17 December 2013 

Canadian survey compares marijuana use across different conditions

Marijuana has a long history of traditional medicinal use. Today, extracts of marijuana, such as nabilone (Cesamet), are available by prescription for the treatment of nausea and to stimulate appetite and, in the case of cannabidiol (Sativex), to treat some symptoms of multiple sclerosis (MS) and pain. In conducting a large survey about marijuana use, Canadian researchers may have uncovered other potential medicinal applications for this herb.

In 2011 and 2012, researchers at the University of British Columbia and elsewhere launched a detailed survey to explore the reasons that Canadians with different medical conditions used marijuana. The survey also enquired about how users perceived the effectiveness of marijuana in treating their symptoms.

The researchers found that among 628 survey participants, across many health conditions, common reasons for marijuana use included the following: managing sleep difficulties, coping with the distress of chronic pain and anxiety. The researchers noted that studies could be done to explore the effect of marijuana on these conditions. Other findings from the survey appear in this CATIE News bulletin.

Study details

Based on previous work and in consultation with medical marijuana users and experts, the research team developed a survey and posted it online where participants from across the country could complete it. To complement this, some surveys could be completed in person at a marijuana dispensary in the interior of B.C.

Many of the participants who completed the survey received marijuana through a program established by Health Canada to facilitate access for medical purposes. Briefly, Health Canada listed two categories of illness under which affected people could apply for access to medical marijuana, as follows:

Category 1:

  • arthritis
  • cancer
  • epilepsy
  • multiple sclerosis (MS)
  • spinal cord injury or disease

Category 2:

  • people with other symptoms and conditions that were assessed by a physician and a specialist and deemed treatable with medical marijuana

The survey was comprehensive and designed to be completed in less than one hour.

Participants were recruited from across Canada via advertisements at marijuana dispensaries and through organizations that serve people affected by some of the conditions listed in Category 1.

The average profile of people who completed the survey was as follows (note that the total proportions of people in categories may not equal 100 due to rounding):

  • gender – 71% male, 29% women
  • common ethno-racial groups – 92% white, 7% Aboriginal                    
  • most participants were between 18 and 55 years
  • nearly 60% had a college or university education
  • 60% earned less than $40,000 per year
  • 78% lived in an urban area

Results—Main conditions

Participants disclosed that they used marijuana to help manage the following conditions, most of which were listed in Category 1 above:

  • arthritis
  • anxiety and/or depression
  • chronic pain
  • spinal pain
  • gastrointestinal disorders
  • MS

Although participants were asked about the main condition for which they sought marijuana treatment, researchers also asked about all symptoms for which marijuana was used. Within the major categories previously mentioned (arthritis, cancer and so on), 99% of participants listed one or more of the following symptoms for which they used marijuana to find relief:

  • anxiety
  • pain
  • sleeping problems

Overall, 57% of participants disclosed that they used marijuana to provide relief from all three problems.

Results—Other conditions

Less than 10% but more than 2% of participants reported that they used marijuana for the following conditions:

  • higher-than-normal blood pressure
  • tics
  • to help normalize blood sugar
  • bladder dysfunction
  • male sexual dysfunction
  • seizures

Results—Uncommon uses

For each of the following conditions, less than 2% of participants reported medicinal use of marijuana:

  • attention deficit disorder
  • chronic fatigue syndrome
  • complications arising from hepatitis C virus infection
  • Parkinson’s disease
  • Tourette’s syndrome
  • Wilson’s disease

Conditions and associations

The study team also found the following associations:

  • People with spinal injuries reported using marijuana to treat muscle spasms.
  • People whose main condition was arthritis-related were more likely than others to disclose that they used marijuana to manage inflammation and to try to decrease elevated pressure within the eyeball.
  • HIV-positive people most commonly reported using marijuana to treat nausea and improve their appetite.
  • People who used marijuana for mental health issues reported having these conditions: anxiety, aggression, depression and psychosis.

