Young adult sequelae of adolescent cannabis use: an integrative analysis

Marijuana and the Pediatric Population

Cannabinoids, the psychoactive compounds in marijuana, are one of the most commonly used substances in the United States. In this review, we summarize the impact of marijuana on child and adolescent health and discuss the implications of marijuana use for pediatric practice. We review the changing epidemiology of cannabis use and provide an update on medical use, routes of administration, synthetic marijuana and other novel products, the effect of cannabis on the developing brain, other health and social consequences of use, and issues related to marijuana legalization.

Economic Effects of Adolescent to Adult Patterns of Cannabis Use: Full-Time Employment and Employment Stability

Research has yet to examine stability in employment as a function of cannabis use once an individual transitions into full-time work. Using data from the Rochester Youth Development Study, trajectories of cannabis use spanning ages 14 to 30 were identified among a sample of predominantly minorities (>80%; 68% African American). After hard-classifying individuals by patterns of cannabis use, probabilities of full-time employment and conditional probabilities of full-time employment were calculated and compared across patterns of use. Abstention or rare cannabis use was associated with a higher likelihood of full-time employment compared with other cannabis use patterns. Full-time employment stability was high for each pattern of cannabis use (>89%) and differences decreased with age and prior periods of employment. The results indicate that patterns of cannabis use spanning adolescence to adulthood have limited impact on the ability to retain full-time employment once employed and are interpreted in light of growing legalization of cannabis use.

Effects of chronic exposure to low doses of Δ9- tetrahydrocannabinol in adolescence and adulthood on serotonin/norepinephrine neurotransmission and emotional behaviors

BACKGROUND

Chronic exposure to the Δ9-tetrahydrocannabinol (THC), the main cannabis pharmacological component, during adolescence has been shown to be associated with an increased risk of depression and suicidality in humans.

AIMS

Little is known about the impact of the long-term effects of chronic exposure to low doses of THC in adolescent compared to adult rodents.

METHODS

THC (1mg/kg i.p., once a day) or vehicle was administered for 20 days in both adolescent (post-natal day, PND 30-50) and young adult rats (PND 50-70). After a long washout period (20 days), several behavioral paradigms and electrophysiological recordings of serotonin (5-HT) and norepinephrine (NE) neurons were carried out.

RESULTS

Adolescent THC exposure resulted in depressive lbehaviors: a significant decrease in latency to first immobility in the forced swim test, increased anhedonia in the sucrose preference test. Decrease entries in the open arm were observed in the elevated plus maze after adolescent and adult exposure, indicating anxiousphenotype. A significant reduction in dorsal raphe serotonergic neural activity without changing locus coeruleus noradrenergic neural activity was found in THC adolescent and adult exposure.

CONCLUSIONS

Altogether, these findings suggest that low doses of chronic THC exposure during the developmental period and adulthood could result in increased vulnerability of the 5-HT system and anxiety symptoms; however, depressive phenotypes occur only after adolescent, but not adult exposure, underscoring the higher vulnerability of young ages to the mental effects of cannabis.

A Web-Based Program for Cannabis Use and Psychotic Experiences in Young People (Keep It Real): Protocol for a Randomized Controlled Trial

BACKGROUND

Young Australians (16-25 years) have the highest rates of past-month cannabis use in the world. Cannabis use increases the risk of alcohol and other drug disorders and depressive disorders, and has a robust dose-response association with psychotic experiences (PEs) and disorders. PEs are subthreshold positive psychotic symptoms, including delusions and hallucinations, which increase the risk of substance use, depressive or anxiety disorders, and psychotic disorders. Access to effective web-based early interventions targeting both cannabis use and PEs could reduce such risk in young people.

OBJECTIVE

The objective of this study is to determine the efficacy and cost-effectiveness of the Keep it Real web-based program compared to an information-only control website among young cannabis users (16-25 years) with PEs.

METHODS

Participants are recruited online, and consenting individuals meeting inclusion criteria (aged 16-25 years, who have used cannabis in the past month and experienced PEs in the past 3 months) are automatically randomized to either the Keep it Real web-based program (n=249) or an information-only control website (n=249). Both websites are self-guided (fully automated). The baseline and follow-up assessments at 3, 6, 9, and 12 months are self-completed online. Primary outcome measures are weekly cannabis use, PEs, and the relative cost-effectiveness for quality-adjusted life years. Secondary outcomes include other substance use and related problems, PE-related distress, cannabis intoxication experiences, severity of cannabis dependence, depression/anxiety symptoms, suicidality, and mental well-being and functioning.

RESULTS

Recruitment commenced in February 2019, and the results are expected to be submitted for publication in mid-2021.

CONCLUSIONS

This study protocol describes a large randomized controlled trial of a new web-based program for young cannabis users experiencing PEs. If effective, the accessibility and scalability of Keep it Real could help reduce growing public health concerns about the significant social, economic, and health impacts of cannabis use.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12618001107213; https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374800.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/15803.

'Standard THC units': a proposal to standardize dose across all cannabis products and methods of administration

BACKGROUND AND AIMS

Cannabis products are becoming increasingly diverse, and vary considerably in concentrations of ∆⁹ -tetrahydrocannabinol (THC) and cannabidiol (CBD). Higher doses of THC can increase the risk of harm from cannabis, while CBD may partially offset some of these effects. Lower Risk Cannabis Use Guidelines currently lack recommendations based on quantity of use, and could be improved by implementing standard units. However, there is currently no consensus on how units should be measured or standardized among different cannabis products or methods of administration.

ARGUMENT

Existing proposals for standard cannabis units have been based on specific methods of administration (e.g. joints) and these may not capture other methods, including pipes, bongs, blunts, dabbing, vaporizers, vape pens, edibles and liquids. Other proposals (e.g. grams of cannabis) cannot account for heterogeneity in THC concentrations among different cannabis products. Similar to alcohol units, we argue that standard cannabis units should reflect the quantity of primary active pharmacological constituents (dose of THC). On the basis of experimental and ecological data, public health considerations and existing policy, we propose that a 'standard THC unit' should be fixed at 5 mg THC for all cannabis products and methods of administration. If supported by sufficient evidence in future, consumption of standard CBD units might offer an additional strategy for harm reduction.

