Sexton Claire E, Allan Charlotte L, Le Masurier Marisa, McDermott Lisa M, Kalu Ukwuori G, Herrmann Lucie L, Mäurer Matthias, Bradley Kevin M, Mackay Clare E, Ebmeier Klaus P
University Department of Psychiatry, University of Oxford, UK.
Arch Gen Psychiatry. 2012 Jul;69(7):680-9. doi: 10.1001/archgenpsychiatry.2011.1862.
Disruption of frontal-subcortical and limbic networks is hypothesized to have a key role in late-life depression (LLD) and can be examined using magnetic resonance imaging (MRI) techniques. Gray matter can be examined using T1-weighted MRI, white matter using T2-weighted MRI and diffusion tensor imaging, and functional connectivity in resting-state networks using functional MRI. Although independent MRI studies have supported gray and white matter abnormalities in frontosubcortical and limbic networks and increased functional connectivity in the default-mode network in depression, no study has concurrently examined gray matter, white matter, and functional connectivity.
To examine whether results of different MRI techniques are complementary, multimodal MRI was used to compare gray matter, white matter, and resting-state networks between LLD and control groups.
Cross-sectional, case-control, multimodal MRI analysis.
University research department.
Thirty-six recovered participants with LLD (mean age, 71.8 years) and 25 control participants (mean age, 71.8 years).
Gray matter was examined across the whole brain using voxel-based morphometry. Subcortical gray matter structures were also automatically segmented, and volumetric and shape analyses were performed. For white matter analysis, fractional anisotropy, axial diffusivity, and radial diffusivity values were examined using tract-based spatial statistics. For resting-state network analysis, correlation coefficients were compared using independent components analysis followed by dual regression.
White matter integrity was widely reduced in LLD, without significant group differences in gray matter volumes or functional connectivity.
The present work strongly supports the hypothesis that white matter abnormalities in frontal-subcortical and limbic networks play a key role in LLD even in the absence of changes in resting functional connectivity and gray matter. Factors that could contribute to the lack of significant differences in gray matter and functional connectivity measures, including current symptom severity, medication status, and age of participants with LLD, are discussed.
额叶 - 皮质下和边缘系统网络的破坏被认为在老年期抑郁症（LLD）中起关键作用，并且可以使用磁共振成像（MRI）技术进行检查。灰质可以通过T1加权MRI进行检查，白质可以通过T2加权MRI和扩散张量成像进行检查，静息态网络中的功能连接可以通过功能MRI进行检查。尽管独立的MRI研究支持额叶皮质下和边缘系统网络中的灰质和白质异常以及抑郁症患者默认模式网络中功能连接性增加，但尚无研究同时检查灰质、白质和功能连接性。
为了研究不同MRI技术的结果是否具有互补性，采用多模态MRI比较LLD组和对照组之间的灰质、白质和静息态网络。
横断面、病例对照、多模态MRI分析。
大学研究部门。
36名康复的LLD参与者（平均年龄71.8岁）和25名对照参与者（平均年龄71.8岁）。
使用基于体素的形态计量学在全脑范围内检查灰质。还自动分割了皮质下灰质结构，并进行了体积和形状分析。对于白质分析，使用基于束的空间统计学检查分数各向异性、轴向扩散率和径向扩散率值。对于静息态网络分析，使用独立成分分析然后进行双回归比较相关系数。
LLD患者的白质完整性普遍降低，灰质体积或功能连接性无显著组间差异。
本研究强烈支持以下假设，即额叶皮质下和边缘系统网络中的白质异常在LLD中起关键作用，即使静息功能连接性和灰质没有变化。讨论了可能导致灰质和功能连接性测量缺乏显著差异的因素，包括当前症状严重程度、用药状态和LLD参与者的年龄。
