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Background: Epidemiological studies show a dose–response association between cannabis use and the risk of psychosis. This review aimed to determine whether there are identifiable risk-thresholds between the frequency of cannabis use and psychosis development. Methods: Systematic search of Embase, MEDLINE, PsycINFO, CINAHL, and Web of Science for relevant studies (1 January 2010–26 April 2021). Case–control or cohort studies that investigated the relationship between cannabis use and the risk of psychosis development that reported effect estimates [odds ratios (OR), hazard ratios (HR), risk ratios (RR)] or the raw data to calculate them, with information on the frequency of cannabis consumption were included. Effect estimates were extracted from individual studies and converted to RR. Two-stage dose–response multivariable meta-analytic models were utilized and sensitivity analyses conducted. The Newcastle Ottawa Scale was used to assess the risk of bias of included studies. Results: Ten original (three cohorts, seven case–control) studies were included, including 7390 participants with an age range of 12–65 years. Random-effect model meta-analyses showed a significant log-linear dose–response association between cannabis use frequency and psychosis development. A restricted cubic-splines model provided the best fit for the data, with the risk of psychosis significantly increasing for weekly or more frequent cannabis use [RR = 1.01, 95% confidence interval (CI) 0.93–1.11 yearly; RR = 1.10, 95% CI 0.97–1.25 monthly; RR = 1.35, 95% CI 1.19–1.52 weekly; RR = 1.76, 95% CI 1.47–2.12 daily] Conclusion: Individuals using cannabis frequently are at increased risk of psychosis, with no significant risk associated with less frequent use. Public health prevention messages should convey these risk-thresholds, which should be refined through further work. [ABSTRACT FROM AUTHOR]

Background and Aims: The most available data on the prevalence of cannabis use come from population surveys conducted in high‐income countries in North America, Oceania and Europe. Less is known about the prevalence of cannabis use in Africa. This systematic review aimed to summarize general population‐level cannabis use in sub‐Saharan Africa since 2010. Methods: A comprehensive search was conducted in PubMed, EMBASE, PsycINFO and AJOL databases in addition to Global Health Data Exchange and grey literature without language restriction. Search terms related to 'substance', 'Substance‐Related Disorders' and 'Prevalence' and 'Africa South of the Sahara' were used. Studies that reported cannabis use in the general population were selected, while studies from clinical populations and high‐risk groups were excluded. Prevalence data on cannabis use in the general population of adolescents (10–17 years) and adults (≥ 18 years) in sub‐Saharan Africa were extracted. Results: The study included 53 studies for the quantitative meta‐analysis and included 13 239 participants. Among adolescents, the life‐time, 12‐month and 6‐month prevalence of cannabis use were 7.9% [95% confidence interval (CI) = 5.4–10.9%], 5.2% (95% CI = 1.7–10.3%) and 4.5% (95% CI = 3.3–5.8%), respectively. The corresponding life‐time, 12‐month and 6‐month prevalence of cannabis use among adults were 12.6% (95% CI = 6.1–21.2%), 2.2% (95% CI = 1.7–2.7%, with data only available from Tanzania and Uganda) and 4.7% (95% CI = 3.3–6.4%), respectively. The male‐to‐female life‐time cannabis use relative risk was 1.90 (95% CI = 1.25–2.98) among adolescents and 1.67 (CI = 0.63–4.39) among adults. Conclusions: Life‐time cannabis use prevalence in sub‐Saharan Africa appears to be approximately 12% for adults and just under 8% for adolescents. [ABSTRACT FROM AUTHOR]

An increased use of high‐potency cannabis products since cannabis legalization in the United States, Canada and elsewhere may increase cannabis‐related harm. Policymakers have good reasons for regulating more potent cannabis in ways that minimize harm, using approaches similar to those used to regulate alcohol; namely, banning the sale of high‐potency cannabis, setting a cap on tetrahydrocannabinol (THC) content and imposing higher rates of taxes on more potent cannabis products. Given the difficulty that US policymakers have had in regulating cannabis extracts and edibles, governments that are planning to legalize cannabis need to put policies on extracts into enabling legislation and evaluate the impact of these policies on cannabis use and cannabis‐related harms. [ABSTRACT FROM AUTHOR]

Objective: Cannabis use is increasingly normalized; psychosis is a major adverse health outcome. We reviewed evidence on cannabis use-related risk factors for psychosis outcomes at different stages toward recommendations for risk reduction by individuals involved in cannabis use. Methods: We searched primary databases for pertinent literature/data 2016 onward, principally relying on reviews and high-quality studies which were narratively summarized and quality-graded; recommendations were developed by international expert consensus. Results: Genetic risks, and mental health/substance use problem histories elevate the risks for cannabis-related psychosis. Early age-of-use-onset, frequency-of-use, product composition (i.e., THC potency), use mode and other substance co-use all influence psychosis risks; the protective effects of CBD are uncertain. Continuous cannabis use may adversely affect psychosis-related treatment and medication effects. Risk factor combinations further amplify the odds of adverse psychosis outcomes. Conclusions: Reductions in the identified cannabis-related risks factors—short of abstinence—may decrease risks of related adverse psychosis outcomes, and thereby protect cannabis users' health. [ABSTRACT FROM AUTHOR]

The author comments on the use of double evidential standards in assessing the adverse and beneficial effects of cannabis. Topics discussed include argument of some critics of publicly funded research on cannabis use, a popular argument for legalization, and characteristics of people with cannabis use disorders (CUDs.)

The article revisits the question of the impact of the COVID-19 pandemic on addictive disorders. Topics covered include consumption of opioid, alcohol and cannabis, levels of gambling problem, and mortality rate. It also discusses the need for studies on harms among people who use stimulant drugs and have underlying respiratory or cardiovascular disease, particularly during the pandemic.

Background and aim: The prevalence of tobacco smoking has declined in most high‐income countries, while cannabis use has been rising. Moreover, cannabis use has been found to have increased among cigarette smokers in recent years in jurisdictions where it has been either decriminalized or legalized. This study measured trends in cannabis, tobacco and the co‐use of cannabis and tobacco in Australia. Design: Age–period–cohort analysis. Setting and participants: Participants were n = 143 344 individuals aged 18–80 years who participated in Australia's National Drug Strategy Household Surveys (NDSHS) between 2001 and 2019. Measurements Regular (weekly/more frequently): (1) tobacco smoking only, (2) cannabis use only and (3) the co‐use of cannabis and tobacco. Findings Prevalence of only smoking tobacco decreased in all age groups (P < 0.001) and birth cohorts between 2001 and 2019, but the co‐use of cannabis and tobacco did not. Younger cohorts were much less likely to co‐use tobacco and cannabis (P = 0.02). Period trends showed that both cannabis use only and the co‐use of cannabis and tobacco have increased since 2013. Conclusion: There has been a consistent decrease in exclusive tobacco smoking across age, period and birth cohorts between 2001 and 2019 in Australia, although there is a recent increasing period trend in cannabis use with or without tobacco. The non‐decreasing trend of co‐use may reflect the strong tobacco control policies introduced over the period and changing attitudes towards cannabis use in Australia. [ABSTRACT FROM AUTHOR]

