摘要目的:探讨脑小血管病（CSVD）伴皮质下缺血性抑郁（SID）患者脑灰质体积及分数低频振幅（fALFF）的变化及其与脑源性神经营养因子（BDNF）基因多态性的关系。方法:选择2017年7月至2020年11月就诊于安徽医科大学第一附属医院神经内科门诊或住院的CSVD患者87例，分别对其进行认知功能和情绪评估、磁共振扫描及BDNF基因检测；根据老年抑郁量表（GDS）评分将CSVD患者分为CSVD伴SID组（CSVD-SD，GDS评分>10分）和CSVD非抑郁组（CSVD-ND，GDS评分≤10分）；利用脑结构和功能磁共振扫描数据进行脑灰质体积及fALFF计算，分析SID脑结构和功能的变化及其与BDNF基因多态性的关联，以及诊断-基因交互作用对脑结构和功能的影响。结果:CSVD-SID组患者灰质体积在后默认网络（pDMN）脑区（如后扣带回、楔前叶）及左侧颞中回脑区显著增加。脑灰质体积的遗传主效应及诊断主效应均不显著，但CSVD-SID诊断与BDNF基因型在楔叶（ F=25.50， P<0.001）、楔前叶（ F=13.61， P<0.001）及小脑（ F=17.23， P<0.001）存在交互作用。在脑功能方面，与CSVD-ND组相比，CSVD-SID患者在额上回脑区fALFF值显著增加（0.363±0.648与-0.427±0.514，簇大小=48体素， t=5.63， P<0.001）。fALFF的遗传及诊断主效应均不显著，且CSVD-SID诊断与BDNF基因无明显交互作用。 结论:CSVD-SID患者存在多个脑区灰质体积及fALFF增加，以pDMN和额叶脑区为著，且仅在脑灰质体积方面，CSVD-SID诊断与BDNF基因型之间存在交互作用。

abstractsObjective:To investigate the relationship between brain derived neurotrophic factor (BDNF) gene polymorphism and the change of grey matter volume (GMV) and fractional amplitude of low-frequency fluctuation (fALFF) in cerebral small vessel disease (CSVD) patients with subcortical ischemic depression (SID).Methods:Eighty-seven CSVD patients in the First Affiliated Hospital of Anhui Medical University were enrolled from July 2017 to November 2020 and divided into CSVD-SID group [Geriatric Depression Scale (GDS) score>10] and CSVD-non - depression group (CSVD-ND group, GDS score≤10) according to GDS. Both GMV and fALFF were calculated based on structural and functional magnetic resonance imaging data, and the interactions between SID diagnosis and BDNF gene on brain function and structure alteration were explored.Results:GMV was significantly increased in the posterior default network (pDMN; such as posterior cingulate gyrus/precuneus and middle temporal gyrus) in the CSVD-SID group compared with the CSVD-ND group. On GMV property, significant interactions between BDNF gene and SID were found in the cuneus ( F=25.50, P<0.001), precuneus lobe ( F=13.61, P<0.001) and cerebellum ( F=17.23, P<0.001). In the aspect of fALFF, the brain functional activity in the superior frontal gyrus was significantly increased in the CSVD-SID group compared with that in the CSVD-ND group (0.363±0.648 vs -0.427±0.514,cluster size=48 voxels, t=5.63, P<0.001). But there was no significant interaction between diagnosis and BDNF genotype on brain function. Conclusions:Both the GMV and fALFF were increased in CSVD-SID, mainly located in the pDMN and frontal lobe. Significant interaction was found between CSVD-SID and BDNF genotype on GMV.