Department of Psychiatry, University of Minnesota Medical School, University of Minnesota, Center for Magnetic Resonance Research, Minneapolis, MN 55454, USA.
J Am Acad Child Adolesc Psychiatry. 2010 Feb;49(2):173-83.e1. doi: 10.1097/00004583-201002000-00011.
Major depressive disorder (MDD) occurs frequently in adolescents, but the neurobiology of depression in youth is poorly understood. Structural neuroimaging studies in both adult and pediatric populations have implicated frontolimbic neural networks in the pathophysiology of MDD. Diffusion tensor imaging (DTI), which measures white matter (WM) microstructure, is a promising tool for examining neural connections and how they may be abnormal in MDD.
We used two separate approaches to analyze DTI data in adolescents with MDD (n = 14) compared with healthy volunteers (n = 14).
The first, hypothesis-driven approach was to use probabilistic tractography to delineate tracts arising from the subgenual anterior cingulate cortex (ACC). Adolescents with MDD demonstrated lower fractional anisotropy (FA) in the WM tract connecting subgenual ACC to amygdala in the right hemisphere. The second, exploratory approach was to conduct a voxelwise comparison of FA. This analysis revealed 10 clusters where adolescents with MDD had significantly lower (uncorrected) FA than the healthy group within WM tracts including right and left uncinate and supragenual cingulum.
These preliminary data support the hypothesis that altered WM microstructure in frontolimbic neural pathways may contribute to the pathophysiology of MDD in adolescents.
重度抑郁症（MDD）在青少年中较为常见，但青少年抑郁症的神经生物学机制仍不清楚。成人和儿科人群的结构神经影像学研究表明，额皮质边缘神经网络与 MDD 的病理生理学有关。弥散张量成像（DTI）可测量白质（WM）的微观结构，是一种很有前途的研究工具，可用于研究神经连接以及它们在 MDD 中可能出现的异常。
我们使用两种独立的方法分析了患有 MDD 的青少年（n = 14）与健康志愿者（n = 14）的 DTI 数据。
第一种，基于假设的方法是使用概率追踪描绘发自扣带回前部皮质下（ACC）的束。MDD 青少年的右半球连接扣带回前部皮质下到杏仁核的 WM 束的各向异性分数（FA）较低。第二种，探索性的方法是对 FA 进行体素比较。该分析显示，在包括右侧和左侧钩束和扣带回上部的 WM 束中，与健康组相比，MDD 青少年有 10 个簇的 FA 值明显降低（未校正）。
这些初步数据支持这样的假设，即额皮质边缘神经网络中的 WM 微观结构改变可能导致青少年 MDD 的病理生理学改变。
