CANNABIS AND MENTAL HEALTH: Responses to the Emerging Evidence SUMMARY

review of the effectiveness of national and international drug policies. The aim of this programme of research and analysis is to assemble and disseminate material that supports the rational consideration of complex drug policy issues, and leads to a more effective management of the widespread use of psychoactive substances in the future. According to United Nations fi gures, cannabis is the most widely used of the psychoactive substances that are prohibited under the UN Drug Control Conventions. Unlike heroin and cocaine, which are produced in relatively concentrated areas of the world, and whose levels of con-sumption vary widely across different countries and regions, cannabis is now widely cultivated and consumed across all continents. Furthermore, the use of cannabis or its derivatives is embedded within many traditional cultures, or has become culturally accepted as a drug of choice by a signifi cant proportion of the population in many countries. Not readily associated with the most visible harms arising from drug use, cannabis is seen by many as a relatively benign drug. Indeed, many use it for its medical, therapeutic, social and spiritual benefi ts. However, there is increas-ing apprehension about its possible role in triggering or exacerbating mental health problems, or of inhibiting young people’s emotional or social development. Cannabis therefore presents unique challenges to the international control system that need to be confronted by policy makers – indeed, the UN Drugs Control Chief Antonio Maria Costa acknowledged, in his closing speech at the 2006 Commission on Narcotic Drugs, that cannabis represents the main weak point in the system that he oversees