When Weed Is The Cure: A Doctor's Case for Medical Marijuana

Transcript

TERRY GROSS, HOST:

This is FRESH AIR. I'm Terry Gross. Medical marijuana is not legal in Philadelphia, Pa., where my guest, Dr. David Casarett, is the director of hospice and palliative care at the University of Pennsylvania Perelman School of Medicine. Nevertheless, he wanted to know what advice to give his patients if they asked about medical marijuana. He wanted to learn if marijuana has any medical value. So he examined the limited medical studies, traveled to places where medical marijuana is being used legally, tested it on himself, learned about the science of cannabinoids, marijuana's active ingredients, and investigated the most effective foods and technologies for delivering cannabinoids to the brain. He also examined the research on the side effects and risks of medical marijuana. After what he describes as a careful and critical look at the evidence, he wrote his new book, "Stoned: A Doctor's Case For Medical Marijuana."

Dr. Casarett, welcome to FRESH AIR. Why are you interested in medical marijuana, coming from the perspective of a hospice and palliative care doctor?

DAVID CASARETT: This topic actually got interesting to me because of a patient I took care of about a year and a half ago. She was a retired English professor, and she had advanced cancer, asked me about some of her symptoms and asked me in passing whether medical marijuana might help her. And I started to give her the answer that I was taught in medical school that medical marijuana is not a real thing. Marijuana is an illegal drug. There's no research to support it. But she asked me whether I was sure that there really was no data. And I had to admit to her that I wasn't sure. I'd never actually looked. And so I started to look. I started to look at some of the studies that had been done, started to talk to researchers and experts and realized there actually was some science there. And so to some degree this book is really an answer to her question of a year and a half ago.

GROSS: Are there certain types of pain that marijuana seems best suited for treating?

CASARETT: Yeah, it turns out that some of the best evidence for medical marijuana is actually for what's called neuropathic pain, which is pain that's caused by the nerves themselves. So unlike pain that's caused by arthritis or sometimes kinds of cancer in which the nerve endings of pain fibers are stimulated, which causes pain, neuropathic pain is caused by disruption of, or damage to, the nerves themselves. We see that sometimes in some forms of advanced cancer where tumors impinge on the nerves themselves. Metabolic conditions like diabetes, people wind up with neuropathic pain as well as long-term effects of some medications, including drugs that are given for chemotherapy. But that's where a lot of the best data are, at least in part because that kind of pain can be really, really difficult to treat. It doesn't respond nearly as well as more traditional nociceptive pain does to drugs like morphine. So there really is a need to find newer, better treatments for neuropathic pain. And so there have been a lot of trials focusing on medical marijuana for neuropathic pain because other alternatives for treatment are really pretty limited.

GROSS: Did you meet a lot of people who use marijuana for neuropathic pain, and if so, what did they report to you?

CASARETT: I did. That was probably one of the most common uses for pain that I saw. Many of them reported significant benefits. The other thing I heard from those patients, which was eye-opening to me but I heard it again and again, was not only that they had switched from opioids to marijuana or had reduced their use of opioids in favor of marijuana and gotten better relief, but many of them were actually trying to escape the side effects of morphine, which are not overwhelming but can include confusion and a little bit of disorientation. Constipation, nausea are often common.

GROSS: Now, you describe in your book using medical marijuana - or should I just say marijuana (laughter) - for back pain as an experiment to see did it help you. How much pain were you in, and what were your results?

CASARETT: (Laughter) If you've ever had a sudden catastrophic back injury, which seems to come with middle-age, the amount of pain that comes on all of a sudden, often without any warning whatsoever, can be really pretty amazingly severe. It's incapacitating. And that happened to me about at the midpoint of writing this book. I had already interviewed patients with similar experiences who tried medical marijuana. But more importantly, I had had the chance to talk with researchers who studied the effects of marijuana on pain and neuropathic pain in particular and had read enough studies to think that there might be something worth trying. And low and behold, I had the opportunity to do that. I think whether you determine that medical marijuana works for pain like that depends on what you have in mind and what sorts of outcomes you're hoping for. I was really hoping for any form of relief whatsoever, even just a few hours of relief from those muscle spasms, and I found it. I found it. Though, at least for me, the cost of most of the most common side effects of acute use of medical marijuana - confusion, hallucinations - I think mostly because the dose that I gave myself being relatively unfamiliar with marijuana and very unfamiliar with the strength of what I managed to obtain - was really blindsided by some of the acute side effects, which I honestly should've expected but didn't.

