The changes in treatment rates are also displayed in Figure 4. Regression models suggest a significantly declining treatment rate only for the Netherlands , Finland , and Slovenia . In ten countries, treatment rates significantly increased. Modest increases were recorded in Greece, Poland, Austria, Slovakia, and Portugal , while more pronounced increases were present in Romania, Belgium, France, Malta, and Sweden . Based on those 17 countries providing continuous data between 2010 and 2019, the upward slope in treatment rates had come to a halt in the year 2015 and has mostly plateaued since then . The available data on TDI coverage suggests a high degree of variation between countries and over time, including a declining number of treatment units from which data were collected since 2014 .Public health monitoring indicates that cannabis use is prevalent in Europe. Although estimates should be interpreted with caution due to potential error, the best available data at present indicates that an estimated 3¢9% of all adults aged 15 to 64 reporting past month use. There is a considerable variation in prevalence of use, ranging from 9¢1% in Spain to less than 1% in Malta, Hungary, and Turkey. Approximately 1 in 7 past-month users were estimated to meet CUD criteria, with substantial heterogeneity between countries. In countries where cannabis use is more common, such as in the Netherlands and Spain, the share of users meeting CUD criteria appears to be lower than in countries where cannabis use is less common, such as Malta and Hungary.

However, there are also exceptions to this, such as the UK, which has both relatively high rates of cannabis use and of CUD. At the European level, the bulk of trend data converge on showing that cannabis use and related problems have increased in the past decade. The available data indicates that rises in prevalence rates were reported in all age groups. Among adults aged 35 to 64 years, trimming tray with screen prevalence of past month use increased by 50% or more. These findings are similar to reports from European student surveys and recent trends in the USA, where the largest increases in prevalence of use have occurred in middle-aged adults. Consistent with rising prevalence of any use and high-risk use patterns, treatment rates have also risen in many countries, reaching a plateau in 2014. The high level of treatment rates for cannabis creates problems for healthcare providers. Psychosocial interventions such as Motivational Interviewing and Cognitive Behavioural Therapy have been shown to be effective at reducing cannabis use. However, there is a lack of approved pharmacotherapies for the treatment of cannabis use disorders, and limited effectiveness of psychosocial interventions for people with comorbid mental health problems such as psychosis. Lastly, stark and modest increases in cannabis potency levels have been registered for resin and herbal cannabis, respectively, corroborating previous analyses in Europe and internationally. In contrast to these trends, CUD prevalence is estimated to have declined in the past decade in most countries. These findings are consistent with survey data from the United States, showing that while the prevalence of cannabis use increased from 2001-2002 to 2012- 2013, the prevalence of cannabis use disorders in cannabis users decreased. However, potency level may be implicated with other health outcomes than CUD, such as psychotic outcomes or genotoxic and epigenotoxic effects.This indicator is based on general population surveys, which have the usual problems of substance use surveys in the last decade: nonrepresentative sampling frame excluding key risk groups, high degree of non-response and use of self-report. Moreover, the validity of prevalence estimates may vary between countries, which could increase risk of bias when comparing estimates across different countries.

Undercoverage is not as easily quantified as for legal substances such as alcohol, as objective indicators such as sales data or wastewater analyses do not routinely exist or are hard to interpret in comparison to the standard indicators. Further, the lack of uncertainty measures prohibited to apply robust statistical methods to study trends in cannabis consumption. Lastly, we do not have any information on the purpose of consumption but assume that only a minor fraction of users do take cannabis for medical purposes . For future monitoring, survey data should distinguish between medical and recreational cannabis users. Despite these limitations, survey-based cannabis use prevalence constitutes one of the best indicators available for public health monitoring purposes. In the 2021 European Drug Report, the EMCDDA focuses on cannabis use among young adults. While we also found indications for increasing use in this age groups, our findings add that cannabis consumption has apparently become more common among 35 to 64 year-olds. Albeit absolute use levels remain lower in this age group, this is a trend worth noting. This trend could be driven by an aging population of users or by the increase in medical use of cannabis. Prescription data from Germany show that patients using cannabis flowers on prescription are on average 46 years old. Another possibility, supported by data from the USA, is that the proportion of older adults who disapprove of cannabis use may have decreased over time. While the underlying reasons for an aging population of cannabis users are yet to be singled out, the prolonged use of cannabis might be associated with an increase in the risk of lung cancer or chronic obstructive pulmonary disease both of which are rather rare among younger adults.

