D.J. Korf

Dutch coffee shops and trends in cannabis use.

Conflicting predictions have been made to the influence of decriminalization on cannabis use. Prohibitionists forecast that decriminalization will lead to an increase in consumption of cannabis, while their opponents hypothesise that cannabis use will decline after decriminalization. Most probably cannabis use in the Netherlands so far evolved in two waves, with a first peak around 1970, a low during the late 1970s and early 1980s, and a second peak in the mid-1990s. It is striking that this trend in cannabis use among youth in the Netherlands rather parallels four identified stages in the availability of cannabis. The number of cannabis users peaked when the cannabis was distributed through an underground market (late 1960s and early 1970s). Then the number decreased as house dealers were superseeding the underground market (1970s), and went up again after coffee shops took over the sale of cannabis (1980s), and stabilised or slightly decreased by the end of the 1990s when the number of coffee shops was reduced. Although changes in cannabis policy went along with changes in availability of cannabis and prevalence of cannabis use, it is questionable whether changes in cannabis policy were causally related to trends in cannabis use. Cannabis use also developed in waves in other European countries that did not decriminalize cannabis, as well as in the US. Consequently, trends in cannabis use seem to develop rather independently of cannabis policy.

Predicting the transition from frequent cannabis use to cannabis dependence: a three-year prospective study.

BACKGROUND Frequent cannabis users are at high risk of dependence, still most (near) daily users are not dependent. It is unknown why some frequent users develop dependence, whereas others do not. This study aims to identify predictors of first-incidence DSM-IV cannabis dependence in frequent cannabis users. METHODS A prospective cohort of frequent cannabis users (aged 18-30, n=600) with baseline and two follow-up assessments (18 and 36 months) was used. Only participants without lifetime diagnosis of DSM-IV cannabis dependence at baseline (n=269) were selected. Incidence of DSM-IV cannabis dependence was established using the Composite International Diagnostic Interview version 3.0. Variables assessed as potential predictors of the development of cannabis dependence included sociodemographic factors, cannabis use variables (e.g., motives, consumption habits, cannabis exposure), vulnerability factors (e.g., childhood adversity, family history of mental disorders or substance use problems, personality, mental disorders), and stress factors (e.g., life events, social support). RESULTS Three-year cumulative incidence of cannabis dependence was 37.2% (95% CI=30.7-43.8%). Independent predictors of the first incidence of cannabis dependence included: living alone, coping motives for cannabis use, number and type of recent negative life events (major financial problems), and number and type of cannabis use disorder symptoms (impaired control over use). Cannabis exposure variables and stable vulnerability factors did not independently predict first incidence of cannabis dependence. CONCLUSIONS In a high risk population of young adult frequent cannabis users, current problems are more important predictors of first incidence cannabis dependence than the level and type of cannabis exposure and stable vulnerability factors.

Cross-sectional and prospective relation of cannabis potency, dosing and smoking behaviour with cannabis dependence: an ecological study

BACKGROUND AND AIMS Increased delta-9-tetrahydrocannabinol (THC) concentrations in cannabis may lead to higher THC exposure, cannabis dependence and treatment need, but users may also adapt the actual intake of THC through reduced inhalation of THC containing smoke (titration). We investigated whether consumers of stronger cannabis use less cannabis per joint or inhale less smoke than those using less potent cannabis and whether these factors predict cannabis dependence severity. METHODS Heavy cannabis users (n = 98) brought their own cannabis, rolled a joint and smoked it ad libitum in a naturalistic setting. We analysed the content of the joint, its association with smoking behaviour and the cross-sectional and prospective (1.5-year follow-up) relations between smoking behaviour and cannabis dependence severity (total number of DSM-IV dependence symptoms). RESULTS THC concentration in cannabis (range 1.10-24.70%) was correlated positively with cannabis dose per joint (b = 0.008, P = 0.01), but the resulting THC concentration per joint (range 0.24-15.72%) was associated negatively with inhalation volume (b = -0.05, P = 0.03). Smoking behaviour measures (number of puffs, inhaled volume, reduction of puff volume and puff duration while smoking) predicted follow-up dependence severity, independently of baseline dependence severity and monthly THC dose (number of joints × cannabis dose × cannabis THC concentration). Monthly THC dose only predicted follow-up dependence severity when unadjusted for baseline severity. CONCLUSIONS Cannabis users titrate their delta-9-tetrahydrocannabinol intake by inhaling lower volumes of smoke when smoking strong joints, but this does not fully compensate for the higher cannabis doses per joint when using strong cannabis. Thus, users of more potent cannabis are generally exposed to more delta-9-tetrahydrocannabinol. Smoking behaviour appears to be a stronger predictor for cannabis dependence severity than monthly delta-9-tetrahydrocannabinol dose.