GROSS: Were the hallucinations upsetting?

CASARETT: They weren't upsetting. Actually, I tell the story in the book of hearing air traffic controllers vectoring flights into and out of the Phoenix airport. Those voices were coming from my living room, where there really weren't any air traffic controllers.

GROSS: (Laughter) You're pretty sure of that?

CASARETT: I'm pretty sure when I finally came to, four or five hours later, I checked and there was no sign of anybody related to the FAA.

GROSS: And did the marijuana help you sleep?

CASARETT: It certainly helped me sleep for that period of time, absolutely.

GROSS: Was the relief that you experienced when you smoked the marijuana lasting?

CASARETT: I only smoked once. I think that one episode with air traffic controllers hanging out on my sofa in my living room was more than enough. That dose lasted six to eight hours, though.

GROSS: So with the episode that you had of some pain relief but also some hallucinations - audio hallucinations, what are your concerns about the cognitive side effects of medical marijuana?

CASARETT: The acute cognitive side effects, meaning what we all experience in the first two to six hours after being exposed to medical marijuana, are fairly well-described. They tend to be fairly short-term. They tend to be predictable. As long as you know what the dose is that you're getting. I think what makes me a little bit nervous, and something that we don't quite understand from the research that's been done yet, but there's been enough research done to make many of us worry that long-term cognitive effects for somebody who smokes half a joint a day for 10, 20, 30 years, there have been several studies now that have found some combination of a decrease in neuropsychological function, often decreases or changes in thinking and memory, also changes in brain structure, decreases in the volume of certain areas of the brain, like the cortex or the amygdala, that are associated with thinking and memory.

The problem, though, with many of those studies is that they've been conducted almost entirely, based on the studies I've seen, in recreational users. And it's very difficult to tease apart whether some of those long-term changes in thinking and brain structure are due to marijuana or are maybe due to other drugs that were used along the way. Some studies are able control for those other drugs, like crystal meth or cocaine or heroin, at least in part, but many can't. So we really don't know what the long-term cognitive effects might be for somebody who is, say, an administrative assistant from Scranton, Pa., who uses a square of marijuana-infused chocolate twice a week to go to sleep. We really don't know what those effects might be, if any.

GROSS: If you're just joining us, my guest is Dr. David Casarett. He's the author of the new book "Stoned: A Doctor's Case For Medical Marijuana." And he directs the hospice and palliative care program at the University of Pennsylvania Perelman School of Medicine. Let's take a short break, then we'll talk some more. This is FRESH AIR.

(SOUNDBITE OF MUSIC)

GROSS: This is FRESH AIR, and if you're just joining us, we're talking about medical marijuana. My guest is Dr. David Casarett. He's the author of the new book, "Stoned: A Doctor's Case For Medical Marijuana." He's the director of the hospice and palliative care program at the University of Pennsylvania Perelman School of Medicine, where he's also a professor.

You hear from a lot of people on chemotherapy that it helps with the nausea that chemotherapy often induces. What evidence do we have for that, you know, in terms of an actual study or, like, crowdsourced evidence?

CASARETT: We actually have studies that come from a variety of areas. Some of the best data come from randomized controlled trials - not of smoked marijuana, but of some of the cannabinoids that are in marijuana. So THC is one, it's the cannabinoid that's responsible for the high and euphoric feeling. CBD is another one, which does not have...

GROSS: Say what CBD is.

CASARETT: Cannabidiol and THC is Tetrahyrdocannibinol.

GROSS: And they're both active ingredients in marijuana?

CASARETT: Yeah, they're the really - the primary active ingredients, although it's important to keep in mind that that's partly a reflection of the state of the science now. There are dozens of cannabinoids that are in marijuana. THC and CBD are present in the largest amounts. They're the cannabinoids that we've studied the most. Who knows - it may be that five years from now, we determine that one of the most valuable cannabinoids is one that's present in much smaller amounts that we really haven't focused on.

