Zero-Field Spin Waves in YIG Nanowaveguides.

Spin-wave-based transmission and processing of information is a promising emerging nanotechnology that can help overcome limitations of traditional electronics based on the transfer of electrical charge. Among the most important challenges for this technology is the implementation of spin-wave devices that can operate without the need for an external bias magnetic field. Here we experimentally demonstrate that this can be achieved using submicrometer wide spin-wave waveguides fabricated from ultrathin films of a low-loss magnetic insulator, yttrium iron garnet (YIG). We show that these waveguides exhibit a highly stable single-domain static magnetic configuration at zero field and support long-range propagation of spin waves with gigahertz frequencies. The experimental results are supported by micromagnetic simulations, which additionally provide information for the optimization of zero-field guiding structures. Our findings create the basis for the development of energy-efficient zero-field spin-wave devices and circuits.

Sex differences in the subjective and reinforcing effects of smoked cannabis.

Preclinical studies have shown sex-based differences in the reinforcing effects of cannabinoid 1 receptor agonists such as delta-9-tetrahydrocannabinol (THC). This study sought to test whether these sex differences translate to humans by assessing the subjective and reinforcing effects of smoked cannabis in male and female volunteers. We pooled data (n = 68; 55M, 13F) from two within-subject randomized controlled trials of healthy, ≥weekly cannabis users comparing the subjective and reinforcing effects of smoked active (~25 mg THC) versus placebo cannabis (0-mg THC). Subjective ratings of drug effects and mood were measured using visual analogue scales, and reinforcing effects were measured with a cannabis self-administration task. Sex-dependent outcomes were explored using generalized linear mixed models. Under active cannabis conditions, female participants reported greater reductions from baseline in cannabis craving and significantly higher cannabis-specific ratings of strength, liking, willingness to take again and good effect, compared with males (interaction p < 0.05). Placebo and active cannabis were self-administered by 22% and 36% of male participants, respectively, and by 15% and 54% of female participants, respectively. Receipt of active cannabis significantly increased likelihood of self-administration (p = 0.011), but a sex difference was not detected (p = 0.176). Although females were more sensitive to certain positive subjective effects of active cannabis, they were not more likely than males to self-administer it. These findings highlight the need to test sex differences as a primary objective in experimental studies and may shed light on accelerated trajectories from initiation to cannabis use disorder observed among women.

Prevalence and correlates of intentional substance use to reduce illicit opioid use in a Canadian setting.

Background: While preliminary evidence has begun to document intentional use of one substance to reduce the use of another, the phenomenon of drug substitution among people who use illicit opioids remains understudied. Therefore, we sought to estimate the prevalence and correlates of intentional substance use to reduce illicit opioid use among persons who use drugs (PWUD). Methods: We analysed data from three prospective cohorts of PWUD in Vancouver, Canada, using multivariable generalized estimating equations (GEE). Results: Between June 2012 and June 2016, 1527 participants were recruited and contributed 4991 interviews. Of those, 336 (22%) illicit opioid-using participants self-reported substitution to reduce illicit opioid use at least once during study period contributing 467 (9.4%) interviews. Among those interviews, substances substituted for opioids were alcohol (15 participants, 3.2%), stimulants (235, 50.3%), cannabis (129, 27.6%), benzodiazepines (21, 4.5%), and others (20, 4.3%). In multivariable GEE model adjusted for socio-demographic factors, reporting substitution to reduce illicit opioid use was positively associated with greater likelihood of daily cannabis use (Adjusted Odds Ratio = 1.56, 95% Confidence Interval: 1.24-1.96]. Conclusions: While daily cannabis use was associated with reporting opioid substitution attempts, additional study is needed to examine potential of cannabis/cannabinoids to reduce illicit opioid use.

Use of Cannabis for Harm Reduction Among People at High Risk for Overdose in Vancouver, Canada (2016-2018).

