University of Groningen, University Medical Center Groningen, Department of Biomedical Sciences of Cells & Systems, Cognitive Neuroscience Center, Groningen, The Netherlands.
Institute of Neuroscience and Medicine, Brain & Behaviour (INM-7), Research Centre Jülich, Jülich, Germany.
J Alzheimers Dis. 2020;78(3):1047-1088. doi: 10.3233/JAD-200962.
Mild cognitive impairment (MCI) is a stage between expected age-related cognitive decline and dementia. Dementias have been associated with changes in neural oscillations across the frequency spectrum, including the alpha range. Alpha is the most prominent rhythm in human EEG and is best detected during awake resting state (RS). Though several studies measured alpha power and synchronization in MCI, findings have not yet been integrated.
To consolidate findings on power and synchronization of alpha oscillations across stages of cognitive decline.
We included studies published until January 2020 that compared power or functional connectivity between 1) people with MCI and cognitively healthy older adults (OA) or people with a neurodegenerative dementia, and 2) people with progressive and stable MCI. Random-effects meta-analyses were performed when enough data was available.
Sixty-eight studies were included in the review. Global RS alpha power was lower in AD than in MCI (ES = -0.30; 95% CI = -0.51, -0.10; k = 6), and in MCI than in OA (ES = -1.49; 95% CI = -2.69, -0.29; k = 5). However, the latter meta-analysis should be interpreted cautiously due to high heterogeneity. The review showed lower RS alpha power in progressive than in stable MCI, and lower task-related alpha reactivity in MCI than in OA. People with MCI had both lower and higher functional connectivity than OA. Publications lacked consistency in MCI diagnosis and EEG measures.
Research indicates that RS alpha power decreases with increasing impairment, and could-combined with measures from other frequency bands-become a biomarker of early cognitive decline.
轻度认知障碍（MCI）是介于预期的与年龄相关的认知能力下降和痴呆之间的一个阶段。痴呆症与整个频谱的神经振荡变化有关，包括α范围。α是人类脑电图中最突出的节律，在清醒静息状态（RS）下最佳检测。尽管有几项研究测量了 MCI 中的α波功率和同步性，但尚未整合研究结果。
整合认知能力下降各阶段α振荡功率和同步性的研究结果。
我们纳入了截至 2020 年 1 月发表的研究，这些研究比较了 1）MCI 患者与认知健康的老年人（OA）或神经退行性痴呆患者之间的α振荡功率或功能连接，以及 2）进行性和稳定 MCI 患者之间的α振荡功率或功能连接。当有足够的数据时，进行随机效应荟萃分析。
共纳入 68 项研究进行综述。AD 患者的 RS α 总功率低于 MCI 患者（ES=-0.30；95%CI=-0.51，-0.10；k=6），也低于 OA 患者（ES=-1.49；95%CI=-2.69，-0.29；k=5）。然而，由于高度异质性，后一项荟萃分析的结果应谨慎解释。综述结果显示，进行性 MCI 患者的 RS α 总功率低于稳定 MCI 患者，MCI 患者的任务相关α反应性低于 OA 患者。MCI 患者的功能连接性低于和高于 OA 患者。研究论文在 MCI 诊断和脑电图测量方面缺乏一致性。
研究表明，RS α 功率随着认知损伤的增加而降低，并且可以与来自其他频带的测量结果相结合，成为早期认知衰退的生物标志物。
