Diabetes：2型糖尿病患的功能性大脑连接显著下降

根据一项发表于7月26日Diabetes杂志的研究报道，2型糖尿病（T2DM）患者在默认模式网络中的功能性大脑连接显著下降。这与在一些大脑区域中的胰岛素抵抗相关。
 
由于注意到2型糖尿病是阿尔茨海默氏症的风险因素，同时，阿尔茨海默氏症易感个体在默认模式网络中的大脑活动有所改变，波士顿的乔斯林糖尿病中心的盖尔木森博士，和他的同事使用休眠状态功能磁共振成像，在10名2型糖尿病患者和11例年龄相匹配的正常人之间，比较大脑默认模式网络区域的功能连接性。

研究人员发现，与对照组相比，2型糖尿病患者大脑的后扣和双侧颞中回，右下和左内侧额叶脑回，以及左侧丘脑之间的联系较弱。稳态模型评估显示，在2型糖尿病患者中，胰岛素抵抗与默认模式网络，尤其是右下额下回和楔前叶的后扣和大脑其他地区之间的功能连接性呈负相关。两组受试者之间，海马体积或认知能力没有差异。

据此，木森和他的同事得出结论："2型糖尿病患者在默认模式下的网络连接功能下降了，这是与特定的大脑区域中的胰岛素抵抗相关的，但与对照组相比，这并没有产生对大脑结构或认知的显著影响，"。

doi:10.1016/j.cell.2011.10.017
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Resting-State Brain Functional Connectivity Is Altered in Type 2 Diabetes

Gail Musen1,2?,Alan M. Jacobson1,2,3,Nicolas R. Bolo2,4,5,Donald C. Simonson6,7,Martha E. Shenton2,8,9,10,Richard L. McCartney1,Veronica L. Flores1 andWouter S. Hoogenboom1,9

Type 2 diabetes mellitus (T2DM) is a risk factor for Alzheimer disease (AD). Populations at risk for AD show altered brain activity in the default mode network (DMN) before cognitive dysfunction. We evaluated this brain pattern in T2DM patients. We compared T2DM patients (n = 10, age = 56 ± 2.2 years, fasting plasma glucose [FPG] = 8.4 ± 1.3 mmol/L, HbA1c = 7.5 ± 0.54%) with nondiabetic age-matched control subjects (n = 11, age = 54 ± 1.8 years, FPG = 4.8 ± 0.2 mmol/L) using resting-state functional magnetic resonance imaging to evaluate functional connectivity strength among DMN regions. We also evaluated hippocampal volume, cognition, and insulin sensitivity by homeostasis model assessment of insulin resistance (HOMA-IR). Control subjects showed stronger correlations versus T2DM patients in the DMN between the seed (posterior cingulate) and bilateral middle temporal gyrus (β = 0.67 vs. 0.43), the right inferior and left medial frontal gyri (β = 0.75 vs. 0.54), and the left thalamus (β = 0.59 vs. 0.37), respectively, with no group differences in cognition or hippocampal size. In T2DM patients, HOMA-IR was inversely correlated with functional connectivity in the right inferior frontal gyrus and precuneus. T2DM patients showed reduced functional connectivity in the DMN compared with control subjects, which was associated with insulin resistance in selected brain regions, but there were no group effects of brain structure or cognition.