Substance use disorder (SUD) often co‐occur at high prevalence with other psychiatric conditions. Among them, attention‐deficit and hyperactivity disorder (ADHD) is present in almost one out of every four subjects with SUD and is associated with higher severity, more frequent polysubstance dependence and increased risk for other mental health problems in SUD patients. Despite studies suggesting a genetic basis in the co‐occurrence of these two conditions, the genetic factors involved in the joint development of both disorders and the mechanisms mediating these causal relationships are still unknown. In this study, we tested whether the genetic liability to five SUD‐related phenotypes share a common background in the general population and clinically diagnosed ADHD individuals from an in‐house sample of 989 subjects and further explored the genetic overlap and the causal relationship between ADHD and SUD using pre‐existing GWAS datasets. Our results confirm a common genetic background between ADHD and SUD and support the current literature on the causal effect of the liability to ADHD on the risk for SUD. We added novel findings on the effect of the liability of lifetime cannabis use on ADHD and found evidence of shared genetic background underlying SUD in general population and in ADHD, at least for lifetime cannabis use, alcohol dependence and smoking initiation. These findings are in agreement with the high comorbidity observed between ADHD and SUD and highlight the need to control for substance use in ADHD and to screen for ADHD comorbidity in all SUD patients to provide optimal clinical interventions.

中文翻译：

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物质使用障碍与注意力缺陷多动障碍之间的遗传重叠和因果关系

物质使用障碍 (SUD) 通常与其他精神疾病同时发生。其中，注意力缺陷和多动障碍 (ADHD) 出现在几乎四分之一的 SUD 受试者中，并且与 SUD 患者的严重程度更高、多种物质依赖更频繁以及其他心理健康问题的风险增加有关。尽管研究表明这两种疾病同时发生有遗传基础，但参与这两种疾病共同发展的遗传因素和介导这些因果关系的机制仍然未知。在这项研究中，我们测试了 5 种 SUD 相关表型的遗传倾向是否在普通人群和来自 989 名受试者的内部样本的临床诊断 ADHD 个体中具有共同背景，并进一步探讨了 ADHD 和 SUD 之间的遗传重叠和因果关系。 -现有的GWAS数据集。我们的结果证实了 ADHD 和 SUD 之间的共同遗传背景，并支持当前关于 ADHD 的责任对 SUD 风险的因果影响的文献。我们添加了关于终生使用大麻对 ADHD 的影响的新发现，并发现了普通人群和 ADHD 中 SUD 潜在共同遗传背景的证据，至少对于终生使用大麻、酒精依赖和开始吸烟而言。