CONCLUSIONS

Standard ∆⁹ -tetrahydrocannabinol (THC) units can potentially be applied among all cannabis products and methods of administration to guide consumers and promote safer patterns of use.

THC and CBD blood and brain concentrations following daily administration to adolescent primates

BACKGROUND

Cannabis availability with high concentrations of Δ-9-tetrahydrocannabinol (THC) and a range of THC to cannabidiol (CBD) ratios has increased in parallel with a rise in daily cannabis consumption by adolescents. Unanswered questions in adolescents include: 1) whether THC blood concentrations and THC metabolites remain stable or change with prolonged daily dosing, 2) whether CBD modulates THC pharmacokinetic properties and alters THC accumulation in brain, 3) whether blood THC levels reflect brain concentrations.

METHODS

In adolescent squirrel monkeys (Saimiri boliviensis), we determined whether a four-month regimen of daily THC (1 mg/kg) or CBD (3 mg/kg) + THC (1 mg/kg) administration (IM) affects THC, THC metabolites, and CBD concentrations in blood or brain.

RESULTS

Blood THC concentrations, THC metabolites and CBD remained stable during chronic treatment. 24 h after the final THC or CBD + THC injection, blood THC and CBD concentrations remained relatively high (THC: 6.0-11 ng/mL; CBD: 9.7-19 ng/mL). THC concentrations in cerebellum and occipital cortex were approximately twice those in blood 24 h after the last dose and did not significantly differ in subjects given THC or CBD + THC.

CONCLUSIONS

In adolescent monkeys, blood levels of THC, its metabolites or CBD remain stable after daily dosing for four months. Our model suggests that any pharmacological interactions between CBD and THC are unlikely to result from CBD modulation of THC pharmacokinetics. Finally, detection of relatively high brain THC concentrations 24 h after the final dose of THC suggests that the prolonged actions of THC may contribute to persistent cognitive and psychomotor disruption after THC- or cannabis-induced euphoria wane.

Assessment of Incorporation of Lessons From Tobacco Control in City and County Laws Regulating Legal Marijuana in California

IMPORTANCE

As marijuana continues to be legalized in many states, little is known about best regulatory practice, exposing the population to significant potential harm.

OBJECTIVE

To assess the extent to which potential best practices, including those from tobacco control, were incorporated into state and local marijuana policies in California.

DESIGN AND SETTING

California legalized medical marijuana in 1996 and adult recreational use in 2016, effective in January 2018. A cross-sectional study with data collection and analysis from February 1 to November 30, 2019, measured the adoption of potential demand reduction and youth protection best practices, including restrictions on sales, products, marketing, warnings, and taxation. Laws in effect by January 31, 2019, were verified and all 539 California local jurisdictions were studied.

MAIN OUTCOMES AND MEASURES

Adoption of potential best practices in marijuana laws for demand reduction and youth protection.

RESULTS

The laws of 534 of California's 539 jurisdictions (99%) were successfully identified; 263 of these 534 jurisdictions (49%) allowed any retail sale of marijuana, covering 57% of the state's population. More than one-third of jurisdictions allow sales of marijuana for adult recreational use (203 of 534 [38%]); of those, 122 allow storefront dispensaries and 81 allow sales by delivery only. A total of 257 of 534 jurisdictions (48%) allow medical sales. Of 147 jurisdictions allowing medical or adult use dispensaries, 93 (63%) limited the number of licenses, with a mean of 1 store for every 19 058 residents (range, 154-355 143). The state imposed no limits on number of dispensaries or deliverers. Forty-two jurisdictions increased the state-specified distances required between dispensaries and schools. Only 8 jurisdictions allowing retail sales imposed restrictions on products exceeding state regulations; 1 prohibited sale of flavored products, 3 prohibited sale of marijuana-infused beverages, and 5 imposed additional restrictions on edible marijuana products. No jurisdictions limited potency of products sold, although 1 established a potency-linked tax. The state did not limit or tax potency, except for establishing a standard 10-mg dose of tetrahydrocannabinol for edible marijuana products, nor did they limit manufacturing or sale of flavored products. The state required only a health warning in 6-point font on packages. Twenty-seven jurisdictions required additional health warnings in stores or on packages, 27 allowed onsite consumption of marijuana products, and 13 allowed marijuana-related events. More than half of jurisdictions legalizing any cannabis commerce (154 of 289 [53%]) did not tax marijuana locally and little revenue was captured for prevention. Much of the state excise and cultivation taxes is slated for youth substance use prevention and treatment.

CONCLUSIONS AND RELEVANCE

In implementing legalization of marijuana in California, local policies varied widely. Where marijuana was legalized, many lessons from tobacco control to reduce demand, limit harm, and prevent youth use were not adopted, potentially creating greater risk of harm.

Commentary on Chan & Hall (2020): Advances in specifying cannabis consumption

Cannabis consumption patterns are not evenly distributed and more frequent users, who are the minority of the population, disproportionately consume cannabis. Accurate measurement of the quantity and frequency of cannabis will require new approaches to surveillance but could lead to better assessment of the health outcomes of cannabis exposure.

Factors related to an increase of cannabis use among adolescents in Chile: National school based surveys between 2003 and 2017

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Cannabis use in adolescents has more than doubled between 2003 and 2017 in Chile.

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Exact prevalence of substance use and effect size of associated factors are given.

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Strongest prevalence factors were friends who use cannabis and low perceived risk.

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Association of low parental rejection with cannabis use has increased.

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Tobacco and alcohol use remained strongly associated with cannabis use in adolescents.

Background

Cannabis is the most commonly used illicit substance worldwide. In Chile, the prevalence of cannabis use among adolescents is the highest in the Americas. Our aim was to identify prevalence trends of cannabis use and associated factors in adolescents.

Methods

We performed multivariate logistic regression analyses of 416,417 cross-sectional school-based surveys of adolescents from 8th to 12th grade conducted between 2003 and 2017 in Chile. Cannabis use was the dependent variable. Age, gender, socio-economic variables, and factors on the individual, school and family level were assessed as independent variables.

