PERSONAL USE ONLY Causal relationship between cannabis use and psychotic symptoms or depression. Should we wait and see? A public health perspective Jokin de Irala 1 , Miguel Ruiz-Canela 2 , Miguel Ángel Martínez-González 1 1 Department of Preventive Medicine and Public Health. Faculty of Medicine, University of Navarra, Spain 2 Department of Biomedical Humanities. Faculty of Medicine University of Navarra, Spain Source of support: Self financing Summary The aim of this paper is to update and critically analyze the public health relevance of available evidence about the causal relationship between cannabis use and psychosis or depression. There are conflicting views about this causal relationship. Two systematic reviews of existing evidence as- sessed this association and were published in 2004, but they came to different conclusions. From a public health perspective a thorough discussion is warranted before attributing any observed ef- fect to potential biases. First, the impact of residual confounding in this causal relationship is dis- cussed. We consider that the attenuation of estimates after controlling for confounding factors cannot be interpreted as evidence to support the claim that residual confounding fully explains this link. Secondly, taking into account the results of recent studies, the time-sequence and dose- response criteria of causality are discussed. The fact that unreported or subclinical psychological problems might have preceded and precipitated cannabis use is a very unlikely explanation when the cannabis-psychosis outcome link is assessed from different longitudinal studies. And finally, available evidence is interpreted with a broad view of public health and by taking into account the precautionary principle. We therefore provide reasons to support the case that stronger preven- tive actions against cannabis are still required in order to avoid the potential increased incidence of psychosocial health problems in the future. key words: marijuana smoking • cannabis • psychosis • drugs • depression • public health Full-text PDF: http://www.medscimonit.com/fulltxt.php?IDMAN=7188 Word count: 2467 Tables: — Figures: — References: 21 Author’s address: Miguel Ruiz-Canela, Ph.D., Departamento de Humanidades Biomédicas, Facultad de Medicina, Universidad de Navarra, Irunlarrea 1, 31080 Pamplona, Navarra, Spain, e-mail: mcanela@unav.es Received: 2005.03.10 Accepted: 2005.05.19 Published: 2005.12.01 RA355 Review Article WWW. MEDSCIMONIT.COM © Med Sci Monit, 2005; 11(12): RA355-358 PMID: 16319805 RA Current Contents/Clinical Medicine • SCI Expanded • ISI Alerting System • Index Medicus/MEDLINE • EMBASE/Excerpta Medica • Chemical Abstracts • Index Copernicus Electronic PDF security powered by ISL-science.com opy is for personal use only - distribution prohibited. This copy is for personal use only - distribution prohibited. This copy is for personal use only - distribution prohibited. This copy is for personal use only - distribution prohibited. This copy is for personal use only - distribu