Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA; Center for Behavior Genetics of Aging, University of California, San Diego, La Jolla, CA, USA.
Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA; Center for Behavior Genetics of Aging, University of California, San Diego, La Jolla, CA, USA; Department of Neurosciences, University of California, San Diego, La Jolla, CA, USA.
Neuroimage. 2019 Jan 1;184:871-880. doi: 10.1016/j.neuroimage.2018.10.016. Epub 2018 Oct 5.
Individual differences in white matter tract microstructure, measured with diffusion tensor imaging (DTI), demonstrate substantial heritability. However, it is unclear to what extent this heritability reflects global genetic influences or tract-specific genetic influences. The goal of the current study was to quantify the proportion of genetic and environmental variance in white matter tracts attributable to global versus tract-specific influences. We assessed fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) across 11 tracts and 22 subdivisions of these tracts in 392 middle-aged male twins from the Vietnam Era Twin Study of Aging (VETSA). In principal component analyses of the 11 white matter tracts, the first component, which represents the global signal, explained 50.1% and 62.5% of the variance in FA and MD, respectively. Similarly, the first principal component of the 22 tract subdivisions explained 38.4% and 47.0% of the variance in FA and MD, respectively. Twin modeling revealed that DTI measures of all tracts and subdivisions were heritable, and that genetic influences on global FA and MD accounted for approximately half of the heritability in the tracts or tract subdivisions. Similar results were observed for the AD and RD diffusion metrics. These findings underscore the importance of controlling for DTI global signals when measuring associations between specific tracts and outcomes such as cognitive ability, neurological and psychiatric disorders, and brain aging.
个体间白质束微观结构的差异，通过弥散张量成像（DTI）测量，表现出显著的遗传性。然而，尚不清楚这种遗传性在多大程度上反映了整体遗传影响或束特异性遗传影响。本研究的目的是量化白质束中可归因于整体和束特异性影响的遗传和环境方差的比例。我们评估了来自越南时代衰老双胞胎研究（VETSA）的 392 名中年男性双胞胎的 11 个白质束及其 22 个细分束中的分数各向异性（FA）、平均弥散度（MD）、轴向弥散度（AD）和径向弥散度（RD）。在 11 个白质束的主成分分析中，代表整体信号的第一成分分别解释了 FA 和 MD 方差的 50.1%和 62.5%。同样，22 个束细分的第一主成分分别解释了 FA 和 MD 方差的 38.4%和 47.0%。双胞胎模型显示，所有束和细分的 DTI 测量值都是可遗传的，并且对全球 FA 和 MD 的遗传影响占束或束细分遗传度的约一半。AD 和 RD 扩散指标也观察到了类似的结果。这些发现强调了在测量特定束与认知能力、神经和精神障碍以及大脑衰老等结果之间的关联时，控制 DTI 整体信号的重要性。
