Cui Ying, Tang Tian-Yu, Lu Chun-Qiang, Ju Shenghong
Department of Radiology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China.
Jiangsu Key Laboratory of Molecular and Functional Imaging, Department of Radiology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China.
J Magn Reson Imaging. 2022 Dec;56(6):1621-1649. doi: 10.1002/jmri.28358. Epub 2022 Jul 19.
Insulin is a peptide well known for its role in regulating glucose metabolism in peripheral tissues. Emerging evidence from human and animal studies indicate the multifactorial role of insulin in the brain, such as neuronal and glial metabolism, glucose regulation, and cognitive processes. Insulin resistance (IR), defined as reduced sensitivity to the action of insulin, has been consistently proposed as an important risk factor for developing neurodegeneration and cognitive impairment. Although the exact mechanism of IR-related cognitive impairment still awaits further elucidation, neuroimaging offers a versatile set of novel contrasts to reveal the subtle cerebral abnormalities in IR. These imaging contrasts, including but not limited to brain volume, white matter (WM) microstructure, neural function and brain metabolism, are expected to unravel the nature of the link between IR, cognitive decline, and brain abnormalities, and their changes over time. This review summarizes the current neuroimaging studies with multiparametric techniques, focusing on the cerebral abnormalities related to IR and therapeutic effects of IR-targeting treatments. According to the results, brain regions associated with IR pathophysiology include the medial temporal lobe, hippocampus, prefrontal lobe, cingulate cortex, precuneus, occipital lobe, and the WM tracts across the globe. Of these, alterations in the temporal lobe are highly reproducible across different imaging modalities. These structures have been known to be vulnerable to Alzheimer's disease (AD) pathology and are critical in cognitive processes such as memory and executive functioning. Comparing to asymptomatic subjects, results are more mixed in patients with metabolic disorders such as type 2 diabetes and obesity, which might be attributed to a multifactorial mechanism. Taken together, neuroimaging, especially MRI, is beneficial to reveal early abnormalities in cerebral structure and function in insulin-resistant brain, providing important evidence to unravel the underlying neuronal substrate that reflects the cognitive decline in IR. EVIDENCE LEVEL: 5 TECHNICAL EFFICACY: Stage 2.
胰岛素是一种因在外周组织中调节葡萄糖代谢而闻名的肽。来自人类和动物研究的新证据表明胰岛素在大脑中具有多方面作用，如神经元和神经胶质代谢、葡萄糖调节及认知过程。胰岛素抵抗（IR）被定义为对胰岛素作用的敏感性降低，一直被认为是发生神经退行性变和认知障碍的重要危险因素。尽管IR相关认知障碍的确切机制仍有待进一步阐明，但神经影像学提供了一系列多样的新对比方法来揭示IR中细微的脑异常。这些成像对比，包括但不限于脑容量、白质（WM）微观结构、神经功能和脑代谢，有望揭示IR、认知衰退和脑异常之间联系的本质及其随时间的变化。本综述总结了当前使用多参数技术的神经影像学研究，重点关注与IR相关的脑异常及针对IR治疗的疗效。根据研究结果，与IR病理生理学相关的脑区包括内侧颞叶、海马体、前额叶、扣带回皮质、楔前叶、枕叶以及遍布全脑的WM束。其中，颞叶的改变在不同成像模式下具有高度可重复性。已知这些结构易受阿尔茨海默病（AD）病理影响，且在记忆和执行功能等认知过程中起关键作用。与无症状受试者相比，2型糖尿病和肥胖等代谢紊乱患者的结果更为复杂，这可能归因于多因素机制。综上所述，神经影像学，尤其是MRI，有助于揭示胰岛素抵抗大脑中脑结构和功能的早期异常，为揭示反映IR中认知衰退的潜在神经元基质提供重要证据。证据水平：5 技术疗效：2期