Results

The prevalence of cannabis use in the past year increased from 13.6% in 2003 to 31.3% in 2017 in a linear trend (F(df:1,6) = 27.6; R² = 0.79; p < 0.01). The strongest association with cannabis use was seen for having friends who regularly use cannabis, and low perceived risk of cannabis use. Between 2003 and 2017, the strength of association between the variable having friends who regularly use cannabis and cannabis use decreased from OR = 6.2 to OR = 2.9, in a significant linear trend (F(df:1,6) = 60.5; R² = 0.89; p < 0.01); whereas the OR for low parental rejection of cannabis use with cannabis use increased in a linear trend (F(df:1,6) = 22.8; R² = 0.75, p < 0.01) from OR = 1.2 to OR = 2.1.

Conclusions

Increasing cannabis use of adolescents in Chile requires adjustments of prevention strategies. Prevalence factors identified here constitute potential targets for interventions.

Rapid increase in the prevalence of cannabis use among people with depression in the United States, 2005-17: the role of differentially changing risk perceptions

AIMS

To estimate trends in the prevalence of cannabis use and risk perceptions of cannabis use from 2005 to 2017 among United States people with and without depression.

DESIGN

Linear time trends of the prevalence of any, daily and non-daily past 30-day cannabis use and perceived great risk associated with regular cannabis use (outcome variables) among people with and without past-year depression were assessed using logistic regression with survey year as the predictor. All analyses were adjusted for gender, age, race/ethnicity and income; models assessing time trends of cannabis use prevalence were also adjusted for perceived risk.

SETTING

The United States: National Survey on Drug Use and Health, an annual cross-sectional survey, 2005-17 public use data files.

PARTICIPANTS

A total of 728 691 people aged ≥ 12 years.

MEASUREMENTS

Self-report of any, daily and non-daily past 30-day cannabis use and perceived great risk associated with regular cannabis use.

FINDINGS

The prevalence of any, daily and non-daily cannabis use in the past month was higher among those with depression versus those without [e.g. 2017 for any use: 18.94 versus 8.67%; adjusted odds ratio (aOR) = 2.17 (95% confidence interval (CI) = 1.92, 2.45)]. Any, daily and non-daily cannabis use increased among people with and without depression from 2005 to 2017, yet the increase in any (aORs = 1.06 versus 1.05; P = 0.008) and daily (aORs = 1.10 versus 1.07; P = 0.021) cannabis use adjusted for socio-demographic characteristics was more rapid among those with depression. Perception of great risk associated with regular cannabis use was significantly lower among those with depression (P < 0.001) and decreased significantly more rapidly over the study period among people with depression, compared with those without (aORs = 0.89 versus 0.92; P < 0.001).

CONCLUSIONS

The prevalence of cannabis use in the United States increased from 2005 to 2017 among people with and without depression and was approximately twice as common among those with depression. People with depression experienced a more rapid decrease in perception of risk, which may be related to the more rapid increase in any and daily past-month cannabis use in this group.

Cannabis use among U.S. adolescents in the era of marijuana legalization: a review of changing use patterns, comorbidity, and health correlates

Decriminalization, medicalization, and legalization of cannabis use by a majority of U.S. states over the past 25 years have dramatically shifted societal perceptions and use patterns among Americans. How marijuana policy changes have affected population-wide health of U.S. youth and what the downstream public health implications of marijuana legalization are topics of significant debate. Cannabis remains the most commonly used federally illicit psychoactive drug by U.S. adolescents and is the main drug for which U.S. youth present for substance use treatment. Converging evidence indicates that adolescent-onset cannabis exposure is associated with short- and possibly long-term impairments in cognition, worse academic/vocational outcomes, and increased prevalence of psychotic, mood, and addictive disorders. Odds of negative developmental outcomes are increased in youth with early-onset, persistent, high frequency, and high-potency Δ-9-THC cannabis use, suggesting dose-dependent relationships. Cannabis use disorders are treatable conditions with clear childhood antecedents that respond to targeted prevention and early intervention strategies. This review indicates that marijuana policy changes have had mixed effects on U.S. adolescent health including potential benefits from decriminalization and negative health outcomes evidenced by increases in cannabis-related motor vehicle accidents, emergency department visits, and hospitalizations. Federal and state legislatures should apply a public health framework and consider the possible downstream effects of marijuana policy change on paediatric health.

Cannabis and the Developing Adolescent Brain

Purpose of Review

This review summarizes (1) recent trends in delta-9-tetrahydrocannabionol [THC] and cannabidiol (CBD) content in cannabis products, (2) neurobiological correlates of cannabis use on the developing adolescent brain, (3) effects of cannabis on psychiatric symptoms and daily functioning in youth (i.e., academic performance, cognition, sleep and driving), (4) cannabis products used to relieve or treat medical issues in youth, and (5) available treatments for cannabis use disorder in adolescence.

Recent findings

Despite marked increases in THC content and availability of cannabis, there has been a decline in perceived risk and an increase in use of THC extract products among youth in the United States. The primary psychiatric symptoms associated with cannabis use in youth are increased risk for addiction, depressive, and psychotic symptoms. Cannabis alters endocannabinoid system function which plays a central role in modulating the neurodevelopment of reward and stress systems. To date, few studies have examined neurobiological mechanisms underlying the psychiatric sequalae of cannabis exposure in youth. Adolescent cannabis exposure results in impaired cognition, sleep, and driving ability. There are very limited FDA-approved cannabinoid medications, none of them supporting their use for the treatment of psychiatric symptoms. Behavioral therapies are currently the mainstay of treating cannabis misuse, with no pharmacotherapies currently approved by the FDA for cannabis use disorder in youth.

Summary

Here, we summarize the most up-to-date knowledge on the neurobiological psychiatric, and daily function effects of the most commonly used cannabinoids, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). We then review FDA approved medical use of cannabinoid treatments as well as pharmacological and psychological treatments for cannabis use disorder in youth. Our current understanding of the effects of cannabis on the developing brain and treatments for cannabis misuse in youth remain limited. Future research aimed at examining the neurobiological effects of cannabis, with objective measures of exposure, over the course of pediatric development and in relation to psychiatric symptoms are needed.

