Aim of this study was to explore the EEG functional connectivity in amnesic mild cognitive impairments (MCI) subjects with multidomain impairment in order to characterize the Default Mode Network (DMN) in converted MCI (cMCI), which converted to Alzheimer’s disease (AD), compared to stable MCI (sMCI) subjects. A total of 59 MCI subjects were recruited and divided -after appropriate follow-up- into cMCI or sMCI. They were further divided in MCI with linguistic domain (LD) impairment and in MCI with executive domain (ED) impairment. Small World (SW) index was measured as index of balance between integration and segregation brain processes. SW, computed restricting to nodes of DMN regions for all frequency bands, evaluated how they differ between MCI subgroups assessed through clinical and neuropsychological four-years follow-up. In addition, SW evaluated how this pattern differs between MCI with LD and MCI with ED. Results showed that SW index significantly decreased in gamma band in cMCI compared to sMCI. In cMCI with LD impairment, the SW index significantly decreased in delta band, while in cMCI with ED impairment the SW index decreased in delta and gamma bands and increased in alpha1 band. We propose that the DMN functional alterations in cognitive impairment could reflect an abnormal flow of brain information processing during resting state possibly associated to a status of pre-dementia.

中文翻译：

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默认模式网络中的小世界指数预测从轻度认知障碍到痴呆症的进展

本研究的目的是探索具有多域障碍的遗忘型轻度认知障碍 (MCI) 受试者的脑电图功能连接，以表征转换为阿尔茨海默病 (AD) 的转换 MCI (cMCI) 中的默认模式网络 (DMN)，与稳定的 MCI (sMCI) 受试者相比。共招募了 59 名 MCI 受试者，并在适当的随访后将其分为 cMCI 或 sMCI。他们进一步分为语言域 (LD) 损伤的 MCI 和执行域 (ED) 损伤的 MCI。小世界（SW）指数被测量为整合和分离大脑过程之间的平衡指数。SW 计算了对所有频段 DMN 区域节点的限制，评估了通过临床和神经心理学四年随访评估的 MCI 亚组之间的差异。此外，SW 评估了这种模式在 MCI 与 LD 和 MCI 与 ED 之间有何不同。结果表明，与 sMCI 相比，cMCI 中 γ 波段的 SW 指数显着降低。在伴有LD损伤的cMCI中，SW指数在δ波段显着下降，而在伴有ED损伤的cMCI中，SW指数在δ和γ波段下降，在α1波段上升。我们提出认知障碍中的 DMN 功能改变可能反映了静息状态下大脑信息处理的异常流动，这可能与痴呆前的状态有关。而在伴有 ED 损伤的 cMCI 中，SW 指数在 delta 和 gamma 波段下降，在 alpha1 波段上升。我们提出认知障碍中的 DMN 功能改变可能反映了静息状态下大脑信息处理的异常流动，这可能与痴呆前的状态有关。而在伴有 ED 损伤的 cMCI 中，SW 指数在 delta 和 gamma 波段下降，在 alpha1 波段上升。我们提出认知障碍中的 DMN 功能改变可能反映了静息状态下大脑信息处理的异常流动，这可能与痴呆前的状态有关。