Old Age Psychiatry, University Psychiatric Centre (UPC) - KU Leuven, Belgium; Translational MRI & Radiology, KU Leuven & University Hospital Leuven, Belgium.
Developmental Imaging, Murdoch Children's Research Institute, Victoria, Australia.
J Affect Disord. 2017 Nov;222:63-70. doi: 10.1016/j.jad.2017.06.063. Epub 2017 Jun 27.
Differences in corpus callosum (CC) morphology and microstructure have been implicated in late-life depression and may distinguish between late and early-onset forms of the illness. However, a multimodal approach using complementary imaging techniques is required to disentangle microstructural alterations from macrostructural partial volume effects.
107 older adults were assessed: 55 currently-depressed patients without dementia and 52 controls without cognitive impairment. We investigated group differences and clinical associations in 7 sub-regions of the mid-sagittal corpus callosum using T1 anatomical data, white matter hyperintensity (WMH) quantification and two different diffusion MRI (dMRI) models (multi-tissue constrained spherical deconvolution, yielding apparent fibre density, AFD; and diffusion tensor imaging, yielding fractional anisotropy, FA and radial diffusivity, RD).
Callosal AFD was lower in patients compared to controls. There were no group differences in CC thickness, surface area, FA, RD, nor whole brain or WMH volume. Late-onset of depression was associated with lower FA, higher RD and lower AFD. There were no associations between any imaging measures and psychotic features or depression severity as assessed by the geriatric depression scale. WMH volume was associated with lower FA and AFD, and higher RD in patients.
Patients were predominantly treatment-resistant. Measurements were limited to the mid-sagittal CC. dMRI analysis was performed on a smaller cohort, n=77. AFD was derived from low b-value data.
Callosal structure is largely preserved in LLD. WMH burden may impact on CC microstructure in late-onset depression suggesting vascular pathology has additional deleterious effects in these patients.
胼胝体（CC）形态和微观结构的差异与老年期抑郁症有关，并且可能区分疾病的晚发和早发形式。然而，需要使用互补的成像技术进行多模态方法来区分微观结构改变和宏观结构部分容积效应。
评估了 107 名老年人：55 名目前无痴呆的抑郁患者和 52 名无认知障碍的对照者。我们使用 T1 解剖数据、脑白质高信号（WMH）量化和两种不同的扩散 MRI（dMRI）模型（多组织约束球分解，产生表观纤维密度，AFD；和弥散张量成像，产生各向异性分数，FA 和径向弥散度，RD）研究了 7 个中矢状 CC 亚区的组间差异和临床相关性。
与对照组相比，患者的胼胝体 AFD 较低。CC 厚度、表面积、FA、RD 以及整个大脑或 WMH 体积在两组之间均无差异。抑郁的晚发与 FA 降低、RD 升高和 AFD 降低有关。任何影像学指标与精神病特征或老年抑郁量表评估的抑郁严重程度均无相关性。WMH 体积与患者的 FA 和 AFD 降低以及 RD 升高有关。
患者主要是难治性的。测量仅限于中矢状 CC。dMRI 分析在较小的队列中进行，n=77。AFD 是从低 b 值数据中得出的。
LLD 中胼胝体结构基本保持完整。WMH 负担可能会对晚发抑郁症的 CC 微观结构产生影响，表明血管病理在这些患者中有额外的有害影响。