Associations Between Marijuana Use Trajectories and Educational and Occupational Success in Young Adulthood

Adolescence and young adulthood is a critical stage when the economic foundations for life-long health are established. To date, there is little consensus as to whether marijuana use is associated with poor educational and occupational success in adulthood. We investigated associations between trajectories of marijuana use from ages 15 to 28 and multiple indicators of economic well-being in young adulthood including achievement levels (i.e., educational attainment and occupational prestige), work characteristics (i.e., full vs part-time employment, hours worked, annual income), financial strain (i.e., debt, trouble paying for necessities, delaying medical attention), and perceived workplace stress. Data were from the Victoria Healthy Youth Survey, a 10-year prospective study of a randomly recruited community sample of 662 youth (48% male; M_age = 15.5), followed biennially for six assessments. Models adjusted for baseline age, sex, SES, high school grades, heavy drinking, smoking, and internalizing and oppositional defiant disorder symptoms. Chronic users (our highest risk class) reported lower levels of educational attainment, lower occupational prestige, lower income, greater debt, and more difficulty paying for medical necessities in young adulthood compared to abstainers. Similarly, increasers also reported lower educational attainment, occupational prestige, and income. Decreasers, who had high early use but quit over time, showed resilience in economic well-being, performing similar to abstainers. Groups did not differ on employment status or perceived workplace stress. The findings indicate that early onset and persistent high or increasingly frequent use of marijuana in the transition from adolescent to young adulthood is associated with risks for achieving educational and occupational success, and subsequently health, in young adulthood.

Heavy cannabis use, dependence and the brain: a clinical perspective

AIMS

To summarize and evaluate our knowledge of the relationship between heavy cannabis use, cannabis use disorder (CUD) and the brain.

METHODS

Narrative review of relevant literature identified through existing systematic reviews, meta-analyses and a PubMed search. Epidemiology, clinical representations, potential causal mechanisms, assessments, treatment and prognosis are discussed.

RESULTS

Although causality is unclear, heavy and dependent cannabis use is consistently associated with a high prevalence of comorbid psychiatric disorders and learning and memory impairments that seem to recover after a period of abstinence. Evidence regarding other cognitive domains and neurological consequences, including cerebrovascular events, is limited and inconsistent. Abstinence after treatment is only achieved in a minority of cases; treatment targeted at reduction in use appears have some success. Potential moderators of the impact of CUD on the brain include age of onset, heaviness of use, CUD severity, the ratio of ∆9-tetrahydrocannabinol to cannabidiol and severity of comorbid disorders.

CONCLUSIONS

Current evidence of long-term effects of daily cannabis use and cannabis use disorder on brain-related outcomes is suggestive rather than conclusive, but use is associated with psychiatric morbidity and with cognitive impairments that recover after a period of abstinence.

Life-course trajectories of cannabis use: a latent class analysis of a New Zealand birth cohort

BACKGROUND AND AIMS

Little is known about how cannabis use over the life-course relates to harms in adulthood. The present study aimed to identify trajectories of cannabis use from adolescence to adulthood and examine both the predictors of these trajectories and adverse adult outcomes associated with those trajectories.

DESIGN

A latent trajectory analysis of a longitudinal birth cohort (from birth to age 35 years).

SETTING AND PARTICIPANTS

General community sample (n = 1065) from New Zealand.

MEASUREMENT

Annual frequency of cannabis use (ages 15-35 years); childhood family and individual characteristics (birth to age 16 years); measures of adult outcomes (substance use disorders, ages 30-35 years; mental health disorders, ages 30-35 years; socio-economic outcomes at age 35 years; social/family outcomes at age 35 years).

FINDINGS

A six-class solution was the best fit to the data. Individuals assigned to trajectories with higher levels of cannabis use were more likely to have experienced adverse childhood family and individual circumstances. Membership of trajectories with higher levels of use was associated with increased risk of adverse outcomes at ages 30-35 years. Adjustment of these associations for the childhood family and individual predictors largely did not reduce the magnitude of the associations.

CONCLUSIONS

In New Zealand, long-term frequent cannabis use, or transition to such use, appears to be robustly associated with diverse harms in adulthood.

Exposure to Cannabis Marketing in Social and Traditional Media and Past-Year Use Among Adolescents in States With Legal Retail Cannabis

PURPOSE

The objective of this study was to examine adolescents' self-reported exposure to cannabis marketing in states with legalized cannabis and its association with past-year cannabis use.

METHODS

We conducted a cross-sectional, online panel survey of 469 adolescents aged 15-19 years residing in four states with legal retail cannabis for adult use. Adolescents self-reported exposure to cannabis marketing on social or traditional media (i.e., outdoor or print) and past-year cannabis use. Logistic regression generated estimated odds of youths' past-year cannabis use by marketing exposure after adjusting for demographic factors and cannabis-related social norms.

RESULTS

Exposure to cannabis marketing on Facebook, Twitter, and Instagram was associated with increased odds of past-year cannabis use of 96% (95% confidence interval [CI]: 15%-234%), 88% (95% CI: 11%-219%), and 129% (95% CI: 32%-287%), respectively. Odds of past-year cannabis use increased by 48% (95% CI: 16%-87%) with each additional social media platform where adolescents reported exposure.

CONCLUSIONS

Despite restrictions that prohibit cannabis advertising on social media, adolescents are exposed to cannabis marketing via social media, and this exposure is associated with recent cannabis use. States should consider further regulation of cannabis marketing on social media.

The Role of Substance Use and Resiliency Factors on Suicidal Ideation among Middle School Students

BACKGROUND

Suicidal ideation, an important risk factor for suicide, is strongly associated with substance use. Factors such as family cohesion, connection with friends, and social support can be protective against suicidal behaviors. The purpose of this study was to explore the association between suicidal ideation, substance use, and resiliency factors among middle school students.

METHODS

The 2013 New Mexico Youth Risk and Resiliency Survey provided the data for this analysis. Suicidal ideation was defined as affirmative responses to questions about thoughts of killing oneself and/or making a suicide plan. We used logistic regression to explore the association between suicidal ideation, substance use, and resiliency factors.

RESULTS

Overall, 23% of students reported suicidal ideation. Among girls, having a caring friend was associated with lower odds of suicidal ideation only among those not using other drugs. Among boys, having a caring friend decreased the odds of suicidal ideation regardless of substance use.

CONCLUSIONS

Suicidal ideation is prevalent among middle school children. Substance abuse is associated with suicidal ideation; however, individual and community support can be protective. Interventions aimed at reducing suicidal behaviors among middle school students should account for the impact of substance use and help strengthen social support.

