Public health implications of legalising the production and sale of cannabis for medicinal and recreational use

We assess the current and describe possible future public health impacts of the legalisation of cannabis production, sale, and use in the Americas. First, we describe global patterns of cannabis use and their most probable adverse health effects. Second, we summarise evidence regarding the effectiveness of cannabinoids for medicinal use and describe approaches that have been used to regulate the use of medicinal cannabis and how these approaches might have affected medicinal and recreational use and harms (eg, road crashes). Third, we describe how jurisdictions that have legalised recreational use have regulated production and sale of cannabis. Fourth, we evaluate the effects of cannabis legalisation on cannabis use and harms and on the use of alcohol, tobacco, and other drugs. Fifth, we use alcohol and tobacco policy examples to identify possible long-term public health effects of cannabis legalisation. Finally, we outline policy approaches that could minimise harms to public health arising from the legalisation of a commercial cannabis industry.

Routes of administration for cannabis use - basic prevalence and related health outcomes: A scoping review and synthesis

BACKGROUND

Cannabis use is common, and associated with adverse health outcomes. 'Routes of administration' (ROAs) for cannabis use have increasingly diversified, in part influenced by developments towards legalization. This paper sought to review data on prevalence and health outcomes associated with different ROAs.

METHODS

This scoping review followed a structured approach. Electronic searches for English-language peer-reviewed publications were conducted in primary databases (i.e., MEDLINE, EMBASE, PsycINFO, Google Scholar) based on pertinent keywords. Studies were included if they contained information on prevalence and/or health outcomes related to cannabis use ROAs. Relevant data were screened, extracted and narratively summarized under distinct ROA categories.

RESULTS

Overall, there is a paucity of rigorous and high-quality data on health outcomes from cannabis ROAs, especially in direct and quantifiable comparison. Most data exist on smoking combusted cannabis, which is associated with various adverse respiratory system outcomes (e.g., bronchitis, lung function). Vaporizing natural cannabis and ingesting edibles appear to reduce respiratory system problems, but may come with other risks (e.g., delayed impairment, use 'normalization'). Vaporizing cannabis concentrates can result in distinct acute risks (e.g., excessive impairment, injuries). Other ROAs are uncommon and under-researched.

CONCLUSIONS

ROAs appear to distinctly influence health outcomes from cannabis use, yet systematic data for comparative assessments are largely lacking; these evidence gaps require filling. Especially in emerging legalization regimes, ROAs should be subject to evidence-based regulation towards improved public health outcomes. Concretely, vaporizers and edibles may offer potential for reduced health risks, especially concerning respiratory problems. Adequate cannabis product regulation (e.g., purity, labeling, THC-restrictions) is required to complement ROA-based effects.

Cannabis use during pregnancy: Pharmacokinetics and effects on child development

The broad-based legalization of cannabis use has created a strong need to understand its impact on human health and behavior. The risks that may be associated with cannabis use, particularly for sensitive subgroups such as pregnant women, are difficult to define because of a paucity of dose-response data and the recent increase in cannabis potency. Although there is a large body of evidence detailing the mode of action of Δ⁹-tetrahydrocannabinol (THC) in adults, little work has focused on understanding how cannabis use during pregnancy may impact the development of the fetal nervous system and whether additional plant-derived cannabinoids might participate. This manuscript presents an overview of the historical and contemporary literature focused on the mode of action of THC in the developing brain, comparative pharmacokinetics in both pregnant and nonpregnant model systems and neurodevelopmental outcomes in exposed offspring. Despite growing public health significance, pharmacokinetic studies of THC have focused on nonpregnant adult subjects and there are few published reports on disposition parameters during pregnancy. Data from preclinical species show that THC readily crosses the placenta although fetal exposures appear lower than maternal exposures. The neurodevelopmental data in humans and animals suggest that prenatal exposure to THC may lead to subtle, persistent changes in targeted aspects of higher-level cognition and psychological well-being. There is an urgent need for well-controlled studies in humans and preclinical models on THC as a developmental neurotoxicant. Until more information is available, pregnant women should not assume that using cannabis during pregnancy is safe.

Cannabis and the Developing Brain: Insights into Its Long-Lasting Effects

The recent shift in sociopolitical debates and growing liberalization of cannabis use across the globe has raised concern regarding its impact on vulnerable populations, such as pregnant women and adolescents. Epidemiological studies have long demonstrated a relationship between developmental cannabis exposure and later mental health symptoms. This relationship is especially strong in people with particular genetic polymorphisms, suggesting that cannabis use interacts with genotype to increase mental health risk. Seminal animal research directly linked prenatal and adolescent exposure to delta-9-tetrahydrocannabinol, the major psychoactive component of cannabis, with protracted effects on adult neural systems relevant to psychiatric and substance use disorders. In this article, we discuss some recent advances in understanding the long-term molecular, epigenetic, electrophysiological, and behavioral consequences of prenatal, perinatal, and adolescent exposure to cannabis/delta-9-tetrahydrocannabinol. Insights are provided from both animal and human studies, including in vivo neuroimaging strategies.

