.主要观察指标:两组反应时间及正确率比较.结果:纳入实验结果分析者18例.①两组反应时间比较:患者辨别30°,45°和180°变化的反应时间比正常组延长,且45°和180°任务差异显著[(1 776.7±570.2),(1 646.3±432.7)ms;(1 845.2±539.4),(1 610.0±416.4)ms,P＜0.05,P＜0.000].②两组正确率比较:患者辨别30°,45°和180°变化的正确率显著低于正常组(62.8±21.4)%,(82.8±15.8)%;(76.7±17.0)%,(95.0±8.7)%;(69.4±26.7)%,(95.0±5.6)%;P＜0.05或P＜0.01].③脑激活图结果:患者在双侧顶叶,双侧颞枕交界处,双侧纹外区皮质的激活强度比对照显著减弱(P＜0.05).结论:轻度认知障碍患者与视空间有关的神经网络激活较正常人减弱,证实轻度认知障碍患者已存在视空间功能受损.
BACKGROUND: Patients with Alzheimer disease (AD) usually have visuospatial dysfunction at an early stage and most patients with AD were evolved from mild cognitive impairment (MCI).OBJECTIVE: To detect whether a patient with MCI has a visuospatial dysfunction similar to AD. To compare the cerebral activation with ferromagnetic resonance between the healthy people and the patients with mild cognitive disorder.DESIGN: A case controlled observationSETTING: The Department of Neurology of the First Hospital of Peking University.PARTICIPANTS: Nine inpatients with mild cognitive disorder hospitalized at the Department of Neurology of the First Hospital of Peking University from April 2000 to March 2003 were involved and other 9 healthy people matching in age, gender and the educational level were also involved.METHODS: The subjects had the task of discriminating the different finger positions on the clockface. They could see the mission clearly showed on the cloth through refractor, and they were supposed to give the corresponding reaction to different cognitive tasks with left and right hands pressing the keys according to visual sign generated by the computer.Block design was adopted in the cognitive task. Stimulus block and baseline block appeared in turn. Baseline block displayed "+" mapped in the center of the image and was kept for 21s. Stimulus block displayed 10 pictures successively. The finger position of the two clockfaces among three clockfaces was the same in one picture. The absolute value of the rotated angles of the different clockfaces in each image on the same stimulus block was the same. The angles formed by six stimulus block fingers arranged randomly were 300, 450, 1800. The two clockfaces had the same finger positions, and the subjects were requested to discriminate the finger position of these two clockfaces. It was carried out on a 1.5 T GEMRTWIN magnetic resonance scanning apparatus. Then t test was performed to work out the right reaction time and proper rate with Excel software between the patients with mild Alzheimer's disease and the healthy persons. Pretreatment and statistical analyses were performed with analysis of functional neuroimages software used internationally.MAIN OUTCOME MEASURES: Comparison of the reaction time and proper rate between the two groups.parison of the reaction time between the two groups: The reaction time for distinguishing the change of 300, 450, 1800 was longer than that in the control group, and there was significant difference in distinguishing the change of 300, 450, 1800 for the patients [(1 776.7±570.2), (1 646.3±432.7)ms;of the proper rate between the two groups: The proper rate for distinguishing the change of 300, 450, 1800 was significantly lower than that in the control group (62.8±21.4)%, (82.8±15.8)% ;(76.7±17.0)%, (95.0±8.7)%; (69.4vation: the activation density at the bilateral parietal lobe, bilateral temporooccipital borderline and bilateral lateral striate cortex in patients was weaker than that in the control group (P ＜ 0.05).CONCLUSION: Neural network activation related with visual space in patients with MCI was weaker than that in the healthy people indicating that visuospatial impairment exists in the patients with mild cognitive impairment.|