Marijuana Use and Potential Implications of Marijuana Legalization

Most states in the United States have legalized medical and/or recreational cannabis in response to public demand. Trends in states adopting such legislation demonstrate an increasing prevalence of cannabis use coincident to decreasing perceptions of risk of harm from cannabis products. When providing anticipatory guidance, pediatricians should be prepared to address childhood unintentional ingestion management and prevention, adolescent problem use, and cannabis as an alternative therapy for seizure disorders and other conditions.

The Changing Legal Landscape of Cannabis Use and Its Role in Youth-onset Psychosis

The rapidly changing landscape of cannabis in terms of availability, potency, and routes of administration, as well as the decrease in risk perception and changing norms, have contributed to an increase in the popularity of cannabis. Cannabis use is associated with a poorer recovery from a psychotic disorder, increasing the risk of relapse, rehospitalization, and lower social functioning. Data are mixed regarding cannabis use as a component cause of psychosis in people at risk for psychotic disorder. Care providers, parents, and schools must educate youth and adolescents about the risks of cannabis use.

Cannabis Use and the Risk for Psychosis and Affective Disorders

Objective: This review discusses the relationship between cannabis use and psychotic, bipolar, depressive, and anxiety disorders, as well as suicide. It summarizes epidemiological evidence from cross-sectional and long-term prospective studies and considers possible etiological mechanisms. Methods: Systematic reviews and methodologically robust studies in the field (from inception to February 2019) were identified using a comprehensive search of Medline, PsychINFO, and Embase and summarized using a narrative synthesis. Results: Consistent evidence, both from observational and experimental studies, has confirmed the important role of cannabis use in the initiation and persistence of psychotic disorders. The size of the effect is related to the extent of cannabis use, with greater risk for early cannabis use and use of high-potency varieties and synthetic cannabinoids. Accumulating evidence suggests that frequent cannabis use also increases the risk for mania as well as for suicide. However, the effect on depression is less clear and findings on anxiety are contradictory with only a few methodologically robust studies. Furthermore, the relationship with common mental disorders may involve reverse causality, as depression and anxiety are reported to lead to greater cannabis consumption in some studies. Pathogenetic mechanisms focus on the effect of tetrahydrocannabinol (THC, the main psychoactive ingredient of cannabis) interacting with genetic predisposition and perhaps other environmental risk factors. Cannabidiol (CBD), the other important ingredient of traditional cannabis, ameliorates the psychotogenic effects of THC but is absent from the high-potency varieties that are increasingly available. Conclusions: The evidence that heavy use of high-THC/low-CBD types of cannabis increases the risk of psychosis is sufficiently strong to merit public health education. Evidence of similar but smaller effects in mania and suicide is growing, but is not convincing for depression and anxiety. There is much current interest in the possibility that CBD may be therapeutically useful.

Are CB2 Receptors a New Target for Schizophrenia Treatment?

Schizophrenia is a complex disorder that involves several neurotransmitters such as dopamine, glutamate, and GABA. More recently, the endocannabinoid system has also been associated with this disorder. Although initially described as present mostly in the periphery, cannabinoid type-2 (CB2) receptors are now proposed to play a role in several brain processes related to schizophrenia, such as modulation of dopaminergic neurotransmission, microglial activation, and neuroplastic changes induced by stress. Here, we reviewed studies describing the involvement of the CB2 receptor in these processes and their association with the pathophysiology of schizophrenia. Taken together, these pieces of evidence indicate that CB2 receptor may emerge as a new target for the development of antipsychotic drugs.

Technology-Delivered Interventions for Substance Use Among Adolescents

Unhealthy alcohol and drug use are common among adolescents. A range of evidence-based interventions are available, but are rarely accessed by adolescents because of barriers such as cost, limited dissemination, lack of motivation to change, and logistical obstacles such as lack of transportation. Technology-delivered approaches may facilitate receipt of treatment in this vulnerable population. The limited number of controlled trials in this area present a mixed picture in terms of efficacy. Although sufficient to merit close attention and expanded research, the current literature points to a strong need for larger samples and greater use of rigorous and replicable methods.

Cannabis use and physical activity among 89,777 adolescents aged 12-15 years from 21 low- and middle-income countries

BACKGROUND

Cannabis legalization and use are increasing globally, however, little is known about associations between cannabis use and other health behaviors, such as physical activity (PA). Importantly, the extent to which cannabis use is associated with PA in adolescents is yet to be explored in low- and middle-income countries (LMICs), where there may be unique sociodemographic and environmental characteristics compared with high-income countries. Therefore, this study examined the association between PA and cannabis use among adolescents in 21 LMICs using data from the 2010-2016 Global School-based Student Health Survey.

METHODS

A multivariable logistic regression analysis was performed among a final sample of 89,777 adolescents (49.2% females) aged 12-15 years with a mean (SD) age of 13.7 (0.9) years.

RESULTS

The overall prevalence of past (i.e., in lifetime but not in past 30 days) and current (in past 30 days) cannabis use were 1.0% and 2.9% respectively, while the prevalence of adequate PA in the past week (7 days/week of 60 min of PA) was 16.6%. The prevalence of adequate levels of PA in past and current cannabis use was 7.3% and 6.9%, respectively. Current and past cannabis use (vs. never) were associated with a significant 0.62 (95% CI = 0.41-0.94) and 0.43 (95%CI = 0.30-0.63) times lower odds for achieving adequate levels of PA, respectively.

CONCLUSION

The results underscore the high prevalence of low PA among adolescents in LMICs, and emphasize the need to understand behavioral factors that may affect PA levels, such as cannabis use, when designing interventions to improve health.

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.

