Department of Psychology, Boston College , Chestnut Hill, MA , USA.
Department of Psychology, Center for Studies in Behavioral Neurobiology, Concordia University , Montreal, QC , Canada.
Front Psychiatry. 2014 Jun 24;5:70. doi: 10.3389/fpsyt.2014.00070. eCollection 2014.
Years-of-school is negatively correlated with illicit drug use. However, educational attainment is positively correlated with IQ and negatively correlated with impulsivity, two traits that are also correlated with drug use. Thus, the negative correlation between education and drug use may reflect the correlates of schooling, not schooling itself. To help disentangle these relations we obtained measures of working memory, simple memory, IQ, disposition (impulsivity and psychiatric status), years-of-school and frequency of illicit and licit drug use in methadone clinic and community drug users. We found strong zero-order correlations between all measures, including IQ, impulsivity, years-of-school, psychiatric symptoms, and drug use. However, multiple regression analyses revealed a different picture. The significant predictors of illicit drug use were gender, involvement in a methadone clinic, and years-of-school. That is, psychiatric symptoms, impulsivity, cognition, and IQ no longer predicted illicit drug use in the multiple regression analyses. Moreover, high risk subjects (low IQ and/or high impulsivity) who spent 14 or more years in school used stimulants and opiates less than did low risk subjects who had spent <14 years in school. Smoking and drinking had a different correlational structure. IQ and years-of-school predicted whether someone ever became a smoker, whereas impulsivity predicted the frequency of drinking bouts, but years-of-school did not. Many subjects reported no use of one or more drugs, resulting in a large number of "zeroes" in the data sets. Cragg's Double-Hurdle regression method proved the best approach for dealing with this problem. To our knowledge, this is the first report to show that years-of-school predicts lower levels of illicit drug use after controlling for IQ and impulsivity. This paper also highlights the advantages of Double-Hurdle regression methods for analyzing the correlates of drug use in community samples.
受教育年限与非法药物使用呈负相关。然而，教育程度与智商呈正相关，与冲动性呈负相关，而这两个特征也与药物使用相关。因此，教育与药物使用之间的负相关可能反映了与受教育程度相关的因素，而不是受教育程度本身。为了帮助理清这些关系，我们在美沙酮诊所和社区药物使用者中获得了工作记忆、简单记忆、智商、性格（冲动和精神状态）、受教育年限以及非法和合法药物使用频率的测量值。我们发现所有测量值之间都存在很强的零阶相关性，包括智商、冲动性、受教育年限、精神症状和药物使用。然而，多元回归分析显示出不同的情况。非法药物使用的显著预测因子是性别、参与美沙酮诊所以及受教育年限。也就是说，在多元回归分析中，精神症状、冲动性、认知和智商不再预测非法药物使用。此外，花费 14 年或以上时间接受教育的高风险受试者（低智商和/或高冲动性）使用兴奋剂和阿片类药物的频率低于受教育年限少于 14 年的低风险受试者。吸烟和饮酒具有不同的相关结构。智商和受教育年限预测了某人是否会成为吸烟者，而冲动性则预测了饮酒次数，但受教育年限没有。许多受试者报告没有使用一种或多种药物，导致数据集中有大量“零”值。Cragg 的双重障碍回归方法被证明是处理这个问题的最佳方法。据我们所知，这是第一项报告表明，在控制智商和冲动性后，受教育年限可以预测非法药物使用水平较低。本文还强调了双重障碍回归方法在分析社区样本中药物使用相关性方面的优势。
