轻度阿尔茨海默病患者和轻度认知功能障碍患者注意功能的研究

背景阿尔茨海默病(Alzheimerdisease,AD)和轻度认知功能障碍(mild cognitive impairment,MCI)患者均以记忆障碍为早期突出表现,但临床上患者常有注意力下降的表现,影响到工作和日常生活.目的探讨轻度AD患者和MCI患者的持续注意、选择注意和分散注意功能.设计病例-对照研究.单位一所大学医院神经内科和一所大学的心理学系.对象实验于2003-11/2004-01在北京大学第一医院神经心理室完成,选择18例轻度AD患者(AD组),19例MCI患者(MCI组)和20例正常对照组.干预对轻度AD患者、MCI患者和正常对照进行持续操作任务(continuousperformance test,CPT)实验测查持续注意功能,简化的斯特鲁普(Stroop)实验测查选择注意功能,应用纸笔形式的双任务实验测查分散注意能力.主要观察指标在CPT和Stroop实验中主要观察反应时和错误率,在双任务实验中主要观察双任务下降程度.结果CPT实验中,轻度AD组反应时、漏报率和虚报率均高于正常对照组[(539.29±103.86)ms比(458.47±40.87)ms,4.08%(3.13,13.64)比0.91%(0.60,1.90),1.51%(0.64,254)比0.43%(0.37,0.84),P＜0.05],MCI组和正常对照组间无差别;3组的漏报率随时间增高,10～15min明显.10 min后轻度AD患者的异常率明显增高(10 min内异常率为33 33%,20min异常率77 8%).Stroop实验中,3组被试均表现出明显的干扰效应;轻度AD组反应时长于MCI组和正常对照组[(57919±89.93)ms,(524.28±68.96 ) ms,(486.75±51.58)ms,P＜0 05],错误率干扰量高于其他两组[11.25%(750,22.50),2 50%(-2.50,5.00),2.50%(0.00,4.38),P＜0.05];MCI组总错误率以及一致和中性条件下的错误率高于正常对照组[5.83%(4.17,8.33)比2.92%(1.67,3.96),5.00%(2.50,7.50)比0.00%(0.00,2.50),500%(2.50,10.00 )比2.50%(0.00,5.00),P＜0.05].双任务实验中轻度AD组双任务减退量高于MCI组和正常对照组[1.03(0.49,3.75),0.46(0.08,1.02),0.10(-0.25,0.64),P＜0.05];MCI组和正常对照组间无差别.同一组轻度AD患者,Stroop实验和CPT实验异常率高于双任务实验(81.25%,77.8%,29.41%).结论与正常老年人相比,轻度AD患者的持续注意、选择注意和分散注意能力下降,选择及持续注意障碍较突出.MCI患者选择注意功能有下降的趋势,持续和分散注意正常.轻度AD患者、MCI患者和正常老年人持续注意能力随时间下降,10min后明显.较长时间的CPT实验容易检出轻度AD患者的持续注意障碍.

Attentional functionin patients with mild Alzheimer disease and those with mild cognitive impairment

BACKGROUND: Memory impairment is the main manifestation of Alzheimer disease (AD) and mild cognitive impairment (MCI) conspicuous in the early stage. However, such patients very often develop attentional dysfunction, which may affect their normal work and daily life.OBJECTIVE: To investigate the attentional function, including continuous attention, selective attention and divided attention, of patients with mild AD and of those with MCI.DESIGN: A case-control study.SETTING: Department of neurology of a university hospital and department of psychology in a university.PARTICIPANTS: The research was completed in the Laboratory of Neuropsychology, the First Hospital of Peking University from November 2003 to January 2004. Totally 18 patients with mild AD and 19 with MCI were enrolled in this study, with 20 normal elderly subjects also included to serve as the normal control group.INTERVENTIONS: Several tests were designed to assess the attentional functions of all the subjects, including continuous performance task (CPT) test for assessing continuous attention, simplified Stroop test for selective attention, and dual task test for divided attention.MAIN OUTCOME MEASURES: The reaction time (RT) and the percentage of false response were recorded in CPT test and Stroop test, and performance decrement in dual task test was observed.RESULTS: In CPT test, the RT of mild AD patients was much longer, and the rates of missing and false responses were higher than those of normal control group [(539.29±103.86) vs (458.47±40.87) ms, 4.08% (3. 13, 13.64) vs0.91% (0.60, 1.90), and 1.51% (0.64, 2.54) vs 0.43% (0.37, 0. 84), respectively, P ＜ 0. 05]. The difference between MCI group and normal control group failed to reach statistical significance. The rate of missing response of all the three groups grow higher with the prolongation of time, with the highest occurring in the third 5 minutes of the test.More AD patients showed sustained attention deficiency after 10 minutes of test (33.33% within 10 minutes and 77.8% within 20 minutes). In Stroop test, all the three groups tended to make more false responses under incongruous condition[11.25% (7.50, 22.50), 2.50% ( -2.50, 5.00), 2.50% (0.00, 4. 38) ], exhibiting significant interference effect, which was the most obvious in mild AD group ( P ＜ 0.05). Patients with mild AD responded more slowly than MCI patients and normal control subjects [ (579. 19 ± 89.93) ms,(524.28 ± 68. 96) ms, (486. 75 ± 51.58) ms, respectively, P ＜ 0.05 ]. MCI group made more false responses than normal control group during the whole course of the test as well as under coincident and neutral conditions[5.83% (4. 17, 8.33) vs2.92% (1.67,3.96); 5.00% (2.50, 7.50) vs0.00% (0.00, 2.50); 5.00% (2.50, 10. 00) vs 2.50% (0.00, 5.00), P ＜ 0. 05]. In dual-task test, a significant decrement in mild AD patients was noted without statistical difference between MCI and normal control group[ 1.03 (0.49,3.75),0.46 (0.08, 1.02),0. 10 ( -0.25, 0. 64), P ＜0.05]. Within mild AD group, more patients showed deficiency in Stroop test and CPT test than in dual-task test (81.25%, 77.8%, and 29.41%, respectively).CONCLUSION: Patients with mild AD suffer impairment in continuous,selective and divided attentions, especially obvious in the former two attentional functions. MCI also impairs selective attention as compared with normal aged subjects, with the continuous and divided attention remaining normal. Mild AD patients, MCI patients and normal elderly subjects all show decreased continuous attention, and longer time (than 10 ninutes) of CPT may more sensitively identify continuous attention deficit.