Current state of cannabis use, policies, and research across sixteen countries: cross-country comparisons and international perspectives

Abstract Introduction Varying public views on cannabis use across countries may explain the variation in the prevalence of use, policies, and research in individual countries, and global regulation of cannabis. This paper aims to describe the current state of cannabis use, policies, and research across sixteen countries. Methods PubMed and Google Scholar were searched for studies published from 2010 to 2020. Searches were conducted using the relevant country of interest as a search term (e.g., “Iran”), as well as relevant predefined keywords such as “cannabis,” “marijuana,” “hashish,” “bhang “dual diagnosis,” “use,” “addiction,” “prevalence,” “co-morbidity,” “substance use disorder,” “legalization” or “policy” (in English and non-English languages). These keywords were used in multiple combinations to create the search string for studies’ titles and abstracts. Official websites of respective governments and international organizations were also searched in English and non-English languages (using countries national languages) to identify the current state of cannabis use, policies, and research in each of those countries. Results The main findings were inconsistent and heterogeneous reporting of cannabis use, variation in policies (e.g., legalization), and variation in intervention strategies across the countries reviewed. European countries dominate the cannabis research output indexed on PubMed, in contrast to Asian countries (Thailand, Malaysia, India, Iran, and Nepal). Conclusions Although global cannabis regulation is ongoing, the existing heterogeneities across countries in terms of policies and epidemiology can increase the burden of cannabis use disorders disproportionately and unpredictably. There is an urgent need to develop global strategies to address these cross-country barriers to improve early detection, prevention, and interventions for cannabis use and related disorders.


Introduction
Cannabis is one of the most frequently used recreational psychoactive substances globally with an estimated 192 million users of cannabis in 2018, 1,2 corresponding to 3.9% of the world population aged 15-64 years. 3 Cannabis use is much more common in North America and high-income countries in Europe and Oceania than in low and middle-income countries (LMICs), where it has been increasing (only remaining low in Asia). 4 Despite growing public support for its use in many countries, this substance is known to be associated with risk of mental health conditions, including suicidality, depression, 5 and psychosis. 6 Cannabis use has also been linked to adverse functional outcomes (e.g., aggression and school dropout) and disability, and to high direct and indirect socioeconomic costs. [7][8][9] Cannabis dependence or problematic use is often influenced by sociopolitical environments, religion, culture, clinical practice, and policies and programs across countries. 10,11 Most culturally distinct groups have used cannabis and other psychoactive substances throughout the ages, and they have accepted cannabis use as an established code of behavior. 12 Moreover, acculturation has been associated with increased use of cannabis use. 13,14 Understanding the epidemiology of cannabis use or dependence, policy measures, and research across countries is valuable to quantify the global extent of cannabis use and changes over time as well as to assist lawmakers, governments, and funding bodies in their decision-making regarding services and policies.
Nevertheless, few organizations regularly compile epidemiological data. [15][16][17][18] Limited information about the various current legalizations, national harm reduction strategies, research trends, programs, and prevalence of cannabis use or dependence is available. 19 This hampers the development of global strategies to understand the extent and impact of cannabis use and address problems that result. Nowadays, many countries and country regions are advancing with or considering legalization and there is little evidence on which to base assessments and foresee the impact of these challenges. 20

Epidemiology
We found a wide range of variations in terms of epidemiological aspects of cannabis use/dependence across the included countries (  In comparison, some Asian countries (Thailand) have reported that the number of cannabis users is shrinking.
In the literature reviewed, cannabis use has often been associated with aggressive behavior, early onset of schizophrenia, and comorbid use of other substances such as opioids (Iran) 25 and alcohol (Ethiopia). 26 It has also been strongly associated with mood and anxiety disorders, 27 truancy, 28 school dropouts, unemployment, other drug use, and risky sexual practices. 29 The prevalence of cannabis use seems higher among males and those with a family history of cannabis dependence and poor peer support. 28 In most countries (e.g., Germany), cannabis is the third most common substance use disorder after alcohol and amphetamines. 30 Furthermore, researchers worldwide (India, Nepal) have attempted to determine the relationship between cannabis use and psychotic, mood, or anxiety disorders and comorbidities with substance use disorders. [31][32][33] Variations were also observed in terms of the patterns of cannabis use in national surveys when conducted (e.g., annual, last 3/6 months, daily, last month, or lifetime prevalence 15,34 ).

Legalizations and decriminalization
The process of lifting prohibitions against cannabis use is known as legalization, while sparing criminal sanctions (such as fines, prison, or mandated treatment) against people possessing or using it is known as decriminalization. 65 Cannabis consumption is legally prohibited in most countries. Country-specific details on these prohibitions and decriminalization laws are listed in Table 2. Almost all countries have adopted legal prohibitions as one of the core strategies to reduce cannabis use. Legal   Punishments for violations of legal regulations include imprisonment and fines across all countries. Table 3 lists national and local level harm reduction strategies adopted in the countries represented by   99 a multi-country regional project (government and activists), dedicated centers Germany Cooperation between insurance providers, the government, non-governmental institutions, policy measures reducing the availability of illicit drugs, school-based prevention activities (e.g., life skills, critical thinking about drug use), family oriented prevention programs (e.g., parenting skills, protective role), outpatient treatment centers serving as additional contact points, harm reduction interventions targeting migrants, rehabilitation programs Turkey Turkey's national strategy and action to combat illegal drugs (2018-2023), prevention programs at several levels in coordination with the relevant organs, AMATEM, alcohol and substance addiction treatment centers, social norms approach for prevention in adolescents and young adults. 49,100 Spain

Harm reduction strategies
The action plan on addictions establishes several prevention programs at different levels 1. Risk awareness raising through media 2. Universal school-based programs 3. School-based surveys for early detection 4. Rehabilitation programs 5. Market control through military and police forces Additionally, cannabis clubs claim they protect consumers from unlawful distribution and problematic use.

Italy
The new national action plan is logically divided into five main areas of intervention: 1. Prevention -early information, universal and selective prevention, early detection of use of drugs (early detection), and educational approach; 2. Treatment and diagnosis of drug addiction -early contact, prompt reception, diagnosis, and appropriate therapies and contextual prevention of related diseases; 3. Rehabilitation and reintegration -social and work; 4. Monitoring and evaluation; 5. Legislation, law enforcement, and juvenile justice -both on the ground and on the internet. The five areas indicated are grouped into two large containers: 1. Demand reduction: prevention, treatment and diagnosis, rehabilitation, and reintegration; 2. Reduction of supply: monitoring and evaluation, legislation, law enforcement, and juvenile justice.   Italy Cross-sectional studies, 106 epidemiological studies, 107 surveys, 108 systematic review, 109 meta-analyses, 110 comorbidity studies, 111 pharmacological and toxicology, 112 efficacy of cannabidiol treatment for anxiety, 113 and use in PTSD 114 The new GDPR has been affecting epidemiological research since 2016 63 France Epidemiological studies (prevalence and correlates) Inadequate funds and human resources for interventional studies or large-scale general population study 115 Brazil Epidemiological studies, 116

Discussion
Cannabis use/dependence seems far more prevalent in some countries or regions compared to others.
However, it is far less common than alcohol, tobacco, or opioids in many countries. Among those countries (Morocco, Nepal, and India), some possible reasons for the higher prevalence may be unemployment poverty, lack of harsh punishment, 118