Birth Outcomes of Neonates Exposed to Marijuana in Utero: A Systematic Review and Meta-analysis

IMPORTANCE

While some studies have found an association between marijuana use and adverse neonatal outcomes, results have not been consistent across all trials.

OBJECTIVE

To assess available data on neonatal outcomes in marijuana-exposed pregnancies.

DATA SOURCES

PubMed, Medline, ClinicalTrials.gov, Cochrane, Scopus, and Web of Science were searched from each database's inception until August 16, 2021.

STUDY SELECTION

All interventional and observational studies that included pregnant women who were exposed to marijuana compared with pregnant women who were not exposed to marijuana and that reported neonatal outcomes were included.

DATA EXTRACTION AND SYNTHESIS

Reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses guideline. Data were extracted by 2 authors for all outcomes, which were pooled using a random-effects model as mean difference or risk ratio (RR) and 95% CI. Data were analyzed from August through September 2021.

MAIN OUTCOMES AND MEASURES

All outcomes were formulated prior to data collection. Outcomes included incidence of birth weight less than 2500 g, small for gestational age (defined as less than the fifth percentile fetal weight for gestational age), rate of preterm delivery (defined as before 37 weeks' gestation), gestational age at time of delivery, birth weight, incidence of neonatal intensive care unit (NICU) admission, Apgar score at 1 minute, Apgar score at 5 minutes, incidence of an Apgar score less than 7 at 5 minutes, fetal head circumference, and fetal length.

RESULTS

Among 16 studies including 59 138 patients, there were significant increases in 7 adverse neonatal outcomes among women who were exposed to marijuana during pregnancy vs those who were not exposed during pregnancy. These included increased risk of birth weight less than 2500 g (RR, 2.06 [95% CI, 1.25 to 3.42]; P = .005), small for gestational age (RR, 1.61 [95% CI, 1.44 to 1.79]; P < .001), preterm delivery (RR, 1.28 [95% CI, 1.16 to 1.42]; P < .001), and NICU admission (RR, 1.38 [95% CI, 1.18 to 1.62]; P < .001), along with decreased mean birth weight (mean difference, -112.30 [95% CI, -167.19 to -57.41] g; P < .001), Apgar score at 1 minute (mean difference, -0.26 [95% CI, -0.43 to -0.09]; P = .002), and infant head circumference (mean difference, -0.34 [95% CI, -0.63 to -0.06] cm; P = .02).

CONCLUSIONS AND RELEVANCE

This study found that women exposed to marijuana in pregnancy were at a significantly increased risk of some adverse neonatal outcomes. These findings suggest that increasing awareness about these risks may be associated with improved outcomes.

Association Between Marijuana Use and Risk of Cancer: A Systematic Review and Meta-analysis

Importance

Marijuana use is common and growing in the United States amid a trend toward legalization. Exposure to tobacco smoke is a well-described preventable cause of many cancers; the association of marijuana use with the development of cancer is not clear.

Objective

To assess the association of marijuana use with cancer development.

Data Sources

A search of PubMed, Embase, PsycINFO, MEDLINE, and the Cochrane Library was conducted on June 11, 2018, and updated on April 30, 2019. A systematic review and meta-analysis of studies published from January 1, 1973, to April 30, 2019, and references of included studies were performed, with data analyzed from January 2 through October 4, 2019.

Study Selection

English-language studies involving adult marijuana users and reporting cancer development. The search strategy contained the following 2 concepts linked together with the AND operator: marijuana OR marihuana OR tetrahydrocannabinol OR cannabinoid OR cannabis; AND cancer OR malignancy OR carcinoma OR tumor OR neoplasm.

Data Extraction and Synthesis

Two reviewers independently reviewed titles, abstracts, and full-text articles; 3 reviewers independently assessed study characteristics and graded evidence strength by consensus.

Main Outcomes and Measures

Rates of cancer in marijuana users, with ever use defined as at least 1 joint-year exposure (equivalent to 1 joint per day for 1 year), compared with nonusers. Meta-analysis was conducted if there were at least 2 studies of the same design addressing the same cancer without high risk of bias when heterogeneity was low to moderate for the following 4 cancers: lung, head and neck squamous cell carcinoma, oral squamous cell carcinoma, and testicular germ cell tumor (TGCT), with comparisons expressed as odds ratios (ORs) with 95% CIs.