Background and Aims: Cannabis withdrawal is a well‐characterized phenomenon that occurs in approximately half of regular and dependent cannabis users after abrupt cessation or significant reductions in cannabis products that contain Δ9‐tetrahydrocannabinol (THC). This review describes the diagnosis, prevalence, course and management of cannabis withdrawal and highlights opportunities for future clinical research. Methods: Narrative review of literature. Results: Symptom onset typically occurs 24–48 hours after cessation and most symptoms generally peak at days 2–6, with some symptoms lasting up to 3 weeks or more in heavy cannabis users. The most common features of cannabis withdrawal are anxiety, irritability, anger or aggression, disturbed sleep/dreaming, depressed mood and loss of appetite. Less common physical symptoms include chills, headaches, physical tension, sweating and stomach pain. Despite limited empirical evidence, supportive counselling and psychoeducation are the first‐line approaches in the management of cannabis withdrawal. There are no medications currently approved specifically for medically assisted withdrawal (MAW). Medications have been used to manage short‐term symptoms (e.g. anxiety, sleep, nausea). A number of promising pharmacological agents have been examined in controlled trials, but these have been underpowered and positive findings not reliably replicated. Some (e.g. cannabis agonists) are used 'off‐label' in clinical practice. Inpatient admission for MAW may be clinically indicated for patients who have significant comorbid mental health disorders and polysubstance use to avoid severe complications. Conclusions: The clinical significance of cannabis withdrawal is that its symptoms may precipitate relapse to cannabis use. Complicated withdrawal may occur in people with concurrent mental health and polysubstance use. [ABSTRACT FROM AUTHOR]

Introductions: In the United States (US), support for cannabis legalization has increased over time. This study examines historical changes in legalization attitudes and the period-specific individual and external influences on these. A systematic search was conducted for publications in PubMed, EMBASE, and PsycINFO up to October 2019. Six studies with a regionally or nationally representative adult US-based populations were included. A secondary analysis was conducted using data from the National Survey of Drug Use and Health. Hierarchical age-period-cohort analysis assessed the trends in perceived harmfulness and availability of cannabis between 1996 and 2018. Ecological comparisons were made between these perceptions and support for cannabis legalization over time. A steep growth in support for cannabis legalization began in the 1990s and continued to grow in a relatively linear manner. Most people developed more liberal views, with no evidence that changes within any one sociodemographic group was disproportionately responsible for the overall attitudinal change. Increases in the proportion of people who use cannabis, non-religious population and political liberalism may partially explain the increased support for legalization. The decline in perceived harmfulness of cannabis, as reflected in the media, may have contributed to the increased support for legalization. However, perceptions of the availability of cannabis remained stable despite significant relaxations in cannabis regulations. The US population has become more accepting of cannabis legalization. The attitudinal change is related to changes in the perceived risks and benefits of cannabis use, influenced by broader political and cultural changes over the study period. [ABSTRACT FROM AUTHOR]

Objective: Cannabis use is increasing among midlife and older adults. This study tested the hypotheses that long-term cannabis use is associated with cognitive deficits and smaller hippocampal volume in midlife, which is important because midlife cognitive deficits and smaller hippocampal volume are risk factors for dementia.Methods: Participants are members of a representative cohort of 1,037 individuals born in Dunedin, New Zealand, in 1972-1973 and followed to age 45, with 94% retention. Cannabis use and dependence were assessed at ages 18, 21, 26, 32, 38, and 45. IQ was assessed at ages 7, 9, 11, and 45. Specific neuropsychological functions and hippocampal volume were assessed at age 45.Results: Long-term cannabis users showed IQ decline from childhood to midlife (mean=-5.5 IQ points), poorer learning and processing speed relative to their childhood IQ, and informant-reported memory and attention problems. These deficits were specific to long-term cannabis users because they were either not present or were smaller among long-term tobacco users, long-term alcohol users, midlife recreational cannabis users, and cannabis quitters. Cognitive deficits among long-term cannabis users could not be explained by persistent tobacco, alcohol, or other illicit drug use, childhood socioeconomic status, low childhood self-control, or family history of substance dependence. Long-term cannabis users showed smaller hippocampal volume, but smaller hippocampal volume did not statistically mediate cannabis-related cognitive deficits.Conclusions: Long-term cannabis users showed cognitive deficits and smaller hippocampal volume in midlife. Research is needed to ascertain whether long-term cannabis users show elevated rates of dementia in later life. [ABSTRACT FROM AUTHOR]

Rationale: There has been increasing attention on cannabis use for medical purposes, but there is currently a lack of data on its epidemiology. Objectives: To examine the epidemiology of self-reported cannabis use for medical purposes by (1) estimating its prevalence, (2) comparing gender and age differences, and (3) investigating what reasons they were used to manage. Methods: Participants included 27,169 respondents (aged 16–65) who completed Wave 1 of The International Cannabis Policy Study (ICPS) conducted across Canada and the USA in 2018 via online surveys. Cannabis policy conditions were "US legal–recreational" (legal for both recreational and medical uses), "US legal–medical only", "US illegal", and "Canada–medical only". Results: The overall prevalence of self-reported ever cannabis use for medical purposes was 27%, with similar rates by sex and the highest prevalence in young adults. Prevalence was higher in US legal–recreational states (34%) than US illegal states (23%), US legal–medical only states (25%), and Canada (25%). The most common physical health reasons include use to manage pain (53%), sleep (46%), headaches/migraines (35%), appetite (22%), and nausea/vomiting (21%). For mental health reasons, the most common were for anxiety (52%), depression (40%), and PTSD/trauma (17%). There were 11% who reported using cannabis for managing other drug or alcohol use and 4% for psychosis. Conclusions: A substantial proportion of the North American population self-reported cannabis use for medical purposes for a variety of medical reasons, including those living in jurisdictions without legal markets. Further research is needed to understand the safety and efficacy of these forms of medical cannabis use. [ABSTRACT FROM AUTHOR]

