The interdependence of cigarette, alcohol, and marijuana use in the context of school-based social networks

The concurrent or sequential usage of multiple substances during adolescence is a serious public health problem. Given the importance of understanding interdependence in substance use during adolescence, the purpose of this study is to examine the co-evolution of cigarette smoking, alcohol, and marijuana use within the ever-changing landscape of adolescent friendship networks, which are a primary socialization context for adolescent substance use. Utilizing Stochastic Actor-Based models, we examine how multiple simultaneous social processes co-evolve with adolescent smoking, drinking, and marijuana use within adolescent friendship networks using two school samples from early waves of the National Longitudinal Study of Adolescent to Adult Health (Add Health). We also estimate two separate models examining the effects from using one substance to the initiation and cessation of other substances for each sample. Based on the initial model results, we simulate the model forward in time by turning off one key effect in the estimated model at a time, and observe how the distribution of use of each substance changes. We find evidence of a unilateral causal relationship from marijuana use to subsequent smoking and drinking behaviors, resulting in the initiation of drinking behavior. Marijuana use is also associated with smoking initiation in a school with a low substance use level, and smoking cessation in a school with a high substance use level. In addition, in a simulation model excluding the effect from marijuana use to smoking and drinking behavior, the number of smokers and drinkers decreases precipitously. Overall, our findings indicate some evidence of sequential drug use, as marijuana use increased subsequent smoking and drinking behavior and indicate that an adolescent's level of marijuana use affects the initiation and continuation of smoking and drinking.

青少年时期同时或先后使用多种物质，是一项严峻的公共卫生问题。鉴于明晰青少年物质使用间相互依存关系的重要性，本研究旨在探究青少年友谊网络这一青少年物质使用的核心社会化情境中，卷烟使用、饮酒与大麻使用的协同演化过程——而青少年友谊网络本身正处于持续动态变化之中。本研究依托随机行动者模型（Stochastic Actor-Based Models），使用来自全国青少年至成人健康纵向研究（National Longitudinal Study of Adolescent to Adult Health，简称Add Health）早期追踪波次的两所学校样本，探究青少年友谊网络中多重同步社会过程与青少年吸烟、饮酒及大麻使用的协同演化机制。此外，针对每一份样本，我们还分别构建了两套独立模型，用以分析某一种物质的使用对其他物质的起始使用与戒断行为的影响。基于初始模型的结果，我们通过依次关闭已估计模型中的某一项关键效应，对模型进行时序向前模拟，并观测各类物质的使用分布如何变化。研究发现，大麻使用对后续吸烟与饮酒行为存在单向因果关联，可推动饮酒行为的起始。此外，在物质使用水平较低的学校中，大麻使用与吸烟起始行为存在相关性；而在物质使用水平较高的学校中，大麻使用则与吸烟戒断行为相关联。此外，在排除大麻使用对吸烟与饮酒行为影响的模拟模型中，吸烟者与饮酒者的数量均出现急剧下降。综合来看，本研究结果为序列性药物使用模式提供了佐证：大麻使用可推动后续的吸烟与饮酒行为，且青少年的大麻使用水平会影响吸烟与饮酒行为的起始与持续进行。