Results

Twenty-five English-language studies (19 case-control, 5 cohort, and 1 cross-sectional) were included; few studies (n = 2) were at low risk of bias. In pooled analysis of case-control studies, ever use of marijuana was not associated with head and neck squamous cell carcinoma or oral cancer. In pooled analysis of 3 case-control studies, more than 10 years of marijuana use (joint-years not reported) was associated with TGCT (OR, 1.36; 95% CI, 1.03-1.81; P = .03; I2 = 0%) and nonseminoma TGCT (OR, 1.85; 95% CI, 1.10-3.11; P = .04; I2 = 0%). Evaluations of ever use generally found no association with cancers, but exposure levels were low and poorly defined. Findings for lung cancer were mixed, confounded by few marijuana-only smokers, poor exposure assessment, and inadequate adjustment; meta-analysis was not performed for several outcomes.

Conclusions and Relevance

Low-strength evidence suggests that smoking marijuana is associated with developing TGCT; its association with other cancers and the consequences of higher levels of use are unclear. Long-term studies in marijuana-only smokers would improve understanding of marijuana's association with lung, oral, and other cancers.

Trial Registration

PROSPERO identifier: CRD42018102457.

E-Cigarette or Vaping Product-Associated Lung Injury: A Review

Since its introduction in the US market in 2007, the use of electronic nicotine delivery systems, colloquially referred to as e-cigarettes or "vaping" products, has increased substantially, particularly among high school children and young men. With the legalization of marijuana within multiple states in the United States and thus, coincident change in the public perception of its risk, the availability of multiple tetrahydrocannabinol (the psychoactive agent in marijuana)- and cannabidiol (a nonpsychogenic agent in marijuana)- containing vaping products has also increased tremendously. Since March 2019, there has been an ongoing epidemic of acute lung injury secondary to the use of e-cigarettes, with over 2600 cases and 60 deaths reported all over the United States; the term e-cigarette- or vaping product-associated lung injury is used. E-cigarette- or vaping product-associated lung injury is defined by the 1) presence of pulmonary infiltrates in imaging; 2) use of electronic nicotine delivery systems within the previous 90 days; and 3) absence of other possible causes such as infection, cardiac, neoplastic, or rheumatologic causes. A significant proportion of patients hospitalized with e-cigarette- or vaping product-associated lung injury have required admission in the intensive care unit, with mechanical ventilation needed in up to one-third of patients. Corticosteroids, supportive care, and further avoidance of vaping products remain the cornerstone of treatment. Although generally associated with an excellent prognosis, older patients and patients with underlying cardiac and pulmonary conditions are at risk for higher mortality and morbidity. This review article aims to describe e-cigarette- or vaping product-associated lung injury, its pathogenesis, clinical and radiological manifestations, and management.

Weeding Out the Problem: The Impact of Preoperative Cannabinoid Use on Pain in the Perioperative Period

BACKGROUND

The recreational and medical use of cannabinoids has been increasing. While most studies and reviews have focused on the role of cannabinoids in the management of acute pain, no study has examined the postoperative outcomes of surgical candidates who are on cannabinoids preoperatively. This retrospective cohort study examined the impact of preoperative cannabinoid use on postoperative pain scores and pain-related outcomes in patients undergoing major orthopedic surgery.

METHODS

Outcomes of patients who had major orthopedic surgery at our hospital between April 1, 2015 and June 30, 2017 were reviewed. Data were obtained from Networked Online Processing of Acute Pain Information, a locally developed database for our Acute Pain Service. Propensity score matching was used to balance baselines variables including age, sex, type of surgery, history of depression or anxiety, and perioperative use of regional anesthesia between patients who reported use of cannabinoids and those not on this substance. Intensity of pain with movement in the early postoperative period (defined as up to 36 hours after surgery) was the primary outcome of this study. The secondary outcomes (all in early postoperative period) were pain at rest, opioid consumption, incidence of pruritus, nausea and vomiting, sedation, delirium, constipation, impairment of sleep and physical activity, patient satisfaction with analgesia, and the length of Acute Pain Service follow-up.