Background and Aims: There has been an increase in the potency of cannabis during the last two decades and adoption of a novel method of administration—vaping. YouTube, a social media platform, has become a popular source to access cannabis‐related information. This study aimed to identify cannabis vaping YouTube videos from 2016 to 2020 and examine the themes and metrics. Design Cross‐sectional sample of 200 YouTube videos. Setting: YouTube, an on‐line video sharing platform. Measurements Videos related to cannabis vaping were identified using the search terms: 'vaping cannabis', 'vaping weed', 'vaping marijuana' and 'vaping THC' [tetrahydrocannabinol]. Videos were independently coded by two researchers. The number of views, likes, dislikes and comments were also collected. Robust regression was used to analyse the relationship between identified video themes and video metrics. Findings Six themes were identified: 'advertisement', 'product review', 'celebratory', 'reflective', 'how‐to' and 'warning'. The 'how‐to' and 'celebratory' videos received the highest number of views and likes. The most popular video was viewed more than 4 000 000 times. Many videos portrayed risky behaviour (e.g. vaping a whole THC cartridge in a single setting). Fifty‐two percent of these videos had no age access restrictions. The robust regression model also found that engagement metric was positively associated with 'reflective' videos and negatively associated with 'advertisement' videos. Conclusions: A large number of videos on cannabis vaping are available on‐line without age‐restriction. Videos that portrayed risky behaviour appear to be prevalent. [ABSTRACT FROM AUTHOR]

Aim: To describe an outbreak of lung injuries in 2019 among people who vaped in the United States (type of injuries, people afflicted, substances vaped and cause of the injuries) and to analyse critically the regulatory responses of public health authorities and the media reporting of the outbreak. Methods: Case studies of the reporting of the e‐cigarette or vaping product use associated lung injury (EVALI) outbreak. We examined data on the number of cases of lung injury provided by the US Centers for Disease Control (CDC), public advice on the causes of the outbreak provided by the CDC and the Food and Drug Administration (FDA), major media reports of the outbreak and proposed regulatory responses by governments in the United States, Australia and the United Kingdom. Results: The CDC initially suggested that the cause of the outbreak was nicotine vaping because the outbreak followed a large increase in nicotine vaping among US adolescents. Case–control studies revealed that the majority of cases had vaped illicit cannabis oils that were contaminated by vitamin E acetate. The CDC's public advice and the media were slow to report the evidence on the role of cannabis vaping. Popular government regulatory proposals—bans on sales of nicotine flavours and vaporizers—were based on the assumption that nicotine vaping was the cause of the outbreak. Conclusions: Media reporting in the United States, Australia and the United Kingdom of the US Centers for Disease Control's analysis of the causes of the e‐cigarette or vaping product use associated lung injury outbreak contributed to regulatory over‐reactions to nicotine vaping by the public health community. [ABSTRACT FROM AUTHOR]

The author examines whether Germany's new cannabis policy reform plans serve public health, as of October 2023. The goals of the new policy include the protection of cannabis consumers' health and safety, youth protection and the reduction of illicit cannabis markets as principal goals. Also cited is the two-step approach for cannabis policy reform in the revised proposal.

Aim: To estimate the proportion of cannabis consumed in Australia by daily cannabis users. Design Monte Carlo simulation using parameters estimated from nationally representative and repeated cross‐sectional household surveys in 2007, 2010, 2013 and 2016. Setting: Australia Participants: Adult samples (mean age = 49.9; 55% females) from four National Drug Strategy Household Surveys (n = 92 243). Measurement Frequency of cannabis use (daily/weekly/about once a month/every few months/once or twice a year). The weighted estimated prevalence of users in each of these frequency levels was multiplied by population size to estimate the total number of users. Quantity of cannabis use was measured as number of joints consumed. The consumption of those who reported using bongs was converted into joints based on the bong to joint ratio estimated from the survey data. We estimated the proportion of cannabis consumed by daily users by Monte Carlo simulation using parameters estimated from the household surveys. We conducted 10 000 simulation trials, and in each trial we [1] simulated the number of users at each consumption level (stratum) based on estimated prevalence and population size[2], for each simulated individual, we simulated the number of days of cannabis use in a year based on frequency data[3], for each consumption day, we simulated the quantity consumed [4] and lastly we calculated the total joints consumed at each consumption level and estimated the proportion of joints consumed by daily users out of the total consumption. Findings The prevalence of past‐year cannabis use increased from 8.9% [95% confidence interval (CI) = 8.5–9.4] in 2007 to 10.5% (95% CI = 10.0–11.1) in 2016, 16% of whom were daily users. Between 2007 and 2016, daily users accounted for between 81.6 and 85.7% of all cannabis consumed. Weekly users accounted for an additional 12.1–15.9%. Conclusion: Between 2007 and 2016, only one in six Australian cannabis users were daily users, but they accounted for more than 80% of the estimated cannabis consumed in Australia. [ABSTRACT FROM AUTHOR]

The authors respond to commentaries made on their article which aimed to alert the addictions field to the critical issue of increased cannabis potency as a public health concern, oppose the cannabis industry argument that such regulation is unnecessary, and canvas some regulatory options. Topics include consumers' need for simpler advice on labels, the fact that the U.S. model of cannabis legalization is not the only model on offer, and the economic drivers of increasing cannabis potency.

The article discusses the Indian Hemp Drugs Commission report from 1894, which recommends the regulation and taxation of cannabis, rather than the prohibition. The report found that excessive ganja use could cause psychosis in rare instances and suggested regulation and taxation to limit excessive use and allow for medical use, preventing the growth of an illicit cannabis market.

Background and aims: A growing body of evidence suggests that cannabis impairs driving ability. We used mortality data to investigate whether the commercial sale of cannabis for recreational use affected traffic fatality rates both in states that legalized it and in neighbouring jurisdictions. Design Interrupted time–series of traffic fatality rates adjusted for seasonality and autocorrelation. Changes are reported as step and trend effects against a comparator of states that had not implemented medicinal or recreational cannabis during the study period (2009–16). Sensitivity analyses added a 6‐month 'phase‐in' to account for lags in production. Meta‐analyses were used to derive pooled results. Setting: Three states that legalized recreational cannabis sales [Colorado (January 2014), Washington State (June 2014) and Oregon (October 2015] and nine neighbouring jurisdictions [Kansas, Nebraska, New Mexico, Oklahoma and Utah (Colorado neighbours); British Columbia and Oregon (Washington neighbours); and California and Nevada (Oregon neighbours)]. Measurements Monthly traffic fatalities rates per million residents using mortality data from CDC WONDER and RoadSafetyBC and census data. Findings There was a pooled step increase of 1.08 traffic fatalities per million residents followed by a trend reduction of −0.06 per month (both P < 0.001), although with significant heterogeneity between sites (step: I2 = 73.7%, P < 0.001; trend: I2 = 68.4%; P = 0.001). Effects were similar in both legalizing (step: 0.90, P < 0.001; trend: −0.05, P = 0.007) and neighbouring sites (step: 1.15, P = 0.005; trend: −0.06, P = 0.001). The 6‐month phase‐in produced similar if larger effects (step: 1.36, P = 0.006; trend: −0.07, P < 0.001). Conclusions: The combination of step increases and trend reductions suggests that in the year following implementation of recreational cannabis sales, traffic fatalities temporarily increased by an average of one additional traffic fatality per million residents in both legalizing US states of Colorado, Washington and Oregon and in their neighbouring jurisdictions. [ABSTRACT FROM AUTHOR]