Objectives. To characterize the prevalence and reasons for the use of cannabis as a strategy to reduce the harms arising from other substances.Methods. We drew data about recent cannabis use and intentions from 3 prospective cohort studies of marginalized people who use drugs based in Vancouver, Canada, from June 2016 to May 2018. The primary outcome was "use of cannabis for harm reduction," defined as using cannabis for substitution for licit or illicit substances such as heroin or other opioids, cocaine, methamphetamine, or alcohol; treating withdrawal; or coming down off other drugs.Results. Approximately 1 in 4 participants reported using cannabis for harm reduction at least once during the study period. The most frequent reasons included substituting for stimulants (50%) and substituting for illicit opioids (31%).Conclusions. The use of cannabis for harm reduction is a common strategy among people who use drugs in our setting. Further research into the factors associated with this strategy is needed. Better characterization of the risks and benefits of substitution strategies, including for opioids and stimulants, may prompt new treatment options for PWUD.

Frequent Cannabis Use and Cessation of Injection of Opioids, Vancouver, Canada, 2005-2018.

Objectives. To evaluate the impact of frequent cannabis use on injection cessation and injection relapse among people who inject drugs (PWID).Methods. Three prospective cohorts of PWID from Vancouver, Canada, provided the data for these analyses. We used extended Cox regression analysis with time-updated covariates to analyze the association between cannabis use and injection cessation and injection relapse.Results. Between 2005 and 2018, at-least-daily cannabis use was associated with swifter rates of injection cessation (adjusted hazard ratio [AHR] = 1.16; 95% confidence interval [CI] = 1.03, 1.30). A subanalysis revealed that this association was only significant for opioid injection cessation (AHR = 1.26; 95% CI = 1.12, 1.41). At-least-daily cannabis use was not significantly associated with injection relapse (AHR = 1.08; 95% CI = 0.95, 1.23).Conclusions. We observed that at-least-daily cannabis use was associated with a 16% increase in the hazard rate of injection cessation, and this effect was restricted to the cessation of injection opioids. This finding is encouraging given the uncertainty surrounding the impact of cannabis policies on PWID during the ongoing opioid overdose crisis in many settings in the United States and Canada.

Frequency of cannabis and illicit opioid use among people who use drugs and report chronic pain: A longitudinal analysis.

BACKGROUND: Ecological research suggests that increased access to cannabis may facilitate reductions in opioid use and harms, and medical cannabis patients describe the substitution of opioids with cannabis for pain management. However, there is a lack of research using individual-level data to explore this question. We aimed to investigate the longitudinal association between frequency of cannabis use and illicit opioid use among people who use drugs (PWUD) experiencing chronic pain. METHODS AND FINDINGS: This study included data from people in 2 prospective cohorts of PWUD in Vancouver, Canada, who reported major or persistent pain from June 1, 2014, to December 1, 2017 (n = 1,152). We used descriptive statistics to examine reasons for cannabis use and a multivariable generalized linear mixed-effects model to estimate the relationship between daily (once or more per day) cannabis use and daily illicit opioid use. There were 424 (36.8%) women in the study, and the median age at baseline was 49.3 years (IQR 42.3-54.9). In total, 455 (40%) reported daily illicit opioid use, and 410 (36%) reported daily cannabis use during at least one 6-month follow-up period. The most commonly reported therapeutic reasons for cannabis use were pain (36%), sleep (35%), stress (31%), and nausea (30%). After adjusting for demographic characteristics, substance use, and health-related factors, daily cannabis use was associated with significantly lower odds of daily illicit opioid use (adjusted odds ratio 0.50, 95% CI 0.34-0.74, p < 0.001). Limitations of the study included self-reported measures of substance use and chronic pain, and a lack of data for cannabis preparations, dosages, and modes of administration. CONCLUSIONS: We observed an independent negative association between frequent cannabis use and frequent illicit opioid use among PWUD with chronic pain. These findings provide longitudinal observational evidence that cannabis may serve as an adjunct to or substitute for illicit opioid use among PWUD with chronic pain.

3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) use and transitions to injection drug use among street-involved youth.