GROSS: So I think interrupted your thought about what evidence we have that marijuana can be useful in overcoming nausea after chemotherapy.

CASARETT: Yeah, nausea after chemotherapy is such a devastating symptom. There really has been a lot of effort to try to find effective treatments, including studies of medical marijuana as well as other drugs. The data about medical marijuana and its constituent, cannabinoids, in chemotherapy-associated nausea come from a couple of different sources. There have been several studies of cannabinoids that had been taken out of medical marijuana, or synthesized, and tested in pill form in randomized control trials. As with most symptoms though, with the possible exception neuropathic pain, the evidence base for chemotherapy-associated nausea is still pretty thin. We really don't have a series of five or eight large-scale, really well-designed randomized control trials. So the use of medical marijuana for chemotherapy-associated nausea is kind of emblematic of the state of the science. There are some intriguing ideas that it might be effective, some preliminary studies, certainly enough data for many patients to say, well, if these drugs don't work, medical marijuana is next on my list. But it's not the home run, I think, that many proponents of medical marijuana are hoping we'll have in our toolkit in five or 10 years.

GROSS: So when we talk about medical marijuana and its possible, you know, helpful effects, and when we talk about just getting high from marijuana, we're talking about two main ingredients. They're both cannabinoids, but one is THC and one is Cannabidiol. Would you explain the difference between those two active ingredients?

CASARETT: Sure. There are actually a lot of cannabinoids out there. There are dozens that are present naturally in medical marijuana and there are probably over a hundred synthetic cannabinoids. So that's actually a fairly large family of these cannabinoids, of which, most, we have no idea what they do at all. Many of the synthetics for instance, have never been tested in humans. The two that we know the most about are THC and CBD, so Tetrahyrdocannibinol and Cannabidiol, and they're very, very different. We know the most about them because they occur in the largest amounts in marijuana. So THC is most important and most popular because it's the cannabinoid that is responsible for the high feeling of euphoria. CBD is a bit more of a mystery because it doesn't have any of those really obvious effects that THC does. We know a little bit about what it does. We know that CBD binds to receptors on something called microglial cells, which are sort of the brain's immune cells. So CBD binds to those microglial cells. CBD also binds to cells in the immune system. So CBD receptors are fairly common in lymph nodes, also in areas of the body where there's a lot of immune activity, like the GI tract.

GROSS: So that means it's the Cannabidiol that's responsible for interactions with the immune system and possibly the anti-inflammatory response. So that means that it might be possible, or maybe it's already possible, to separate the THC from the Cannabidiol so that you could get a medical response that you want from the CBD, the Cannabidiol, without getting high because you've taken out the THC.

CASARETT: Exactly. And...

GROSS: 'Cause getting high isn't always a desirable effect of medical marijuana.

CASARETT: Exactly, and it's very undesirable for many people. And that's already happening in a couple of ways. There are strains of marijuana that have been tested. Dispensaries sell these, so you can go into a dispensary where medical marijuana is legal and ask for a strain that is a low-THC, high-CBD strain, for instance if you're really interested in those effects. In fact, Barth Wilsey, who is an anesthesiologist and a pain researcher I spent some time with researching this book, is very interested in the use of marijuana to treat neuropathic pain, and he's becoming increasingly convinced that it might actually be CBD and not THC that's responsible for some of the benefits for neuropathic pain. And he's doing clinical trials that are involving lower and lower amounts of THC and higher and higher amounts of CBD and seeing some of the same effects on pain, which is interesting because again, CBD doesn't cause that high, euphoric feeling, but if it has therapeutic benefits, there are enormous opportunities for figuring out how to use that appropriately and productively for those people - and there are a lot of them - who really don't want to feel high, they don't want any of that recreational marijuana feeling. They really just want relief of pain or nausea.

GROSS: So one of the things you investigated is what's the most effective way of ingesting medical marijuana. And smoking it isn't always a desired - I mean, it's sometimes a very undesirable way. If you have any kind of respiratory issue or throat issue, you probably don't want to be smoking it. So how effective is eating marijuana?

