摘要目的 利用静息态血氧水平依赖功能磁共振(BOLD-fMRI)数据,构建大脑功能网络,探讨阿尔茨海默病(AD)患者脑功能网络的小世界属性是否改变.方法 收集2009年1月至2010年6月复旦大学上海医学院附属华山医院神经内科门诊33例AD患者和20名健康老年志愿者参加试验.受试者行简易智能状态检查( MMSE)和Mattis痴呆评定量表(DRS)测试,评估其认知水平.采集静息态BOLD-fMRI数据,计算90个区域之间的相关系数,构建N×N(N =90)的相关性Z值矩阵.检验AD患者和正常老年人大脑网络的小世界属性,通过双样本t检验探索AD患者相关参数变化.结果 行为学结果:AD组和正常对照组MMSE平均分值分别为20.6±2.3、28.2±1.8.AD组和正常对照组DRS平均分值分别为96 ±11、123±14.两组差异均有统计学意义(均P＜0.01).在0.1≤Sparsity≤0.4范围内,AD组和正常对照组均符合小世界属性.但AD患者的聚类系数和平均路径长度在所有阈值点均显著大于正常对照组(P＜0.05).结论 AD患者的大脑功能网络仍具有小世界属性,但聚类系数和平均路径长度均高于正常人,提示AD患者脑功能网络信息传递能力和脑区之间信息整合能力受损,该发现对从网络角度研究AD病理机制具有重要意义.

abstractsObjective To construct the functional networks of human brains by resting-state functional magnetic resonance imaging (fMRI) and examine whether or not the small-world property of functional brain networks changes in patients with Alzheimer disease (AD).Methods A total of 33 AD patients and 20 healthy old volunteers were recruited.Their cognitive functions were evaluated by the minimental state examination (MMSE) and Mattis dementia rating scale (DRS).The resting-state BOLD-fMRI data were acquired and preprocessed. Then the correlation coefficient of every pair of 90 regions was calculated and correlation matrix Z ( N × N,N =90) generated by Fisher Z transformation.The small-world property of functional brain networks was tested for AD patients and normal elders according to the definition of small-worldness.The changes of relevant parameters in AD patients were examined by two sample t-tests.Results Behavioral results:the MMSE scores of AD group and normal controls (NOR) were 20.6 ± 2.3and 28.2 ± 1.8 respectively. The DRS scores of AD and NOR groups were 96 ± 11 and 123 ± 14 respectively.The MMSE and DRS scores were statistically different between two groups. Calculation of small-world parameters:Within the range of 0.1 ≤ Sparsity ≤ 0.4,both groups satisfied the small-world property.However,the clustering coefficient Cp and the average shortest path Lp of AD group were significantly higher than those of NOR group at each threshold (P ＜ 0.05).Conclusion The functional brain networks in AD patients still have the property of small-world.But the levels of Cp and Lp are higher in AD patients than those in normal controls. It suggests that the capacity of information transmission in functional brain networks and the ability of information integration in different brain regions in AD patients are impaired.This finding is of great importance in elucidating the pathological mechanisms of AD from the viewpoint of networks.