Stanford Center for Neurosciences in Women's Health, Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 95305-5723, USA.
Neurobiol Aging. 2013 Mar;34(3):641-9. doi: 10.1016/j.neurobiolaging.2012.06.006. Epub 2012 Jul 6.
Brain imaging studies in Alzheimer's disease research have demonstrated structural and functional perturbations in the hippocampus and default mode network (DMN). Additional evidence suggests risk for pathological brain aging in association with insulin resistance (IR). This study piloted investigation of associations of IR with DMN-hippocampal functional connectivity among postmenopausal women at risk for Alzheimer's disease. Twenty middle-aged women underwent resting state functional magnetic resonance imaging. Subjects were dichotomized relative to fasting plasma insulin levels (i.e., > 8 μIU/mL [n = 10] and < 8 μIU/mL [n = 10]), and functional connectivity analysis contrasted their respective blood oxygen level-dependent signal correlation between DMN and hippocampal regions. Higher-insulin women had significantly reduced positive associations between the medial prefrontal cortex and bilateral parahippocampal regions extending to the right hippocampus, and conversely, between the left and right hippocampus and medial prefrontal cortex. Neuropsychological data (all within normal ranges) also showed significant differences with respect to executive functioning and global intelligence. The results provide further evidence of deleterious effects of IR on the hippocampus and cognition. Further imaging studies of the IR-related perturbations in DMN-hippocampal functional connectivity are needed.
阿尔茨海默病研究中的脑影像学研究表明，海马体和默认模式网络（DMN）存在结构和功能紊乱。更多的证据表明，与胰岛素抵抗（IR）相关的病理性脑老化存在风险。本研究初步探讨了绝经后妇女中，与阿尔茨海默病风险相关的 IR 与 DMN-海马体功能连接之间的关联。20 名中年女性接受了静息状态功能磁共振成像。根据空腹血浆胰岛素水平（即 > 8 μIU/mL [n = 10] 和 < 8 μIU/mL [n = 10]）将受试者分为两组，并进行功能连接分析，对比 DMN 和海马体区域之间各自的血氧水平依赖信号相关性。高胰岛素组女性的内侧前额叶皮层和双侧海马旁回之间的正相关显著减少，延伸至右侧海马体，相反，左侧和右侧海马体与内侧前额叶皮层之间的负相关显著增加。神经心理学数据（均在正常范围内）也显示出执行功能和整体智力方面的显著差异。研究结果进一步证明了 IR 对海马体和认知的有害影响。需要进一步进行与 IR 相关的 DMN-海马体功能连接紊乱的影像学研究。