CASARETT: It can be very effective, in terms of being certain that you're going to get a dose. The problems with eating are twofold. One is the absorption time can be widely variable. So you and I might eat a square of marijuana-infused chocolate at the same time, but because of differences in the way that our GI tracts work, differences in the degree that our livers metabolize the main forms of cannabinoids that are occurring in medical marijuana - CBD and THC - you may feel the effects within 15 minutes. I may not feel those effects for an hour or more, or I may never feel those effects. Or vice versa. Also, in general, it takes a long time - long in terms of half an hour to an hour - before people begin to feel the full effects. And a common problem that many first-time users experience is eating a brownie or a square of chocolate or a gummy bear - waiting for 15, 20 minutes, not feeling an effect, and so they try another one, and another one, and another one. All the while, those doses are stacking up, so when they begin to feel an effect in an hour, an hour and a half, they've taken too much, but it takes a while for those effects to wear off. So it's fairly easy to get the active ingredients in medical marijuana by eating, but it takes some care and some timing and some familiarity with what you're doing, how you're doing it and what the concentrations of THC and CBD are in that gummy bear or that square of chocolate.

GROSS: And the question of how you ingest it is a really important question for people administering medical marijuana because you want to know what kind of dose a patient is getting.

CASARETT: That's been a real challenge, I think, in a lot of the research on oral ingestion and edibles. It really makes research very difficult if you give half of the people in the clinical trial an edible form of medical marijuana, but you're not really sure - through luck of the draw, patient characteristics, whatever - you're not really sure how much they're actually getting, when they're actually getting it. So a lot of the research has turned to other forms of administration where the dose and the effective dose can be better calibrated so you know what you're doing.

GROSS: One of the things being tried now is vaporizing marijuana, and people are probably familiar with e-cigarettes where you're vaping, you're smoking, like, the vapor. So how does vaporized marijuana work?

CASARETT: Vaporized marijuana works pretty much the way it sounds. Cannabinoids in medical marijuana - THC and CBD - for the most part vaporize at a lower temperature, about 200 degrees Celsius, more or less, that is below the point at which marijuana would start to burn. So the idea is you heat the marijuana bud - it's often ground-up first - you vaporize the CBD, the THC, other cannabinoids in smaller amounts that comes off as vapor, which is inhaled, leaving all of the particulate stuff - the junk, the plant matter, and avoiding some of the tar and particulates that you really don't want to be inhaling.

GROSS: Is it any easier to understand - to calibrate what the dose is and what the proportion of THC and CBD is if the cannabinoids are being vaporized?

CASARETT: Well, it's certainly easier if you're vaporizing or if you're smoking. I would treat those pretty much the same. I'm not sure it's any easier in vaporizing than it is in smoking, but it's much easier for both of those than it is for edibles. The neat thing about either vaporizing or smoking is that you know within five or 10 seconds what that effect is going to be, and so you can titrate your effect accordingly.

GROSS: My guest is Dr. David Casarett, author of the new book, "Stoned: A Doctor's Case For Medical Marijuana." After we take a short break, we'll talk more about medical marijuana and about his work as a hospice and palliative care doctor. I'm Terry Gross, and this is FRESH AIR.

(SOUNDBITE OF MUSIC)

GROSS: This is FRESH AIR. I'm Terry Gross, back with Dr. David Casarett, author of the new book "Stoned: A Doctor's Case For Medical Marijuana." He directs the hospice and palliative care program at the University of Pennsylvania Perelman School of Medicine. Medical marijuana is not legal in Pennsylvania, but he's often asked about it by patients. So he examined the medical studies, traveled to places where medical marijuana is being used legally, tested it on himself, learned about the science of cannabinoids and examined the research on the side effects and risks of medical marijuana.

So having done all the research for your new book, "Stoned," how have your thoughts changed about the use of medical marijuana?

CASARETT: You know, a year and a half ago, when I first started this project, I really thought of medical marijuana as a joke - something that, if it were a medicine, would always be described in pretty much that way, with ironic air quotes on either end. And I've come to realize, first of all, that there really are real medical benefits. There's a fair amount of science behind it, and there probably will be more with every passing year as we get more experience doing research. And those are medical benefits that people in the medical marijuana world, including advocates and patients, really take seriously.