An intergenerational investigation of the associations between parental marijuana use trajectories and child functioning

Diverse patterns of life-course marijuana use may have differential health impacts for the children of users. Data are drawn from an intergenerational study of 426 families that included a parent, their oldest biological child, and (where appropriate) another caregiver who were interviewed 10 times from 2002 to 2018; the current study used data from 380 families in waves 6-10. Analyses linked parent marijuana use trajectories estimated in a previous publication (Epstein et al., 2015) to child marijuana, alcohol, and nicotine use; promarijuana norms; internalizing; externalizing; attention problems; and grades using multilevel modeling among children ages 6 to 21. Four trajectories had been found in the previous study: nonuser, chronic, adolescent-limited, and late-onset. Results indicate that children of parents in the groups that initiated marijuana use in adolescence (chronic and adolescent-limited) were most likely to use substances. Children of parents in the late-onset group, where parents initiated use in young adulthood, were not at increased risk for substance use but were more likely to have attention problems and lower grades. Results held when parent current marijuana use was added to the models. Implications of this work highlight the importance of considering both current use and use history in intergenerational transmission of marijuana use, and the need to address parent use history in family based prevention. Prevention of adolescent marijuana use remains a priority. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

"Debt on Me Head": A Qualitative Study of the Experience of Teenage Cannabis Users in Treatment

BACKGROUND

Cannabis is the most commonly used illicit drug in most western countries. In Ireland, it now accounts for most new presentations to substance use treatment services. Cannabis use for most of these people commenced during adolescence. Although a significant amount of research has been conducted on the effects of cannabis on physical and mental health, less is known about the experiences of young cannabis users.

OBJECTIVE

The aim of this study was to understand more about the experience of young, treatment-seeking, cannabis users.

METHODS

This descriptive qualitative study interviewed eight adolescents who were attending outpatient treatment services for cannabis misuse in Dublin, Ireland. Data were analyzed using thematic analysis.

RESULTS

Six themes were identified incorporating the early onset of cannabis and heavy use, involvement in criminality including drug dealing to pay for cannabis, ambivalence, experience of treatment, and damage to relationships. These themes are discussed in light of emerging literature.

CONCLUSION

Young cannabis users in treatment can clearly identify many negative aspects of their cannabis use but are particularly ambivalent toward cannabis. Reluctance to aim for abstinence is common.

The efficacy of spiritual/religious interventions for substance use problems: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Spiritual/religious (S/R) interventions are commonly used to treat substance use problems, but this is the first systematic review and meta-analysis to examine their efficacy for these problems.

METHODS

Ten electronic databases were searched to identify eligible studies (i.e., randomized controlled trials) published between January 1990 and February 2018 that examined S/R interventions' efficacy for substance use or psycho-social-spiritual outcomes. Two reviewers independently screened studies, extracted data, and assessed risks of bias. Robust variance estimation in meta-regression was used to estimate effect sizes and conduct moderator analysis.

RESULTS

Twenty studies comprising 3700 participants met inclusion criteria. Four studies used inactive controls, 14 used active controls, and two used both inactive and active controls and were therefore included in estimating both absolute and relative effect sizes. The absolute effect of S/R interventions (compared with inactive controls such as no treatment) was moderate but non-significant (six studies, d = .537, 95% confidence interval [CI] = -.316, 1.390), possibly due to low power. The relative effect of S/R interventions (compared with other interventions) was statistically significant (16 studies, d = .176, 95% CI = .001, .358). Because only 12-step-oriented interventions were compared with other interventions, this finding does not apply to the relative effect of non-12-step-oriented S/R interventions. Moderator analysis showed that relative effect sizes differ significantly by country.

CONCLUSION

We found evidence of S/R interventions' efficacy in helping people with substance use problems. More high-quality efficacy studies of non-12-step-oriented S/R interventions for substance use problems are needed.

Associations between adolescent cannabis use frequency and adult brain structure: A prospective study of boys followed to adulthood

BACKGROUND

Few studies have tested the hypothesis that adolescent cannabis users show structural brain alterations in adulthood. The present study tested associations between prospectively-assessed trajectories of adolescent cannabis use and adult brain structure in a sample of boys followed to adulthood.

METHODS

Data came from the Pittsburgh Youth Study - a longitudinal study of ˜1000 boys. Boys completed self-reports of cannabis use annually from age 13-19, and latent class growth analysis was used to identify different trajectories of adolescent cannabis use. Once adolescent cannabis trajectories were identified, boys were classified into their most likely cannabis trajectory. A subset of boys (n = 181) subsequently underwent structural neuroimaging in adulthood, when they were between 30-36 years old on average. For this subset, we grouped participants according to their classified adolescent cannabis trajectory and tested whether these groups showed differences in adult brain structure in 14 a priori regions of interest, including six subcortical (volume only: amygdala, hippocampus, nucleus accumbens, caudate, putamen, and pallidum) and eight cortical regions (volume and thickness: superior frontal gyrus; caudal and rostral middle frontal gyrus; inferior frontal gyrus, separated into pars opercularis, pars triangularis, and pars orbitalis; lateral and medial orbitofrontal gyrus).

RESULTS

We identified four adolescent cannabis trajectories: non-users/infrequent users, desisters, escalators, and chronic-relatively frequent users. Boys in different trajectory subgroups did not differ on adult brain structure in any subcortical or cortical region of interest.

CONCLUSIONS

Adolescent cannabis use is not associated with structural brain differences in adulthood.

Effects of Adolescent Cannabis Use on Motivation and Depression: A Systematic Review

Purpose of review

This article reviews recent behavioral and neuroimaging studies to elucidate whether adolescent cannabis use is related to reduced motivation and increased risk of depression.

Recent findings

Recent work suggests that heavy adolescent cannabis use predicts poorer educational outcomes, often presumed to reflect reduced academic motivation, as well as increased levels of depressive symptoms. However, evidence of a link between cannabis use and general motivation was lacking. Factors such as concurrent alcohol and tobacco use, trajectories of cannabis use during adolescence, and cannabis-related changes in underlying neurocircuitry may impact associations among cannabis use, motivation, and depression.

Summary

Heavy adolescent cannabis use is associated with poorer educational outcomes and increased levels of depressive symptoms. The role of depression in how cannabis may affect motivation, broadly, is not yet clear, as most studies have not examined associations among all three constructs. Future work should explore possible overlap between cannabis effects on motivation and depression, and clarify the temporality of these associations.

Cannabinoids for the treatment of rheumatic diseases - where do we stand?

As medical use of cannabis is increasingly legalized worldwide, a better understanding of the medical and hazardous effects of this drug is imperative. The pain associated with rheumatic diseases is considered a prevalent indication for medicinal cannabis in various countries. Thus far, preliminary clinical trials have explored the effects of cannabis on rheumatoid arthritis, osteoarthritis and fibromyalgia; preliminary evidence has also found an association between the cannabinoid system and other rheumatic conditions, including systemic sclerosis and juvenile idiopathic arthritis. The potential medicinal effects of cannabis could be attributable to its influence on the immune system, as it exerts an immunomodulatory effect on various immune cells, including T cells, B cells and macrophages. However, the available evidence is not yet sufficient to support the recommendation of cannabinoid treatment for rheumatic diseases.