Background: Despite the popularity of 3,4-methylenedioxymethamphetamine (MDMA; ecstasy) among young people across North America and Europe, MDMA is rarely explored in studies of young people at high risk of injecting drugs. We conducted a study among street-involved youth who use illicit drugs in Vancouver, Canada, to understand if use of MDMA is associated with initiation of injection drugs. Methods: We followed injection-naïve participants in the At-Risk Youth Study (ARYS), an ongoing prospective cohort of street-involved youth aged 14-26 who use illicit drugs. Bivariate and multivariate extended Cox models with time-updated variables were used to examine the association between MDMA use and initiation of injection drug use between September 2005 and May 2015. Results: Among 483 youth, 306 (63.4%) had a history of MDMA use and 218 (45.1%) had used MDMA in the previous 6 months at baseline. A total of 105 (21.7%) youth initiated injection drug use over the 10-year period, yielding an incidence density of 8.51 (95% confidence interval [CI]: 6.96-10.30) per 100 person-years. MDMA use was not significantly associated with initiating injection drugs at the bivariate (hazard ratio: 0.93, 95% CI: 0.61-1.42) or multivariate (adjusted hazard ratio: 0.88, 95% CI: 0.57-1.35) level, after adjusting for socio-demographic and substance use confounders. Conclusions: Amid ongoing frequent use of MDMA among some young people in North America, we did not observe an elevated risk of injection initiation among those who used MDMA in this cohort of street-involved youth.

Patterns of Non-injection Drug Use Associated with Injection Cessation among Street-Involved Youth in Vancouver, Canada.

Although abstinence from drug use is often a key goal of youth substance use treatment, transitioning to less harmful routes and types of drug use is desirable from both a clinical and public health perspective. Despite this, little is known about the trajectories of youth who inject drugs including changes in patterns of non-injection drug use. The At-Risk Youth Study (ARYS) is a longitudinal cohort of street-involved youth who use drugs in Vancouver, Canada. We used linear growth curve modeling to compare changes in non-injection drug use among participants who ceased injecting drugs for at least one 6-month period between September 2005 and May 2015 to matched controls who continued injecting over the same period. Of 387 eligible participants, 173 (44.7%) reported ceasing drug injection at least once. Non-injection drug use occurred during 160 (79.6%) periods of injection cessation. In adjusted linear growth curve analyses, the only non-injection drug use pattern observed to decrease significantly more than controls following injection cessation was daily crack/cocaine use (p = 0.024). With the exception of frequent crack/cocaine use, transitions out of injection drug use did not appear to coincide with increased reductions in patterns of non-injection drug use. Our findings indicate that most (80%) of the observed injection cessation events occurred in the context of ongoing substance use. Given that transitioning out of drug injection represents a significant reduction in risk and harm, efforts supporting vulnerable youth to move away from injecting may benefit from approaches that allow for ongoing non-injection drug use.

Prescription Opioid Injection Among HIV-Positive People Who Inject Drugs in a Canadian Setting.

Prescription opioids (POs) are commonly prescribed to patients living with HIV/AIDS, while the illicit use of POs remains a major public health concern throughout Canada and the United States. We sought to identify the prevalence and correlates of PO injection among HIV-positive people who inject drugs (PWID) in Vancouver, Canada, where HIV/AIDS treatment and care is offered at no cost. We examined data from 634 individuals from an ongoing prospective cohort of HIV-positive PWID. Between December 2005 and November 2013, the median prevalence of recent PO injection was 24.2 % [interquartile range (IQR): 21.5-25.8 %]. In a multivariable generalized estimating equation model, Caucasian ethnicity, heroin injection, and drug dealing were positively associated with PO injection, while older age and methadone maintenance treatment were negatively associated with PO injection (all p < 0.05). Engagement on antiretroviral therapy was inversely associated with PO injection in a bivariable analysis, but did not remain significant after adjusting for heroin injection. These findings describe a particularly vulnerable sub-group of PWID who may benefit from targeted efforts to both minimize drug-related risk behaviors and support HIV/AIDS treatment.

Prescription opioid use and non-fatal overdose in a cohort of injection drug users.

