An economic analysis of addictive behaviors and drug policy in France.

Summary The objective of this thesis, composed of six theoretical and empirical articles, is to identify the most effective ways to encourage drug users - legal and illegal - to adopt healthier habits by reducing their consumption. The first step is to assess the magnitude of the problem by measuring the social cost of drugs (tobacco, alcohol and illicit drugs) in France in 2010. Despite massive prevention campaigns, the worrying proportion of substance users, but above all, the high proportion of people declaring that they regret having started their consumption, lead us to reconsider the traditional paradigm of rational addiction, which is the basis of most research on addictions in economics. On the contrary, admitting a cognitive polyphasy in individuals with, on the one hand, a planner making his decisions as rationally as his cognitive capacities allow him to do so, and on the other hand, a doer seeking only to reach immediate satisfaction, allows us to build an original theoretical framework taking into account the short-term and long-term emotions of the agents, as well as the role of social norms on their addictive consumption decisions. The model built from this framework, as well as its analysis on a panel of French smokers, allows us to propose innovative policies aiming at reinforcing the motivation of individuals to stop their addictive consumption by reducing their self-control problems, by acting on their perception of the dangers linked to drug use, and by targeting a normative change of their consumption. Most of these recommendations are not applicable to illegal drugs because of their legal status. As a result, the only lever for defining a strategy to reduce the costs involved is the study of legal alternatives to the penalization of consumption, particularly with regard to cannabis, which is the most widely used illicit drug in France, but also in most developed countries.