RESULTS

A total of 3793 patients were included in the study. Of these, 155 patients were identified as being on cannabinoids for recreational or medical indications in the preoperative period. After propensity score matching, we compared data from 155 patients who were on cannabinoids and 155 patients who were not on cannabinoids. Patients who were on preoperative cannabinoids had higher pain numerical rating score (median [25th, 75th percentiles]) at rest (5.0 [3.0, 6.1] vs 3.0 [2.0, 5.5], P = .010) and with movement (8.0 [6.0, 9.0] vs 7.0 [3.5, 8.5], P = .003), and a higher incidence of moderate-to-severe pain at rest (62.3% vs 45.5%, respectively, P = .004; odds ratio, 1.98; 95% CI, 1.25-3.14) and with movement (85.7% vs 75.2% respectively, P = .021; odds ratio, 1.98; 95% CI, 1.10-3.57) in the early postoperative period compared to patients who were not on cannabinoids. There was also a higher incidence of sleep interruption in the early postoperative period for patients who used cannabinoids.

CONCLUSIONS

This retrospective study with propensity-matched cohorts showed that cannabinoid use was associated with higher pain scores and a poorer quality of sleep in the early postoperative period in patients undergoing major orthopedic surgery.

Prevalence and outcomes of prenatal recreational cannabis use in high-income countries: a scoping review

BACKGROUND

With expanding recreational cannabis legalisation, pregnant women and their offspring are at risk of potentially harmful consequences.

OBJECTIVES

To assess the prevalence of recreational cannabis use among pregnant women, health outcomes associated with prenatal recreational cannabis use, and the potential impact of recreational cannabis legalisation on this population.

SEARCH STRATEGY

Five databases and the grey literature were systematically searched (2000-2019).

SELECTION CRITERIA

Human studies published in English or French reporting on the prevalence of prenatal recreational cannabis use in high-income countries.

DATA COLLECTION AND ANALYSIS

Data on study characteristics, prenatal substance use, and health outcomes were extracted and qualitatively synthesised.

MAIN RESULTS

Forty-one publications met our inclusion criteria. The overall prevalence of prenatal cannabis use varied substantially (min-max: 0.24-22.6%), with the greatest use in the first trimester. In the three studies with temporal data available, rates of prenatal cannabis use increased across years. Only 7/41 and 5/41 studies provided information on gestational age of exposure and frequency of use, respectively. The concomitant use of alcohol, illicit drugs, and tobacco was higher among cannabis users than nonusers. Prenatal cannabis use was associated with select neonatal, but not maternal, health outcomes. There were insufficient data to compare prenatal cannabis use between the pre- and post-legalisation periods.

CONCLUSION

Cannabis use among pregnant women is prevalent and may be associated with adverse neonatal outcomes. Future studies should assess the gestational age and frequency of cannabis exposure, and usage patterns prior to and following legalisation.

TWEETABLE ABSTRACT

Women who consume cannabis during pregnancy could risk predisposing their newborns to poor birth outcomes.

The association between regular marijuana use and adult mental health outcomes

OBJECTIVE

The present study is a prospective examination of the relationship between regular marijuana use from adolescence through young adulthood and mental health outcomes at age 33.

METHODS

Data came from a gender-balanced, ethnically diverse longitudinal panel of 808 participants from Seattle, Washington. Outcomes included symptom counts for six mental health disorders. Regular marijuana use was tracked during adolescence and young adulthood. Regression analyses controlled for demographics and early environment, behaviors, and individual risk factors.

RESULTS

Nonusers of marijuana reported fewer symptoms of alcohol use disorder, nicotine dependence, and generalized anxiety disorder than any category of marijuana users. More persistent regular marijuana use in young adulthood was positively related to more symptoms of cannabis use disorder, alcohol use disorder, and nicotine dependence at age 33.

CONCLUSIONS

Findings highlight the importance of avoiding regular marijuana use, especially chronic use in young adulthood. Comprehensive prevention and intervention efforts focusing on marijuana and other substance use might be particularly important in the context of recent legalization of recreational marijuana use in Washington and other U.S. states.

Immunoregulatory Role of Cannabinoids during Infectious Disease

Although the endocannabinoid system (ECS) is involved in the regulation of several physiological processes, including sleep and the immune response, its role during infections has not been fully studied. It is well known that the use of this drug increases susceptibility to infections because of the impact on the modulation of the immune system. Concerning the medicinal or recreational use of marijuana, its influence on the course of an infection, whether this has been caused by bacteria, viruses, parasites, and to a lesser degree, fungi, has been reported. Furthermore, there is evidence suggesting the involvement of the ECS in the control and elimination of infectious agents such as bacteria, viruses, and some protozoa; in the case of fungi, few studies are available so far. The purpose of this review is to present the existing studies related to infections and the ECS, the microbicidal effects of compounds isolated from Cannabis sativa, and the association between marijuana use and the development of rare pathologies in specific diseases.

