In 2018, Massachusetts legalized the recreational sale and consumption of cannabis for adults. Since then, the cannabis has steadily grown statewide, with more than 250 dispensaries opening up and sales totaling more than $1.5 billion last year alone. Since 2012, 23 states and the District of Columbia have legalized recreational cannabis for adult use and recent studies show that nearly 18% of Americans have used it in the last four years. Despite this recent embrace of cannabis, lingering questions still remain about the health risks and benefits associated with using it. To help us get a better understanding of what the latest research tells us, GBH's All Things Considered host Arun Rath spoke to Dr. Peter Grinspoon, a cannabis specialist and instructor in medicine at Harvard Medical School. He's also the author of "Seeing Through the Smoke: A Cannabis Specialist Untangles The Truth About Marijuana".
Rath: To start off, I'm curious about the current state of cannabis research. I know that for quite a long time it was difficult to actually do the research and I get the impression that in the last few years we've seen some worthwhile studies. Is that the case and what have we learned?
Grinspoon: Well, absolutely. First of all, there's been cannabis research all along, but because of the war on drugs and the U.S. government's policy, virtually all of the research was oriented towards finding harms, not into finding benefits. To be funded over the last 50 years in cannabis research, you had to find a drop in IQ or drop in sperm count, a drop in motivation, or something harmful about cannabis. Finally, that's starting to lighten up a little bit, and we're able to research both the benefits as well as harms. However, I do want to mention that cannabis is still scheduled as Schedule One in the Controlled Substance Act, which by definition says no medical utility and high abuse liability, neither of which is true. Obviously, it has lots of medical utility and there are several cannabis derived FDA-approved drugs on the market. So, it has medical utility and it has low to moderate abuse liability, not high abuse liability. The fact that it's still a Schedule One, where we lock up the most onerous and dangerous drugs, it makes it very difficult to do research. We are doing better and more balanced research now, but a lot of the research is happening, for better or worse, in other countries, such as in Europe and in Israel, where they don't have such strict and onerous restrictions on cannabis research.
Rath: What are some of the big discoveries that have been made recently?
Grinspoon: Well, it's a little hard to generalize. There were 1400 studies that came out in the year 2022. People have a lot of confirmation bias with cannabis, but what I think is coming out, the things that I find really interesting, are that with legalization, teen use has not been rising, which is really good. I think we're finding increasingly that cannabis is helpful in older Americans, particularly to help them get off many of the other drugs, the polypharmacy, that they're afflicted with. We're continuing to learn that cannabis can be a helpful way to treat both insomnia, chronic pain, and because it could treat chronic pain, it could help mitigate many of the harms that we find with other pain medications such as opiates or non-steroidals, which cause a lot of heart attacks, a lot of ulcers, and a lot of kidney disease. So, I think we're confirming a lot of what people have been saying anecdotally in terms of the benefits now that we're more able to study the benefits of cannabis.
Rath: I also know from our reporting about some experimental uses showing promise for relief for patients with dementia and other neurological problems.
Grinspoon: When I look at medical cannabis as a clinician, I don't say, "Is cannabis safe?" I say, "Is cannabis safer than whatever else I'd be using?" And the medications we use for older Americans, in general, tend to be more dangerous. That's why cannabis for many of them is a palatable alternative. For dementia, there's no great treatment yet. But for many of the behavioral disturbances and problems – the aggression, the confusion, and the anxiety – we tend to load these patients up on heavy-duty neuroleptics such as Haldol and Thorazin, and people are finding cannabis to be a much more palatable option. It results almost universally, if you look at the studies, in an improved quality of life.
Rath: Getting to the point that you were just making about safe versus safer, we've also seen some recent studies that seem to correlate the availability of cannabis with lower rates of opioid overdoses.
Grinspoon: Absolutely. I've been treating people with opiate addiction for at least the last decade, and I find cannabis to be very helpful in a number of ways in terms of helping people who are addicted to opiates. It helps with the pain, the anxiety, the insomnia and when they're withdrawing from opiates. Unfortunately, I can say I have personal experience. Fifteen years ago, when I was addicted to opiates, cannabis was much more effective than any of the other medications for opiate withdrawal symptoms, which are just miserable. You don't die from them, but they're utterly miserable. Now, the one area that I don't think we've arrived at yet is with methadone and buprenorphine, also known as Suboxone. We have very good data that there's a 50% to 80% reduction in overdose deaths, and we don't have that evidence yet for cannabis. So, I certainly use it to get people off opiates and for chronic pain, but when it comes to opiate addiction, I usually prescribe Suboxone and use cannabis as an adjunct just because there isn't the same level of data, and all other things being equal, you have to go with the data.
Rath: Back to the risk, you mentioned how earlier studies had a certain confirmation bias looking for bad things with cannabis. With recent research, do we have a better understanding of what risks there may be?
Grinspoon: My dad was a legendary cannabis specialist at Harvard Medical School for a half century at least, Dr. Lester Grinspoon. Something very clever he used to say, was that we spent so much money trying to vilify and prove harm with cannabis, that we actually have proven that, relatively speaking, it's fairly safe. A lot of harms just haven't panned out. For example, they tried so hard to show that cannabis causes lung cancer. While doctors don't recommend that you smoke anything, cannabis just hasn't been associated with lung cancer. That said, there are certain populations that we don't recommend cannabis for because it's much more dangerous. We don't recommend that teenagers use it because it can harm their developing brains. We say to teenagers, "just say wait." We don't say, "just say no." For pregnant women or breastfeeding women, there's no evidence that it's safe in these conditions. Again, this can come back to what is safer because if someone has severe chronic pain, for example, when they're pregnant, none of the other medications are particularly safe either. So, you try to figure out which is the least toxic alternative, which is part of what's so stressful about being a doctor in general. Lastly, people with a history or family history of psychosis should certainly avoid cannabis because it can exacerbate or worsen the psychosis. So, there are people that shouldn't use cannabis or use it with extreme caution. Generally, if you're not in any of those categories and you use it modestly and responsibly, it's a fairly safe medication.
Rath: Dr. Grinspoon, always fascinating talking with you. Thank you so much.
Grinspoon: My pleasure. Thank you so much for these great questions.