BACKGROUND: There is growing concern regarding rising rates of prescription drug-related deaths among the general North American population as well as increasing availability of illicitly obtained prescription opioids. Concurrently among people who inject drugs (IDU), illicit prescription opioid use has increased while non-fatal overdose remains a major source of morbidity. OBJECTIVES: To evaluate whether the use of prescription opioids was associated with non-fatal overdose among IDU in Vancouver, Canada. METHODS: Data was obtained from two open prospective cohorts of IDU between December 2005 and May 2013. We used generalized estimating equation (GEE) logistic regression to evaluate the association between prescription opioid use and non-fatal overdose, adjusting for various social, demographic, and behavioral factors. RESULTS: There were 1614 IDU, including 541 (33.5%) women, who were recruited and included in this analysis. At baseline, 526 (32.6%) reported using prescription opioids and 118 (7.3%) reported experiencing an overdose in the previous six months. In a multivariable analysis, prescription opioid use remained independently associated with non-fatal overdose (adjusted odds ratio: 1.61, 95% confidence interval: 1.32-1.95), after adjusting for confounders. CONCLUSION: We observed relatively high rates of prescription opioid use among IDU in this setting, and found an independent association between prescription opioid use and non-fatal overdose. Our data is likely representative of riskier substance use associated with those who use prescription opioids within our sample. Interventions to prevent and respond to overdoses should consider the higher risk profiles of IDU who use prescription opioids.

The Global Psychedelic Survey: Consumer characteristics, patterns of use, and access in primarily anglophone regions around the world.

OBJECTIVES: Despite advancements in policies governing psychedelic substances globally, our understanding of real-world psychedelic use and its variations across international jurisdictions remains limited. We implemented the Global Psychedelic Survey (GPS) to capture information about psychedelic consumer characteristics, access, and usage patterns around the world. METHODS: The GPS was administered online in Spring 2023 to English-speaking adults (≥21 years) who use(d) psychedelics. We categorized survey responses into major catchment regions (Canada/US, Europe/UK, Australia/NZ, All Other). We used descriptive and bivariable statistics to characterize consumers' socio-demographic characteristics, psychedelic access sources, and usage patterns. We examined regional differences in psychedelic use patterns using multinomial logistic regression. RESULTS: We analyzed 6379 responses from 85 countries including Canada/US (n = 4434), Europe/UK (n = 771), Australia/NZ (n = 864), and Other (n = 310). Psilocybin, LSD, and MDMA were the most used psychedelics and personal growth was the most common use motive across all catchments. There were significant regional differences in psychedelic use patterns, including types of psychedelics used (e.g., less ibogaine use in Europe/UK and Australia/NZ relative to Canada/US), frequency of use (e.g., lower frequency use in Australia/NZ relative to Canada/US), motivations for use (e.g., less therapeutic use in Europe/UK and Other relative to Canada/US), and types of dosing regimens (e.g., more "micro"-dosing in Canada/US). DISCUSSION: In this large sample of adult psychedelic consumers from regions around the world, infrequent psychedelic use centered around life enhancement was common. Respondents indicated preference for legal access via quality-controlled sources. Jurisdictional differences in access and usage patterns likely reflect region-specific regulations and traditional practices. Further research should explore opportunities to increase representation of non-White respondents in psychedelic research via translation of studies into several languages and incorporation of culturally reflective, community-based study development.

Age-related Patterns of Medical Cannabis Use: A Survey of Authorized Patients in Canada.

Objective: An increasing number of Canadians are registering as authorized users of medical cannabis. Older patients comprise a growing subset of this population; however, relatively little information exists around age-related patterns of medical cannabis use. Methods: The Canadian Cannabis Patient Survey (CCPS) is a large cross-sectional survey of authorized medical cannabis patients in Canada. This publication summarizes the results of the CCPS 2021, with a focus on age-related outcomes and the elderly sub-population. Results: The survey was completed by 2,697 patients. The mean age of participants was 54.3 years of age and the proportion of female respondents was 49.1%. Among older patients, pain was the most common symptom, while anxiety was the most common symptom reported by younger patients. Older patients exhibited a significant preference for oral administration over inhalation of medical cannabis when compared to younger patients, respectively (p>0.05). Among patients taking prescription opioids, most of whom were older patients, 54% reported a decrease in use concurrent with medical cannabis. Conclusions: Older patients comprise a growing subset of medical cannabis patients, which is also reflected in CCPS participants over time. This patient population exhibits different patterns of use compared to their younger counterparts, preferring high CBD orally ingested formulations, which they use primarily to treat pain-related illnesses/symptoms. Overall, study participants reported that cannabis had a high degree of efficacy in alleviating their illness/symptoms, and many reported a reduction in their use of prescription opioids, alcohol, tobacco, and other substances.