An examination of consequences among college student drinkers on occasions involving alcohol-only, marijuana-only, or combined alcohol and marijuana use

This event-level study examined within-person differences in consequences for college students who engaged in alcohol-only, marijuana-only, or simultaneous alcohol and marijuana (SAM) use across 18 weekend days. Participants (n = 451) were asked to report consequences they experienced on each occasion across five different types of events: (a) heavier alcohol combined with marijuana; (b) lighter alcohol combined with marijuana; (c) heavier alcohol only; (d) lighter alcohol only; and (e) marijuana only. Occasions involving heavy drinking, alone and in combination with marijuana, were associated with higher rates of consequences relative to lighter alcohol-only occasions, lighter alcohol combined with marijuana occasions, and marijuana-only occasions. Light alcohol-only occasions did not significantly differ on consequences from lighter alcohol combined with marijuana occasions or marijuana-only occasions. Past research has shown SAM use is associated with more consequences compared with alcohol-only use. The current findings suggest that SAM use is not necessarily riskier than drinking or using marijuana alone. Results suggested that on heavy drinking occasions, the number of consequences did not significantly change by also using marijuana. Findings suggest the benefit of targeted intervention strategies to reduce harms associated with heavy drinking occasions with and without SAM use. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Cannabis use and adherence to antipsychotic medication: a systematic review and meta-analysis

BACKGROUND

Substance use may increase the risk of non-adherence to antipsychotics, resulting in negative outcomes in patients with psychosis.

METHOD

We aimed to quantitatively summarize evidence regarding the effect of cannabis use, the most commonly used illicit drug amongst those with psychosis, on adherence to antipsychotic medication. Studies were identified through a systematic database search. Adopting random-effects models, pooled odds ratios (OR) for risk of non-adherence to antipsychotic medications were calculated comparing: cannabis-users at baseline v. non-users at baseline; non users v. continued cannabis users at follow-up; non-users v. former users at follow-up; former users v. current users.

RESULTS

Fifteen observational studies (n = 3678) were included. Increased risk of non-adherence was observed for cannabis users compared to non-users (OR 2.46, n = 3055). At follow-up, increased risk of non-adherence was observed for current users compared to non-users (OR 5.79, n = 175) and former users (OR 5.5, n = 192), while there was no difference between former users and non-users (OR 1.12, n = 187).

CONCLUSIONS

Cannabis use increases the risk of non-adherence and quitting cannabis use may help adherence to antipsychotics. Thus, cannabis use may represent a potential target for intervention to improve medication adherence in those with psychosis.

Marijuana Use and Organ Transplantation: a Review and Implications for Clinical Practice

PURPOSE OF REVIEW

Physicians of all disciplines must rapidly adjust their clinical practices following the expansion of marijuana legalization across the country. Organ transplantation teams are uniquely struggling in this gray zone with eight states having passed laws explicitly banning the denial of transplant listing based on a patient's use of medical marijuana. In this review, we examine the clinical evidence of marijuana use in transplant patients to enable psychiatric providers to meaningfully contribute to the relevant medical and psychiatric aspects of this issue in a unique patient population.

RECENT FINDINGS

There is no consensus among experts regarding marijuana use in transplantation patients. There are extant case reports of post-transplant complications attributed to marijuana use including membranous glomerulonephritis, ventricular tachycardia, and tacrolimus toxicity. However, recent studies suggest that the overall survival rates in kidney, liver, lung, and heart transplant patients using marijuana are equivalent to non-users. Transplant teams should not de facto exclude marijuana users from transplant listing but instead holistically evaluate a patient's candidacy, integrating meaningful medical, psychiatric, and social variables into the complex decision-making process. Psychiatric providers can play a key role in this process. Appropriate stewardship over donor organs, a limited and precious resource, will require a balance of high-clinical standards with inclusive efforts to treat as many patients as possible.

Cannabis Use and Hypomania in Young People: A Prospective Analysis

BACKGROUND

Cannabis use in young people is common and associated with psychiatric disorders. However, the prospective link between cannabis use and bipolar disorder symptoms has rarely been investigated. The study hypothesis was that adolescent cannabis use is associated with hypomania in early adulthood via several potential etiological pathways.

METHODS

Data were used from the Avon Longitudinal Study of Parents and Children, a UK birth cohort study. The prospective link between cannabis use at age 17 and hypomania at age 22-23 years was tested using regression analysis, adjusted for gender, early environmental risk factors, alcohol and drug use, and depression and psychotic symptoms at age 18 years. Path analysis examined direct and indirect effects of the link and whether gender, childhood family adversity, or childhood abuse are associated with hypomania via an increased risk of cannabis use.