Abstract: Aims: This review provides an up‐to‐date curated source of information on alcohol, tobacco and illicit drug use and their associated mortality and burden of disease. Limitations in the data are also discussed, including how these can be addressed in the future. Methods: Online data sources were identified through expert review. Data were obtained mainly from the World Health Organization, United Nations Office on Drugs and Crime and Institute for Health Metrics and Evaluation. Results: In 2015, the estimated prevalence among the adult population was 18.4% for heavy episodic alcohol use (in the past 30 days); 15.2% for daily tobacco smoking; and 3.8, 0.77, 0.37 and 0.35% for past‐year cannabis, amphetamine, opioid and cocaine use, respectively. European regions had the highest prevalence of heavy episodic alcohol use and daily tobacco use. The age‐standardized prevalence of alcohol dependence was 843.2 per 100 000 people; for cannabis, opioids, amphetamines and cocaine dependence it was 259.3, 220.4, 86.0 and 52.5 per 100 000 people, respectively. High‐income North America region had among the highest rates of cannabis, opioid and cocaine dependence. Attributable disability‐adjusted life‐years (DALYs) were highest for tobacco smoking (170.9 million DALYs), followed by alcohol (85.0 million) and illicit drugs (27.8 million). Substance‐attributable mortality rates were highest for tobacco smoking (110.7 deaths per 100 000 people), followed by alcohol and illicit drugs (33.0 and 6.9 deaths per 100 000 people, respectively). Attributable age‐standardized mortality rates and DALYs for alcohol and illicit drugs were highest in eastern Europe; attributable age‐standardized tobacco mortality rates and DALYs were highest in Oceania. Conclusions: In 2015 alcohol use and tobacco smoking use between them cost the human population more than a quarter of a billion disability‐adjusted life years, with illicit drugs costing further tens of millions. Europeans suffered proportionately more, but in absolute terms the mortality rate was greatest in low‐ and middle‐income countries with large populations and where the quality of data was more limited. Better standardized and rigorous methods for data collection, collation and reporting are needed to assess more accurately the geographical and temporal trends in substance use and its disease burden. [ABSTRACT FROM AUTHOR]

Abstract: A major impediment to any nation abandoning the policy of drug prohibition has been the fact that international drug treaties to which the majority of United Nations (UN) member states are signatory prohibit the non‐medical use of amphetamines, cannabis, cocaine and heroin. The future of these treaties is now uncertain because of decisions by Uruguay, eight US states and Canada to legalize cannabis use. This paper: (1) provides a brief account of the international drug control treaties; (2) outlines the major criticisms of the treaties; (3) analyses critically proposals for treaty reform; and (4) provides a personal view on policies that nation states could adopt to minimize the harms from the use of cannabis, party drugs and hallucinogens, opioids, stimulants and new psychoactive substances. It is argued that: a major risk of cannabis legalization in the United States is promotion of heavy use and increased harm by a weakly regulated industry; some cautious national experiments with the regulation of party drugs and hallucinogens would be informative; a strong case remains for prohibiting the nonmedical use of opioids while mitigating the adverse effects that this policy has on opioid‐dependent people; stimulant legalization will probably increase problem use but prohibition is difficult to enforce, highlighting the urgency of finding better ways to reduce demand for these drugs and respond to problem users; and that it is unclear what the best approach is to reducing possible harms that may arise from the use of new psychoactive substances. [ABSTRACT FROM AUTHOR]

Review evidence for cannabinoids as adjunctive treatments for treatment-resistant epilepsy. Systematic search of Medline, Embase and PsycINFO was conducted in October 2017. Outcomes were: 50%+ seizure reduction, complete seizure freedom; improved quality of life (QoL). Tolerability/safety were assessed by study withdrawals, adverse events (AEs) and serious adverse events (SAEs). Analyses were conducted in Stata V.15.0. 36 studies were identified: 6 randomised controlled trials (RCTs), 30 observational studies. Mean age of participants was 16.1 years (range 0.5-55 years). Cannabidiol (CBD) 20 mg/kg/day was more effective than placebo at reducing seizure frequency by 50%+(relative risk (RR) 1.74, 95% CI 1.24 to 2.43, 2 RCTs, 291 patients, low Grades of Recommendation, Assessment, Development and Evaluation (GRADE) rating). The number needed to treat for one person using CBD to experience 50%+ seizure reduction was 8 (95% CI 6 to 17). CBD was more effective than placebo at achieving complete seizure freedom (RR 6.17, 95% CI 1.50 to 25.32, 3 RCTs, 306 patients, low GRADE rating), and improving QoL (RR 1.73, 95% CI 1.33 to 2.26), however increased risk of AEs (RR 1.24, 95% CI 1.13 to 1.36) and SAEs (RR 2.55, 95% CI 1.48 to 4.38). Pooled across 17 observational studies, 48.5% (95% CI 39.0% to 58.1%) of patients reported 50%+ reductions in seizures; in 14 observational studies 8.5% (95% CI 3.8% to 14.5%) were seizure-free. Twelve observational studies reported improved QoL (55.8%, 95% CI 40.5 to 70.6); 50.6% (95% CI 31.7 to 69.4) AEs and 2.2% (95% CI 0 to 7.9) SAEs. Pharmaceutical-grade CBD as adjuvant treatment in paediatric-onset drug-resistant epilepsy may reduce seizure frequency. Existing RCT evidence is mostly in paediatric samples with rare and severe epilepsy syndromes; RCTs examining other syndromes and cannabinoids are needed.Prospero Registration Number: CRD42017055412. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To examine briefly the (i) rationales for two policy proposals in the United States to make it mandatory for cigarettes to contain very low levels of nicotine and to legalize cannabis for recreational use by adults; and (ii) possible lessons that participants in each policy debate may learn from each other. Method: We briefly describe the diverging policies towards cannabis and tobacco in the United States, explain and critically analyse their rationales and discuss possible policy lessons. Results: Advocates of cannabis legalization have argued that prohibition has been an ineffective and expensive policy that penalizes ethnic minority users unjustly of a drug that is far less harmful than alcohol. The prohibition of traditional tobacco cigarettes has been advocated as a way to eliminate cigarette smoking. These proposals embody very different attitudes towards the harms of recreational adult drug use. Advocates of nicotine prohibition demand that alternative methods of nicotine delivery must be shown to be completely safe before adults are allowed to use them. Advocates of tobacco prohibition ignore evidence that smokers may not use these products and the likelihood of expanding the illicit tobacco market. Advocates of legalizing and regulating recreational cannabis ignore the need to tax and regulate sales in order to minimize the harms of heavy use. Conclusions: It is not clear that the prohibition of adult use has a useful role to play in the regulation of either cannabis or tobacco. If both products remain legal, the goals of regulating tobacco and cannabis products should be to restrict youth access, promote the use of the least harmful products, provide users with evidence‐based information on both absolute and differential product risks of use and use differential taxes and marketing controls to promote ways of using these products that cause the least harm to their users. [ABSTRACT FROM AUTHOR]

