Fundación para la Investigación y Docencia Maria Angustias Giménez (FIDMAG) Germanes Hospitalàries, Barcelona; Centro de Investigación Biomédica en Red de Salud Mental, Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain.
Fundación para la Investigación y Docencia Maria Angustias Giménez (FIDMAG) Germanes Hospitalàries, Barcelona; Centro de Investigación Biomédica en Red de Salud Mental, Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid, Spain.
Biol Psychiatry. 2014 Aug 1;76(3):239-48. doi: 10.1016/j.biopsych.2013.09.027. Epub 2013 Oct 4.
Evidence from decades of magnetic resonance imaging (MRI) research in bipolar disorder has been summarized in meta-analyses of various MRI modalities. Notably, although structural MRI studies suggest gray matter reductions are restricted to specific cortical regions, functional MRI has also shown involvement of subcortical dysfunction. Such disparity in results is open to discussion and requires further exploration with additional MRI modalities.
We applied whole-brain high angular resolution molecular diffusion imaging to compare different properties of the water diffusion process in brain tissues, using different contrasts. Specifically, we looked at fractional anisotropy, mean diffusivity, probability of return to the origin, and generalized fractional anisotropy in a sample of 40 euthymic patients with bipolar disorder and 40 well-matched healthy control subjects.
Convergent abnormalities were detected by contrasts in various tissue types. Apart from alterations in white matter (in corpus callosum, cingulum bundle, corona radiata, and superior fronto-occipital fasciculus) and cortical gray matter (in medial frontal cortex, left insula, Heschl's gyrus, and cerebellum), three of the contrasts (fractional anisotropy, mean diffusivity, and generalized fractional anisotropy) revealed abnormalities in subcortical structures, including the hippocampus, the thalamus and the caudate nucleus.
Our findings point to a wider pattern of axonal pathology in bipolar disorder than previously thought. Although findings related to cortical gray matter are consistent with structural meta-analyses, subcortical abnormalities suggest a cytoarchitectonic basis for previously reported subcortical dysfunction. Diffusion results could be interpreted in terms of loss of tissue volume and/or altered membrane permeability, agreeing with both hypotheses of mitochondrial malfunction and neuroinflammation.
几十年来，双相情感障碍的磁共振成像（MRI）研究证据已在各种 MRI 方式的荟萃分析中得到总结。值得注意的是，尽管结构 MRI 研究表明灰质减少仅限于特定的皮质区域，但功能 MRI 也显示了皮质下功能障碍的参与。这种结果的差异有待讨论，需要进一步用其他 MRI 方式进行探索。
我们应用全脑高角分辨率分子扩散成像来比较脑组织中不同的水扩散过程的性质，使用不同的对比。具体来说，我们观察了 40 名双相情感障碍的 euthymic 患者和 40 名匹配良好的健康对照组在不同组织类型中的分数各向异性、平均弥散度、返归原点概率和广义分数各向异性。
在各种组织类型的对比中发现了趋同的异常。除了白质（胼胝体、扣带束、辐射冠和额枕上束）和皮质灰质（内侧额叶皮质、左侧岛叶、Heschl 回和小脑）的改变外，三种对比（分数各向异性、平均弥散度和广义分数各向异性）显示了皮质下结构的异常，包括海马体、丘脑和尾状核。
我们的发现表明，双相情感障碍的轴突病理比以前认为的更为广泛。虽然与皮质灰质相关的发现与结构荟萃分析一致，但皮质下异常提示了先前报道的皮质下功能障碍的细胞结构基础。扩散结果可以根据组织体积的丧失和/或膜通透性的改变来解释，这与线粒体功能障碍和神经炎症的两种假说一致。