RESULTS

Data were available on 3370 participants. Cannabis use at least 2-3 times weekly was associated with later hypomania (OR = 2.21, 95% CI = 1.49-3.28) after adjustment. There was a dose-response relationship (any use vs weekly). Cannabis use mediated the association of both childhood sexual abuse and hypomania, and male gender and hypomania. The cannabis use-hypomania link was not mediated by depression or psychotic symptoms.

CONCLUSIONS

Adolescent cannabis use may be an independent risk factor for future hypomania, and the nature of the association suggests a potential causal link. Cannabis use mediates the link between childhood abuse and future hypomania. As such it might be a useful target for indicated prevention of hypomania.

Unintentional Pediatric Cannabis Exposures After Legalization of Recreational Cannabis in Canada

This cross-sectional study examines changes in emergency department visits and hospitalizations due to cannabis exposures among children after legalization of recreational cannabis in Canada.

Marijuana use in young mothers and adverse pregnancy outcomes: a retrospective cohort study

OBJECTIVE

To evaluate the association between marijuana use and a composite adverse pregnancy outcome using biological sampling.

DESIGN

Retrospective cohort study.

SETTING

Single tertiary center.

POPULATION

Young women (13-22 years old) with singleton, non-anomalous pregnancies delivered from September 2011 to May 2017.

METHODS

Exposure was defined as marijuana detected on universal urine toxicology testing or by self-report. Multivariable logistic regression modelling was used to estimate the effect of any marijuana use on the primary composite outcome. The effect of marijuana exposure was also estimated for self-reported use, toxicology-detected use, and multiple use detected by toxicology.

MAIN OUTCOME MEASURE

The primary composite outcome included spontaneous preterm birth, hypertensive disorders of pregnancy, stillbirth, or small for gestational age.

RESULTS

Of 1206 pregnant young women, 17.5% (n = 211) used marijuana. Among the women who used marijuana, 8.5% (n = 18) were identified by self-report alone, 63% (n = 133) by urine toxicology alone, and 28.4% (n = 60) by both. Urine toxicology testing results were available for 1092 (90.5%) births. The composite outcome occurred more frequently in pregnancies exposed to marijuana (46 versus 34%, P < 0.001). This remained significant after adjusting for race/ethnicity and tobacco in the multivariable model (adjusted OR 1.50, 95% CI 1.09-2.05). When marijuana exposure was defined by self-report only, the association with adverse pregnancy outcome became non-significant (adjusted OR 1.01, 95% CI 0.62-1.64).

CONCLUSION

In a population of young women with nearly universal biological sampling, marijuana exposure was associated with adverse pregnancy outcomes. The heterogeneity of findings in existing studies evaluating the impact of marijuana on mothers and neonates may result from the incomplete ascertainment of exposure.

TWEETABLE ABSTRACT

Marijuana use, as detected by universal urine testing, was associated with a composite adverse pregnancy outcome among young mothers.

Which biological and self-report measures of cannabis use predict cannabis dependency and acute psychotic-like effects?

BACKGROUND

Changes in cannabis regulation globally make it increasingly important to determine what predicts an individual's risk of experiencing adverse drug effects. Relevant studies have used diverse self-report measures of cannabis use, and few include multiple biological measures. Here we aimed to determine which biological and self-report measures of cannabis use predict cannabis dependency and acute psychotic-like symptoms.

METHOD

In a naturalistic study, 410 young cannabis users were assessed once when intoxicated with their own cannabis and once when drug-free in counterbalanced order. Biological measures of cannabinoids [(Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol (CBN) and their metabolites)] were derived from three samples: each participant's own cannabis (THC, CBD), a sample of their hair (THC, THC-OH, THC-COOH, CBN, CBD) and their urine (THC-COOH/creatinine). Comprehensive self-report measures were also obtained. Self-reported and clinician-rated assessments were taken for cannabis dependency [Severity of Dependence Scale (SDS), DSM-IV-TR] and acute psychotic-like symptoms [Psychotomimetic State Inventory (PSI) and Brief Psychiatric Rating Scale (BPRS)].

RESULTS

Cannabis dependency was positively associated with days per month of cannabis use on both measures, and with urinary THC-COOH/creatinine for the SDS. Acute psychotic-like symptoms were positively associated with age of first cannabis use and negatively with urinary THC-COOH/creatinine; no predictors emerged for BPRS.

CONCLUSIONS

Levels of THC exposure are positively associated with both cannabis dependency and tolerance to the acute psychotic-like effects of cannabis. Combining urinary and self-report assessments (use frequency; age first used) enhances the measurement of cannabis use and its association with adverse outcomes.

