Marijuana: the dope
News@nature.com rounds up the facts after the US Supreme Court ruling against medical marijuana.
The Supreme Court of the United States ruled on 6 June that medical use of marijuana is illegal under federal law, even though 11 individual states allow it. The judgement is the result of an appeal by Bush's government over a case against two women in California who use the drug medicinally. The pair may now be arrested.
Technically, the ruling means that federal authorities may prosecute the doctors, patients and suppliers involved in medicinal marijuana use, although lawyers point out that federal enforcement is likely to be lax.
The ruling is seen as a victory by those who dispute the medical benefits of marijuana use. "The medical marijuana farce is done," says John Walters, the White House's anti-drug tsar. "I don't doubt that some people feel better when they use marijuana, but that's not modern science. That's snake oil," he says.
Patients' advocates hope that things won't change much for those who use the drug and find it helps with their illnesses. They note that Congress has the capacity to change the law to allow medical use of marijuana.
News@nature.com answers some key questions behind the medical marijuana debate.
Where is marijuana use legal?
Medical use of marijuana has been allowed in Canada since 2001, and the Netherlands since 2003. Although it is strictly illegal in Britain, legal authorities have generally taken a lenient attitude towards medicinal users. In most countries, certain marijuana extracts are also available on prescription.
California's Compassionate Use Act of 1996 ensures that "seriously ill Californians have the right to obtain and use marijuana for medical purposes". Similar acts allow limited marijuana use in Alaska, Arizona, Colorado, Hawaii, Maine, Montana, Nevada, Oregon, Vermont and Washington. These state laws remain in effect, so prosecution of users would have to be a federal undertaking.
How many people use it medicinally?
Marijuana is the most frequently used illegal drug in the United States. According to federal statistics, nearly 95 million Americans over the age of 12 have tried marijuana at least once.
It is commonly said that thousands of people in North America use marijuana for medicinal purposes, but the numbers are difficult to assess. In Canada, where there is a federally sanctioned process for getting marijuana on prescription, a surprisingly small number of people actually have permission to use the drug: 821, to be precise, as of April 2005. The Canadian government currently receives about 40 applications a month for 'authorization to possess' the drug.
What is in marijuana?
The dried leaves of the plant Cannabis sativa contain more than 60 active chemicals. The most psychoactive is delta-9-tetrahydrocannabinol (9-THC), which scientists believe stimulates the brain to release the neurotransmitter dopamine. This drug, often known as cannabis, is also available as a resin or oil made from the plant.
The quality of the drug as bought on the street varies widely. Experts in the United States say that today's marijuana is generally much stronger that it was in the 1960s. The average strength of cannabis in Europe seems to have remained fairly steady at around 6-8% THC1.
How do patients get it?
In Canada there is a federally sanctioned operation that grows plants in a controlled environment in an abandoned mine. Patients have to go through their doctors to get permission to use it.
Before the US government prohibited the use of marijuana in 1937, many medicines containing the drug were legally available. Today, other cannabinoids are available on prescription. In April this year, Canada approved the use of a cannabis spray called Sativex (marketed by Bayer), which contains THC and cannabidiol, to give pain relief to people who suffer from multiple sclerosis. Marinol, which contains synthetic THC called dronabinol and is marketed by Solvay, can be prescribed in the United States to control nausea and appetite loss.
But many medicinal users buy their cannabis from the same sources as recreational users do.
Does marijuana have medical benefits?
Many people use cannabis to treat pain. Others use it to increase appetite and suppress nausea, which can be a side-effect of HIV or cancer treatments. And many multiple sclerosis sufferers say that it helps to ease the tremors and pain associated with the disease. Some small clinical trials have shown that cannabis can have these medical benefits (see ' Cannabis study shows small MS benefit').
An influential US Institute of Medicine report2 from 1999 concluded that no health benefits were yet proven, and called for more research in the area.
Is it bad for you?
Taking cannabis can induce panic attacks and paranoia. A study from the Institute of Psychiatry in London showed that cannabis significantly increases the risk of schizophrenia, and exacerbates symptoms in people who already have mental health problems (see ' Cannabis boosts risk of psychosis'). Long-term use can affect memory and sap a user's motivation.
Because most patients smoke cannabis, the increased risk of lung cancer and other diseases is at least as much as for cigarette smokers3. Sativex and Marinol were formulated as oral drugs to avoid this problem.
Is it addictive? Does it lead to more drug use?
Although there is still debate around whether marijuana is physically addictive, people can certainly become compulsive users of the drug. The UK Department of Health says that "cannabis is a weakly addictive drug but does induce dependence in a significant minority of regular users". Some users can experience withdrawal symptoms such as cramps and shaking when they stop taking the drug.
The 1999 US Institute of Medicine report found no evidence that marijuana led to use of harder drugs, or that allowing medical use would markedly increase wider recreational use.
Are people continuing to research marijuana?
Absolutely. The National Institute on Drug Abuse, which is the only legal source of cannabis in the United States, supports research on the drug's effects, although researchers have sometime found it difficult to get approval for medicinal trials (see ' Marijuana researchers reach for pot of gold' ).
Other research projects abound. The University of California's Centre for Medicinal Cannabis Research is conducting clinical trials on pain relief. And the Multidisciplinary Association for Psychedelic Studies, based in Sarasota, Florida, has spent more than $2 million since 1995 on education and research into medical marijuana use.
Do other recreational drugs have medicinal purposes?
Yes. There are a number of ongoing studies into the possible benefits of MDMA, the active ingredient in ecstasy, for treatment of stress-related syndromes (see ' The ups and downs of ecstasy' ).
The hallucinogenic peyote cactus, which is traditionally used by some Native Americans to cure drug addiction and alcoholism, contains the promising drug mescaline. Researchers are investigating its effects.
And there are some trials involving psilocybin, the active ingredient in 'magic' mushrooms. These aim to see whether it can manage symptoms of obsessive-compulsive disorder or relieve anxiety in terminally ill cancer patients.
- King L. A., An overview of cannabis potency in Europe, Office for Official Publications of the European Communities (2004).
- Institute of Medicine report 'Marijuana and Medicine', http://books.nap.edu/html/marimed/ (1999).
- Sridhar K. S., et al. J. Psychoactive Drugs, 26. 285 - 288 (1994).