Medical, therapeutic, and recreational use of cannabis among young men who have sex with men living with HIV

Cannabis plays a role in symptoms management in HIV, especially the alleviation of pain and nausea and stimulation of appetite, and prevalence of cannabis use in HIV-positive populations exceeds that of the general U.S. population. Previous research has described an "overlap" between medical and recreational cannabis use among persons living with HIV. To understand better the motives associated cannabis use among young men who have sex with men living with HIV (HIV+ YMSM), we conducted semi-structured interviews with 30 HIV+YMSM in Denver and Chicago. Interviews were audio-recorded, transcribed, and coded by a diverse team of analysts. In addition to findings that mapped onto previously identified medical motives and recreational motives, we identified several themes that straddled medical and recreational use in a domain we describe as therapeutic. Themes identified in this therapeutic domain of cannabis use include (a) enhanced introspection among individuals that promotes psychological adjustment to an HIV diagnosis, improved medical management, and future orientation; (b) reflection processes that mitigate interpersonal conflict and improve interpersonal communication; and (c) a social-therapeutic phenomena of cannabis use among young persons with living HIV that is characterized by both enhanced introspection and improved interpersonal communication. Our findings suggest a spectrum of cannabis use among HIV+ YMSM that may be characterized not only by an overlap between medical and recreational use, but also by a distinct therapeutic domain that incorporates stress alleviation and cognitive expansion processes to improve focus on HIV management and self-care.

Exposure to and Content of Marijuana Product Reviews

Many individuals now seek out product reviews in order to make an informed decision prior to making a purchase. In this study, we investigate consumers' exposure to and content within product reviews about marijuana because of their potential to shape marijuana purchasing decisions. The terms "weed review," "marijuana review," and "cannabis review" were searched on YouTube on June 10-11, 2015; the team viewed and coded the content of 83 product review videos about marijuana. In addition, we surveyed young adult (18-34 years old) current (past month) marijuana users (n = 742) from across the USA online to assess exposure to product reviews about marijuana and associations with socio-demographic characteristics and marijuana use behaviors. In our content analysis of videos, we observed that the reviewers tended to consume marijuana during the video and often shared personal, favorable experiences towards the marijuana they ingested (e.g., became as high as possible or experienced positive effects on physical and mental health). Most videos normalized marijuana use and could be easily accessed by underage youth. About one third (34%) of the survey participants viewed/sought a product review about marijuana in the past 30 days. In a multivariable logistic regression model, living in a state where recreational use is legal or using multiple forms of marijuana was associated with increased odds of viewing/seeking marijuana reviews. Prevention messages should counter product reviews about marijuana that tend to normalize and promote marijuana use given that they are more readily viewed by individuals who are increasingly susceptible to marijuana's potential harms.

Associations Between Cannabis Use and Cardiometabolic Risk Factors: A Longitudinal Study of Men

OBJECTIVE

This study tested longitudinal associations between cannabis use and cardiometabolic risk factors that underlie the development of cardiovascular diseases.

METHODS

Participants were men from the youngest cohort of the Pittsburgh Youth Study who were followed prospectively from approximately age 7 to 32 years (N = 253). Frequency of cannabis use was assessed yearly from approximately ages 12 to 20 years and again at approximately ages 26, 29, and 32 years. The following cardiometabolic risk factors were assessed during a laboratory visit at approximately age 32 years: body mass index (BMI), waist-hip ratio, high- and low-density lipoprotein cholesterol, triglycerides, fasting glucose, insulin resistance, blood pressure, interleukin 6, and C-reactive protein.

RESULTS

Greater cannabis exposure was associated with relatively lower BMI (β = -0.31, p < .001), smaller waist-hip ratio (β = -0.23, p = .002), better high- (β = 0.14, p = .036) and low-density lipoprotein cholesterol (β = -0.15, p = .026), lower triglycerides (β = -0.17, p = .009), lower fasting glucose (β = -0.15, p < .001) and insulin resistance (β = -0.21, p = .003), lower systolic (β = -0.22, p < .001) and diastolic blood pressure (β = -0.15, p = .028), and fewer metabolic syndrome criteria (β = -0.27, p < .001). With exception of BMI, cannabis users' mean levels on cardiometabolic risk factors were generally below clinical cutoffs for high risk. Most associations between cannabis use and cardiometabolic risk factors remained after adjusting for tobacco use, childhood socioeconomic status, and childhood health. However, after adjusting for adult BMI, these associations were no longer apparent, and mediation tests suggested that cannabis users' relatively lower BMI might explain their lower levels of risk on other cardiometabolic risk factors.

CONCLUSIONS

Cannabis use is associated with lower BMI, and lower BMI is related to lower levels of risk on other cardiometabolic risk factors.

Time since first cannabis use and 12-month prevalence of cannabis use disorder among youth and emerging adults in the United States

AIM

This study estimated whether and how the 12-month prevalence of cannabis use disorder among US youth aged 12-17 and emerging adults aged 18-25 varied by time since first cannabis use.

DESIGN

Repeated cross-sectional survey data from the 2015-17 National Surveys on Drug Use and Health (NSDUH).

SETTING

United States.

PARTICIPANTS

A total of 101 000 NSDUH participants aged 12-25.

MEASUREMENTS

Past 12-month cannabis use disorder was assessed using DSM-IV criteria.

FINDINGS

Among youth, the life-time prevalence of cannabis use was 15.3% [95% confidence interval (CI) = 14.86-15.65%]. Among emerging adults, the life-time prevalence of cannabis use was 52.4% (95% CI = 51.77-53.01%). The adjusted 12-month prevalence of cannabis use disorder among youth with life-time cannabis use was 10.9% (95% CI = 9.24-12.75%) in the first year after starting cannabis use, 15.3% (95% CI = 13.68-17.12%) in the second year, 17.7% (95% CI = 15.55-19.97%) in the third year and 20.6% (95% CI = 18.23-23.17%) in the fourth year and beyond, which was consistently higher after the first year (linear trend only: P < 0.0001). The adjusted 12-month prevalence of cannabis use disorder among emerging adults with life-time use ranged from 5.6% (95% CI = 4.26-7.23%) in the first year after starting cannabis use, 7.7% (95% CI = 6.45-9.17%) in the second year and 9.1% (95% CI = 7.81-10.57%) in the third year to 10.5% (95% CI = 9.87%-11.12%) in the fourth year and beyond, which was consistently higher after the first year (linear trend only: P < 0.0001). Within each time-frame since first cannabis use, the adjusted 12-month prevalence of cannabis use disorder was higher among youth life-time users than their emerging adult counterparts.