Psychedelic substitution: altered substance use patterns following psychedelic use in a global survey.

Introduction: Recent research suggests that psychedelics may have potential for the treatment of various substance use disorders. However, most studies to date have been limited by small sample sizes and neglecting to include non-North American and European populations. Methods: We conducted a global, cross-sectional online survey of adults (n = 5,268, 47.2% women) self-reporting past or current psychedelic use and investigated whether psychedelic use was associated with changes in use of other substances. Results: Nearly three-quarters (70.9%; n = 3,737/5,268) reported ceasing or decreasing use of one or more non-psychedelic substances after naturalistic psychedelic use. Among those with previous use, 60.6% (n = 2,634/4,344) decreased alcohol use, 55.7% (n = 1,223/2,197) decreased antidepressant use, and 54.2% (n = 767/1,415) decreased use of cocaine/crack. Over a quarter of the sample indicated that their decrease in substance use persisted for 26 weeks or more following use of a psychedelic. Factors associated with decreased use included a motivation to either decrease one's substance use or self-treat a medical condition. Importantly, 19.8% of respondents also reported increased or initiated use of one or more other substances after psychedelic use, with illicit opioids (14.7%; n = 86/584) and cannabis (13.3%; n = 540/4,064) having the highest proportions. Factors associated with increased substance use included having a higher income and residing in Canada or the US. Discussion: Although limited by cross-sectional study design, this large observational study will help inform future studies aiming to investigate the relationship between substance use patterns and psychedelic use.

Shifts in medical cannabis use in Canada during the COVID-19 pandemic. / Changements observés au Canada dans la consommation de cannabis à des fins médicales pendant la pandémie de COVID-19.

INTRODUCTION: The COVID-19 pandemic has had widespread secondary negative health impacts including loss of material security and exacerbation of mental illness in at-risk populations. While increases in the nonmedical use of certain substances, including cannabis, have been observed in samples of the Canadian population, no research has documented COVID-concurrent shifts in medical cannabis use in Canada. METHODS: Data were derived from the 2021 Canadian Cannabis Patient Survey, an online survey administered in May 2021 to people authorized to use medical cannabis recruited from one of two Canadian licensed medical cannabis producers. McNemar tests assessed for changes in past 3-month medical cannabis frequency from before to during the pandemic. We explored correlates of increasing frequency of cannabis use since before the pandemic in bivariable and multivariable logistic models. RESULTS: In total, 2697 respondents (49.1% women) completed the survey. Daily medical cannabis use increased slightly but significantly from before the pandemic (83.2%) to during the pandemic (90.3% at time of survey; p < 0.001). Factors significantly associated with increasing frequency of medical cannabis use included female gender, younger age, pandemic-related job loss, primary cannabis use to manage mental health, prescription drug use and nonmedical cannabis use (p < 0.05). CONCLUSION: There were slight shifts towards higher frequency of medical cannabis use after the onset of the COVID-19 pandemic. While short- and long-term impacts of cannabis use on pandemic-related mental distress are unknown, clinicians working with patients who use medical cannabis should be aware of possible changes in use patterns during the pandemic.

Changes in secondary substance use after the onset of the COVID-19 pandemic among people who use cannabis: Findings from a web-based sample of adults in the United States.