Moreover, acute cannabis use is a risk factor for traffic collisions and this affects all ages regardless of the purpose of use. Thus, if the aging and growing population of cannabis users are driving under the influence of cannabis, this could increase the number of motor vehicle accidents in Europe. Our findings further suggest an increase in daily cannabis use prevalence. While similar trends have been reported for the USA, such patterns have not been reported for Europe so far. Further research should examine whether prevalence of risky use patterns increased over and above prevalence of any use or in other words: have use patterns among current users become riskier?In contrast to all other trends, the prevalence of CUD did not show indications of increases in Europe. As the CUD data constitute smoothed estimates obtained from statistical models, there are some problems inherent to these data, such as not appropriately representing the true fluctuation in the data. However, as CUD prevalence is estimated from cannabis use prevalence, the diverging trends question the validity of the CUD estimates. The consistency of select GBD estimates have been questioned in previous studies and our results add that estimation procedures for CUD prevalence may be revisited and improved. An additional consideration is that the validity of CUD estimates may vary between countries, which limits comparability of estimates across countries. Given the outlined limitations associated with available TDI and CUD data, there is a need to improve indicators for high-risk cannabis use or experience of cannabis-related problems in Europe. We propose to use high-frequency use patterns, such as daily use and the EMCDDA should provide these data by country, year, sex, and age on their website. In the long-run, however, an indicator for high-risk use considering more than just frequency of use should be established, ideally supplemented with data on quantity of use .Our analyses show that the number of treatment units contributing to the TDI varies greatly between countries and over time.

The large gaps in treatment rates far exceed the variation that would be expected based on prevalence of use and of CUD, questioning the validity of the estimates across time and space. Moreover, up-to-date information on TDI coverage, i.e., the share of all relevant treatment units covered in each country, is not available. Thus, we recommend that between-country comparisons should not be undertaken without accounting for methodological differences. Further, an increase in treatment rates can reflect a number of different factors , such as TDI reporting completeness or quality, a higher willingness of users to seek treatment, or increased availability of treatment. We recommend that, where feasible, improvements to TDI data quality should be made to facilitate understanding of true treatment demand and enable robust estimates of change.As such, they should not be assumed to be representative of the type of cannabis used at the retail level. Law enforcement methods create a risk of bias in selection according to various factors such as degree of criminal involvement, ethnicity, age, gender, and location. By contrast, cannabis potency data reported by the Netherlands can be assumed to be representative of cannabis available at the retail level, as data are collected using a standardised protocol consisting of random sampling from national retail outlets each year. We recommend that, where possible, additional European countries should sample cannabis from sources other than seizures in order to improve the reliability and validity of the data. As policies towards cannabis are becoming more permissive in Europe, this may facilitate improved monitoring of cannabis potency at the retail level. An additional consideration is that for all countries reporting data on cannabis potency, the reliability of data may be influenced by the sample size of cannabis products used to create summary estimates for each country and year, and the laboratory equipment and analytical protocol used to estimate potency. Information on these potentially confounding variables are not available at present. Finally, trimming tray for weed concentrations of cannabidiol are not monitored at present.

The public health relevance of cannabis potency indicators is evidenced by findings that THC concentration was associated with progression to the first symptom of CUD and greater severity of CUD, especially among younger people. High-potency cannabis was also associated with increased risk of psychosis, and with frequency of use, cannabis-related problems and anxiety. Our findings suggest greater THC concentrations in cannabis resin, which is produced by extracting material from the cannabis plant. The increase in potency of cannabis resin in Europe may be attributable to a shift towards THC-dominant cannabis plants in Morocco – the primary producer of cannabis resin for the European market. The increased THC concentrations in resin may translate into greater risk of harm for users preferring this type of cannabis. Possibly, the increased risk could be offset by dose titration or higher concentration of cannabidiol found in resin . However, as findings on the protective effects of cannabidiol have been inconsistent, it remains to be studied empirically whether resin use is associated with an increased risk. In light of the increased public health risks and the uncertainty in the underlying data, we see the need for improved monitoring of cannabis potency in Europe. The need for better data is further substantiated by changes in the cannabis market, such as the emergence of products containing high levels of cannabidiol in Europe and the widespread use of highly concentrated cannabis extracts in North America.Despite an extensive history of use as a medicinal plant spanning ancient cultures, cannabis use is contentious in many jurisdictions as it has been considered a social drug of abuse since the mid-1930s. Over the last two decades, meaningful legal, sociocultural and economic change has led to the establishment of medicinal cannabis research programs in several countries, which have validated the therapeutic use of cannabis for indications including: chronic neuropathic pain, certain intractable epilepsies, the vomiting and spasticity of multiple sclerosis, and chemotherapy-induced nausea. Further to this, the use of medicinal cannabis has expanded into paediatric and vulnerable patient groups and regulated markets for recreational use have developed in some jurisdictions. Accordingly, quality control across the supply chain is increasingly important to ensure that cannabis products are safe and have well-defined chemical and therapeutic profiles. Critically, the complex relationship between chemical profiles and therapeutic activity requires further exploration. Presently, the activities of the three most abundant neutral cannabinoids – Δ9 -THC, CBD, and CBG – have been studied closely, exhibiting properties including: analgesic, anticonvulsant, and anti-inflammatory. However, the full potential of medicinal cannabis may not be realised without leveraging the full diversity of cannabinoids. Over 140 cannabinoids have been identified, many of which have their own inherent pharmacological properties. This includes the acidic cannabinoids which have significant anticonvulsant activities, contrary to the historical perspective that they were inert precursors which only acquired activity after decarboxylating into the neutral cannabinoids.