遗传和环境因素对青少年脑灰质容积和皮层厚度影响的双生子研究

Genetic and environmental contributions to gray matter volume and cortical thickness in adolescents: a twin study

目的通过双生子法探索遗传和环境因素对青少年脑灰质容积、皮层厚度的影响。方法采用横断面研究设计,募集12~18岁双生子。采血液标本提取DNA进行卵型鉴定;采用韦氏儿童智力量表中国修订版进行智商测定;用3.0 T MRI进行头颅结构扫描,采集全脑166层矢状位图像并处理计算个体脑皮层分区灰质容积、皮层厚度;使用双生子结构方程分析遗传和环境对脑灰质容积、皮层厚度的影响。结果纳入57对双生子,其中同卵双生子30对,异卵双生子27对。灰质容积的最佳模型为AE模型,其中各脑区遗传度均有统计学意义(P<0.01);皮层厚度的最佳模型为ACE模型,各脑区中仅双侧扣带回及右侧额叶遗传度有统计学意义(P<0.05),其他脑区遗传度无统计学意义(P>0.05)。相比较影响各脑区皮层厚度的遗传度(A)、共享环境因素贡献度(C)与特异性环境因素(E),特异性环境因素(E)贡献度明显上升。结论在灰质容积和皮层厚度中,青少年脑的可塑性变化可能主要体现在皮层厚度改变上;遗传因素对灰质容积的影响主要驱动因素为皮层面积扩张,而非皮层厚度。

Objective To explore genetic and environmental contributions to gray matter volume and cortical thickness in adolescents by twin method.Methods Twins aged from 12 to 18 years were recruited by using cross-sectional design.DNA was extracted from venous blood samples to identify zygosity.And intelligence quotient(IQ)of participants were measured using the China modified version of Wechsler Intelligence Scale for Children(C-WISC).Brain structure MR imaging on the twins was conducted by 3.0 T MRI,and 166-layer sagittal images of the whole brain were collected.Gray matter volume and cortical thickness were calculated in different brain regions.Twins'structural equation was used for statistical analysis.Results Fifty-seven eligible twin pairs were enrolled,including 30 pairs of monozygotic twins and 27 pairs of dizygotic twins.In the optimal model AE,heritability of gray matter volume in all regions were significant(with a majority of P<0.01).In the optimal model ACE,heritability of cortical thickness were significant in the bilateral cingulate gyrus and right frontal lobe only(P<0.05).Contribution of specific environmental variance(E)was remarkably increased after comparing heritability of cortical thickness in each region,as well as contribution of shared environmental variance(C),and specific environmental variance(E).Conclusion The changes of brain plasticity may be mainly reflected in the changes of cortical thickness.The genetic factors largely contribute to cortical expansion rather than cortical thickness.