CONCLUSIONS

Among youth and emerging adults in the United States, the prevalence of cannabis use disorder appears to increase with time since initiation of use and is higher among youth than among emerging adults during each examined time-frame.

Association of Cannabis Use in Adolescence and Risk of Depression, Anxiety, and Suicidality in Young Adulthood: A Systematic Review and Meta-analysis

Importance

Cannabis is the most commonly used drug of abuse by adolescents in the world. While the impact of adolescent cannabis use on the development of psychosis has been investigated in depth, little is known about the impact of cannabis use on mood and suicidality in young adulthood.

Objective

To provide a summary estimate of the extent to which cannabis use during adolescence is associated with the risk of developing subsequent major depression, anxiety, and suicidal behavior.

Data Sources

Medline, Embase, CINAHL, PsycInfo, and Proquest Dissertations and Theses were searched from inception to January 2017.

Study Selection

Longitudinal and prospective studies, assessing cannabis use in adolescents younger than 18 years (at least 1 assessment point) and then ascertaining development of depression in young adulthood (age 18 to 32 years) were selected, and odds ratios (OR) adjusted for the presence of baseline depression and/or anxiety and/or suicidality were extracted.

Data Extraction and Synthesis

Study quality was assessed using the Research Triangle Institute item bank on risk of bias and precision of observational studies. Two reviewers conducted all review stages independently. Selected data were pooled using random-effects meta-analysis.

Main Outcomes and Measures

The studies assessing cannabis use and depression at different points from adolescence to young adulthood and reporting the corresponding OR were included. In the studies selected, depression was diagnosed according to the third or fourth editions of Diagnostic and Statistical Manual of Mental Disorders or by using scales with predetermined cutoff points.

Results

After screening 3142 articles, 269 articles were selected for full-text review, 35 were selected for further review, and 11 studies comprising 23 317 individuals were included in the quantitative analysis. The OR of developing depression for cannabis users in young adulthood compared with nonusers was 1.37 (95% CI, 1.16-1.62; I2 = 0%). The pooled OR for anxiety was not statistically significant: 1.18 (95% CI, 0.84-1.67; I2 = 42%). The pooled OR for suicidal ideation was 1.50 (95% CI, 1.11-2.03; I2 = 0%), and for suicidal attempt was 3.46 (95% CI, 1.53-7.84, I2 = 61.3%).

Conclusions and Relevance

Although individual-level risk remains moderate to low and results from this study should be confirmed in future adequately powered prospective studies, the high prevalence of adolescents consuming cannabis generates a large number of young people who could develop depression and suicidality attributable to cannabis. This is an important public health problem and concern, which should be properly addressed by health care policy.

Alcohol and parenthood: An integrative analysis of the effects of transition to parenthood in three Australasian cohorts

AIMS

To determine the extent to which the transition to parenthood protects against heavy and problematic alcohol consumption in young men and women.

DESIGN

Integrated participant-level data analysis from three population-based prospective Australasian cohort studies.

SETTING

General community; participants from the Australian Temperament Study, the Christchurch Health and Development Study, and the Victorian Adolescent Health Cohort Study.

MEASUREMENTS

Recent binge drinking, alcohol abuse/dependence and number of standard drinks consumed per occasion.

FINDINGS

4015 participants (2151 females; 54%) were assessed on four occasions between ages 21 and 35. Compared to women with children aged <12 months, women who had not transitioned to parenthood were more likely to meet the criteria for alcohol abuse/dependence (fully adjusted risk ratio [RR] 3.5; 95% CI 1.5-7.9) and to report recent binge drinking (RR 3.0; 95% CI 2.1-4.3). The proportion of women meeting the criteria for alcohol abuse/dependence and/or binge drinking increased with the age of participants' youngest child, as did the mean number of standard drinks consumed on each occasion (1.8 if the youngest child was <1 year of age vs. 3.6 for 5+ years of age). Associations between parenthood and male drinking behaviour were considerably weaker.

CONCLUSIONS

For most women in their twenties and thirties, parenting a child <1 year of age was associated with reduced alcohol consumption. However, this protective effect diminished after 12 months with drinking levels close to pre-parenthood levels after five years. There was little change in male drinking with the transition to parenthood.

Trends of major depressive episode among people with cannabis use: Findings from the National Survey on Drug Use and Health 2006-2015

Background: A dose-response association, suggesting that heavy cannabis users are more likely to report depressive disorders, has been hypothesized. However, evidence is not conclusive, and we aimed at testing the existence of a linear association between different levels of cannabis use and depressive disorders using large, representative, repeated surveys. Methods: We examined prevalence rates of different levels of past-year cannabis use and major depressive episode (MDE), separately for young people (12-17 years) and adults (18-64 years), using data between 2006 and 2015 from the National Survey on Drug Use and Health. Prevalence rates estimates with 95% confidence intervals were computed, and the association between past-year MDE and cannabis use was assessed. We then investigated whether time-period trends existed for MDE and, if so, whether these differed by cannabis use levels. Models included both time period, to evaluate trend changes in past-year MDE from 2006 to 2015, and time period by cannabis level interaction terms. Results: Cannabis users were more likely, using both single-year and pooled survey data, to have suffered from MDE in the past year. Multiple logistic regression models, after adjusting for time period, age, and gender, showed an association between MDE and cannabis use, regardless of its levels. However, a roughly dose-response relationship was detectable only for adults. Trends in past-year MDE prevalence rates among subjects with different levels of cannabis use did not differ from trends among nonusers. Women were more likely to report concurrent past-year MDE and cannabis use than men. Conclusions: Cannabis users have consistently higher prevalence rates of depressive disorders compared with nonusers, suggesting the need for integrated screening and treatment programs to tackle this comorbid condition.