Perceptions of driving after marijuana use compared to alcohol use among rural American young adults

INTRODUCTION AND AIMS

Substance use contributes to motor vehicle crashes, the leading cause of death among young adults. The current qualitative study examined perceptions of the acceptability and harms associated with driving after marijuana versus alcohol use in rural America. Illuminating rural perspectives is critical given that the motor vehicle fatality rate is twice as high in rural as in urban areas in the USA.

DESIGN AND METHODS

In 2015-2016, 72 young adults aged 18-25 years (Mage  = 20.2; 50.7% female) living in Montana, USA, participated in 11 focus groups. A list of descriptive codes was generated inductively and two individuals coded participant comments. Discussion, memoing and concept mapping were used to uncover broader themes and transcripts were reviewed for evidence of these themes.

RESULTS

There was shared consensus that, with regard to crash risk, driving after marijuana use was safer than driving after alcohol use. While alcohol was thought to impair driving ability universally, marijuana's impacts depended on individual characteristics (e.g. compensatory behaviours) and the marijuana itself (e.g. type). Participants expressed conflicting beliefs about policies surrounding marijuana use and driving but were more knowledgeable about alcohol-related policies. Participants viewed older adults and those in frontier areas as more disapproving of driving after marijuana use.

DISCUSSION AND CONCLUSIONS

Misinformation about the consequences of driving after marijuana use is common, demonstrating the need for future research and educational interventions. Developing and disseminating guidelines for driving after marijuana use would help marijuana users make informed decisions and mitigate driving-related risks.

Impact of pregnancy marijuana use on birth outcomes: results from two matched population-based cohorts

OBJECTIVE

To examine associations between in utero marijuana exposure and birth outcomes.

STUDY DESIGN

In two separate cohorts (Appalachian, Rocky Mountain), data were collected from medical records. Marijuana exposure was positive based on urine drug screening at delivery, with nonexposed controls matched on multiple factors including other substance exposure.

RESULT

Marijuana-exposed newborns (n = 531) had significantly worse birth outcomes than controls (n = 531), weighing 218 g less, 82%, 79%, and 43% more likely to be low birth weight, preterm, or admitted to the NICU, respectively, and significantly lower Apgar scores.

CONCLUSION

Marijuana exposure in utero predicted newborn factors linked to longer-term health and development issues. Effects were not attributable to other comorbidities in this study due to rigorous matching and biochemical verification of marijuana and other drug use. Findings add to growing evidence linking marijuana exposure to adverse birth and longer-term outcomes. Women should be encouraged to avoid marijuana use during pregnancy.

Adolescent cannabis use and brain systems supporting adult working memory encoding, maintenance, and retrieval

Given prior reports of adverse effects of cannabis use on working memory, an executive function with a protracted developmental course during adolescence, we examined associations between developmental patterns of cannabis use and adult working memory (WM) processes. Seventy-five adults with longitudinal assessments of cannabis use (60 with reported use, 15 with no reported use) and prenatal drug exposure assessment completed a spatial WM task during fMRI at age 28. All subjects passed a multi-drug urine screen on the day of testing and denied recreational drug use in the past week. A fast event-related design with partial trials was used to separate the BOLD response associated with encoding, maintenance, and retrieval periods of the WM task. Behavioral results showed that subjects who began using cannabis earlier in adolescence had longer reaction times (RT) than those with later initiation. Cannabis age of onset was further associated with reduced posterior parietal cortex (PPC) encoding BOLD activation, which significantly mediated age of onset WM RT associations. However, cannabis age of onset brain-behavior associations did not differ between groups with a single reported use and those with repeated use, suggesting age of onset effects may reflect substance use risk characteristics rather than a developmentally-timed cannabis exposure effect. Within repeated cannabis users, greater levels of total cannabis use were associated with performance-related increases in dorsolateral prefrontal cortex (DLPFC) activation during maintenance. This pattern of significant results remained unchanged with inclusion of demographic and prenatal measures as covariates. Surprisingly, however, at the group level, cannabis users generally performed better than participants who reported never using cannabis (faster RT, higher accuracy). We extend previous investigations by identifying that WM associations with cannabis age of onset may be primary to PPC stimulus encoding activity, while the amount of cannabis use is associated with DLPFC maintenance processes. Poorer performance of participants who reported never using cannabis and the consistency of cannabis age of onset associations across single and repeated users limit interpretation of direct developmental effects of cannabis on WM in adulthood.

