皮质下血管性认知功能障碍的脑默认网络静息态功能磁共振研究

The default mode network research of subcortical ischemic vascular cognitive impairment with resting state functional magnetic resonance imaging

目的运用静息态功能磁共振成像(rs-fMRI)研究皮质下缺血性血管性认知功能障碍(VCI-SIVD)患者在静息状态下的脑默认网络(DMN)。方法收集缺血性脑小血管疾病患者68例,经临床痴呆量表评分后分为血管性痴呆组(VaD组)12例,非痴呆型血管性认知功能障碍组(VCIND组)21例,认知功能正常者35例为对照组,分别采集高分辨率结构像和静息态功能磁共振数据,通过独立成分分析方法(ICA)计算并对比3组患者脑功能活动的改变。采用两样本t检验分别对VCIND组与正常对照组、VaD组与VCIND组、VaD组与正常对照组DMN的功能连接进行组间比较,观察静息状态下脑默认网络的改变情况,并分析VaD患者DMN默认网络与认知功能间的相关性。结果与正常对照组相比,VCIND组患者默认网络脑区的功能连接既有增高也有降低,增高的脑区包括双侧顶叶及颞中回,降低的脑区包括眶额叶、内侧前额叶、前扣带回及双侧枕叶;VaD组患者出现双侧小脑的功能连接增强,VaD组眶额叶、额中回、额下回、双侧枕叶及双侧颞叶的功能连接减低;VaD患者DMN统计脑图与数字连线A、数字符号转换、MOCA等多个临床量表评分存在显著相关性,差异有统计学意义(P<0.05)。结论在静息状态下,血管性认知功能障碍患者的大脑默认模式网络存在异常,并存在以执行功能障碍为主的多个领域的认知功能损害,其认知功能障碍可能与额叶-皮质下环路受损有关。独立成分分析在评价血管性认知功能障碍及其早期诊断中有重要价值。

Objective To explore the default mode network（DMN）of patients with subcortical ischemic vascular cognitive dementia（SIVD）,a subtype of vascular cognitive impairment（VCI）,under the resting state,by the means of resting state functional magnetic resonance imaging（rs-fMRI）.Methods 68 patients with cerebral small vessel disease,who were matched on age,gender,and education level after evaluation with the clinical dementia criterion,were collected in this work.Of those 60 patients,12were vascular dementia（VaD）,21 were vascular cognitive impairment-no dementia（VCIND）,and 35 were normal cognitive function that was classified as a control group.The high resolution structure image and resting-state fMRI data were acquired.The changes in brain activity of patients in three groups were calculated and compared through the independent component analysis（ICA）method.The situation of changes in brain default networks under resting state between the two groups was observed using two-sample t-test,respectively.Also,the correlation between the DMN and cognitive function in patients with VaD was analyzed.Results Compared with normal control group,the default function of the network connection in VCIND patients exhibited both higher and lower brain areas,i.e.,the higher brain regions included the bilateral parietal and temporal gyrus,while,the lower brain regions included the orbitofrontal cortex,medial prefrontal cortex,anterior cingulate cortex,and bilateral occipital lobe.In VaD patients,the bilateral cerebellar functional connectivity was enhanced,whereas,the functional connection in orbital frontal,frontal gyrus,inferior frontal gyrus,bilateral occipital and bilateral temporal lobe was reduced.DMN of VaD group had a significant correlation with Digital connection A,digit symbol conversion and MOCA scale score,with statistically significant difference（P〈0.05）.Conclusion Under the resting state,the DMN in patients with SIVD exists abnormity.The cognitive impairment in multiple dominating fields for executive dysfunction was also exists in SIVD patients.The cognitive dysfunction may be associated with frontal-subcortical loop impairment.ICA dysfunction and early diagnosis have an important value in the evaluation of vascular cognition.