I was really surprised at how many people I met who were using medical marijuana, including most notably - I tell the story in the book of two people who began to use CBD oil to treat their daughter's seizures. For them, medical marijuana is not a joke. It's not funny. It's not something that's the source of humor about munchies or hallucinations. This really is, for many of them, a treatment that they have come to rely on and they take very, very seriously. They understand that we don't have as much evidence as we could someday, but they really see the need for evidence as being urgent - a matter of life and death for some of them.

GROSS: If you could prescribe it, what do you think you might want to prescribe it for? And you live in Pennsylvania, where there is no legal medical marijuana.

CASARETT: Right, that's true. Having said that, my patients do ask me whether I would recommend medical marijuana for them, knowing that we live and I practice in the state in which it's not legal. And I used to tell them that I couldn't make a recommendation because it's not legal. It became obvious to me in a series of conversations many of my patients, though, that often when people ask me whether they should use it, what they often tell me is, well, good, I'm glad you said that because I have been using it. And they were just reluctant to tell me that. So if I hear that question, I usually give people an explanation of where the data are, but I usually take the opportunity also to counsel people about risks - the risks of driving under the influence, the risk of addiction, which is moderate, but significant, as well as some warning about some of the other acute side effects that people might experience so they're not surprised by them.

GROSS: Do you run any risks in Pennsylvania, where medical marijuana is not legal, by counseling patients about its use?

CASARETT: That's a good question. I don't know. I always tell my patients that it is illegal, so I'm not making any promises or any recommendations. The way I would phrase my advice is this is what we know, in the same way that when patients ask me for any advice, I'd tell them what we know and what we - what we don't know. I certainly hope that I'm not at risk. This is something that people are using. It's not something I promulgate. I wouldn't actually tell a patient that I think you should use medical marijuana. But if people ask me, particularly when they ask me and they tell me that they are using it, it really seems to be if not outright malpractice, then at least a disservice to patients to ignore those questions because of legal concerns.

GROSS: Do you think of the war on drugs and the moral questions that people have placed on the use of drugs has held back research that might be useful in understanding how marijuana works and how it might be useful in medical settings?

CASARETT: Oh, absolutely. The researchers that I've talked to - there's no question that the war on drugs has set back medical marijuana research and cannabinoid research, in general, by probably decades. Marijuana in the United States is classified as a schedule one substance, which is reserved for those substances, like heroin, that have significant risks, including the risk of addiction, but, in theory, no medical benefits. And that categorization really has slowed down the process of research. It's been hard to get medical marijuana. It's been hard to do clinical trials. It's left a lot of patients essentially to their own devices using - figuring out how to use on their own, crowdsourcing to some degree, trying to figure out on their own what to use and how to use it. Hopefully, research will catch up, but there's no question - the war on drugs really has set back that evidence base.

GROSS: If you're just joining us, my guest is Dr. David Cassarett. He's the author of the new book "Stoned: A Doctor's Case For Medical Marijuana." And he directs the hospice and palliative care program at the University of Pennsylvania Perelman School of Medicine. We'll be back after a break. This is FRESH AIR.

(SOUNDBITE OF MUSIC)

GROSS: If you're just joining us, my guest is Dr. David Casarett, who's the author of the new book, "Stoned: A Doctor's Case For Medical Marijuana." And he's also the director of the hospice and palliative care program at the University of Pennsylvania Perelman School of Medicine. Let's just talk, in the remaining time we have, about your work in hospice and palliative care. Why did you go into that aspect of medicine?

CASARETT: For a lot of reasons. I think one of the biggest was it's really a chance to have a very notable, immediate, obvious impact on people's lives. There is such a dearth of good palliative care, meaning care that's focused on comfort, quality of life, decision-making, symptom management, emotional and spiritual support. It's something that health systems really don't do well. And there really is a chance to walk into a patient's room to talk with the patient, talk with a family, and within 5, 10, 15 minutes, really, really make a difference. And that's something that's hard to find, I think, in medicine these days. And that's something that really called to me as a way to make a difference in people's lives at a point in their lives when they really, really need that additional help.

