SMOKING

Effects of cannabis on pulmonary structure, function and symptoms

Sarah Aldington¹, Mathew Williams¹, Mike Nowitz², Mark Weatherall³, Alison Pritchard¹, Amanda McNaughton¹, Geoffrey Robinson¹, Richard Beasley¹

¹ Medical Research Institute of New Zealand, Wellington, New Zealand
² Pacific Radiology, Wakefield Hospital, Wellington, and Wellington School of Medicine and Health Sciences, Wellington, New Zealand
³ Wellington School of Medicine and Health Sciences, Wellington, New Zealand

Professor Richard Beasley, Medical Research Institute of New Zealand, P O Box 10055, Wellington 6143, New Zealand; Richard.Beasley{at}mrinz.ac.nz

Background: Cannabis is the most widely used illegal drug worldwide. Long-term use of cannabis is known to cause chronic bronchitis and airflow obstruction, but the prevalence of macroscopic emphysema, the dose-response relationship and the dose equivalence of cannabis with tobacco has not been determined.

Methods: A convenience sample of adults from the Greater Wellington region was recruited into four smoking groups: cannabis only, tobacco only, combined cannabis and tobacco and non-smokers of either substance. Their respiratory status was assessed using high-resolution CT (HRCT) scanning, pulmonary function tests and a respiratory and smoking questionnaire. Associations between respiratory status and cannabis use were examined by analysis of covariance and logistic regression.

Results: 339 subjects were recruited into the four groups. A dose-response relationship was found between cannabis smoking and reduced forced expiratory volume in 1 s to forced vital capacity ratio and specific airways conductance, and increased total lung capacity. For measures of airflow obstruction, one cannabis joint had a similar effect to 2.5–5 tobacco cigarettes. Cannabis smoking was associated with decreased lung density on HRCT scans. Macroscopic emphysema was detected in 1/75 (1.3%), 15/92 (16.3%), 17/91 (18.9%) and 0/81 subjects in the cannabis only, combined cannabis and tobacco, tobacco alone and non-smoking groups, respectively.

Conclusions: Smoking cannabis was associated with a dose-related impairment of large airways function resulting in airflow obstruction and hyperinflation. In contrast, cannabis smoking was seldom associated with macroscopic emphysema. The 1:2.5–5 dose equivalence between cannabis joints and tobacco cigarettes for adverse effects on lung function is of major public health significance.

Abbreviations: COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 s; FRC, functional residual capacity; FVC, forced vital capacity; MMEF, maximum mid-expiratory flow; RV, residual volume; sGaw, specific airways conductance; SVC, slow vital capacity; THC, tetrahydrocannabinol; TLC, total lung capacity; TLCO, carbon monoxide transfer factor

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

Relevant Article

Cannabis and the lung

Peter Lange
Thorax 2007 62: 1036-1037. [Extract] [Full Text] [PDF]

This article has been cited by other articles:

• Reece, A. S. (2009). Severe multisystem dysfunction in a case of high level exposure to smoked cannabis. BMJ Case Reports 2009: bcr0820080798-bcr0820080798 [Abstract] [Full Text]  
• Pinot, D., Breen, D., Peloni, J-M., Gaubert, J-Y., Dutau, H., Vervloet, D. (2009). An incidental finding in a 34-year-old male under investigation for haemoptysis. Eur Respir J 33: 1227-1229 [Full Text]  
• Tashkin, D. P. (2009). Does smoking marijuana increase the risk of chronic obstructive pulmonary disease?. CMAJ 180: 797-798 [Full Text]  
• Tan, W. C., Lo, C., Jong, A., Xing, L., FitzGerald, M. J., Vollmer, W. M., Buist, S. A., Sin, D. D., for the Vancouver Burden of Obstructive Lung Disea, (2009). Marijuana and chronic obstructive lung disease: a population-based study. CMAJ 180: 814-820 [Abstract] [Full Text]  
• (2009). ANSWER. Thorax 64: 74-74 [Full Text]  
• Agrawal, A., Pergadia, M. L., Saccone, S. F., Lynskey, M. T., Wang, J. C., Martin, N. G., Statham, D., Henders, A., Campbell, M., Garcia, R., Broms, U., Todd, R. D., Goate, A. M., Rice, J., Kaprio, J., Heath, A. C., Montgomery, G. W., Madden, P. A. F. (2008). An Autosomal Linkage Scan for Cannabis Use Disorders in the Nicotine Addiction Genetics Project. Arch Gen Psychiatry 65: 713-721 [Abstract] [Full Text]  
• Thomson, W. M., Poulton, R., Broadbent, J. M., Moffitt, T. E., Caspi, A., Beck, J. D., Welch, D., Hancox, R. J. (2008). Cannabis Smoking and Periodontal Disease Among Young Adults. JAMA 299: 525-531 [Abstract] [Full Text]  
• Lange, P. (2007). Cannabis and the lung. Thorax 62: 1036-1037 [Full Text]