Department of Psychiatry, Otto-von-Guericke University, Magdeburg, Germany.
J Affect Disord. 2013 Jul;149(1-3):116-28. doi: 10.1016/j.jad.2012.12.026. Epub 2013 Mar 13.
Depression is commonly conceptualized as corticolimbic dysregulation. Due to insufficient studies in normal aged populations especially subcortical sources of disconnection are unclear in contrast to potentially general parietal white matter (WM) deficits. This may be due to important influences of variable patient characteristics, most importantly episode severity. Especially thalamic disconnections have been functionally revealed, however, their structural correlates have not been distinctly investigated for its highly diverse subnuclei.
We compared 20 major depressive disorder (MDD) patients with mixed Hamilton depression rating scale (HAMD) severity to matched controls in fractional anisotropy (FA) derived from diffusion tensor imaging (DTI). Robust acquisition of 4 repetitions restricted to twelve directions, also to match the same parameters used by Eckert et al. (2011) who described a preferential architecture of centromedian (CM) and mediodorsal (MD) thalamic connections. Second to whole brain analysis, we tested for group differences within the preferred structural network of these two nuclei using a tract of interest (TOI) approach.
Significant FA deficits in a whole brain analysis were only found in right parietal WM (p<0.05, corrected). Effects of severity were found for increasing thalamic FA. Post hoc analysis revealed this effect to be restricted to CM specific tracts. In contrast, we found MD to dorsolateral prefrontal cortex (DLPFC) tracts to be decreased in FA. Unspecific decreases between MD and CM towards amygdala were paralleled by primary amygdala FA reductions.
Specificity of the TOI approach and heterogenous sample.
Robust parietal FA reductions, controlled for age effects were found in MDD. Further we revealed subcortical disease state dependency of FA in thalamic tracts, specific to predescribed preferential connections.
抑郁症通常被概念化为皮质边缘系统失调。由于在正常老年人群体中研究不足，与潜在的普遍顶叶白质（WM）缺陷相比，皮质下的连接中断尚不清楚。这可能是由于患者特征的重要影响，尤其是发作严重程度。特别是丘脑连接已经在功能上被揭示出来，然而，由于其高度多样化的亚核，其结构相关性尚未得到明确研究。
我们比较了 20 名混合汉密尔顿抑郁评定量表（HAMD）严重程度的重度抑郁症（MDD）患者与匹配对照组在弥散张量成像（DTI）中得出的各向异性分数（FA）。采用 4 次重复的稳健采集，限制在 12 个方向，也与 Eckert 等人（2011 年）使用的相同参数相匹配，他们描述了中央（CM）和中背（MD）丘脑连接的优先结构。除了全脑分析之外，我们还使用感兴趣的束（TOI）方法测试了这两个核的首选结构网络内的组间差异。
在全脑分析中仅发现右侧顶叶 WM 的 FA 缺陷显著（p<0.05，校正）。严重程度的影响发现与增加的丘脑 FA 有关。事后分析表明，这种效应仅限于 CM 特定束。相反，我们发现 MD 到背外侧前额叶皮质（DLPFC）的 FA 降低。MD 与 CM 之间向杏仁核的非特异性减少与杏仁核 FA 减少相平行。
TOI 方法的特异性和样本的异质性。
在 MDD 中发现了与年龄效应相匹配的稳健的顶叶 FA 减少。此外，我们还揭示了丘脑束中 FA 的亚皮质疾病状态依赖性，这是特定于预先规定的优先连接的。
