JEFFREY BROWN: And finally tonight: the benefits and limitations of medical marijuana treatments.
Sixteen states have passed laws that allow patients to use the drug to treat side effects of various illnesses. But now some are moving to either limit or repeal those laws. One of them is Montana.
Special correspondent Anna Rau of Montana PBS recently produced a documentary examining the experiences of patients and doctors. This excerpt focuses primarily on what scientists are learning about marijuana's therapeutic effects.
MEDICAL MARIJUANA USER: I used to be on approximately 14 different prescriptions, and I would still have up to 12 seizures a day. I used to have to take two handfuls of pills. No more.
ANNA RAU, Montana PBS: While this 27-year-old epilepsy patient in Montana is relieved to be taking medical marijuana...
WOMAN: I'm not using it to get any psychological effects off of it. I'm just eating the butter raw with bread.
ANNA RAU: ... she's considerably more anxious about showing her face, and has requested we conceal her identity.
Why do you not want to show your face?
MEDICAL MARIJUANA USER: I am not comfortable showing my face because of all of discrimination that has already happened.
ANNA RAU: She says both she and her husband have lost jobs when she spoke openly about using marijuana to treat her seizures.
Medical marijuana use has been legal in Montana since 2004, when voters there approved an initiative allowing doctors to recommend it to their patients. However, the federal government still classifies the plant as a schedule one drug. That makes it illegal for doctors to prescribe it, and it means state law doesn't protect patients from federal arrest and prosecution.
MEDICAL MARIJUANA USER: But the fact of the matter is, somebody has to speak up, or nobody will hear these stories.
ANNA RAU: She told us her story in her artist's studio. Here, she creates much happier works than she did even a few years ago, when her self-portraits plainly showed the toll epilepsy had taken since she was diagnosed at 15.
MEDICAL MARIJUANA USER: I have taken pretty much every anti-epileptic on the market, and some with a little bit more success than others.
ANNA RAU: None of them stopped her seizures, and, by her early 20s, the epilepsy had also spawned depression, anxiety and insomnia. She had to withdraw from college just a few credits short of a fine arts degree. Unable to hold a job, she was bed-bound for years while the epilepsy ruled her life.
MEDICAL MARIJUANA USER: It's not a life, to live like that.
ANNA RAU: Then she remembered reading stories about the potential of cannabis to treat epileptic seizures, and she desperately wanted to try it, but her home state doesn't have a medical marijuana law.
MEDICAL MARIJUANA USER: So, I did what I could do. I moved to a state where I could treat it myself.
ANNA RAU: Medical marijuana critic Dr. Eric Voth says the problem is, patients are treating themselves with a plant that's voter-approved, not FDA-approved.
DR. ERIC VOTH, Institute on Global Drug Policy: So much of the medical excuse movement has come through ballot initiatives and legislative initiatives. And that's not the way we bring medicines to market. We bring them to market through the FDA and a very careful process of proving safety and efficacy.
ANNA RAU: Dr. Voth is an addiction and pain specialist in Kansas, and he's also the chairman of the Institute on Global Drug Policy. He says scientific research is the only legitimate route to understanding marijuana's medical potential, not a hodgepodge of state laws and anecdotal stories.
He says, when patients smoke or ingest marijuana, they are getting a complex and largely unresearched mix of chemicals known as cannabinoids.
DR. ERIC VOTH: If we're delivering THC, which is the major active ingredient, shouldn't we be delivering that alone or other cannabinoids alone? But, in fact, what we're doing is we're delivering not only one, but 66 cannabinoids. On top of that, were delivering hundreds of contaminants.
ANNA RAU: This epilepsy patient says she's willing to take the risk, because something in that cornucopia of substances has changed her life.
How did that impact your seizures?
MEDICAL MARIJUANA USER: They started slowing down. I had to build it up in my system. And it wasn't until I started ingesting it that they really stopped completely.
DR. ERIC VOTH: I'm very suspicious about it because for someone to have been on 14 medications and not solve her problem, and then have this miraculous benefit from one medicine, I just find that suspect.
ANNA RAU: But the potential of marijuana to mitigate epileptic seizures has been recognized by the U.S. Institute of Medicine. The institute has released two reports on the therapeutic potential of cannabis.
The first report, from 1982, found "substantial evidence from animal studies to indicate that cannabinoids are effective in blocking seizures." Scientists who wrote the 1999 report also found marijuana had anti-seizure effects, but doubted it could be developed into a pharmaceutical-grade epilepsy drug.