GROSS: Now, correct me if I'm wrong here, but I think Medicare is going to start reimbursing doctors for end-of-life discussions with patients. What's that going to mean in your field?

CASARETT: So Medicare has proposed a rule - the final rule - that will be published in November and then would go into effect in January of 2016 that would pay doctors and other healthcare providers, including nurse practitioners, to have these discussions. I'm not sure how it's going to affect our field or patients' families in general. The final rule has has not been published, obviously.

I think this kind of attention, though, to having these sorts of discussions is extraordinarily valuable. And it proves, I think, that we've come a long way in the last three or four years since this idea was floated and was shot down as involving death panels by a vice presidential candidate. The fact that we can now have this discussion seriously about paying for these conversations in a way that I think the public generally accepts with not a lot of backlash means to me that the culture around end-of-life care and decision-making really has come an awfully long way in just a couple of years. And that makes me really quite optimistic about what the state of palliative care could look like in the United States in another five years.

GROSS: What are some of the more perplexing questions that you are often asked by patients who are near the end of their lives?

CASARETT: Some of the more difficult questions to answer, I think, for me, are predictions about how long I have. Prognosis is something that we're not good at. I've been doing this for 17, 18 years now, and still, often what I can offer my patients, whether it's in terms of years or weeks or month or days, sometimes hours, is a best guess. And the challenge for me and for my colleagues who do this is not to try to give people the exact estimate of prognosis, but to try to figure out what they want to know, what frame of reference would be most useful to them, so we can build an estimate, a prediction around what's important to them. So, for instance, if they're trying to figure out whether to call a daughter in from California to see a grandfather before he dies, that's helpful to know because that tells me what sort of window to anticipate. And then other questions people ask me have to do with the trajectory of what lies in front of them, so what can I expect in terms of symptoms, in terms of quality of life, in terms of function? What will my life be like a week from now, a month from now, six months from now, if I'm still alive? Those questions also are difficult to answer. They're not a simple closed-ended answer, but it usually involves a conversation of figuring out what's important to people and helping to guide the trajectory. It's partly a discussion. It's partly an answer. But it's also assistance in decision-making. What's important and how do we get there?

GROSS: Can I confess to you something I worry about, which will hopefully be way, way, way down the road? But, you know, I think we all worry about pain, and there are, you know, opioids and things like that to help address pain. But, you know, I've seen people - not nearly as many as you have - who have some form of dementia at the end and are not living in the moment that they are actually in. They're living at some point in the past. That might be a happy point in the past, and it might be the lowest point in their lives kind of past. I read a story about somebody who was a Holocaust survivor - and this was nonfiction - who, after having dementia, thought that they were back in a concentration camp, in a death camp. And I thought, like, that's just the most horrible way of dying, to be, you know, a prisoner in a death camp again. And I wonder how often you see that happen, you know, that somebody is flashing back at the end of their life to, like, the most tragic or most painful episodes of their life.

CASARETT: Well, just to take a step back, it's interesting that you should say that because, as I talk with people who are nearing the end, lots of my patients have something that they're really worried about. Sometimes it's pain. Sometimes it's loss of function. Sometimes it's dignity. Sometimes it's inability to recognize their family. Sometimes it's that fear of past memories. But lots of people have something, and I think a lot of what hospice and palliative care does is to figure out what that something is, to figure out what people are really most worried about and then to do what we can to address that and to avoid it if we can. So, yes, we do see that in my hospice - our hospice unit, which is in downtown Philadelphia. We have, actually, a protocol. When patients come in who we know have had difficult experiences in the past, particularly still, occasionally, holocaust survivors, we make sure that everybody knows that this is something that's potentially concerning to them. But again, you don't really know what somebody's greatest fear is or what the biggest risk is unless you ask.

GROSS: One of the issues facing hospice care now is, should patients have the right to terminate their life when they have decided their life should end? Do you have a strong opinion about that?

