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New psychoactive substances (NPS) continue to be considered as a major public health concern in many European countries. The study was implemented within the framework of a transnational project of six European countries (Germany, Hungary, Ireland, Netherlands, Poland, Portugal). Our aim here is to report on the distinct and differentiating characteristics of marginalised NPS users. Three subgroups of a total of 3023 adult NPS users (socially marginalised, night life, online community) were examined regarding their socio-demographic characteristics, substance use, and external motives towards NPS use. Poland and Hungary reported higher rates of NPS use in comparison to traditional controlled drugs. The external/contextual motives did not play a central role in the background of NPS use, the least important motives were alleged legality and non-detectability of these substances. Marginalised (defined as those accessing low threshold harm reduction services) users’ substance use patterns are different from the other two groups in terms of showing more intense and riskier drug use. The most important variables which contributed to be categorised as a marginalised NPS user were lower level education, being older, having an unfavourable labour market position and using drugs intravenously. Contextual motives did not play a decisive role in being categorised as a marginalised user when drug use pattern was controlled. These identified discriminative features of marginalised drug users should inform policy makers to develop and implement tailor-made interventions targeting this user group to successfully tackle the elevated public health concerns associated with NPS use.

Felvinczi, K., Benschop, A., Urbán, R., Van Hout, M.C., Dąbrowska, K., Hearne., E., Henriques, S., Kaló, Z., Kamphausen, G., Silva, J.P., Wieczorek, Ł., Werse, B., Bujalski, M., Demetrovics, Z., Korf, D.J. (2019). Discriminative Characteristics of Marginalised Novel Psychoactive Users: a Transnational Study. International Journal of Mental Health and Addiction, pp 1-20.


For thousands of years, humans have been using substances that are called ‘drugs’ today, for example to relieve pain, to relax, to gain energy, or in the course of cultural and religious rituals. In search for explanations as to why so many people in the 21st century use drugs, and why in such a wide variety, several macro level factors or drivers need to be addressed.

Chapters in this volume contribute to the understanding of drug use, drug users, drug markets and drug policy in Europe. All the authors work in this field, and are involved in local, national or international research on drug use, drug users or drug dealers. Their research is not carried out in laboratories nor treatment centres. Some of it is predominantly conducted in libraries and archives, but most takes place elsewhere – on the streets, in nightclubs, in private drug-dealing settings. The authors are social scientists from different disciplines – anthropology, criminology, geography, economics, linguistics, psychology, sociology, social psychiatry – and many of them have an interest in, or are specifically oriented to qualitative research methods, including participant observation, informal conversations and in-depth interviews. In the search for explanations as to why particular groups turn to or continue to use certain substances over others, why some people use drugs, why users prefer particular methods of supply, and why current drug policies exists, each of the chapters underline the utmost importance of this book, which captures many of the complexities of how drug use and drug dealing is explained, experienced and often problematised today.

Kaló, Z., Tieberghien, J., Korf, D.J. (Eds.) (2019). Why? Explanations for drug use and drug dealing in social drug research. Lengerich: PABST Science Publishers.

Het bezoeken van een café gaat bijna altijd gepaard met het drinken van alcohol. Amsterdamse cafébezoekers drinken vaak en veel met een gemiddelde van 6 glazen per uitgaansavond. Toch lijken alcoholvrije alternatieven aan te slaan. Andere drugs, met name ecstasy en cocaïne worden ook weleens gebruikt, maar zelden in het café.

Dit zijn enkele opvallende resultaten uit Antenne Amsterdam 2018. Dit jaarlijkse onderzoek van de Hogeschool van Amsterdam en Jellinek brengt al een kwart eeuw het middelengebruik onder jongeren en jongvolwassenen in de hoofdstad in kaart. In 2018 is voor de vijfde maal een survey onder cafébezoekers gehouden. Voor dit onderzoek hebben 540 bezoekers cafés in Amsterdam, met een gemiddelde leeftijd van 26 jaar, een vragenlijst ingevuld en is een uitgaanspanel ondervraagd.

