Cannabis is by far the most commonly used illicit drug used in developed countries, with use more recently spreading to low- and middle-income countries (Hall and Degenhardt, 2007; United Nations Office on Drugs and Crime, 2014). The average lifetime prevalence of cannabis use among adolescents in ESPAD countries (16 %) was considerably lower than that recorded in comparable school surveys in the United States (31 %) or Spain (27 %). Nevertheless, rates of use varied substantially between ESPAD countries. Lifetime experience of cannabis in the Czech Republic (37 %) even exceeded the level observed in the United States. At the lowprevalence end, rates of under 10 % could be found in five of the Nordic countries (the Faroes, Finland, Iceland, Norway and Sweden), in several Balkan states (including Albania, the former Yugoslav Republic of Macedonia, Moldova, Montenegro and Romania) and in Cyprus and Greece.
The reasons for the large differences in cannabis use between European countries are unclear. The frequently found strong relationship between cannabis availability and use has often been interpreted as evidence for the preventive effect of restrictive drug policies (Gervilla et al., 2011; Gillespie et al., 2009; Höfler et al., 1999; von Sydow et al., 2002). Moreover, a study among adolescents in 32 European countries, investigating the effects of perceptions about cannabis on the use of the drug, identified strong and persistent individual-level effects for perceived availability, perceived harm and the number of cannabis-using friends. The effects on cannabis use prevalence and frequency were more pronounced than country-level effects such as cannabis price and last-12-month cannabis use prevalence in the adult population (Piontek et al., 2013). It has generally been assumed that drug availability is inversely related to the level of drug law enforcement and the severity of the legal sanctions. However, when comparing changes in cannabis policy with subsequent changes in prevalence, only in a few countries did the prevalence of use follow the expected pattern of change, i.e. a decrease in prevalence following an increase in sanctions and vice versa (European Monitoring Centre for Drugs and Drug Addiction, 2011). In a recent paper on cannabis policy prepared within the ‘Addiction and lifestyles in contemporary Europe reframing addictions project’ (Alice Rap), the authors argued that the prohibition approach has largely failed and, drawing on global and European experience in regulating tobacco and alcohol, they called for legal regulatory cannabis policies that protect public health, wealth and well-being (Alice Rap, 2014). The high prevalence of perceived cannabis availability and cannabis use among adolescents in many European countries may appear to support their view. However, since the relationship between cannabis policy and prevalence was not analysed in the present report, no conclusions can be drawn.
Trends in cannabis use indicate an increase in both lifetime and current use between 1995 and 2015, from 11 % to 17 % and from 4 % to 7 %, respectively. However, prevalence peaked in 2003 and decreased slightly thereafter. The observed decrease in cannabis prevalence after 2003 is supported by the results of the HBSC study. Temporal trends in last-12-month cannabis use among 15-year-olds in Europe between 2002 and 2010 showed, with the exception of eastern Europe, a general decrease in all regions (Hublet et al., 2015). However, the pattern of change in ESPAD countries since 2003 is not uniform. In contrast to the general trend, lifetime cannabis use increased in Bulgaria, Cyprus, Greece, Lithuania, Malta, Poland and Romania. Thus, when discussing the reasons for the change in cannabis use, factors other than legal regulations may play a significant role. For instance, in addition to drug control measures, other factors such as norms of use, competing responsibilities and attractions that demand or favour drug use abstinence, as well as societal or cultural responses to drug problems, may impact on consumption, in an upward or downward direction. It has been argued that the increasing trend in cannabis use, particularly evident in eastern European countries, may be explained by factors related to post-communist transition (Hublet et al., 2015). Firstly, the relative isolation of the former Soviet Union countries led to a delay in the development of cannabisdistribution networks, with the subsequent growth igniting an upward trend; secondly, social and economic changes, along with increases in wealth and leisure opportunities, have driven substance use; and thirdly, because public health authorities and decision-makers were not prepared for the growth in illicit drug use, countermeasures were slow to be implemented (Elekes and Kovacs, 2002).
New psychoactive substances
New psychoactive substances (NPS) are narcotic or psychotropic drugs that are not controlled by the United Nations drug conventions, but may pose a public health threat comparable to that caused by substances listed in these conventions. On average, 4 % of the students surveyed have tried NPS — substances that imitate the effects of illicit drugs — and 3 % have used them in the past 12 months. On average, these substances seem to be more commonly used than amphetamine, ecstasy, cocaine or LSD, all of which have lower lifetime prevalence rates. Several countries could be identified that showed above-average last-12-month use of NPS. Students in Estonia and Poland (both 8 %) were most likely to have experiences with NPS, followed by Bulgaria and Croatia (6 %) and Ireland and Italy (5 %). Rather low lifetime rates of NPS use were reported in Belgium (Flanders), Denmark, the Faroes, Finland, the former Yugoslav Republic of Macedonia, Moldova, the Netherlands, Norway and Portugal (1 %).
The 2015 ESPAD study is one of the first international epidemiological studies to assess NPS use. On an international scale, there is not much information available against which to compare the results. As an exception, the Flash Eurobarometer, a comprehensive EU-wide survey among young people aged 15 to 24 years, reported an overall lifetime prevalence of 8 % (European Commission, 2016). The regional patterns in the Eurobarometer study were slightly different to those observed in the present study, with France, Ireland, Slovenia and Spain being the top four countries regarding the prevalence of use. Differences in NPS prevalence rates between ESPAD and the Flash Eurobarometer, although the same definition was used, may be due to differences in the sampling frame (schools versus general population) and age (15-16 years versus 15- 24 years). NPS comprise a variety of substances ranging from synthetic cannabinoids simulating the effects on the brain of THC (the principal psychoactive substance in cannabis) to synthetic cathinones that mimic the effects of amphetamine, methamphetamine or ecstasy (Hohmann et al., 2014). These substances are variously marketed as ‘research chemicals’, ‘plant food’, ‘bath salts’ or other misleading product names, with false content descriptions, in efforts to avoid control measures. Identification of the substance in question is very difficult, for the consumer, law enforcement and, critically in the event of poisoning, medical staff.
In a recent document on the outcome of the UN General Assembly Special Session on Drugs (2016), NPS are mentioned in 10 paragraphs and dominate the section on emerging and persistent challenges and threats (https://www.incb.org/documents/News/A_S-30_L.1.pdf). The UN promotes data collection and early warning systems (EWS) and prioritises the review of the most prevalent, persistent and harmful NPS. To this end, an international action group on NPS has been established, consisting of UN member states and international organisations, to coordinate and drive the international response to NPS. At European level, the EMCDDA is responsible for a well-established EWS. The European EWS on NPS is a multidisciplinary network of 30 national early warning mechanisms that collect, appraise and rapidly disseminate information on new drugs and products (http://www.emcdda.europa.eu/attachements.cfm/att_157279_EN_EWS%20profiles.pdf). The challenge associated with NPS is demonstrated by the increasing number, type and availability of new substances. Within the European EWS, almost 100 new substances were reported for the first time in 2015. Overall, the total number of new substances monitored by the EWS since its inception amounts to over 560.