Docherty Anna R, Hagler Donald J, Panizzon Matthew S, Neale Michael C, Eyler Lisa T, Fennema-Notestine Christine, Franz Carol E, Jak Amy, Lyons Michael J, Rinker Daniel A, Thompson Wesley K, Tsuang Ming T, Dale Anders M, Kremen William S
Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA 23220, USA.
Department of Radiology, University of California, San Diego, La Jolla, CA 92093, USA.
Neuroimage. 2015 Feb 1;106:154-60. doi: 10.1016/j.neuroimage.2014.11.040. Epub 2014 Nov 26.
The phenotypic and genetic relationship between global cortical size and general cognitive ability (GCA) appears to be driven by surface area (SA) and not cortical thickness (CT). Gyrification (cortical folding) is an important property of the cortex that helps to increase SA within a finite space, and may also improve connectivity by reducing distance between regions. Hence, gyrification may be what underlies the SA-GCA relationship. In previous phenotypic studies, a 3-dimensional gyrification index (3DGI) has been positively associated with cognitive ability and negatively associated with mild cognitive impairment, Alzheimer's disease, and psychiatric disorders affecting cognition. However, the differential genetic associations of 3DGI and SA with GCA are still unclear. We examined the heritability of 3DGI, and the phenotypic, genetic, and environmental associations of 3DGI with SA and GCA in a large sample of adult male twins (N = 512). Nearly 85% of the variance in 3DGI was due to genes, and 3DGI had a strong phenotypic and genetic association with SA. Both 3DGI and total SA had positive phenotypic correlations with GCA. However, the SA-GCA correlation remained significant after controlling for 3DGI, but not the other way around. There was also significant genetic covariance between SA and GCA, but not between 3DGI and GCA. Thus, despite the phenotypic and genetic associations between 3DGI and SA, our results do not support the hypothesis that gyrification underlies the association between SA and GCA.
全球皮质大小与一般认知能力（GCA）之间的表型和遗传关系似乎是由表面积（SA）而非皮质厚度（CT）驱动的。脑回形成（皮质折叠）是皮质的一个重要特性，有助于在有限空间内增加表面积，还可能通过缩短区域间距离来改善连通性。因此，脑回形成可能是SA与GCA关系的基础。在先前的表型研究中，三维脑回形成指数（3DGI）与认知能力呈正相关，与轻度认知障碍、阿尔茨海默病以及影响认知的精神障碍呈负相关。然而，3DGI和SA与GCA的遗传关联差异仍不清楚。我们在一个成年男性双胞胎大样本（N = 512）中研究了3DGI的遗传力，以及3DGI与SA和GCA的表型、遗传和环境关联。3DGI近85%的变异归因于基因，并且3DGI与SA有很强的表型和遗传关联。3DGI和总SA与GCA均呈正表型相关。然而，在控制3DGI后，SA与GCA的相关性仍然显著，反之则不然。SA和GCA之间也存在显著的遗传协方差，但3DGI和GCA之间不存在。因此，尽管3DGI和SA之间存在表型和遗传关联，但我们的结果不支持脑回形成是SA与GCA关联基础的假设。