Background: Recent reports suggest an increase in use of extremely potent cannabis concentrates such as Butane Hash Oil (BHO) in some developed countries. The aims of this study were to examine the characteristics of BHO users and the effect profiles of BHO.Design: Anonymous online survey in over 20 countries in 2014 and 2015. Participants aged 18 years or older were recruited through onward promotion and online social networks. The overall sample size was 181,870. In this sample, 46% (N=83,867) reported using some form of cannabis in the past year, and 3% reported BHO use (n=5922).Measurements: Participants reported their use of 7 types of cannabis in the past 12 months, the source of their cannabis, reasons for use, use of other illegal substances, and lifetime diagnosis for depression, anxiety and psychosis. Participants were asked to rate subjective effects of BHO and high potency herbal cannabis.Findings: Participants who reported a lifetime diagnosis of depression (OR=1.15, p=0.003), anxiety (OR=1.72, p<0.001), and a larger number of substance use (OR=1.29, p<0.001) were more likely to use BHO than only using high potency herbal cannabis. BHO users also reported stronger negative effects and less positive effects when using BHO than high potency herbal cannabis (p<0.001) CONCLUSION: Mental health problems and other illicit drug use were associated with use of BHO. BHO was reported to have stronger negative and weaker positive effects than high potency herbal cannabis. [ABSTRACT FROM AUTHOR]

Background. Cannabis use is common in North America, especially among young people, and is associated with a risk of various acute and chronic adverse health outcomes. Cannabis control regimes are evolving, for example toward a national legalization policy in Canada, with the aim to improve public health, and thus require evidence-based interventions. As cannabis-related health outcomes may be influenced by behaviors that are modifiable by the user, evidence-based Lower-Risk Cannabis Use Guidelines (LRCUG)--akin to similar guidelines in other health fields--offer a valuable, targeted prevention tool to improve public health outcomes. Objectives. To systematically review, update, and quality-grade evidence on behavioral factors determining adverse health outcomes from cannabis that may be modifiable by the user, and translate this evidence into revised LRCUG as a public health intervention tool based on an expert consensus process. Search methods. We used pertinent medical search terms and structured search strategies, to search MEDLINE, EMBASE, PsycINFO, Cochrane Library databases, and reference lists primarily for systematic reviews and meta-analyses, and additional evidence on modifiable risk factors for adverse health outcomes from cannabis use. Selection criteria. We included studies if they focused on potentially modifiable behavior-based factors for risks or harms for health from cannabis use, and excluded studies if cannabis use was assessed for therapeutic purposes. Data collection and analysis. We screened the titles and abstracts of all studies identified by the search strategy and assessed the full texts of all potentially eligible studies for inclusion; 2 of the authors independently extracted the data of all studies included in this review. We created Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow-charts for each of the topical searches. Subsequently, we summarized the evidence by behavioral factor topic, quality-graded it by following standard (Grading of Recommendations Assessment, Development, and Evaluation; GRADE) criteria, and translated it into the LRCUG recommendations by the author expert collective on the basis of an iterative consensus process. Main results. For most recommendations, there was at least "substantial" (i.e., good-quality) evidence. We developed 10 major recommendations for lower-risk use: (1) the most effective way to avoid cannabis use-related health risks is abstinence, (2) avoid early age initiation of cannabis use (i.e., definitively before the age of 16 years), (3) choose low-potency tetrahydrocannabinol (THC) or balanced THC-to-cannabidiol (CBD)-ratio cannabis products, (4) abstain from using synthetic cannabinoids, (5) avoid combusted cannabis inhalation and give preference to nonsmoking use methods, (6) avoid deep or other risky inhalation practices, (7) avoid high-frequency (e.g., daily or near-daily) cannabis use, (8) abstain from cannabis-impaired driving, (9) populations at higher risk for cannabis use-related health problems should avoid use altogether, and (10) avoid combining previously mentioned risk behaviors (e.g., early initiation and high-frequency use). [ABSTRACT FROM AUTHOR]

The work of Robins and her colleagues on heroin addiction among Vietnam veterans sets out in microcosm many of the key factors that play out in the development and maintenance of substance addiction beyond the pharmacology of the drug: price, availability, the process of delivery of the addictive substance, availability of other substances, social norms, education and life circumstances. Robins' studies found high rates of heroin use (34%) and symptoms of heroin dependence (20%) among US soldiers while serving in Vietnam. In the first year after returning to the United States only 1% became re-addicted to heroin, although 10% tried the drug after their return. Like other seminal studies, this work needs to be read in the original, because relying upon secondary interpretations risks being given a selectively edited version of their findings in service of varied policy and theoretical agendas. [ABSTRACT FROM AUTHOR]

Background and aims Since 2012 four US states have legalized the retail sale of cannabis for recreational use by adults, and more are likely to follow. This report aimed to (1) briefly describe the regulatory regimes so far implemented; (2) outline their plausible effects on cannabis use and cannabis-related harm; and (3) suggest what research is needed to evaluate the public health impact of these policy changes. Method We reviewed the drug policy literature to identify: (1) plausible effects of legalizing adult recreational use on cannabis price and availability; (2) factors that may increase or limit these effects; (3) pointers from studies of the effects of legalizing medical cannabis use; and (4) indicators of cannabis use and cannabis-related harm that can be monitored to assess the effects of these policy changes. Results Legalization of recreational use will probably increase use in the long term, but the magnitude and timing of any increase is uncertain. It will be critical to monitor: cannabis use in household and high school surveys; cannabis sales; the number of cannabis plants legally produced; and the tetrahydrocannabinol (THC) content of cannabis. Indicators of cannabis-related harms that should be monitored include: car crash fatalities and injuries; emergency department presentations; presentations to addiction treatment services; and the prevalence of regular cannabis use among young people in mental health services and the criminal justice system. Conclusions Plausible effects of legalizing recreational cannabis use in the United States include substantially reducing the price of cannabis and increasing heavy use and some types of cannabis-related harm among existing users. In the longer term it may also increase the number of new users. [ABSTRACT FROM AUTHOR]

The article presents a summary on a discussion on how to respond to the road safety issue posed by cannabis at the Third International Symposium on Drug & Impaired Driving in Lisbon, Portugal in October 2017. Topics include effect of cannabis intoxication on performance in driving simulators, reasons that the proportion of fatalities attributed to cannabis is smaller than that are attributable to alcohol, and the adoption of a common approach to laws against cannabis and impaired driving.

