Researchers from the University of Ottawa and the Ottawa Hospital found that marijuana smokers have a higher rate of emphysema and airway diseases compared to cigarette smokers.
The findings, published in Radiology , examined chest CT scans of 56 marijuana smokers, 57 non-smokers, and 33 tobacco-only smokers between 2005 and 2020. They determined higher rates of paraseptal emphysema and inflammatory changes in the airways, such as bronchiectasis, bronchial wall thickening and mucoid impaction, in marijuana smokers.
Image : Pulmonary emphysema in (A, B) marijuana smokers and (C, D) tobacco smokers. (A) Axial and (B) coronal CT images of a 44-year-old male marijuana smoker show paraseptal emphysema (arrowheads) in the bilateral upper lobes. (C) Axial and (D) coronal CT images in a 66-year-old tobacco smoker with centrilobular emphysema represented by areas of centrilobular transparency (arrowheads).
Giselle Revah, a radiologist and assistant professor in the Faculty of Medicine, was looking for answers about the effect of marijuana on the lungs and its health implications, especially with little information available in the current literature, since marijuana was only legalized in Canada in 2018.
“I can tell if someone is a heavy smoker or long-time cigarette smoker when I look at a CT scan. With marijuana being the second most inhaled substance after tobacco, I began to wonder: What does inhaling marijuana look like on a CT scan? Would you be able to tell if someone was a marijuana smoker, is it different from cigarette smoke? says Revah, a radiologist at The Ottawa Hospital, where the research was conducted.
“What’s unique about this study is that there has been nothing comparing imaging findings in tobacco smokers to marijuana smokers before. “In fact, there is a lack of imaging research on marijuana, probably because it is still illegal in many parts of the world and in many US states, so I think we were the first to do a project like this.”
Despite the small sample size, Revah’s findings suggest that marijuana smokers saw additional effects on the lungs over tobacco alone, including more cases of large and small airway diseases.
"We have identified an association between marijuana use and damage to the small and large airways," he said. “We still need more research before we can affect policy change. “We need larger, more robust prospective studies with more patients to confirm this.”
Marijuana and electronic cigarettes can damage the heart like traditional cigarettes
New study shows that these substances can cause heart disorders
E-cigarettes and marijuana have similar harmful effects on the heart as tobacco cigarettes, opening the door to abnormal heart rhythms, a team of UC San Francisco researchers reports.
The study was published in the journal Heart Rhythm .
"We found that cigarettes, e-cigarettes, and marijuana greatly interfere with the electrical activity, structure, and neuronal regulation of the heart," said senior author Huiliang Qiu, MD, PhD, a postdoctoral fellow in the Division of Cardiology at UCSF. Often, any individual change can provoke arrhythmia disease. Unfortunately, these adverse effects on the heart are quite comprehensive."
For the heart to work well, it must pump blood efficiently and at the right time. The heart has its own electrical control system that results from the nerves that control it. It also has the ability for electrical impulses to move through the heart muscle in a way that synchronizes the entire heart to correctly time pumping. If parts of the heart do not handle electrical signals correctly, then different regions of the heart act asynchronously, essentially fighting each other, rather than functioning as a single efficient pump, leading to potentially life-threatening arrhythmias.
Smoking tobacco causes several types of harmful cardiovascular effects, including increasing the chances of arrhythmias. E-cigarettes and heated tobacco products (sometimes called burn-not products) have become popular because they are perceived by the public as less harmful than smoking. Similarly, legal recreational marijuana has become more common in recent years, and is also often viewed by the public as safer than smoking tobacco.
In this study, researchers exposed rats for eight weeks to a single daily exposure session to smoke from the Marlboro Red cigarette, aerosol ("vapor") from the popular electronic cigarette JUUL, aerosol from the heated tobacco product IQOS, and smoke from marijuana cigarettes. , and modified marijuana smoke that lacks all cannabinoids, compared to just air. The exposures modeled a single real smoking/vaping session: rats inhaled the smoke or aerosol for five seconds twice per minute for five minutes, with clean air between smoke inhalations. This was done once a day for five days a week for eight weeks.
During that time, the heart function of rats exposed to the products (but not air) progressively worsened and blood pressure increased.
At the end of the study, the researchers performed several tests to determine the electrical and physical properties of the hearts. They found that all of the products caused increased scarring in the hearts, a decrease in the number of blood vessels, a change in the type of nerves found in the heart, a reduction in the important ability to vary heart rate and hearts were more likely to develop arrhythmias.
“It’s notable that all of these tobacco and marijuana products had similar effects,” said senior author Matthew Springer, PhD, professor of cardiology at UCSF. "And what’s really surprising is that this was caused by a single realistic smoking/vaping session per day."
Springer noted that there are some limitations to the study. “While rats are a good model for many cardiovascular effects in humans, there are still differences and firm conclusions about effects in humans cannot be drawn from rat studies alone,” he said.
However, he noted that the results are consistent with several reports in the medical literature of heart rhythm disturbances in users of electronic cigarettes or marijuana. The observation of various physical disorders in the heart, such as scarring and nerve changes, suggests a similar explanation, despite differences in nicotine or cannabinoid content.
“The bottom line is that e-cigarettes, IQOS and marijuana cigarettes still involve many of the potential harmful effects of tobacco smoking,” Springer said, “None of these products should be assumed to be a harmless replacement for smoking. In other words, just breathe air.”
