There is a growing popular belief that cannabis is natural and therefore harmless to use. In fact many people who are addicted to opioids believe that cannabis use is a substitute to methadone and can help them control opioid withdrawal symptoms. In addition there are an increasing number of studies advocating for the use of cannabis instead of opioids for chronic pain. Is cannabis harmless for everyone as claimed? Will making cannabis legal and eventually more accessible do harm or good?
Criminalization of cannabis has been ineffective in reducing its use, generating larger societal costs with minimal effect on public health. Canada is moving towards legalization of cannabis, and therefore it is important for the public to be aware of potential risks of cannabis on people, especially people with opioid addiction in the current opioid epidemic before cannabis becomes widely available.
Public perception of cannabis is that it is a harmless substance, mainly because it is unlikely to lead to death due to overdose. While there are no documented reports of fatal overdoses from cannabis, other adverse consequences have been noted, including cognitive impairment, respiratory problems, and psychotic symptoms. Vulnerable populations, such as those with existing addictions, are at greater risk of experiencing these adverse events.
Opioid addiction (or opioid use disorder) has skyrocketed around the globe, and is especially pervasive in Canada where it was declared a public health crisis. Deaths from opioid overdoses have become commonplace in Canada; the urgent need for adequate treatment options for those with opioid addictions has been emphasized by clinicians and the public.
Cannabis is a widely used substance and is the most commonly used drug among patients in methadone treatment (60% of men and 44% of women).
Methadone maintenance treatment is currently the oldest and most widely used pharmacological treatment for opioid addiction. Those in treatment receive a daily dose of methadone, a long-acting synthetic opioid, to reduce cravings and relieve withdrawal symptoms without producing the same euphoric effects of other opioids.
Although methadone treatment is effective for many patients, there are others who continue to use illicit opioids during treatment which poses a serious health risk for overdose and death. Cannabis is a widely used substance and is the most commonly used drug among patients in methadone treatment (60% of men and 44% of women). It is used at much higher rates than the general population, leading to the question of what effects cannabis has on this population.
In our study recently published in Biology of Sex Differences, we investigated the association between cannabis use and methadone treatment outcomes, in particular, concurrent illicit opioid use. Previous research has found differences in clinical profile and treatment outcomes between men and women, and therefore our study aimed to explore sex differences in cannabis use.
We included 777 participants in this study (414 men and 363 women). About 60% of men and 44% of women reported using cannabis. After controlling for age, methadone dose, and length of time in treatment, we found women were 82% more likely to also use illicit opioids while on methadone treatment if they were cannabis users.
We found women were 82% more likely to also use illicit opioids while on methadone treatment if they were cannabis users.
Women in methadone treatment also have significantly worse physical and psychological functioning and higher rates of comorbid psychiatric disorders. A recent study found the motivation for using cannabis varied between men and women, whereby women tended to report the primary purpose for using it was for self-medication, whereas men more often reported using cannabis was for recreational purposes. However what we see in this study is that women who use cannabis are not fairing well compared to men. Cannabis has not helped women and was associated with worse health outcomes for them.
Where do we go next?
Historically, addiction was a male-dominated problem, and thus past research and subsequently clinical practices are largely male-centric. Addiction treatment programs should adopt a more gender-informed approach to treatment to address the unique needs of men and women. The first step towards doing this may be to systematically screen for cannabis use in women on MMT, and aim to address their underlying physical and psychological symptoms in addition to the opioid addiction in order to improve treatment outcomes.