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Cannabis Use Does Not Impair Lung Functioning: A Study from the Journal of the American Medical Association (JAMA, Dec 2011)

Don’t inhale this headline!

A 2 decade study of moderate pot smokers conducted by the US government narrowly focused on effects of pot smoking on lung functioning. The study revealed that such moderate use does not contribute to COPD (Chronic Pulmonary Obstructive Disease). In some cases they discovered that some of the 5,000 participants had some improvement in pulmonary functioning.

This study will certainly be a banner headline for proponents of legalization of marijuana touting the supposed health benefits of cannabis, yet there’s more to the story, a lot more.

This study did not look at the carcinogenic effects that smoking any type of substance has on the human body – they did not report on cancer, they did not report on the neurological impact that smoking has on the body and the sample of heavy smokers included in the study was very small proportionate to the total participants.

What happens when we breathe deeply is an exercise in keeping our airways open and healthy. Adding smoke does irritate the air passages – this was noted in the study yet downplayed by the national media outlets. As noted by Stefan Kertesz, MD, an assistant professor of medicine at the University of Alabama at Birmingham, this study was “not about the Cheech and Chongs” of this world. Although the study noted that lung capacity improved over time with light marijuana users, that improvement was negligible – equivalent to a few tablespoons of air.

Quoting from the article published in Journal of the American Medical Association (JAMA, December 2011) “Marijuana smoke contains many of the same constituents as tobacco smoke, but whether it has similar adverse effects on pulmonary function is unclear.” Dr Doug Davies, MD, a specialist in tobacco use, made note that superheated smoke introduced into the lungs has medical ramifications that are undisputedly linked to cancer, brain damage and impaired physical functioning. Dr Davies underscored that substances ingested via smoke such as tobacco, cannabis, ‘Spice,’ methamphetamines are mood altering and potentially addictive and life threatening/life shortening.

Recent articles in JAMA note that cannabis impairs cognitive functioning, cannabis smoke contributes to periodontal disease among young adults and for heavy cannabis smokers there’s a correlation with psychotic episodes.

There will be an enduring discussion about the safe use and unsafe abuse of cannabis – it certainly is not an evil drug ravaging the body and minds of our youth, but it isn’t benign and it’s medicinal value is quite narrow. Let’s watch out for media hype that simply blows smoke because it will create a buzz on the social media networks.


Association Between Marijuana Exposure and Pulmonary Function Over 20 Years

Mark J. Pletcher, MD, MPH; Eric Vittinghoff, PhD; Ravi Kalhan, MD, MS; Joshua Richman, MD, PhD; Monika Safford, MD; Stephen Sidney, MD, MPH; Feng Lin, MS; Stefan Kertesz, MD. JAMA. 2012;307(2):173181.

Univ of Florida, Dept of Psychiatry, Dr Doug Davies

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