Could medical marijuana help or hinder your health? Find out the latest research on cannabis.

There are few topics more controversial in health circles than medical marijuana. To some, the cannabis plant provides a miracle treatment that can erase pain, ease nausea, reduce seizures and combat a long list of other serious health issues. To others, marijuana is an unproven, risky, illegal substance that can lead to long-term health problems.

Until recently, that debate remained largely rhetorical. That's because tight government restrictions and a lack of funding for research—as well as a stigma against marijuana—made studies virtually impossible to conduct in countries like Canada. But now, shifting attitudes are slowly opening the door to more research into how the drug works and what conditions it may be useful in treating. In Canada, several clinical trials have been approved or are underway, and a growing number of experts believe that, within a decade, we will have clear answers about the true benefits—and risks—of medical cannabis.

But many Canadians aren't willing to wait for further testing. As medical marijuana becomes more widely accessible, the number of people registered to use it has soared—from just 500 patients in 2001 to nearly 38,000 in 2013, according to Health Canada. And on the sidelines, many more are wondering if the drug might be right for them or one of their loved ones—and how to avoid the potential risks.

Here is where the research is headed and what you need to know.

How does the system work?
Despite numerous anecdotal success stories, the safety of cannabis has not been thoroughly assessed by Health Canada, nor has the drug been approved as a medical treatment. But because of a court ruling, the federal government must provide patients with reasonable access to medical marijuana from a list of licensed producers. So physicians across the country are now the gatekeepers of medical cannabis, despite a lack of clear evidence of how well it works. It's a confusing situation—one that puts both doctors and patients in a challenging position.

"There's certainly something within the cannabis plant that has benefits for patients living with various different chronic conditions," says Jason J. McDougall, arthritis and pain researcher at Dalhousie University in Halifax. "I would recommend they consider it and keep an open mind."

How does marijuana work as a medicine?
The healing power of medical marijuana is believed to lie in compounds found in the plant called cannabinoids. When it comes to marijuana, the two best-known and most widely studied cannabinoids are tetrahydrocannabinol (THC) and cannabidiol (CBD). Cannabinoids are naturally occurring in the body and send important messages to help regulate and control pleasure, pain, appetite and responses to other stimuli. That's why some people report an improvement in symptoms after smoking marijuana, says M-J Milloy, assistant professor in the department of medicine at The University of British Columbia.

What conditions can medical marijuana treat?
It remains a thorn in the side of scientists that there have been few reliable cannabis trials. However, according to an analysis of 79 randomized trials, published last June in The Journal of the American Medical Association, there is evidence that suggests cannabis may be an effective treatment for chronic pain and muscle stiffness caused by multiple sclerosis (MS).
 
One 2010 study published in the Canadian Medical Association Journal found that people dealing with neuropathic pain from an injury or surgery experienced less pain and were able to sleep better when they took three puffs of cannabis a day. The researchers used a low dose to limit any psychoactive effects of the drug, such as paranoia, impaired memory and hallucinations. They said it's possible higher potencies and flexible dosing strategies could yield different results. But more research is needed to make such conclusions.

Dr. David Casarett, a Philadelphia palliative-care physician and the author of Stoned: A Doctor's Case for Medical Marijuana, says that, in addition to relieving pain and muscle problems in MS patients, cannabis also may boost the appetites of cancer and HIV-AIDS patients.

Do patients have to smoke it?
The way a patient consumes marijuana—smoking it, vaporizing it or eating it in baked goods—usually depends on personal preference and the reason for its use, but smoking and vaporizing bring near-immediate results, says Dr. Casarett. When smoked or vaporized, the drug goes from the lungs to the brain, bypassing the stomach and liver, and the effects are felt in minutes. When eaten, it can take one to two hours before the drug fully takes effect.

What conditions need more research?
While some people swear that cannabis helps with the effects of post-traumatic stress disorder, insomnia, glaucoma, autism and epilepsy, additional research is required.

At UBC, Milloy has conducted research that found that among people recently infected with HIV, those regularly using cannabis had significantly less of the virus in their blood than those who didn't use it frequently or at all. In June of last year, medical marijuana startup National Green Biomed donated $1 million to The University of British Columbia to support Milloy's research.

In July, The Arthritis Society revealed that it's funding a three-year animal study, led by McDougall, to see if cannabis-like compounds can help repair damaged nerves and alleviate joint pain. "The treatments that we do have currently available for chronic pain conditions are not 100 percent effective in all patients," says McDougall. "We need to find alternative ways to treat these symptoms, and cannabis could potentially be one way of doing it."

And last September, The Globe and Mail reported that an Alberta mother travelled to Ontario to get a medical marijuana prescription for her daughter's severe epilepsy after her own doctor said he could no longer provide it; Sarah Wilkinson said cannabis oil extracted from marijuana is the only thing that stopped her daughter from having up to 100 seizures a day.

What about the risks?
People who use marijuana recreationally may suffer lung damage due to smoke inhalation, short-term memory loss, addiction and the increased possibility of mental illness. Children and adolescents, whose brains are still developing, are particularly at risk. Several studies have linked the use of marijuana by young people to an increased risk of mental illness, including psychotic disorders such as schizophrenia, depression and anxiety. It's unclear whether early marijuana use may cause a psychotic disorder or may simply trigger it earlier in those predisposed, but the U.S. National Institute on Drug Abuse notes the best evidence to date suggests the biggest risks are in those predisposed to mental illness.

Does that mean patients who use medical marijuana are at risk of mental illness, too? Researchers still aren't sure. But it's a calculated risk those who turn to the drug for relief are willing to make.

Psychedelic drugs may be next
Marijuana isn't the only illicit substance stepping out of the shadows. There is growing interest in the potential for psychedelic drugs such as lysergic acid diethylamide (LSD), mescaline (also known as peyote) and methylenedioxy­methamphetamine (MDMA or ecstasy) to treat a range of conditions, including post-traumatic stress disorder (PTSD), anxiety and addiction. Psychedelic drugs can affect mood, thoughts and perception.

A group of B.C. researchers recently published a commentary in the Canadian Medical Association Journal urging policymakers to rethink their perceptions of those drugs and to allow more research. The paper notes that a Swiss study published in 2014 found that LSD paired with psychotherapy helped reduce anxiety in terminal cancer patients. And U.S. research has shown that MDMA-assisted psychotherapy may help reduce symptoms of PTSD.

However, other experts warn of the risks associated with psychedelic drugs, such as increased heart rate, hallucinations and risk-taking behaviour, and say that research must be approached with caution. 

Learn about other new developments in Canadian health care.

This story was originally titled "Need For Weed?" in the March 2016 issue. Subscribe to Canadian Living today and never miss an issue!