Korf, D.J., Nabben, T., & Benschop, A. (2019). Antenne 2018. Trends in alcohol, tabak en drugs bij jonge Amsterdammers. Amsterdam: Rozenberg publishers


Introduction Amphetamine-type stimulants (ATS) including amphetamine, methylenedioxymethamphetamine/‘ecstasy’, methamphetamine, synthetic cathinones and ‘Ritalin’ are the second most commonly used illicit drugs globally. Yet, there is little evidence on which factors are associated with the development of different patterns of ATS use over the life course. This study aims to examine which individual, social and environmental factors shape different pathways and trajectories of ATS consumption. The study will be conducted in five European countries: Germany, the Netherlands, Poland, Czech Republic and the UK.

Methods and analysis We will use a sequential mixed-methods study design to investigate the multiple factors (familial, social and occupational situation, critical life events, general risk behaviour, mental and physical health, satisfaction with life) that shape individual ATS use pathways. A systematic literature review will be performed to provide an overview of the current academic literature on the topic. In module 1, qualitative semistructured interviews (n=ATS users and non-users) will be conducted to explore individual experiences of, and perspectives on, dynamics of change in stimulant consumption patterns. In module 2, structured questionnaires (n=2000 ATS users and non-users) will be administered via tablet computers to validate and enhance the generalisability of the interview findings. Data integration will take place at two key points. First, during the study, where the findings from the first qualitative interviews will inform the design of the structured questionnaire. Second, at the end of the study, where mixed methods data will be brought together to generate an in-depth, contextualised understanding of the research topic.

Ethics and dissemination The study has been approved by the respective responsible ethics committee in each participating country. Data will be treated confidentially to ensure participants’ anonymity. Findings will be disseminated in peer-reviewed scientific journals, national and international conferences, and in briefings for policy and practice.

Rosenkranz, M., O'Donnell, A., Verthein, U., Zurhold, H., Addisson, M., Liebregts, N., Rowicka, M., Bartak,M., Petruzelka, B., Kaner, E.F.S., & Martens, M. (2019). Understanding pathways to stimulant use: a mixed-methods examination of the individual, social and cultural factors shaping illicit stimulant use across Europe (ATTUNE): study protocol. BMJ Open 2019; 9:e029476. doi: 10.1136/bmjopen-2019-029476

Purpose: The purpose of this paper is to: describe and contextualize the aims and distinctive and common characteristics of cannabis festivals in countries with different cannabis policies; assess characteristics of participants; identify reasons to attend cannabis festivals; explore to which extent cannabis festivals contribute to the social and cultural acceptance of cannabis, as perceived by attendees. Design/methodology/approach: The approach incorporates three methods of data collection in the research design; quantitative research among 1,355 participants, participant observation and interviews with the organizers. Findings: Cannabis festivals in Amsterdam, Berlin, Rome and Athens have common features but also maintain and reproduce local, social and cultural characteristics. Cannabis festivals, as well as their attendees, represent heterogeneous categories. The style of the festival – music festival or march combined with music – affects the main reason for attendance by the participants. In cannabis festivals more similar to music festivals the majority of the respondents attended for entertainment while at the cannabis festivals in the form of a march combined with music the majority attended for protest. Furthermore, increasing age, residency and the high frequency of cannabis use are factors that led the participants to attend for protest. Originality/value: The research on cannabis festivals is limited. This paper not only explores the aims of cannabis festivals in four capital cities of Europe and the characteristics of their attendees including motivations, but also offers interesting insights for understanding the ways in which political and social constructions like cannabis festivals shape attitudes, perception and behaviors around cannabis use.

Skliamis, K. & Korf, D.J. (2019). Cannabis festivals and their attendees in four European cities with different national cannabis policies, International Journal of Event and Festival Management.


Background: Frequent Cannabis use has been linked to a variety of negative mental, physical, and social consequences. We assessed the effects of digital prevention and treatment interventions on Cannabis use reduction in comparison with control conditions.

Methods: Systematic review with two separate meta-analyses. Thirty randomized controlled trials met the inclusion criteria for the review, and 21 were included in the meta-analyses. Primary outcome was self-reported Cannabis use at post-treatment and follow-up. Hedges’s g was calculated for all comparisons with non-active control. Risk of bias was examined with the Cochrane risk-of-bias tool.