Griffith Edwards played an important role in cannabis policy debates within government advisory committees in the United Kingdom from the early 1970s until the early 1980s. This has largely been hidden from public knowledge by the confidentiality of these committee discussions. The purpose of this paper is to use Griffith's writings and the results of recent historical scholarship to outline the views he expressed, the reasons he gave for them, and to provide a brief assessment of his contribution to the development of British cannabis policy. [ABSTRACT FROM AUTHOR]

Aims To examine changes in the evidence on the adverse health effects of cannabis since 1993. Methods A comparison of the evidence in 1993 with the evidence and interpretation of the same health outcomes in 2013. Results Research in the past 20 years has shown that driving while cannabis-impaired approximately doubles car crash risk and that around one in 10 regular cannabis users develop dependence. Regular cannabis use in adolescence approximately doubles the risks of early school-leaving and of cognitive impairment and psychoses in adulthood. Regular cannabis use in adolescence is also associated strongly with the use of other illicit drugs. These associations persist after controlling for plausible confounding variables in longitudinal studies. This suggests that cannabis use is a contributory cause of these outcomes but some researchers still argue that these relationships are explained by shared causes or risk factors. Cannabis smoking probably increases cardiovascular disease risk in middle-aged adults but its effects on respiratory function and respiratory cancer remain unclear, because most cannabis smokers have smoked or still smoke tobacco. Conclusions The epidemiological literature in the past 20 years shows that cannabis use increases the risk of accidents and can produce dependence, and that there are consistent associations between regular cannabis use and poor psychosocial outcomes and mental health in adulthood. [ABSTRACT FROM AUTHOR]

Objectives: Stimulants may worsen psychotic symptoms but there is limited evidence about the impact of stimulant abuse in people with schizophrenia. This study examined the prevalence and correlates of stimulant and other drug disorders in a population-based sample of people with schizophrenia, examining associations with frequent service use, physical health comorbidities and accommodation instability. Methods: New South Wales (NSW) hospital, community mental health and emergency department data were used to examine health service contact over 5 years in 13,624 people with a diagnosis of schizophrenia. Associations of stimulant disorders were examined with multinomial logistic regression, comparing people with no substance disorders to those with cannabis disorders, stimulant disorders or both. Results: Of people with schizophrenia, 51% had substance disorders, including 14% with stimulant disorders. Stimulant disorders were more common in young adults and in urban areas, less common in migrants, and unrelated to initial social disadvantage. More than 80% of those with stimulant disorders also had cannabis disorders. Service use and harms were most common in this group, including frequent mental health admissions (59%), frequent emergency department presentations (52%), admissions with injury or self-harm (44%), infectious disease diagnoses (22%), multiple changes of residence (61%), movement to more disadvantaged locations (42%) and periods of homelessness (18%). People with stimulant disorders alone had higher rates of self-harm, infectious disease and non-mental health admissions than people with cannabis disorders alone. Conclusions: Stimulant disorders occur in people with schizophrenia and in first-episode psychosis at rates more than 10 times that of the broader population. Stimulant disorders are likely to worsen the burden of psychosis, and strategies are needed to engage and support the highly disadvantaged group of people with schizophrenia who have cannabis and stimulant disorders. [ABSTRACT FROM AUTHOR]

Introduction and Aims This study aimed to investigate whether there were changes from 2001 to 2010 in the characteristics of young adults who used party drugs or other illicit drugs and to determine if the prevalence of tobacco smoking differed depending on the type of drugs used. Design and Methods We analysed confidentialised data from the 2001 and 2010 National Drug Strategy Household Surveys. We compared young adults (aged 18-29) who used party drugs to other drug users and non-users on demographic variables. We assessed relationships between (i) illicit drug use and smoking; (ii) illicit drug use and smoking while controlling for social and demographic differences; and (iii) illicit drug use and smoking after controlling for social and demographic variables along with cannabis and alcohol use. Results There was little difference between 2001 and 2010 in drug user characteristics and smoking. Party drug users were more educated and of higher socioeconomic status than illicit drug users and non-users. Party drug users and users of other illicit drugs were far more likely to smoke tobacco; however, a large part of this relationship was explained by the higher rate of cannabis and alcohol use in these groups. Discussion and Conclusions Over the last decade, party drug users have been a relatively socially advantaged sub-population, yet smoking prevalence among these and other drug users has remained higher than among non-users. This might be explained by the common sequence of drug involvement in which people initiate smoking, then cannabis use and followed by other drugs. [Fraser D, Gartner C, Hall W. Patterns of tobacco smoking among illicit drug users in Australia 2001-2010. Drug Alcohol Rev 2014;33:534-9] [ABSTRACT FROM AUTHOR]

The article investigates the effectiveness and safety of cannabinoids in various conditions. The use of the Cochrane Central Register of Controlled Trials (CENTRAL) search strategy to determine systematic reviews and randomised controlled trials with regard to cannabinoids is cited. The use of cannabinoids for muscle spasticity in multiple sclerosis, other types of neuropathic pain and cancer pain is discussed. It also mentions the adverse effects of chronic recreational cannabis smoking.

Aims To examine changes in illicit drug consumption between peak holiday season (23 December-3 January) in Australia and a control period two months later in a coastal urban area, an inland semi-rural area and an island populated predominantly by vacationers during holidays. Design Analysis of representative daily composite wastewater samples collected from the inlet of the major wastewater treatment plant in each area. Setting Three wastewater treatment plants. Participants Wastewater treatment plants serviced approximately 350 000 persons in the urban area, 120 000 in the semi-rural area and 1100-2400 on the island. Measurements Drug residues were analysed using liquid chromatography coupled to a tandem mass spectrometer. Per capita drug consumption was estimated. Changes in drug use were quantified using Hedges' g. Findings During the holidays, cannabis consumption in the semi-rural area declined (g = −2.8) as did methamphetamine (−0.8), whereas cocaine (+1.5) and ecstasy (+1.6) use increased. In the urban area, consumption of all drugs increased during holidays (cannabis +1.6, cocaine +1.2, ecstasy +0.8 and methamphetamine +0.3). In the vacation area, methamphetamine (+0.7), ecstasy (+0.7) and cocaine (+1.1) use increased, but cannabis (−0.5) use decreased during holiday periods. Conclusions While the peak holiday season in Australia is perceived as a period of increased drug use, this is not uniform across all drugs and areas. Substantial declines in drug use in the semi-rural area contrasted with substantial increases in urban and vacation areas. Per capita drug consumption in the vacation area was equivalent to that in the urban area, implying that these locations merit particular attention for drug use monitoring and harm minimisation measures. [ABSTRACT FROM AUTHOR]

