阿尔茨海默病病程演进中默认脑网络功能连接改变的fMRI研究

Study of fMRI on default brain network functional connectivity changes in different stages of Alzheimer’s disease course

目的:探讨阿尔茨海默病(AD)病程演变不同阶段默认网络(DMN)功能连接的改变规律,以期在脑功能水平探索AD患者的病理生理机制,为AD的早期诊断提供影像学依据。方法:收集22例AD患者(AD组)、22例轻度认知功能障碍(MCI)患者(MCI组)和25例主观认知功能下降(SCD)患者(SCD组)。同期纳入25例与以上3组年龄及性别相匹配的健康志愿者作为对照组。所有受试者均行3.0 T MRI常规序列、3D-T1WI及静息态fMRI序列扫描。以后扣带回为种子点,提取DMN,分析DMN功能连接在4组间的差异。结果:AD组较对照组功能连接减弱脑区有左侧小脑下部、左侧颞下回、左侧颞上回、右侧梭状回、右侧颞下回等10个脑区;AD组较SCD组功能连接减弱脑区有右侧中央后回;AD组较MCI组功能连接减弱脑区有右侧颞中回。MCI组较对照组功能连接减弱脑区有左侧小脑、左侧舌回、左侧角回、右侧颞中回及右侧内侧额上回;MCI组较SCD组在左侧背外侧额上回功能连接降低,而在右侧颞中回功能连接增加。SCD组较对照组功能连接减弱脑区有右侧颞下回、右侧枕下回、右侧颞中回及右侧距状裂周围皮质。结论:随着从SCD、MCI到AD的进展,DMN的功能连接出现进行性降低,但在早期有些脑区功能激活程度不降低反而增强。

Objective:To explore the changes of default mode network(DMN)connections in different stages of Alzheimer’s disease(AD)course,so as to explore the pathophysiological mechanism of AD patients at the level of brain function and provide imaging basis for the early diagnosis of AD.Methods:22 cases of AD,22 cases of mild cognitive impairment(MCI)and 25 cases of subjective cognitive decline(SCD)were collected.Meanwhile,25 healthy volunteers matched with the age and sex of that three groups were selected as the control group.All subjects were scanned with 3.0 T MRI conventional sequence,3D-T1WI and resting-state fMRI sequence.After that,the cingulate gyrus was used as the seed to extract DMN,and then the differences of DMN functional connectivity(FC)among the four groups were analyzed.Results:FC in AD group was weaker than that in the control group,including left inferior cerebellum,left inferior temporal gyrus,left superior temporal gyrus,right fusiform gyrus and right inferior temporal gyrus.Compared with SCD group,the FC of right postcentral gyrus weakened in AD group.In addition,FC in the right middle temporal gyrus in AD group was weaker than that in MCI group.FC in MCI group was weaker than that in control group,including the left cerebellum,left lingual gyrus,left angular gyrus,right middle temporal gyrus and right medial superior frontal gyrus.Compared with SCD group,the FC of MCI group decreased in the left dorsolateral superior frontal gyrus and increased in the right middle temporal gyrus.Besides,FC in SCD group was weaker than that in the control group,including the right inferior temporal gyrus,the right suboccipital gyrus,the right middle temporal gyrus and the right cortex around talar fissure.Conclusion:With the development of AD,the FC of DMN decreased progressively,but the functional activation of some brain regions increased in the early stage.