What is the CANDIDE Study?
The CANDIDE Study is the latest stage of the Springer Lab’s quest over the past decade to evaluate how the potential harmful cardiovascular effects of cannabis smoke compare to the known harmful effects of tobacco smoke. The question arose from an unlikely source for a medical research project: a rock concert.
Dr. Springer explains: In 2010, Paul McCartney played a concert at the Giants ballpark in San Francisco. I was in the audience, pretty far back. It was an unforgettable evening for two reasons: first, it was a simply amazing concert. Paul just kept on going and seemingly got LESS tired as the 3-hour show went on, incredible. Second, at one point during this outdoor open-air stadium concert, the people in front of me lit up cigarettes and started smoking, and then more and more people did the same. I was briefly perplexed because it was surprising that in San Francisco, a bunch of people would just start smoking in the stands and the people sitting by them wouldn’t complain; but then I quickly realized it was marijuana smoke I was smelling. Pretty soon, a whole cloud of smoke blanketed the stands. Paul stopped between numbers, made a sniffing motion, and said “There’s something in the air, must be San Francisco!”
A classic moment, but also a crystalizing moment because I realized that all these people who wouldn’t tolerate having to breath in someone else’s secondhand tobacco smoke were fine with secondhand cannabis smoke, probably assuming that it was harmless. I started wondering how that could be the case, because smoke from burning plant material—any plant material—contained thousands of chemicals unrelated to nicotine, many of which are toxic. We were already studying the cardiovascular effects of secondhand tobacco smoke in a rat model, and I realized that it would be much easier to study the effects of exposing rats to marijuana smoke than humans. We embarked on a project that ultimately showed that rat blood vessels react to brief secondhand cannabis smoke exposures similarly to secondhand tobacco smoke: the blood vessels temporarily don’t function as well, even if the smoke was from cannabis lacking THC and other cannabinoids. This demonstrated that exposure to secondhand cannabis smoke had at least one of the unhealthy effects of secondhand tobacco smoke, and clearly wasn’t completely harmless. That realization led us to propose a clinical study in which we wouldn’t expose people to cannabis smoke, but instead would recruit people who smoke cannabis or are frequently exposed to secondhand cannabis smoke. Thus, CANDIDE was born, a study to determine whether there are harmful cardiovascular effects of smoking cannabis, being exposed frequently to secondhand cannabis smoke, using leaf vaporizers, or using THC edibles, compared to tobacco smokers and to non-smokers.
Matt Springer, PhD
Principal Investigator