The Ragnar Frisch Centre for Economic Research, N-0349 Oslo, Norway.
Proc Natl Acad Sci U S A. 2013 Mar 12;110(11):4251-4. doi: 10.1073/pnas.1215678110. Epub 2013 Jan 14.
Does cannabis use have substantial and permanent effects on neuropsychological functioning? Renewed and intense attention to the issue has followed recent research on the Dunedin cohort, which found a positive association between, on the one hand, adolescent-onset cannabis use and dependence and, on the other hand, a decline in IQ from childhood to adulthood [Meier et al. (2012) Proc Natl Acad Sci USA 109(40):E2657-E2664]. The association is given a causal interpretation by the authors, but existing research suggests an alternative confounding model based on time-varying effects of socioeconomic status on IQ. A simulation of the confounding model reproduces the reported associations from the Dunedin cohort, suggesting that the causal effects estimated in Meier et al. are likely to be overestimates, and that the true effect could be zero. Further analyses of the Dunedin cohort are proposed to distinguish between the competing interpretations. Although it would be too strong to say that the results have been discredited, the methodology is flawed and the causal inference drawn from the results premature.
大麻使用是否对神经心理学功能有实质性和永久性的影响？最近对达尼丁队列的研究重新引起了人们对这个问题的强烈关注，该研究发现，一方面，青少年期开始使用大麻和依赖大麻，另一方面，从儿童期到成年期，智商下降[Meier 等人（2012）美国国家科学院院刊 109（40）：E2657-E2664]。作者对这种关联进行了因果解释，但现有研究提出了一种基于社会经济地位对智商的时变影响的替代混淆模型。对混淆模型的模拟再现了来自达尼丁队列的报告关联，表明 Meier 等人估计的因果效应可能被高估，而真实效应可能为零。建议对达尼丁队列进行进一步分析，以区分相互竞争的解释。尽管说这些结果已经名誉扫地还为时过早，但该方法存在缺陷，从结果中得出的因果推论还不成熟。
