Department of Clinical Neurosciences, Scientific Institute and University Vita-Salute San Raffaele, Milano, Italy.
Bipolar Disord. 2011 Jun;13(4):414-24. doi: 10.1111/j.1399-5618.2011.00938.x.
A growing body of evidence suggests that, independent of localized brain lesions, mood disorders can be associated with dysfunction of brain networks involved in the modulation of emotional and cognitive behavior. We used diffusion tensor (DT) tractography to quantify the presence and extent of structural injury to the connections between the amygdala and other brain regions, which included the subgenual, the supragenual and posterior cingulate, the parahippocampal, the orbitofrontal and dorsolateral prefrontal cortices, as well as the insula.
Using a 3.0 Tesla scanner, conventional and DT magnetic resonance imaging sequences of the brain were acquired from 15 adult patients with major depressive disorder (MDD), 15 with bipolar disorder (BD), and 21 age-matched healthy controls. Using FSL software, diffusivity changes of the white matter (WM) fiber bundles belonging to the emotional network were measured.
Compared to controls and MDD patients, BD patients had significantly decreased average fractional anisotropy, increased average mean diffusivity, and increased average axial and radial diffusivity values in the majority of the WM fiber bundles connecting structures of the anterior limbic network (p-values ranging from 0.002 to 0.040). Medication load did not influence the results with the exception of lithium, which was associated with normal diffusivity values in tracts connecting the amygdala with the subgenual cingulate cortex.
We detected specific WM abnormalities, suggestive of disrupted integrity of fiber bundles in the brains of patients with BD. These abnormalities might contribute to understanding both mood dysregulation and cognitive disturbances in BD, and might provide an objective marker to monitor treatment efficacy in this condition.
越来越多的证据表明，除了局部脑损伤外，情绪障碍还可能与参与调节情绪和认知行为的大脑网络功能障碍有关。我们使用弥散张量（DT）轨迹法来量化杏仁核与其他大脑区域之间连接的结构损伤的存在和程度，这些区域包括：扣带回前、中、后下部，海马旁回，眶额回和背外侧前额叶皮质以及脑岛。
使用 3.0T 扫描仪，从 15 名成年重度抑郁症（MDD）患者、15 名双相情感障碍（BD）患者和 21 名年龄匹配的健康对照者中采集大脑的常规和 DT 磁共振成像序列。使用 FSL 软件测量属于情感网络的白质（WM）纤维束的弥散变化。
与对照组和 MDD 患者相比，BD 患者在前边缘网络结构的大多数 WM 纤维束中，具有明显较低的平均各向异性分数、较高的平均平均弥散度、以及较高的平均轴向和径向弥散度值（p 值范围从 0.002 到 0.040）。药物负荷除了锂以外，不会影响结果，锂与连接杏仁核与扣带回前下部的束状结构的正常弥散值有关。
我们检测到了 BD 患者大脑中 WM 的特定异常，提示纤维束的完整性受损。这些异常可能有助于理解 BD 中的情绪失调和认知障碍，并可能为监测这种情况下的治疗效果提供客观标记。
