**6. Acknowledgments**

This work was conducted within the clinical research project "Dependence Network 1994- 2000". The Network received the support of the Institut National de la Santé et de la Recherche Médicale (Réseau Inserm n° 494013) and of the Fondation de France. The promoter of the project is the Institut Mutualiste Montsouris. All the centres participating in the project should be acknowledged: Department of Adolescent and Young Adult Psychiatry, Institut Mutualiste Montsouris, Paris, France ; Department of Psychiatry, Hôpital Pinel, Amiens, France ; Department of Psychiatry, Hôpital Saint-Jacques, Nantes, France ; Department of Psychiatry Hôpital Universitaire, Besançon, France ; Department of Child and Adolescent Psychiatry, SUPEA, Lausanne, Switzerland.
