2型糖尿病患者脑血流和功能连接变化及与记忆功能的关系

Changes of cerebral blood flow,functional connectivity and the relationships with memory function in type 2 diabetes mellitus

目的纵向观察2型糖尿病(T2DM)患者脑血流量(CBF)及功能连接(FC)变化,分析CBF、FC与记忆功能的关系。方法对27例T2DM患者(T2DM组)及36名健康志愿者(对照组)行头部MR检查及记忆功能测评,并于5年后随访复查。对CBF行重复测量方差分析,以CBF改变存在显著组别×时间交互效应的脑区作为种子点行FC分析,评估FC的交互效应,并分析CBF、FC与记忆功能之间的相关性。结果双侧枕叶皮层CBF存在组别×时间交互效应(FDR校正,P<0.05)。T2DM组与对照组枕叶皮层基线CBF差异无统计学意义(P>0.05);5年后T2DM组枕叶皮层CBF显著低于对照组(P<0.05)。视皮层左侧V1背侧区(LV1d)亚区与双侧颞叶间FC的组别×时间交互效应显著(FDR校正,P<0.05)。T2DM组右侧颞叶基线FC高于对照组(P<0.05),5年后随访时T2DM组双侧颞叶FC均较基线水平下降(P均<0.05)。T2DM患者LV1d与右侧颞叶间基线FC与短时记忆表现呈正相关(r=0.446,P=0.033);5年后随访时枕叶皮层CBF与数字顺背评分呈正相关(r=0.493,P=0.012)。结论T2DM早期视听皮层间FC代偿性增强,随着血流供应减少,视听皮层间FC代偿逐渐下降,这可能是T2DM患者记忆功能下降的神经机制之一。

Objective To longitudinally observe the changes of cerebral blood flow(CBF)and functional connectivity(FC)in patients with type 2 diabetes mellitus(T2DM),and to analyze the relationships of these changes with memory function.Methods Twenty-seven T2DM patients(T2DM group)and 36 healthy volunteers(control group)underwent head MRI and memory assessments as well as the same examinations 5 years later.Then repeated measuring analysis of variance models was performed of CBF.Taken brain area with significant CBF interaction effect as the seed point,the interaction effects of whole brain FC were evaluated,and the correlations of CBF,FC and memory behavior indicators were analyzed.Results The group×time interaction effect was significant in bilateral occipital lobes(FDR corrected,P<0.05).The baseline CBF of occipital cortex was not significantly different between T2DM group and control group(P>0.05),but 5 years later,that in T2DM group was significantly lower than in control group(P<0.05).FC between the left V1 dorsal area(LV1d)of the visual cortex and bilateral temporal lobes showed significant interaction effect(FDR corrected,P<0.05).FC of the right temporal lobe at baseline in T2DM group was significantly higher than that in control group(P<0.05),whereas 5 years later,FC of bilateral temporal lobes were significantly decreased compared with baseline in T2DM group(both P<0.05).The baseline FC between the LV1d and the right temporal lobe in T2DM patients were positively correlated with short-time memory performances(r=0.446,P=0.033),and CBF 5 years later were positively correlated with forward digital span(r=0.493,P=0.012).Conclusion FC between the visual and auditory cortices compensatory increased in early stage T2DM patients.However,with the decrease of blood supply,FC compensation in the audiovisual cortex gradually decreased,which might be one of the neural mechanisms of the memory function decline in T2DM patients.