Results: The systematic review included 10 prevention interventions targeting 8138 participants (aged 12 to 20) and 20 treatment interventions targeting 5195 Cannabis users (aged 16 to 40). The meta-analyses showed significantly reduced Cannabis use at post-treatment in the prevention interventions (6 studies, N = 2564, g = 0.33; 95% CI 0.13 to 0.54, p =  0.001) and in the treatment interventions (17 comparisons, N = 3813, g = 0.12; 95% CI 0.02 to 0.22, p =  0.02) as compared with controls. The effects of prevention interventions were maintained at follow-ups of up to 12 months (5 comparisons, N = 2445, g = 0.22; 95% CI 0.12 to 0.33, p <  0.001) but were no longer statistically significant for treatment interventions.

Conclusions: Digital prevention and treatment interventions showed small, significant reduction effects on Cannabis use in diverse target populations at post-treatment compared to controls. For prevention interventions, the post-treatment effects were maintained at follow-up up to 12 months later.

Boumparis, N., Loheide-Niesmann, L., Blankers, M., Ebert, D., korf, D.J., D., Schaub, M., Spijkerman, R., Tait, R., J. and Riper, H. (2019) The short- and long-term effects of digital prevention and treatment interventions for cannabis use reduction: A systematic review and meta-analysis. Drug and Alcohol Dependence. 200, 82-94.

The Netherlands has long been considered a leader of progressive drug policy, but it is increasingly being left behind by policy innovations outside Europe. Nonetheless Dutch cities are leading the way towards more progressive and locally adapted cannabis policies. Produced as part of a the "New Approaches in Harm Reduction Policies and Practices" project, this Country Report seeks to understand the drivers of Dutch cannabis policy today, and the possibilities for its future. The project is a joint project of the Transnational Institute (TNI), based in the Netherlands ICEERS (Spain), Forum Droghe (Italy) and Diogenis (Greece).

Korf, D.J. (2019). Cannabis Regulation in Europe: Country Report Netherlands. Amsterdam: Transnational Institute.

Use of new psychoactive substances (NPS) across Europe remains a public health challenge. The study describes potentials and limitations of methods in a transnational survey of recent marginalised, nightlife and online community NPS users in Germany, Hungary, Ireland, the Netherlands, Poland and Portugal (n = 3023). In terms of demographic profile, drug use history and type of NPS, different methods reached different segments of the NPS-using population. Last year use of different NPS varied across countries and groups. Respondents used NPS in a variety of settings, with public spaces most common in the marginalised group. The study suggests that prevalence rates can reveal a picture of the NPS market that significantly deviates from what law enforcement seizures indicate. Outreach in nightlife settings and peer education are recommended to inform users about health risks and to improve access to drug services and care.

Korf, D. J., Benschop, A., Wernse, B., Kamphausen, G., Felvinczi, K., Dabrowska, K., Hernriques, S., Nabben, A. L. W. M., Wieczorek, L., Bujalski, M., Kalo, Z., Hearne, . E. & van Hout, M. C. (2019) International Journal of Mental Health and Addiction. () 1-18


Aanleiding voor dit onderzoek was de constatering dat de groei in het aantal aangepakte criminele samenwerkingsverbanden (csv’s) niet terug te zien was in de ontwikkeling van het aantal vrijheidsstraffen. Om de georganiseerde misdaad terug te dringen werd in 2012 tussen de (toen nog) Minister van Veiligheid en Justitie, de politie en het OM afgesproken dat er meer csv’s zouden moeten worden aangepakt: in 2014 twee keer zoveel als in 2009. Probleemstelling: Welke verklaring(en) ligt/liggen ten grondslag aan het achterblijven/ uitblijven van een stijging in het aantal strafopleggingen bij het aantal door het OM gerapporteerde aangepakte csv’s over de periode 2009-2015?

Korf, D.J., Luijk, S.J., Meijer, M.E. de (2019). Criminele samenwerkingsverbanden. Ontwikkelingen in aanpak en duiding van effectiviteit. Amsterdam: Rozenberg Publishers