Studies: Marijuana Benefits Overstated, Lung Damage Is a Real Threat

Health Professional, Medical Reviewer

In order to understand how drug effectiveness or benefits are evaluated, it’s crucial to understand the difference between anecdotal evidence and scientific proof. It’s also important to see the type of study that evaluated the drug. The gold standard of research is a double-blind study in which neither the participants nor the researchers know who is receiving the treatment. This type of study prevents bias. As it turns out, medical marijuana’s stated benefits may be based more on anecdotes than on vetted science, while marijuana's dangers -- when it comes to lung health -- may be sorely underestimated.

A 2015 investigation published in the Journal of the American Medical Association based on a systemic review and meta-analysis of accumulated research suggested that there was only limited quality evidence supporting the therapeutic benefits of medical marijuana. Those benefits were also only clear for certain conditions. The authors of the investigative report felt that the bulk of research on medical marijuana was of less than optimal quality and was more likely based on bias.

The investigation reviewed 79 randomized trials which (all) suggested that users of marijuana for a range of conditions including psychosis, Tourette syndrome, nausea from chemotherapy, sleep disorders, anxiety, loss of appetite due to HIV, multiple sclerosis spasms, and depression, felt improvements. In many of the studies, the researchers admitted that they could not support the findings completely, because they could not validate that a clear statistical benefit was noted, compared to placebo. Still, authors of the investigative study suggested that for chronic pain, medical marijuana may be helpful to some patients. The broad state of evidence was still considered “insufficient,” and larger, more robust randomized trials were recommended.

The status of medical marijuana has evolved, despite the dearth of clear prescribing guidelines. Currently, there are 28 states with broad legal marijuana use plus the District of Columbia. Some of the states have expansive laws also allowing for recreational use. Mounting evidence of its therapeutic value has driven this legislation. Regulation of the drug is still confounding many states. In a recent national meeting of chest physicians, one lecture, "Evidence of Medical Marijuana Up in Smoke," suggested the limited federal dollars allotted to study medical marijuana and the fact that so much of the information we currently have is based on people self-reporting quantity, duration of use and other subjective variables.

Additionally, studies on marijuana typically compare it to placebo, not other pain-relieving medications.   Medical marijuana is considered one of the fastest growing business sectors in the United States. Many people feel that it’s safe because of slowly evolving looser laws for recreational marijuana and the burgeoning medical marijuana industry. A 2017 report from the National Academy of Sciences, The Health Effects of Cannabis and Cannabinoids, suggests limited proof for oral use to combat chemotherapy-induced nausea and vomiting, and no clear evidence that “it beats” neurokinin-1 inhibitors, the newest antiemetic agents. There’s also no clear evidence that inhaled plant cannabis is superior to those newer drugs. Pure cannabidiol (CBD) pills appear to have some efficacy treating multiple sclerosis (MS), compared to THC (tetrahydrocannabinol) pills. There is however growing concern in the medical community regarding the unknown and the downsides of marijuana.

Marijuana can be addictive. About nine percent of individuals who experiment with marijuana (nearly 17 percent of teens in that group) will become addicted. Up to half the people who smoke it daily become addicted. Marijuana products today are stronger compared to just a few decades ago. Some edible marijuana products (baked products, chocolate) can be 10 times stronger than traditional joints. These types of products can take hours to hit their full potency, which means someone can be driving or operating equipment thinking it’s safe because it’s hours after ingestion. It’s unclear whether marijuana is a gateway drug that leads to more dangerous drug use. It is, however, associated with risk of inducing acute and chronic psychosis in vulnerable individuals. Some studies suggest that marijuana is a general immunosuppressant, with a possible trigger effect that promotes cancer growth.

As a lung specialist, I’m concerned about the respiratory implications of smoking marijuana. In fact, there’s a bit of a medical conundrum because some literature has floated the use of marijuana as a treatment for asthma. One study found that cannabinoids have antitussive behavior, with a potential to reduce bronchial responsiveness to certain stimuli. Another study found that short-term marijuana use acted as a bronchodilator. Still, marijuana smoke contains about 60 chemicals, among them ammonia, hydrogen cyanide, formaldehyde (also present in cigarette smoke) and THC. Marijuana smokers typically inhale the smoke directly into their lungs. Marijuana smokers can develop a cough or wheeze. Research presented during a May 2017 lung specialist meeting suggests that adults over age 40 who had a past history of smoking pot appeared to experience an increased risk of lung exacerbation-like illnesses.

The Canadian Obstructive Lung Disease (COLD) study of more than 5,000 adults over age 40 showed higher rates of lung exacerbation illness in individuals who smoked marijuana compared to non-smokers. The marijuana smokers had higher rates of these illnesses compared to regular cigarette smokers. The highest rate was among individuals who smoked cigarettes and pot. In the Canadian Cohort of Obstructive Lung Disease (CanCOLD) study of more than 1,100 adults, higher but similar rates of lung exacerbation illness in the over 40-year-old population were noted. It’s important to emphasize that dual smokers of both marijuana and cigarettes had the highest rates of these exacerbations. Those who "just smoked pot" still had significantly more of these illness events compared to non-smokers and cigarette smokers.

In terms of symptom complaints, middle-age cigarette smokers were more likely to complain of chronic cough, chronic phlegm, wheeze, dyspnea, while middle-age individuals with a pot smoking history tended to have more chronic cough, more chronic phlegm and more overall dyspnea. People with dual smoking history tend to have all the symptoms.

What’s clear in all of this is that any kind of smoke is bad for your lungs and respiratory health. We can’t lull ourselves into thinking that because marijuana may have the potential to offer therapeutic benefits that smoking pot on a regular or even intermittent basis does not come with potential downsides. It might be the case that using products that don’t involve smoking could be a safer option, but much more research is needed to confirm dosages, upper safety levels of use and other aspects of medical marijuana.

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