Trends in marijuana edible consumption and perceptions of harm in a cohort of young adults

BACKGROUND

Rates of marijuana legalization have increased rapidly in recent years resulting in the marketing of alternative products like edibles that do not involve inhaling smoke. Edibles however pose unique public health challenges due to their greater risk for over-intoxication.

METHODS

1858 young adults were surveyed every six months from 2016 to 2018. Logistic regression models examined trends in use and perceptions of harm. Chi-squared tests compared demographic and behavioral characteristics of edible users and non-users by frequency of marijuana use.

RESULTS

Perceptions of no harm from edibles increased (25.4%, 27.3%, 26.7%, 28.4%, 29.6%; p = 0.006) while it declined for smoking marijuana (12.2%, 13.5%, 11.7%, 10.6%, 9.1%; p < 0.001). Among non-daily marijuana users, edible use increased (20.3%, 24.8%, 30.5%, 36.2%, 36.6%; p < 0.001) while smoking marijuana declined for both daily and non-daily users. Among daily users, edible users were more likely to use all modes of consumption than non-edible users. Among non-daily users, edible users were less likely to smoke marijuana and perceive harm from edibles and were more likely to perceive harm from smoking marijuana and have visited a dispensary than non-edible users.

CONCLUSIONS

Edibles are increasingly consumed and perceived to not be harmful, despite the greater danger of over-intoxication. However, daily use of edibles alone is uncommon. The finding that edible users were more likely to have visited a dispensary provides a potential intervention point for consumer education. Strong scientific evidence is needed to guide policymakers in best practices for communicating knowledge and potential harms of these products.

Cannabis Use in Pregnancy and Neonatal Outcomes: A Systematic Review and Meta-Analysis

Objective: To determine whether prenatal cannabis use alone increases the likelihood of fetal and neonatal morbidity and mortality. Study Design: We searched bibliographic databases, such as PubMed, Embase, Scopus, Cochrane reviews, PsycInfo, MEDLINE, Clinicaltrials.gov, and Google Scholar from inception through February 14, 2022. Cohort or case-control studies with prespecified fetal or neonatal outcomes in pregnancies with prenatal cannabis use. Primary outcomes were preterm birth (PTB; <37 weeks of gestation), small-for-gestational-age (SGA), birthweight (grams), and perinatal mortality. Two independent reviewers screened studies. Studies were extracted by one reviewer and confirmed by a second using a predefined template. Risk of bias assessment of studies, using the Newcastle-Ottawa Quality Assessment Scale, and Grading of Recommendations Assessment, Development, and Evaluation for evaluating the certainty of evidence for select outcomes were performed by two independent reviewers with disagreements resolved by a third. Random effects meta-analyses were conducted, using adjusted and unadjusted effect estimates, to compare groups according to prenatal exposure to cannabis use status. Results: Fifty-three studies were included. Except for birthweight, unadjusted and adjusted meta-analyses had similar results. We found very-low- to low-certainty evidence that cannabis use during pregnancy was significantly associated with greater odds of PTB (adjusted odds ratio [aOR], 1.42; 95% confidence interval [CI], 1.19 to 1.69; I2, 93%; p=0.0001), SGA (aOR, 1.76; 95% CI, 1.52 to 2.05; I2, 86%; p<0.0001), and perinatal mortality (aOR, 1.5; 95% CI, 1.39 to 1.62; I2, 0%; p<0.0001), but not significantly different for birthweight (mean difference, -40.69 g; 95% CI, -124.22 to 42.83; I2, 85%; p=0.29). Because of substantial heterogeneity, we also conducted a narrative synthesis and found comparable results to meta-analyses. Conclusion: Prenatal cannabis use was associated with greater odds of PTB, SGA, and perinatal mortality even after accounting for prenatal tobacco use. However, our confidence in these findings is limited. Limitations of most existing studies was the failure to not include timing or quantity of cannabis use. This review can help guide health care providers with counseling, management, and addressing the limited existing safety data. Protocol Registration: PROSPERO CRD42020172343.

Potential harms from legalization of recreational cannabis use in Canada

With the recent legalization of recreational cannabis use in Canada, questions remain concerning optimal regulation to minimize harms and ensure public health and safety. Patterns of use are subject to change following legalization, and it is important to consider the potential adverse effects that this may have on public health. Important areas of consideration are methods of consumption (e.g., vaping, edibles) and product proliferation; acute and long-term health and behavioural effects (including impaired driving); and use in vulnerable groups, such as children and youth, pregnant women, individuals with mental illness, individuals with low socio-economic status, and Indigenous populations. To support harm reduction measures and evidence-based policy, there is a need to anticipate the potential ramifications that legalization of recreational cannabis use may have on public health in Canada.