School of Psychology, National University of Ireland, Galway, Ireland.
J Adolesc. 2011 Aug;34(4):665-73. doi: 10.1016/j.adolescence.2010.09.006. Epub 2010 Oct 22.
Using academic achievement as the key outcome variable, 7377 Icelandic adolescents were surveyed for cigarette smoking, alcohol use, daytime sleepiness, caffeine use, and potential confounders. Structural equation modeling (SEM) was used to examine direct and indirect effects of measured and latent variables in two models: the first with caffeine excluded and the second with caffeine included. A substantial proportion of variance in academic achievement, which might otherwise have been attributed to the harmful effects of cigarette smoking and alcohol use, was found to be attributable to caffeine. Evidence was obtained that daytime sleepiness, which was found to be independently associated with usage of licit substances (nicotine and alcohol) and caffeine, may be an important mediator of the negative impact of those substances on academic achievement. Findings suggest the importance of including measurements of caffeine consumption in future studies of adolescent substance use.
以学业成绩为关键结果变量，对 7377 名冰岛青少年进行了吸烟、饮酒、日间嗜睡、咖啡因使用以及潜在混杂因素的调查。结构方程模型（SEM）用于在两个模型中检验测量和潜在变量的直接和间接影响：第一个模型排除了咖啡因，第二个模型包括了咖啡因。学业成绩的很大一部分差异，原本可能归因于吸烟和饮酒的有害影响，现在发现归因于咖啡因。有证据表明，日间嗜睡与合法物质（尼古丁和酒精）和咖啡因的使用独立相关，它可能是这些物质对学业成绩产生负面影响的一个重要中介因素。研究结果表明，在未来青少年物质使用的研究中，纳入咖啡因消费测量的重要性。
