静息态功能磁共振观察阿尔茨海默病患者丘脑功能连接特点

Impaired functional connectivity of thalamus in Alzheimer＇ s disease expiored by resting state functional magnetic resonance imaging

目的研究静息状态下阿尔茨海默病（Alzheimer’s disease，AD）患者丘脑的功能连接模式及其与认知功能的关系。方法对30例AD患者和26名认知功能正常的健康对照者进行静息状态下功能磁共振扫描，比较两组之间丘脑功能连接模式的差异，并分析神经心理评估（MMSE分数、听觉词语学习测试的即刻回忆和延迟回忆等）结果与功能连接强度的关系。结果AD组的MMSE分数（19．7±4．1），听觉词语学习测试的即刻回忆（2．8±1．7）、延迟回忆（0．7±1．3）成绩（词数）均低于健康对照组（28．8±1．0、5．9±1．2、5．7±2．2），差异有统计学意义（t=11．09、8．09、10．51，均P〈0．05）。与健康对照组相比，AD患者左侧丘脑与右侧后／中扣带回、左侧内侧前额叶、右侧额上回／内侧前额叶的功能连接减弱，与左侧颞下回、右侧颞中回、左侧中央后回、左侧小脑后叶、双侧旁中央小叶的功能连接增强；右侧丘脑与右侧额上回／前额叶内侧面、右侧后／中扣带回和右侧海马的功能连接减弱，与左侧额下回、右侧岛叶、左侧中央后回／旁中央小叶、双侧前额叶内侧面以及右侧中央后回的功能连接增强。功能连接强度与神经心理评估成绩存在相关。结论AD患者丘脑功能连接模式存在异常，增强的功能连接可能是大脑对降低的功能连接的一种代偿反应，这种变化与认知功能相关。

Objective To study the functional connectivity （FC） pattern of thalamus in patients with Alzheimer＇ s disease （AD）. Methods In the present study, resting state functional magnetic resonance imaging （MRI） data were obtained from 30 patients with AD and 26 subjects with normal cognition （NC）. The altered functional connectivity pattern in AD was evaluated by comparing to NC. Then a correlation analysis was performed between the strength of FC of the identified regions and various clinical variables for evaluating the relationships between the strength of FC and the cognitive abilities （ MMSE, immediate recall and delayed recall of Auditory Verbal Learning Test） of the AD patients. Results The MMSE（ 19. 7 ＋ 4. 1 ）, immediate recall （ 2. 8 ± 1.7 ） and delayed recall （ 0. 7 -＋ 1.3 ） of Auditory Verbal Learning Test in AD patients were lower than NC group （28.8 ±1. 0, 5.9 ± 1.2, 5.7 ± 2. 2 ; t = 11.09, 8.09, 10. 51 ,all P 〈0. 05）. Compared to NC, AD patients showed decreased FC between the left thalamus and several regions of brain including right posterior/middle cingulate cortex （PCC/MCC. R） , left medial prefrontal cortex （ MPFC. L） and right superior frontal gyms/medial prefrontal cortex （ SFG/MPFC. R）. For the right thalamus, decreased FC was found in SFG/MPFC. R, PCC/MCC. R and right hippocampus. We also found increased FC between the bilateral thalamus and many regions of brain including inferior temporal gyrns, medial temporal gyrus, SFG, postcentral gyrns, paracentral lobule, inferior frontal gyrus and insula. Significant correlations between the fitted FC strength and clinical variables were also detected. Conclusions FC pattern of thalamus in AD group is impaired. Increased FC in AD may indicate the presence of a compensatory mechanism. The alteration is related with cognitive function in AD.