The association between having a sibling diagnosed with alcohol use disorder (AUD) and risk for suicide attempt may be attributable to shared genetic liability between AUD and suicidal behavior, effects of environmental exposure to a sibling’s AUD, or both. To distinguish between these alternatives, we conducted a series of Cox regression models using data derived from Swedish population-based registers with national coverage. Among full sibling pairs (656,807 males and 607,096 females), we found that, even after we accounted for the proband’s AUD status, the proband’s risk for suicide attempt was significantly elevated when the proband’s sibling was affected by AUD. Furthermore, the proband’s risk for suicide attempt was consistently higher when the sibling’s AUD registration had occurred more recently. Our findings provide evidence for exposure to sibling AUD as an environmental risk factor for suicide attempt and suggest that clinical outreach may be warranted following a sibling’s diagnosis with AUD.

兄弟姐妹被诊断患有酒精使用障碍 (AUD) 与自杀企图风险之间的关联可能归因于 AUD 与自杀行为之间的共同遗传倾向、环境暴露对兄弟姐妹 AUD 的影响，或两者兼而有之。为了区分这些替代方案，我们使用来自覆盖全国的瑞典人口登记册的数据进行了一系列 Cox 回归模型。在全兄弟姐妹对（656,807 名男性和 607,096 名女性）中，我们发现，即使我们考虑了先证者的 AUD 状态，当先证者的兄弟姐妹受到 AUD 影响时，先证者自杀未遂的风险也会显着升高。此外，当先证者的 AUD 登记时间较晚时，先证者自杀未遂的风险始终较高。我们的研究结果提供了证据，证明接触兄弟姐妹 AUD 是自杀企图的环境危险因素，并表明在兄弟姐妹诊断出患有 AUD 后可能需要进行临床外展。