However, both reports detailed the promising ability of cannabis to treat pain and disease differently than conventional pharmaceuticals. That's exactly what scientists at the California Center for Medicinal Cannabis Research found during several placebo-controlled clinical trials.
Dr. Igor Grant is the center's director, and he says marijuana is not just an anti-nausea drug.
DR. IGOR GRANT, University of California, San Diego: I can say that the cannabinoids are almost certain to be useful in pain, based on the research that we have done, and probably have a place in muscle spasm.
DR. DONALD ABRAMS, University of California, San Francisco: Marijuana contains anti-inflammatory, anti-oxidant and probably anti-cancer compounds in it.
ANNA RAU: Dr. Donald Abrams is an oncology physician who conducted some of the center's clinical research. He agrees the cannabis plant is a complex mix of substances, but he believes this is a medical benefit, not a detriment.
DR. DONALD ABRAMS: I'm a cancer doctor, and I often suggest to my patients that they consider marijuana for their loss of appetite, nausea, pain, depression and insomnia. It's one medicine they could use, instead of five.
ANNA RAU: Critics like Dr. Voth are especially skeptical of these kinds of claims. How is it possible that one plant has the potential to impact so many different ailments?
Intriguing answers started appearing in the early '90s, when researchers pinpointed receptors in the brain and the body that bind with cannabis. Receptors can be described as locks on the surface of a cell, and when the correct key binds with the correct lock, or receptor, it opens the door and delivers messages. Sometimes, the messages are urgent, for example, that the body is feeling pain, or that there's an invader and the immune system must attack.
Researchers believe cannabinoids can turn down those messages, helping to temper chronic pain and autoimmune disorders. These special receptors are extremely abundant in the brain, but they are also found all over the body and in the major organs, the heart, the liver, kidneys and pancreas.
After finding all these locks that accepted the cannabis key, researchers made the next big discovery: The human body makes its own cannabinoids.
DR. DONALD ABRAMS: We have these circulating chemicals that we produce ourselves that really are very, very similar to the chemicals in the marijuana plant.
DR. PRAKASH NAGARKATTI, University of South Carolina: The only difference is that the cannabinoids that we produce are in such small quantities, and they're also rapidly degraded, so that, therefore, we are not high all the time.
ANNA RAU: Dr. Prakash Nagarkatti is a professor of pathology and microbiology at the University of South Carolina. He's one of many scientists in a race to unlock the mysteries of the receptors by using newly created synthetic drugs, instead of tightly restricted whole cannabis.
These synthetics have made research much easier and potentially lucrative. The U.S. patent database shows numerous large pharmaceutical companies have filed recent patents, claiming their cannabinoid receptor drug has the potential to treat almost everything: multiple sclerosis, Alzheimer's, Parkinson's, rheumatoid arthritis, Tourette's, epilepsy, heart disease, obesity, various mental illnesses and the Holy Grail of medicine, a cancer cure.
Dr. Nagarkatti and his team of researchers were one of the first labs to prove a cannabinoid key can seek out a cancerous cell in the immune system, unlock the receptor, and direct the cancer cell to self-destruct.
DR. PRAKASH NAGARKATTI: So, basically, telling the cells basically to commit suicide.
ANNA RAU: Dr. Nagarkatti's experimental drug was able to eradicate almost 100 percent of the cancer in test tubes. And when they moved on to live mice:
DR. PRAKASH NAGARKATTI: To our surprise, we found that almost 25 to 30 percent of the mice completely rejected the tumor. They were completely cured.
ANNA RAU: Tumors in the rest of the mice shrank significantly. The results have been so promising that Dr. Nagarkatti is already beginning clinical trials with leukemia patients.
Dr. Voth believes researchers like Nagarkatti are headed in the right direction.
DR. ERIC VOTH: Let's keep it in the corridors of science. Let's keep it in the FDA. Let's deliver what's really medicine. That is the individual cannabinoids.
ANNA RAU: But this epilepsy sufferer says patients cannot afford to wait on science.
MEDICAL MARIJUANA USER: I don't know how long it's going to be before they really find out exactly what is working for me and for others.
ANNA RAU: Medical marijuana remains legal in Montana, for now. In April, lawmakers passed a full repeal of the law, but Gov. Brian Schweitzer vetoed it.
JEFFREY BROWN: Anna Rau's one-hour documentary, "Clearing the Smoke: The Science of Cannabis," is airing on many public television stations this summer.