Perceived effectiveness

As the researchers’ analysis was based on a survey (rather than several well-designed clinical trials), we cannot be certain about users’ experiences with marijuana. However, researchers reported that, overall, 72% of participants noted that marijuana was “always helpful” when managing the conditions for which they sought relief. The researchers stated that this level of user assessment was “relatively consistent across [different] conditions.” One exception to this was the category HIV/AIDS.

The team noted that HIV-positive participants had a relatively lower endorsement of marijuana’s effects, with 55% of them finding it “always helpful” for reducing nausea or improving appetite.

The researchers stated that nearly 60% (358 people) of all participants disclosed that they were taking medications in addition to marijuana to help manage conditions. Of these 358 people, 79% reported that marijuana had “fewer side effects” than their medicines used to treat the same condition.

Personal history of marijuana use

Overall, 82% of participants disclosed that they had previously used marijuana for what the researchers termed “non-therapeutic purposes”—presumably this meant to get high. The age at which participants first used marijuana recreationally was 17 years and the age at first therapeutic use was 28 years.

The researchers stated that “individuals with and without history of non-therapeutic use did not differ with regard to demographic characteristics, or conditions and symptoms.”

Furthermore, they added, “Most participants who reported prior use reported increased use with the initiation of therapeutic use,” as follows:

  • 33% of participants reported a large increase
  • 32% of participants reported a small increase
  • 7% reported a large decrease
  • 10% reported a small decrease

Amounts, frequency and mode of use

Participants used varying amounts of marijuana per week, from less than 2 grams to more than 14 grams.

Most participants used marijuana at least twice daily, with nearly one-third of participants using it four or more times daily.

Participants preferred to ingest marijuana mainly in the following three ways:

  • smoking
  • using a vapourizer
  • eating it in baked goods


According to researchers, about 32% of participants were authorized by Health Canada to possess marijuana for therapeutic purposes. Another 12% had applications in process and 3% who had applied for authorization had their application declined.

Participants who used marijuana for relief of sleeping problems and anxiety were less likely to have Health Canada authorization for marijuana compared to participants who had other conditions such as MS or gastrointestinal problems. Indeed, overall, the researchers noted that participants whose main reason(s) for using marijuana were for conditions not listed in the Health Canada program were less likely to obtain authorization for the therapeutic use of marijuana.

Present and future research

Researchers found that some Canadians are using marijuana to help manage many conditions. Commonly treated symptoms included sleeping problems, anxiety and depression across major health conditions. This finding raises the possibility that marijuana or its extracts could be studied for the treatment of these symptoms.

The study team urged a degree of caution when interpreting its findings until a more rigorous study is done to confirm them. The reasons for such caution with the present study arise because of at least the following reasons:

  • Participants were not randomly selected but instead chose themselves. This self-selection could have inadvertently biased the type of people who responded and affected the study’s results.
  • As recruitment was done through organizations that support the medical use of marijuana, it is possible that people whose medical conditions respond favourably to marijuana were over-represented in this survey.
  • Independent medical confirmation of each participant’s health problems was not available. It is therefore possible that some participants could have misclassified their conditions, inadvertently leading to another source of potential bias.

However, these limitations may be “counterbalanced” because the researchers argued that their study had several strengths, such as the following:

  • having an “in-person subsample to complement the online survey”
  • using a community research board to help develop the survey
  • general adherence to “established standards for reporting Internet-based surveys”

The research team states that its survey is “the largest and most comprehensive study of the therapeutic use of [marijuana] in Canada.”

The present study provides a foundation for developing plans for well-designed clinical trials to explore the potential therapeutic effects of marijuana on human health. In particular, the study researchers suggest that marijuana be studied for its potential in helping to relieve conditions such as anxiety and sleeping disorders.


Health Canada’s program for medical access to marijuana is changing. For further information visit the Health Canada webpage.

—Sean R. Hosein


Walsh Z, Callaway R, Belle-Isle L, et al. Cannabis for therapeutic purposes: Patient characteristics, access and reasons for use. International Journal on Drug Policy. 2013; in press.