Objective Functional magnetic resonance imaging (fMRI) technology and dynamic amplitude of lowfrequency fluctuation (dALFF) were used to detect differences in the temporal variability of neural activity in the brains of patients with major depressive disorder (MDD), including, those who were in their first-episode (FE) and those with recurrent (RE), as well as healthy controls (HCs). Methods Sixty-eight FE patients and 42 RE patients were prospectively selected as the study group and completed the 17-item Hamilton rating, scale for depression (HAMD-17) and 9-item Patient Health Questionnaire (PHQ-9). During, the same period, one hundred and ten age-and sex-matched HCs were recruited and completed PHQ-9. Resting-state fMRI data were collected from all subjects. DPABI software was used to preprocess the raw data, and one-way ANCOVA was used to compare the differences in dALFF among, the 3 groups. The mean values of the time series of brain regions with differences in dALFF between the 3 groups were extracted, and post-hoc pairewise comparison of dALFF values was performed using, LSD-t test. The obtained results were Bonferroni corrected. Additionally, other window sizes, step sizes and window types were used to replicate all the above analyses. Results The PHQ-9 scores were higher in the FE and RE groups than in the HC group (all P<0.05). No significant differences in dALFF among the FE and RE groups for the PHQ-9 and HAMD-17 scores (all P>0.05). A significant difference in dALFF among, the three groups was found at the right middle occipital gyrus (P<0.05, FWE correction). Post-hoc analysis showed that both the FE and RE groups showed significantly decreased dALFF values compared to the HC group at the right middle occipital gyrus (all P<0.016). No significant difference was found between the two patient groups. The validation analyses supported these findings. Conclusions The FE and RE patients with MDD both showed significantly decreased temporal variability of spontaneous brain activity fluctuations at the night mild iccipital gyrus, indicating, an inflexible adaptability of the brain to the environment. This might be a trait abnormality in patients with MDD.

目的 采用功能MRI(f MRI)技术，通过动态低频振幅（dALFF）分析来检测首发（FE）、复发（RE）抑郁症病人和健康对照（HC）之间脑自发活动的动态异常。方法 作为前瞻性研究纳入了FE病人68例和RE病人42例，均完成汉密顿抑郁量表（HAMD-17）和病人健康问卷（PHQ-9）评定。另招募与病人性别、年龄相匹配的110例健康人作为HC组，均完成PHQ-9评定。采集所有受试者的静息态f MRI影像。采用DPABI软件对f MRI数据进行预处理，采用单因素协方差分析比较3组间dALFF差异。在3组间dALFF有差异脑区中测算时间序列均值（dALFF值），事后两两比较采用Bonferroni校正的LSD-t检验。采用不同的窗宽、步长和窗类型对上述分析进行验证。结果 FE和RE组的PHQ-9评分均高于HC组（均P0.05）。3组间右侧枕中回d ALFF值的差异有统计学意义（P0.05）。采用不同参数组合进行验证，结果均一致。结论 FE和RE抑郁症病人均表现出右侧枕中回脑自发活动的动态性降低，提示其对外部信息处理的灵活性下降，且这可能是抑郁症病人的特质性异常。

国家自然科学基金面上项目（82071531）;国家自然科学基金青年项目（82101597）;; 北京市医院管理中心青年人才培养“青苗”计划项目（QML20231901）