CASARETT: I do, and it's not a really popular one. I generally think that a lot of the discussion about assisted suicide and its legalization is, first of all, born out of fears that are unjustified. You know, I don't want to lose my dignity. I don't want to die in pain, so I'm going to end my life now. And I think it should be a right for everybody. That's what I hear people saying. And although I understand that logically, the two big problems for that, for me, are not really moral ones. I've certainly - I've taken care of patients who I'm pretty sure have ended their own lives. Not with my consent or not something that I condoned, but I'm pretty sure that they did. And it was something that, in retrospect, at least for several of them, probably was the right choice for them, so I'm not making a moral judgment. It's just that when people make that decision based on fears of what might happen in the future, often I've found, almost always, people's fears of the future are not borne out by really. So any discussion of the right to assisted suicide really needs to include some acknowledgement that we're not always rational beings, and we're not always making the right decisions. And second of all and most importantly, there are so many opportunities to improve end-of-life care in this country - improved pain management, improved decision-making, attention to dignity in nursing homes. I could develop, at the drop of a hat, a list of 20 or 30 things we absolutely need to do now to make sure we all have the sort of comfort, quality of life and dignity near the end of life that Americans deserve. And it really bothers me when we're spending time as a country talking about rights to assisted suicide. We're not talking about rights to decision-making or rights to adequate pain management. That's really where our - where our focus should be.

GROSS: Is it still the case that, in order to go into hospice, you have to basically sign a statement saying that you'll forgo any kind of other treatments, you know, that it will only be palliative?

CASARETT: Well, sort of. So the two criteria for hospice enrollment are you need two physicians to say that you have a prognosis of six months or less if your illness runs its usual course, which is usually interpreted to mean without aggressive treatment, and you need to embrace a plan of comfort care. Different hospices define comfort care in different ways. So the criteria are not nearly as cut and dried as many people think. The other thing that's important to know is that hospice eligibility criteria, at least under Medicare, are related to the hospice admitting diagnosis. So if you have cancer and you're also receiving dialysis, for instance, it's an odd, but often, for patients, very useful feature of the Medicare benefit that you could enroll in hospice for cancer, receive comfort care for cancer, but continue receiving dialysis, which is arguably aggressive life-saving treatment for another condition. Also, finally, people can change their minds. So people do need to embrace a plan of comfort care when they enroll in hospice, but if they decide, as some of my patients do, a week, a month later that they've change their mind, new treatment available, they want to get a second opinion, there's no restriction on their being able to do that.

GROSS: Has your work as a hospice and palliative care doctor affected your own - like, how you deal with your inevitable mortality, which we hope is in the far future?

CASARETT: I think so. Not as much as you might imagine. I think all human beings are pretty good at compartmentalizing, and I think we, at one stage, try to learn from the stories that we hear. And that's been very helpful for me, seeing how many people manage to go through their final years, months, weeks and days in comfort, with a sense of dignity, surrounded by family members. And I think - and I'm speaking for many of my colleagues as well. One of the biggest things that shapes our thinking in doing the work that we do is realizing that death is usually sad, often tragic, but it doesn't have to be scary. And that may not translate into things that I do right now anticipating that, but there is this underlying belief, I think of many people, that it's terrifying. It's something we should never talk about. And that familiarity, I think, makes us more comfortable, and I'm certainly more aware, on a daily basis, that the end could come at any point, but that doesn't scare me as much as it might have before I chose this career. It does nudge me a little bit. I try to be, I think, nicer to people, knowing that, at any point, that could be the last conversation. I certainly try to do things today rather than tomorrow, as I think many of us do, but it's really that lack of overarching, behind-the-black-curtain fear that drives a lot of people that, I think, is less relevant to those of who do this and see these stories unfold, often beautifully.

GROSS: Dr. Casarett, thank you so much for talking with us.

CASARETT: Oh, gosh, Terry, I'm a big fan. This has been a real treat. Thanks.

GROSS: Dr. David Casarett is the author of the new book, "Stoned: A Doctor's Case For Medical Marijuana." He directs the hospice and palliative care program at the University of Pennsylvania Perelman School of Medicine. Coming up, rock critic Ken Tucker review the new album by a singer and songwriter Jason Isbell. This is FRESH AIR. Transcript provided by NPR, Copyright NPR.