Couvy-Duchesne Baptiste, Ebejer Jane L, Gillespie Nathan A, Duffy David L, Hickie Ian B, Thompson Paul M, Martin Nicholas G, de Zubicaray Greig I, McMahon Katie L, Medland Sarah E, Wright Margaret J
QIMR Berghofer Medical Research Institute, Brisbane, Australia.
School of Psychology, University of Queensland, Brisbane, Australia.
PLoS One. 2016 Jan 8;11(1):e0146271. doi: 10.1371/journal.pone.0146271. eCollection 2016.
Head motion (HM) is a well known confound in analyses of functional MRI (fMRI) data. Neuroimaging researchers therefore typically treat HM as a nuisance covariate in their analyses. Even so, it is possible that HM shares a common genetic influence with the trait of interest. Here we investigate the extent to which this relationship is due to shared genetic factors, using HM extracted from resting-state fMRI and maternal and self report measures of Inattention and Hyperactivity-Impulsivity from the Strengths and Weaknesses of ADHD Symptoms and Normal Behaviour (SWAN) scales. Our sample consisted of healthy young adult twins (N = 627 (63% females) including 95 MZ and 144 DZ twin pairs, mean age 22, who had mother-reported SWAN; N = 725 (58% females) including 101 MZ and 156 DZ pairs, mean age 25, with self reported SWAN). This design enabled us to distinguish genetic from environmental factors in the association between head movement and ADHD scales. HM was moderately correlated with maternal reports of Inattention (r = 0.17, p-value = 7.4E-5) and Hyperactivity-Impulsivity (r = 0.16, p-value = 2.9E-4), and these associations were mainly due to pleiotropic genetic factors with genetic correlations [95% CIs] of rg = 0.24 [0.02, 0.43] and rg = 0.23 [0.07, 0.39]. Correlations between self-reports and HM were not significant, due largely to increased measurement error. These results indicate that treating HM as a nuisance covariate in neuroimaging studies of ADHD will likely reduce power to detect between-group effects, as the implicit assumption of independence between HM and Inattention or Hyperactivity-Impulsivity is not warranted. The implications of this finding are problematic for fMRI studies of ADHD, as failing to apply HM correction is known to increase the likelihood of false positives. We discuss two ways to circumvent this problem: censoring the motion contaminated frames of the RS-fMRI scan or explicitly modeling the relationship between HM and Inattention or Hyperactivity-Impulsivity.
头部运动（HM）是功能磁共振成像（fMRI）数据分析中一个众所周知的干扰因素。因此，神经影像学研究人员通常在分析中将HM视为一个干扰协变量。即便如此，HM与感兴趣的特质之间仍可能存在共同的遗传影响。在此，我们使用从静息态fMRI中提取的HM以及多动症症状与正常行为优势与劣势（SWAN）量表中母亲报告和自我报告的注意力不集中及多动冲动特质测量值，来研究这种关系在多大程度上归因于共享的遗传因素。我们的样本包括健康的年轻成年双胞胎（N = 627（63%为女性），包括95对同卵双胞胎和144对异卵双胞胎，平均年龄22岁，其母亲报告了SWAN；N = 725（58%为女性），包括101对同卵双胞胎和156对异卵双胞胎，平均年龄25岁，自我报告了SWAN）。这种设计使我们能够区分头部运动与多动症量表之间关联中的遗传因素和环境因素。HM与母亲报告的注意力不集中（r = 0.17，p值 = 7.4E - 5）和多动冲动（r = 0.16，p值 = 2.9E - 4）呈中度相关，这些关联主要归因于多效性遗传因素，遗传相关性[95%置信区间]为rg = 0.24 [0.02, 0.43]和rg = 0.23 [0.07, 0.39]。自我报告与HM之间的相关性不显著，这主要是由于测量误差增加所致。这些结果表明，在多动症的神经影像学研究中将HM视为干扰协变量可能会降低检测组间效应的效能，因为HM与注意力不集中或多动冲动之间独立性的隐含假设是不合理的。这一发现对多动症的fMRI研究具有问题性影响，因为已知不应用HM校正会增加假阳性的可能性。我们讨论了两种规避此问题的方法：审查静息态fMRI扫描中受运动污染的帧，或明确建立HM与注意力不集中或多动冲动之间的关系模型。
