In a recent Radiology journal study, researchers report chest computed tomography (CT) findings that the lungs of marijuana smokers exhibit more significant levels of airway inflammatory markers and emphysema as in comparison with those of tobacco-only smokers.

Study: Chest CT Findings in Marijuana Smokers. Image Credit: PIJITRA PHOMKHAM / Shutterstock.com

The health effects of smoking marijuana

Marijuana is essentially the most widely used psychoactive drug throughout the world, with its global use continuing to rise following its decriminalization and/or legalization in lots of countries. Inside Canada, for instance, 20% of people over the age of 15 have reported having used marijuana up to now three months. Similarly, almost 13% of adults in america have reported marijuana use inside the past 12 months.

Although marijuana is the second mostly smoked substance after tobacco on the earth, it could possibly be consumed in several other ways including vaporization and ingestion. As in comparison with tobacco smoking, marijuana smoking often involves the inhalation of greater volumes of smoke for longer periods of time. Moreover, marijuana is regularly smoked with no filter.

Like tobacco smoke, marijuana smoke also consists of varied carcinogens and chemicals able to causing respiratory disease. In actual fact, several studies have confirmed that marijuana smoking can result in respiratory symptoms like cough, sputum production, and wheezing, all of that are also commonly reported amongst tobacco smokers. The presence of those symptoms has been found to change pulmonary function tests in marijuana smokers, thus indicating the likely presence of airway inflammation in these individuals.

Assessing the consequences of marijuana smoke through CT imaging

Along with pulmonary function tests, CT lung imaging may provide necessary information on the impact of marijuana smoking on the lungs.

To this end, the researchers of the present study compared chest CT studies from 56 marijuana smokers, 57 nonsmokers, and 33 tobacco-only smokers obtained between October 2005 and July 2020 in Ottawa, Canada. All patients included in the present study were matched by age and sex.

Importantly, the researchers were limited of their ability to quantify each day marijuana use among the many patients attributable to the retrospective nature of this study. In actual fact, only 28 of the 56 patients had provided details about their each day marijuana consumption rates, which averaged to 1.85 grams every day. Fifty of the 56 marijuana smokers also smoked tobacco.

As in comparison with non-smokers, the CT findings for marijuana smokers indicated different rates of emphysema, bronchial thickening, bronchiectasis, mucoid impaction, and centrilobular nodules, all of that are CT markers for airway inflammation. Gynecomastia was also reported in 38% of marijuana patients as in comparison with 16% of non-smokers.

Upon comparison of CT findings between marijuana and tobacco-only smokers, the researchers reported differences in bronchial thickening, bronchiectasis, and mucoid impaction. Moreover, higher rates of emphysema were observed in age-matched marijuana smokers as in comparison with tobacco-only smokers of 93% and 67%, respectively. No differences were observed when comparing the occurrence of centrilobular nodules between marijuana and tobacco-only smokers; nevertheless, this will likely be attributable to the high rate of tobacco smokers who also smoked marijuana.

Paraseptal emphysema was also more regularly identified in marijuana smokers as in comparison with the lungs of tobacco-only smokers. Conversely, centrilobular emphysema was primarily visualized within the lungs of tobacco-only smokers.

Future outlook

In the longer term, larger cohort studies are needed to verify the CT findings on this study, in addition to elucidate possible pathogenic mechanisms answerable for the consequences of marijuana smoke on lung damage. Moreover, since most marijuana smokers on this study also smoked tobacco, it’s difficult to determine whether the CT findings reported on this study were attributable to marijuana smoke or in the event that they are synergistic effects of each marijuana and tobacco smoke on the lungs.

Journal reference:

• Murtha, A., Sathiadoss, P., Salameh, J., et al. (2022). Chest CT Findings in Marijuana Smokers. Radiology. doi:10.1148/radiol.212611.