Network Processes and Heavy Marijuana Use among Homeless Youth

Objectives:  Public health has become increasingly interested in how population-level network processes impact substance using behavior (e.g. smoking overtime).  Such data rarely exist among high risk populations such as homeless youth (HY) despite the overwhelming evidence that HY report more substance use and abuse than housed youth.  The transience of such populations increases the complexity of this research.   We examine “heavy” marijuana use (at least daily) among HY in population-level network data overtime.

Methods:   Network data were collected from two populations of RHY recruited from drop-in centers in Los Angeles, every six months for one year (Network 1: n= 237, 263, 312; Network 2: n=138, 149, 131). For each panel, a sociomatrix was generated based on youth nominating other youth in the sample.  K-core defined peripheral/non-peripheral network positions and degree centrality defined network prominence; logistic regression assessed associations with heavy marijuana use.

Results: Approximately 60% of the membership of network 1 and 85% of the membership of network 2 changed between panels. More central actors reported more heavy marijuana use in all panels except one in network 2.  Peripheral position was associated with reduced use in all panels except one in network 2.

Conclusions: For HY, network membership is highly transient overtime and yet central actors consistently report more heavy marijuana use and peripheral positions less. These results suggest that in transient, high-risk populations, social influence processes may be less important that selection processes.  Heavy marijuana use appears to be important to the construction and reconstruction of these networks overtime.