Selective Vulnerability Related to Aging in Large-Scale Resting Brain Networks

Normal aging is associated with cognitive decline. Evidence indicates that large-scale brain networks are affected by aging; however, it has not been established whether aging has equivalent effects on specific large-scale networks. In the present study, 40 healthy subjects including 22 older (aged 60–80 years) and 18 younger (aged 22–33 years) adults underwent resting-state functional MRI scanning. Four canonical resting-state networks, including the default mode network (DMN), executive control network (ECN), dorsal attention network (DAN) and salience network, were extracted, and the functional connectivities in these canonical networks were compared between the younger and older groups. We found distinct, disruptive alterations present in the large-scale aging-related resting brain networks: the ECN was affected the most, followed by the DAN. However, the DMN and salience networks showed limited functional connectivity disruption. The visual network served as a control and was similarly preserved in both groups. Our findings suggest that the aged brain is characterized by selective vulnerability in large-scale brain networks. These results could help improve our understanding of the mechanism of degeneration in the aging brain. Additional work is warranted to determine whether selective alterations in the intrinsic networks are related to impairments in behavioral performance.

正常衰老与认知衰退密切相关。已有研究表明，大规模脑网络会受到衰老的影响，但目前尚未明确衰老对各特异性大规模脑网络的影响是否具有一致性。本研究共纳入40名健康受试者，其中年轻组18名（年龄22~33岁），老年组22名（年龄60~80岁），所有受试者均接受静息态功能磁共振成像（resting-state functional MRI）扫描。研究提取了4种经典静息态网络，即默认模式网络（default mode network, DMN）、执行控制网络（executive control network, ECN）、背侧注意网络（dorsal attention network, DAN）以及突显网络（salience network），并对比了年轻组与老年组在这些经典网络内的功能连接差异。结果发现，与衰老相关的静息态大规模脑网络存在显著的破坏性改变：执行控制网络受影响最为严重，其次为背侧注意网络；而默认模式网络与突显网络的功能连接破坏程度较轻。视觉网络作为对照网络，在两组受试者中均未出现显著改变，保持相对完整。本研究结果提示，衰老大脑的特征为大规模脑网络存在选择性易损性。该研究结果有助于加深我们对衰老大脑退行性变机制的理解。未来仍需开展进一步研究，以明确内在网络的选择性改变是否与行为表现受损相关。