Aims Debate continues about whether the association between cannabis use in adolescence and common mental disorders is causal. Most reports have focused on associations in adolescence, with few studies extending into adulthood. We examine the association from adolescence until the age of 29 years in a representative prospective cohort of young Australians. Design Nine-wave, 15-year representative longitudinal cohort study, with six waves of data collection in adolescence (mean age 14.9-17.4 years) and three in young adulthood (mean age 20.7, 24.1 and 29.1 years). Participants Participants were a cohort of 1943 recruited in secondary school and surveyed at each wave when possible from mid-teen age to their late 20s. Setting Victoria, Australia. Measurements Psychiatric morbidity was assessed with the Revised Clinical Interview Schedule ( CIS-R) at each adolescent wave, and as Composite International Diagnostic Interview ( CIDI)-defined ICD-10 major depressive episode and anxiety disorder at 29 years. Frequency of cannabis use was measured in the past 6 months in adolescence. Cannabis use frequency in the last year and DSM- IV cannabis dependence were assessed at 29 years. Cross-sectional and prospective associations of these outcomes with cannabis use and dependence were estimated as odds ratios (OR), using multivariable logistic regression models, with the outcomes of interest, major depressive episode ( MDE) and anxiety disorder ( AD) at 29 years. Findings There were no consistent associations between adolescent cannabis use and depression at age 29 years. Daily cannabis use was associated with anxiety disorder at 29 years [adjusted OR 2.5, 95% confidence interval ( CI):< 1.2-5.2], as was cannabis dependence (adjusted OR 2.2, 95% CI: 1.1-4.4). Among weekly+ adolescent cannabis users, those who continued to use cannabis use daily at 29 years remained at significantly increased odds of anxiety disorder (adjusted OR 3.2, 95% CI: 1.1-9.2). Conclusions Regular (particularly daily) adolescent cannabis use is associated consistently with anxiety, but not depressive disorder, in adolescence and late young adulthood, even among regular users who then cease using the drug. It is possible that early cannabis exposure causes enduring mental health risks in the general cannabis-using adolescent population. [ABSTRACT FROM AUTHOR]

The article presents the DSM-IV Cannabis Use and Cannabis Use Disorders in Australia study that aimed to find out its prevalence, correlates, and treatment. Methods of the study involved a sample survey using a modified version of the World Mental Health Composite International Diagnostic Interview [WMH-CIDI (Kessler and Ustun, 2004)]. The study found that the occurrence of cannabis use disorders were comparable with those in the U.S. and concentrated largely in young Australians.

Introduction and Aims. Perceived risks of cannabis use have rarely been researched in Australia. This paper reports on the beliefs about the adverse effects of cannabis use on health, social well-being, driving, mental health and changes in cannabis over time. Design and Methods. Survey of 918 Australian adults was conducted as part of a quarterly omnibus self-report survey of an established panel. Results. Respondents believed that cannabis use can cause health and social problems, can adversely affect a person's ability to drive a car, can be addictive, and can lead to use of other illicit drugs. They were uncertain as to whether cannabis can cause schizophrenia and depression, and whether cannabis had become more potent over time. Implications. Prevention efforts should focus on educating the Australian people about the nature of cannabis-related harms.[Calabria B, Swift W, Slade T, Hall W, Copeland J. The perceived health risks of cannabis use in an Australian household survey. Drug Alcohol Rev 2012;31:809-812] [ABSTRACT FROM AUTHOR]

The article focuses on the illicit drug use and dependence. It states that health consequences of using illicit drug including cocaine, opioids, and amphetamine may involve overdose, mental disorders, and accidental injury and violence. It mentions that studies identified the risk factors for cannabis use in developed countries which include family factors, individual factors, and social and contextual factors.

The article presents a study on the prevalence of psychological distress and affective disorders among smokers and cannabis-dependent people in Australia from 1997 to 2007. The researchers interviewed English-speaking Australians living in private dwellings, who were asked if they currently or formerly smoked tobacco. They found that elevated psychological distress and affective disorders were more common among current tobacco smokers than never-smokers in the surveys conducted in 1997 and 2007.

Aims To examine trends in patterns of cannabis use and related harm in the Australian population between 1993 and 2007. Design Analysis of prospectively collected data from: (1) the National Drug Strategy Household Survey (NDSHS) and Australian Secondary Student Alcohol and Drug Survey (ASSADS); (2) the National Hospital Morbidity Database (NHMD); and (3) the Alcohol and Other Drug Treatment Services National Minimum Dataset (AODTS-NMDS). Participants Australians aged 14 years and over from the general population; students aged 12–17 years; public and private hospital in-patients; public and private in-patients and out-patients attending for drug treatment. Measurement Prevalence of 12-month cannabis use among the general population and secondary students. Proportions in the general population by age group reporting: daily cannabis use; difficulties in controlling cannabis use; and heavy cannabis use on each occasion. Number of hospital and treatment presentations for cannabis-related problems. Findings Prevalence of past-year cannabis use has declined in the Australian population since the late 1990s. Among those reporting past-year use, daily use is prevalent among 40–49-year-olds, while heavy patterns of use are prevalent among 14–19-year-olds. Hospital presentations for cannabis-related problems reflect similar trends. Past-year cannabis use has decreased among the 10–19-year age group, but those who are daily users in this age group report using large quantities of cannabis. Conclusions Despite declines in the prevalence of cannabis use, continued public health campaigns warning of the harms associated with cannabis use are essential, aimed particularly at users who are already experiencing problems. The increasing demand for treatment for cannabis problems in Australia suggests the need for more accessible and more effective interventions for cannabis use disorders. [ABSTRACT FROM AUTHOR]

Issues. To conduct a comprehensive search of the peer-reviewed literature to assess risk of cannabis-related mortality. Approach. Systematic peer-reviewed literature searches were conducted in Medline, EMBASE and PsycINFO to identify data on mortality associated with cannabis use. Search strings for cannabis and mortality were used. Searches were limited to human subjects and the publication timeframe of January 1990 to January 2008. Reference lists of review articles and of specific studies deemed important by colleagues were searched to identify additional studies. A list of the selected articles was emailed to experts in the field asking for comment on completeness. Key Findings. There is insufficient evidence, particularly because of the low number of studies, to assess whether the all-cause mortality rate is elevated among cannabis users in the general population. Case–control studies suggest that some adverse health outcomes may be elevated among heavy cannabis users, namely, fatal motor vehicle accidents, and possibly respiratory and brain cancers. The evidence is as yet unclear as to whether regular cannabis use increases the risk of suicide. Conclusions. There is a need for long-term cohort studies that follow cannabis using individuals into old age, when the likelihood of any detrimental effects of cannabis use are more likely to emerge among those who persist in using cannabis into middle age and older. Case–control studies of cannabis use and various causes of mortality are also needed.[Calabria B, Degenhardt L, Hall W, Lynskey M. Does cannabis use increase the risk of death? Systematic review of epidemiological evidence on adverse effects of cannabis use. Drug Alcohol Rev 2010] [ABSTRACT FROM AUTHOR]

