Los Angeles, CA: Chronic cannabis smokers who cease using the substance report experiencing fewer adverse respiratory symptoms compared to those who continue their use, according to a longitudinal cohort study to be published in COPD, the Journal of Chronic Obstructive Pulmonary Disease.
Investigators at the David Geffen School of Medicine at the University of California, Los Angeles (UCLA) assessed the long-term impact of cannabis smoking on symptoms of chronic bronchitis. Researchers reported that cannabis smoking "significantly increased" the likelihood of having chronic bronchitis compared to both never smokers and former smokers. However, former smokers were "no more likely to have chronic respiratory symptoms at follow-up than never smokers."
Authors concluded: "Findings from this longitudinal cohort study indicate that continuing smoking of marijuana, either alone or with tobacco, is associated with a net persistence of symptoms of chronic bronchitis, similar to the findings in continuing smokers of tobacco alone. In contrast, complete cessation of smoking by former habitual smokers of either marijuana or tobacco alone or of marijuana plus tobacco was accompanied by substantial declines in chronic respiratory symptoms. … These findings provide, for the first time, documented evidence of the benefit of marijuana smoking cessation with respect to the resolution of pre-existing symptoms of chronic bronchitis."
Separate studies have previously linked long-term marijuana smoking to an increased risk of bronchitis, cough, phlegm, and wheezing.
A 2007 study published in the Harm Reduction Journal found that cannabis consumers who vaporized the substance reported fewer adverse respiratory symptoms compared to those who smoked it.
For more information, please contact Paul Armentano, NORML Deputy Director, at: paul@norml.org. Full text of the study, "Impact of changes in regular users of marijuana use and/or tobacco on chronic bronchitis," will appear in COPD.