Background: Bipolar disorder (BD) is a severe mental disorder, characterized by prominent mood swings and emotion regulation (ER) deficits. The uncinate fasciculus (UF), a white matter tract connecting the amygdala and the ventral prefrontal cortex, has been implicated in ER. Aberrancies in UF microstructure may be an endophenotype associated with increased risk for BD. However, findings in individuals with BD and at familial risk for BD (AR) have yielded inconsistent findings. This meta-analysis takes a region-of-interest approach to consolidate the available evidence and elucidate the role of the UF in the risk-architecture of BD. Methods: Using web-based search engines, we identified diffusion tensor imaging studies focusing on the left and right UF and conducted meta-analyses comparing fractional anisotropy (FA) and radial diffusivity (RD) between BD or AR to healthy volunteers (HV). Results: We included 32 studies (BD: n=1186, HV: n=2001; AR: n=289, HV-AR: n=314). Compared to HV, individuals with BD showed lower FA in the right (p<.0001) and left UF (p=.010), and higher RD in the right UF (p=.009). We found no significant differences between AR and HV. In the right but not the left UF, AR individuals showed higher FA than BD (p=.043). Conclusion: Comparable UF microstructure between AR and HV and higher FA in the right UF in AR compared to BD suggest that aberrancies in UF microstructure is not an endophenotype for BD. Longitudinal studies are needed to determine when UF abnormalities emerge in the context of BD.

中文翻译：

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钩状束在双相情感障碍风险结构中的作用：荟萃分析

背景：双相情感障碍（BD）是一种严重的精神障碍，其特征是显着的情绪波动和情绪调节（ER）缺陷。钩状束 (UF) 是连接杏仁核和腹侧前额叶皮层的白质束，与 ER 相关。UF 微观结构的异常可能是与 BD 风险增加相关的内表型。然而，在患有 BD 和具有家族性 BD (AR) 风险的个体中的发现产生了不一致的发现。该荟萃分析采用感兴趣区域的方法来整合现有证据并阐明 UF 在 BD 风险架构中的作用。方法：使用基于网络的搜索引擎，我们确定了关注左右 UF 的扩散张量成像研究，并进行了荟萃分析，比较了 BD 或 AR 与健康志愿者 (HV) 之间的分数各向异性 (FA) 和径向扩散率 (RD)。结果：我们纳入了 32 项研究（BD：n=1186，HV：n=2001；AR：n=289，HV-AR：n=314）。与 HV 相比，BD 患者右侧 (p<.0001) 和左侧 UF (p=.010) 的 FA 较低，右侧 UF 的 RD 较高 (p=.009)。我们发现 AR 和 HV 之间没有显着差异。在右侧而非左侧 UF 中，AR 个体的 FA 高于 BD (p=.043)。结论：与 BD 相比，AR 和 HV 之间可比的 UF 微观结构以及 AR 中正确 UF 中更高的 FA 表明 UF 微观结构中的异常不是 BD 的内表型。