Background Urinalysis testing in the work-place has been adopted widely by employers in the United States to deter employee drug use and promote ‘drug-free’ work-places. In other countries, such as Canada, testing is focused more narrowly on identifying employees whose drug use puts the safety of others at risk. Aims We review 20 years of published literature on questions relevant to the objectives of work-place drug testing (WPDT), with a special emphasis on cannabis, the most commonly detected drug. Results We conclude (i) that the acute effects of smoking cannabis impair performance for a period of about 4 hours; (ii) long-term heavy use of cannabis can impair cognitive ability, but it is not clear that heavy cannabis users represent a meaningful job safety risk unless using before work or on the job; (iii) urine tests have poor validity and low sensitivity to detect employees who represent a safety risk; (iv) drug testing is related to reductions in the prevalence of cannabis positive tests among employees, but this might not translate into fewer cannabis users; and (v) urinalysis has not been shown to have a meaningful impact on job injury/accident rates. Conclusions Urinalysis testing is not recommended as a diagnostic tool to identify employees who represent a job safety risk from cannabis use. Blood testing for active tetrahydrocannabinol (THC) can be considered by employers who wish to identify employees whose performance may be impaired by their cannabis use. [ABSTRACT FROM AUTHOR]

Abstract: Background: The adverse health effects of cannabis are a source of contention in debates about policies towards the drug. Methods: This paper provides a review of epidemiological evidence on the major adverse health effects of cannabis use and considers its implications for policy. Results: The evidence strongly suggests that cannabis can adversely affect some users, especially adolescents who initiate use early and young adults who become regular users. These adverse effects probably include increased risks of: motor vehicle crashes, the development of cannabis dependence, impaired respiratory function, cardiovascular disease, psychotic symptoms, and adverse outcomes of adolescent development, namely, poorer educational outcomes and an increased likelihood of using other illicit drugs. Conclusions: Politically, evidence of adverse health effects favours the status quo in developed countries like Australia where cannabis policy has been framed by the media as a choice between two views: (1) either cannabis use is largely harmless to most users and so we should legalize, or at the very least decriminalize its use; or (2) it harms some of its users so we should continue to prohibit its use. [Copyright &y& Elsevier]

The article explores the adverse health effects of non-medical cannabis use based on epidemiological, clinical and laboratory studies during the past 10 years. A background of the pattern of cannabis use in the U.S. is presented, as well as the primary psychoactive constituent of cannabis preparations. Among the acute effects of cannabis are anxiety, panic reactions, and psychotic symptoms. The article also examines its reproductive, chronic, and psychosocial effects and the public health burden it poses.

The article discusses the research on cannabis use as a risk factor for psychosis. The authors note that from observational studies, cannabis use has been found to be associated with schizophrenia and psychosis. However, debates surfaced on the credibility of such observational studies, which resulted to the question of including a category of psychosis from cannabis use in the revision of the Global Burden of Disease (GBD).

This paper outlines the major policy challenges in reducing cannabis-related harm in Australia. The first is uncertainty about the health effects of cannabis, especially in young people. The second is uncertainty about the extent and severity of harms attributed to cannabis prohibition by its critics. The paper summarises and briefly states the extent of these putative harms to the degree that the data allow. The third challenge is a consequence of the first two, and the very different weightings that proponents of more liberal or restrictive policies give to harms arising from cannabis use and those arising from prohibition, namely, strong disagreements within the community about how we should respond to cannabis use by young people. In the face of such disagreement the formulation of cannabis policy necessitates a political compromise. The compromise that has emerged is a continued prohibition of cannabis production, sale and use, combined with either civil penalties for use in some states and reduced penalties or diversion in others. It concludes with suggestions about what needs to be learned about the health effects of cannabis use and the costs and benefits of cannabis prohibition if we are to develop policies that are more effective in reducing harms caused by cannabis use.[Hall WD. Challenges in reducing cannabis-related harm in Australia. Drug Alcohol Rev 2009;28:110–116] [ABSTRACT FROM AUTHOR]

Aims To describe the formulation of a National Cannabis Strategy in Australia in 2006 and discuss the contribution that research evidence has made to its development. Methods A description of trends in cannabis use in Australia and policy responses to it from the early 1970s to the present, with an analysis of the evidence and arguments that have been used to support competing policies towards cannabis use. Results In 1977 an Australian Senate Committee recommended that a national cannabis policy should be developed that removed criminal penalties for personal possession and use. The arguments for the recommendation echoed those used to support similar earlier recommendations made in Canada, the Netherlands, the United Kingdom and the United States in the late 1960s and early 1970s. They were reiterated by a National Cannabis Task Force in 1994, but a national cannabis strategy was not developed until 2006. By default, the strategy supported continued prohibition on the production and sale of cannabis, and left penalties for cannabis use to state governments. It advocated public education campaigns to discourage young people, especially those at high risk, from initiating cannabis use, and to reduce the progression to regular use among young people who had used cannabis. It also supported efforts to reduce the availability of cannabis and to improve treatment for problem cannabis users. The research evidence which was cited as motivating the development of a national cannabis policy was epidemiological data on rising rates of use among young people, and emerging evidence from longitudinal studies in Australian and New Zealand that some adolescent cannabis users experienced harm as a result of their use. Conclusions The impact that research evidence has had on Australian cannabis policy over the past three decades has, as in many comparable countries, been constrained by the limited policy options under consideration, and by the fact that interpretation of the evidence has been contested by advocates of the limited policy options under debate. [ABSTRACT FROM AUTHOR]

An editorial is presented in which the authors discuss a study concerning whether the use and health effects of cannabis by adolescents can be predicted in U.S. states that have legalized cannabis for adult use, and point to an article published in the journal about the subject.

Objective: To assess whether cannabis use in adolescence and young adulthood is a contributory cause of schizophreniform psychosis in that it may precipitate psychosis in vulnerable individuals.Method: We reviewed longitudinal studies of adolescents and young adults that examined the relations between self-reported cannabis use and the risk of diagnosis with a psychosis or of reporting psychotic symptoms. We also reviewed studies that controlled for potential confounders, such as other forms of drug use and personal characteristics that predict an increased risk of psychosis. We assessed evidence for the biological plausibility of a contributory causal relation.Results: Evidence from 6 longitudinal studies in 5 countries shows that regular cannabis use predicts an increased risk of a schizophrenia diagnosis or of reporting symptoms of psychosis. These relations persisted after controlling for confounding variables, such as personal characteristics and other drug use. The relation did not seem to be a result of cannabis use to self-medicate symptoms of psychosis. A contributory causal relation is biologically plausible because psychotic disorders involve disturbances in the dopamine neurotransmitter systems with which the cannabinoid system interacts, as demonstrated by animal studies and one human provocation study.Conclusion: It is most plausible that cannabis use precipitates schizophrenia in individuals who are vulnerable because of a personal or family history of schizophrenia. [ABSTRACT FROM AUTHOR]