Zhang Yichen, Wu Guorong, De Witte Sara, Baeken Chris
Faculty of Medicine and Health Sciences, Department of Head and Skin, Ghent Experimental Psychiatry Lab, Ghent University, Ghent, Belgium.
Faculty of Medicine and Health Sciences, Department of Head and Skin, Ghent Experimental Psychiatry Lab, Ghent University, Ghent, Belgium; Key Laboratory of Cognition and Personality, Faculty of Psychology, Southwest University, Chongqing, China.
Biol Psychiatry Cogn Neurosci Neuroimaging. 2025 Mar 3. doi: 10.1016/j.bpsc.2025.02.010.
Major depressive disorder (MDD) is characterized by impaired emotional and cognitive functions. Previous studies have focused on the long-range white matter bundles within the deep white matter connecting distant cortices. Less is known about the superficial white matter (SWM), which consists of short bundles connecting adjacent and precise cortices. Therefore, we investigated the differences in SWM between patients with MDD and healthy control participants (HCs) and its relationship with core clinical depressive symptoms.
Probabilistic tractography was used to generate the SWM bundles in 62 antidepressant-free patients with MDD and 77 HCs. Diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) were used to compare the microstructural differences of SWM between the 2 groups. Correlations were calculated between the diffusion metrics in the SWM showing significant between-group differences and core clinical depressive symptoms.
Compared with HCs, patients with MDD showed DTI metric changes in the SWM bundles connecting frontal-parietal-temporal-occipital cortices. For the NODDI metrics, patients with MDD showed a lower neurite density index in the SWM bundles connecting frontal-parietal-temporal cortices. Here, the neurite density index in the SWM bundles connecting prefrontal-insula regions was significantly negatively correlated with anhedonia and suicidal ideation. Patients with MDD displayed a higher orientation dispersion index in the SWM bundles connecting parietal, occipital, and posterior cingulate cortices.
SWM plays a crucial role in the neuropathology of MDD. The decreased neurite density in the SWM connecting prefrontal-insula regions may underlie anhedonia and suicidal ideation. Furthermore, NODDI metrics may offer more specific detection of SWM microstructural abnormalities than DTI metrics.
重度抑郁症（MDD）的特征是情绪和认知功能受损。以往的研究主要集中在深部白质中连接远处皮质的长程白质束。对于由连接相邻且精确皮质的短束组成的浅部白质（SWM），人们了解较少。因此，我们研究了MDD患者与健康对照参与者（HCs）之间SWM的差异及其与核心临床抑郁症状的关系。
采用概率纤维束成像技术在62例未服用抗抑郁药的MDD患者和77例HCs中生成SWM束。利用扩散张量成像（DTI）和神经突方向离散度与密度成像（NODDI）比较两组间SWM的微观结构差异。计算SWM中显示出显著组间差异的扩散指标与核心临床抑郁症状之间的相关性。
与HCs相比，MDD患者在连接额-顶-颞-枕皮质的SWM束中显示出DTI指标变化。对于NODDI指标，MDD患者在连接额-顶-颞皮质的SWM束中神经突密度指数较低。在此，连接前额叶-脑岛区域的SWM束中的神经突密度指数与快感缺失和自杀观念显著负相关。MDD患者在连接顶叶、枕叶和后扣带回皮质的SWM束中显示出较高的方向离散度指数。
SWM在MDD的神经病理学中起关键作用。连接前额叶-脑岛区域的SWM中神经突密度降低可能是快感缺失和自杀观念的基础。此外，与DTI指标相比，NODDI指标可能对SWM微观结构异常提供更特异性的检测。
