School of Pharmacy, Memorial University of Newfoundland, St. John's, Canada.
Addiction. 2022 Oct;117(10):2673-2682. doi: 10.1111/add.15943. Epub 2022 May 20.
Existing research on mental health comorbidities of youth e-cigarette use is subject to confounding bias and reverse causality. This study aimed to measure the effects of e-cigarette use on youth mental health, using e-cigarette minimum legal age (MLA) law in Canada as a natural experiment.
We used difference-in-differences (DD), difference-in-differences-in-differences (DDD) and two-sample instrumental variables (TSIV) methods.
Data were from nationally representative Canadian Community Health Surveys 2008-2019 and Canadian Student Tobacco Alcohol and Drugs Surveys 2008-2019.
The study sample comprised of respondents aged 15 to 18 (in DD analysis; n = 33 858) and aged 15 to 24 (in DDD analysis; n = 78 689).
Primary outcomes were self-reported mood disorders and anxiety disorders. Secondary outcomes were cannabis use, illicit drug use, cigarette use and strength of peer relationships at schools.
After the e-cigarette MLA laws, risks of mood disorders declined by 1.9 percentage points (95% CI, 0.0-3.8; P = 0.05) in the DD analysis and by 2.6 percentage points (95% CI, 0.2-5.0; P = 0.03) in the DDD analysis. For anxiety disorders, while the DD estimate was negative but imprecisely estimated, the MLA law reduced risks of anxiety disorder by 3.6 percentage points (95% CI, 0.9-6.2; P = 0.01) in the DDD analysis. Youths in provinces with MLA laws were also less likely to report cannabis use and illicit drug use and more likely to feel being part of schools. TSIV analysis indicates that youth e-cigarette use increased the likelihood of mood and anxiety disorders by 44% and 37%, respectively.
In Canada, the e-cigarette minimum legal age law appears to have reduced risks of mood and anxiety disorders, lowered substance use and improved peer relationships at schools. Combined with previous evidence of lower e-cigarette use following the minimum legal age law, our findings indicate that youth e-cigarette use increases risks of mood and anxiety disorders.
现有关于青少年电子烟使用与心理健康共病的研究受到混杂偏倚和反向因果关系的影响。本研究旨在利用加拿大电子烟最低法定年龄（MLA）法作为自然实验，衡量电子烟使用对青少年心理健康的影响。
我们使用了差分法（DD）、差分-差分-差分法（DDD）和两样本工具变量法（TSIV）。
数据来自全国代表性的加拿大社区健康调查 2008-2019 年和加拿大学生烟草酒精和毒品调查 2008-2019 年。
研究样本包括年龄在 15 至 18 岁的受访者（在 DD 分析中；n=33858）和年龄在 15 至 24 岁的受访者（在 DDD 分析中；n=78689）。
主要结果是自我报告的情绪障碍和焦虑障碍。次要结果是大麻使用、非法药物使用、香烟使用以及学校同伴关系的强度。
在电子烟 MLA 法颁布后，DD 分析中情绪障碍的风险下降了 1.9 个百分点（95%CI，0.0-3.8；P=0.05），DDD 分析中下降了 2.6 个百分点（95%CI，0.2-5.0；P=0.03）。对于焦虑障碍，虽然 DD 估计值为负，但估计值不精确，DDD 分析表明，MLA 法使焦虑障碍的风险降低了 3.6 个百分点（95%CI，0.9-6.2；P=0.01）。在有 MLA 法的省份，青少年也不太可能报告大麻使用和非法药物使用，而更有可能觉得自己是学校的一部分。TSIV 分析表明，青少年电子烟使用分别使情绪和焦虑障碍的可能性增加了 44%和 37%。
在加拿大，电子烟最低法定年龄法似乎降低了情绪和焦虑障碍的风险，降低了物质使用，改善了学校同伴关系。结合最低法定年龄法颁布后电子烟使用量下降的先前证据，我们的研究结果表明，青少年电子烟使用会增加情绪和焦虑障碍的风险。
