SIMUSE: an agent-based simulation on recreational polydrug users

This paper describes an attempt to capture individual and social characteristics of polydrug use in a generic agent-based model called SimUse. We consider poly-drug use and its social context as a complex adaptive system and use a generative framework to create an iterative dialogue between observations, theoretical constructs and computer simulations. This iterative process allows us, through abductive reasoning, to progressively build an ontological representation of the different factors influencing poly-drug use patterns. The ontological structure includes three levels of influence: neurological effects of drugs; physiological and social responses of users; and peer influences in a given societal context. First we introduce our generative framework; then, we describe the overall structure of the model before detailing important aspects of SimUse: (1) the neurological engine and its physiological consequences; (2) the behavioural patterns associated with different drug use stages;and (3) the social influences amongst peer networks. We conclude with an example of how the model reacts to external shocks (such as drug availability or disruption of the drug dealing market) and their consequences for decision-makers. Key-words: polysubstance use, agent-based model, social simulation, sociology, deviance.