The coronavirus disease 2019 (COVID-19) pandemic has had widespread impacts on mental health and substance use. Increases in cannabis use have been documented in the United States, but little is known about how other substance use has changed among people who use cannabis. We sought to examine changes in alcohol, tobacco, opioid, and stimulant use during COVID-19 and explore how these changes relate to patterns of cannabis use. Data were obtained from a web-based survey of adults in the United States who use cannabis (n = 1,471) administered in September 2020. Using data reported in retrospective (prepandemic) and time-of-survey assessment periods, we explored changes in the prevalence of regular (≥ weekly) alcohol, tobacco, opioid, and stimulant use during COVID-19 among respondents who used medical and nonmedical cannabis. We used modified Poisson regression to examine cannabis-related correlates of increasing or decreasing secondary substance use during the pandemic. There was a slight but significant increase in ≥weekly alcohol use in the medical use group only (41.4%-47.0%, p = .034). ≥ Weekly tobacco, opioid, and stimulant use did not change significantly. Pandemic-concurrent shifts in secondary substance use depended on interacting cannabis-related factors including medical cannabis use, prepandemic cannabis frequency, and pandemic-concurrent frequency changes. For example, ≥ weekly prepandemic cannabis use was significantly and positively associated with decreasing opioid use frequency among the medical cannabis use group only. Assessments of the pandemic's effects on substance use should consider relationships between cannabis and other substances, which may differ according to cannabis-specific behaviors, motives, and contexts of use. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Selective Changes in Medical Cannabis Use Early in the COVID-19 Pandemic: Findings from a Web-Based Sample of Adults in the United States.

Background: The COVID-19 pandemic has had widespread impacts on mental health and substance use. While increases in nonmedical cannabis use during COVID-19 have been documented among people who use cannabis across a diversity of settings, changes in specific medical applications of cannabis during the COVID-19 pandemic have not been characterized. We sought to examine changes in the prevalence, frequency, and mode of use of medical cannabis for a range of commonly treated conditions and symptoms during COVID-19. Methods: Data were obtained from an online survey of a sample of adults in the United States who use cannabis (n=1886), administered in September 2020. This study was restricted to participants who self-reported past-year medical cannabis use (n=598). Using data reported in a retrospective (pre-COVID) and current assessment period, we examined changes in cannabis use prevalence, frequency, and inhalation as the primary mode of administration for 11 commonly treated conditions. Results: There were slight but statistically significant increases in weekly (from 21.4% to 23.4%) and daily (from 16.2% to 20.7%) self-reported medical cannabis use during COVID-19 (p<0.001). Anxiety was the only specific therapeutic purpose for which daily cannabis use increased statistically significantly during COVID-19 (18.5% to 25.4%; p=0.004). In multivariable logistic regression, the odds of increasing cannabis use for anxiety during COVID-19 were statistically significantly higher for women, respondents from Western states, and states with legal medical and nonmedical cannabis. Discussion: We detected slight shifts toward higher frequencies of medical cannabis use during COVID-19. Disaggregated by therapeutic indication, daily cannabis use to manage anxiety increased during the pandemic. There is a need to assess whether changes in cannabis use that coincided with the pandemic will be sustained over time, and how these changes are connected to mental health outcomes, particularly among women.

Cannabis use to manage opioid cravings among people who use unregulated opioids during a drug toxicity crisis.

BACKGROUND: Accumulating evidence has indicated that cannabis substitution is often used as a harm reduction strategy among people who use unregulated opioids (PWUO) and people living with chronic pain. We sought to investigate the association between cannabis use to manage opioid cravings and self-reported changes in opioid use among structurally marginalized PWUO. METHODS: The data were collected from a cross-sectional questionnaire administered to PWUO in Vancouver, Canada. Binary logistic regression was used to analyze the association between cannabis use to manage opioid cravings and self-reported changes in unregulated opioid use. RESULTS: A total of 205 people who use cannabis and opioids were enrolled in the present study from December 2019 to November 2021. Cannabis use to manage opioid cravings was reported by 118 (57.6%) participants. In the multivariable analysis, cannabis use to manage opioid cravings (adjusted Odds Ratio [aOR] = 2.13, 95% confidence interval [CI]: 1.07, 4.27) was significantly associated with self-reported reductions in opioid use. In the sub-analyses of pain, cannabis use to manage opioid cravings was only associated with self-assessed reductions in opioid use among people living with moderate to severe pain (aOR = 4.44, 95% CI: 1.52, 12.97). In the sub-analyses of males and females, cannabis use to manage opioid cravings was only associated with self-assessed reductions in opioid use among females (aOR = 8.19, 95% CI: 1.20, 55.81). CONCLUSIONS: These findings indicate that cannabis use to manage opioid cravings is a prevalent motivation for cannabis use among PWUO and is associated with self-assessed reductions in opioid use during periods of cannabis use. Increasing the accessibility of cannabis products for therapeutic use may be a useful supplementary strategy to mitigate exposure to unregulated opioids and associated harm during the ongoing drug toxicity crisis.

