To establish a trait-dispositional variable as an indicator of liability for the development of substance use disorders (SUDs), the trait must share heritable variance with SUDs and its association should not be primarily attributable to a direct impact of SUDs on characteristics that define the trait. The current work applied a co-twin control (CTC) modeling approach to data from two monozygotic twin samples to investigate the degree to which different measures of trait-impulsiveness represent indicants of vulnerability to SUDs (liability indicators), or outcomes or concomitants of SUDs (exposure indicators). The Five Factor Model (FFM) trait of conscientiousness was assessed via self-report, and a counterpart neurobehavioral trait of disinhibition was assessed both through self-report and using self-report and brain response measures combined. FFM trait data were available for one twin sample (N = 298); data for variants of P3 brain response were available along with a scale measure of disinhibition in the other (N = 258). CTC analyses revealed only an exposure effect of SUD symptomatology on FFM conscientiousness, indicating that this self-report assessed trait does not index liability for SUDs. By contrast, the disinhibition scale measure showed pronounced liability and weaker exposure-based associations with SUDs – and when quantified using scale scores together with P3 brain response, the exposure-based association was eliminated, such that this disinhibition measure related to SUD symptoms exclusively as a function of liability influences. These findings highlight a distinct advantage of quantifying traits in neurobehavioral terms – namely, the capacity to effectively index dispositional liability for psychopathological outcomes.

要建立一个特质倾向变量作为物质使用障碍 (SUD) 发展的责任指标，该特质必须与 SUD 共享遗传变异，并且其关联不应主要归因于 SUD 对定义物质使用障碍的特征的直接影响特征。当前的工作对来自两个单卵双胞胎样本的数据应用了联合双胞胎控制 (CTC) 建模方法，以研究不同的性状冲动度量代表对 SUD 的脆弱性指标（责任指标）或 SUD 的结果或伴随物的程度（曝光指标）。五因素模型 (FFM) 的尽责性特征通过自我报告进行评估，并且通过自我报告和结合使用自我报告和大脑反应措施来评估相应的去抑制神经行为特征。N  = 298); P3 脑反应变体的数据以及另一种去抑制的量表测量（N = 258）。CTC 分析仅显示 SUD 症状学对 FFM 尽责性的暴露影响，表明这种自我报告评估的特征并不能指示 SUD 的责任。相比之下，去抑制量表测量显示出明显的责任和与 SUD 的基于暴露的较弱关联——当使用量表评分和 P3 大脑反应进行量化时，基于暴露的关联被消除，因此这种去抑制测量仅与 SUD 症状相关责任影响的函数。这些发现突出了在神经行为方面量化特征的一个明显优势——即有效地索引心理病理结果的倾向责任的能力。