The Cannabis-Dependent Relationship Between Methadone Treatment Dose and Illicit Opioid Use in a Community-Based Cohort of People Who Use Drugs.

Background: Methadone maintenance treatment (MMT) is an effective treatment for opioid use disorder. However, subtherapeutic dosing may lead to continued opioid use by failing to suppress opioid withdrawal and craving. Preclinical and pilot experimental research suggests that cannabinoids may reduce opioid withdrawal and craving. We sought to test whether the association between low methadone dose and illicit opioid use differs according to concurrent cannabis use patterns. Methods: Data for this study were derived from two community-recruited cohorts of people (≥18 years old) who use illicit drugs in Vancouver, Canada. We used generalized estimating equations to estimate the adjusted association between lower daily MMT dose (<90 mg/day) and daily illicit opioid use, testing for interaction between dose and daily cannabis use. Results: Between December 2005 and December 2018, 1389 participants reported MMT enrolment and were included in the study. We observed a significant interaction (p<0.01) between daily cannabis and lower MMT dose on concurrent daily illicit opioid use: lower MMT doses increased the odds of daily illicit opioid use by 86% (adjusted odds ratio [AOR]=1.86, 95% confidence interval [CI]=1.61-2.16) during periods of no or low-frequency cannabis use and by 30% during periods of daily cannabis use (AOR=1.30, 95% CI=1.01-1.67). Discussion: This study provides preliminary observational evidence that cannabis may mitigate some of the negative effects of subtherapeutic MMT dosing, guiding future clinical investigations into the safety and efficacy of cannabis and cannabinoids as adjunct treatment for MMT.

Use of Cannabis as a Harm Reduction Strategy Among People Who Use Drugs: A Cohort Study.

Introduction: While substance use contributes to a substantial burden of disease, access to evidence-based harm reduction interventions remains limited or inaccessible. Preliminary research suggests that some individuals use cannabis to reduce the harms associated with their use of other substances, including opioids and stimulants. This study examines factors associated with the self-reported use of cannabis for harm reduction among people who use drugs (PWUD). Methods: We drew data from three prospective, community-recruited cohorts of PWUD in Vancouver, Canada, between June 2016 and May 2018. Multivariable generalized linear mixed-effects modeling was used to examine factors associated with the primary outcome of "use of cannabis for harm reduction," defined as self-reported use of cannabis to substitute for other substances, treat withdrawal, or come down off other drugs. Results: One thousand nine hundred thirty-six participants contributed 5706 observations. In adjusted analyses, daily methamphetamine use (adjusted odds ratio [AOR]=1.43, 95% confidence interval [CI]: 1.09-1.89), experiencing barriers to accessing addiction treatment (AOR=1.92, 95% CI: 1.21-3.03), and enrollment in addiction treatment modalities other than opioid agonist therapy (AOR=1.64, 95% CI: 1.17-2.29) were positively associated with using cannabis for harm reduction. Older age was negatively associated (AOR=0.97, 95% CI: 0.95-0.98). Among 1281 (66.2%) participants who use cannabis, daily cannabis use and obtaining cannabis from unregulated dispensaries were also independent correlates of using cannabis for harm reduction. Discussion and Conclusions: Individuals who were more likely to use cannabis for harm reduction reported difficulty accessing addiction treatment or used substances, such as methamphetamines, where effective treatments are limited. These findings highlight the need to better understand the potential harm-reducing impacts of cannabis among PWUD in these scenarios.