Mental health differences between frequent cannabis users with and without dependence and the general population

AIMS To compare the prevalence of mental disorders between frequent cannabis users with and without dependence and the general population. DESIGN Cross-sectional comparison of interview data. SETTING Enriched community sample of frequent cannabis users and a representative sample of non-users and non-frequent users from the general population. PARTICIPANTS A total of 521 young adult (aged 18-30 years) frequent cannabis users, 252 of whom were with DSM-IV cannabis dependence (D+) and 269 without DSM-IV cannabis dependence (D-), and 1072 young adults from the general population. MEASUREMENTS Multinomial logistic regression was used to compare groups regarding the presence of DSM-IV mental disorders. Detailed measures of cannabis use, childhood adversity and other substance use were considered confounders. FINDINGS Compared with the general population, externalizing disorders were more prevalent in D- [odds ratio (OR) = 8.91, P < 0.001] and most prevalent in D+ (OR = 17.75, P < 0.001), but internalizing disorders were associated only with D+ (mood OR = 4.15, P < 0.001; anxiety OR = 2.20, P = 0.002). Associations were attenuated (and often became non-significant) after correction for childhood adversity and substance use other than cannabis. However, the prevalence of mental disorders remained higher in D+ compared with D- (OR = 2.40, P < 0.001), although cannabis use patterns were remarkably similar. CONCLUSIONS Cannabis use patterns, childhood adversity and the use of other substances are similar in dependent and non-dependent frequent cannabis users. With the exception of more externalizing disorders, the mental health condition of non-dependent frequent cannabis users is similar to that of the general population, whereas it is worse in dependent frequent cannabis users.

Estimating the Number of Heroin Users: A Review of Methods and Empirical Findings from the Netherlands

This article reviews major methods applied to estimate the number of heroin users in a community, predominantly urban areas. The main focus is on applicability of methods to the available data. Methodologies are evaluated with regard to reliability, validity, and feasibility from the perspective of empirical findings, in particular in the Netherlands. Findings from Amsterdam and Rotterdam are presented in more detail in order to discuss major criteria for application of the capture/recapture and the nomination techniques.

Open Drug Scenes: A Cross-National Comparison of Concepts and Urban Strategies

Several new concepts have originated in the international debate on drug policy interventions in recent years. ‘Open drug scenes’ is one of these concepts. Findings, predominantly qualitative, from 9 uropean cities are presented. From a contrast analysis, the concept of open drug scenes is elaborated along three dimensions (visibility, size and site), resulting in a typology of local drug scenes (concentrated open scenes, dispersed open scenes and hidden scenes). This typology is then confronted with local definitions and perceptions, as well as with major issues in the local policy debate on drug problems. As a next step, two contrasting strategies to control drug scenes are presented. These strategies are evaluated in reference to our typology dimensions as well as to the local drug policy key issues. Finally, some conclusions are drawn about the relationship between urban drug policies and the visibility of drug problems.

Lessons from conducting trans-national Internet-mediated participatory research with hidden populations of cannabis cultivators.

BACKGROUND Internet-mediated research methods are increasingly used to access hidden populations. The International Cannabis Cultivation Questionnaire (ICCQ) is an online survey designed to facilitate international comparisons into the relatively under-researched but increasingly significant phenomenon of domestic cannabis cultivation. The Global Cannabis Cultivation Research Consortium has used the ICCQ to survey over 6000 cannabis cultivators across 11 countries. In this paper, we describe and reflect upon our methodological approach, focusing on the digital and traditional recruitment methods used to access this hidden population and the challenges of working across multiple countries, cultures and languages. METHODS Descriptive statistics showing eligibility and completion rates and recruitment source by country of residence. RESULTS Over three quarters of eligible respondents who were presented with the survey were included in the final sample of n=6528. English-speaking countries expended more effort to recruit participants than non-English-speaking countries. The most effective recruitment modes were cannabis websites/groups (33%), Facebook (14%) and news articles (11%). While respondents recruited through news articles were older, growing practice variables were strikingly similar between these main recruitment modes. CONCLUSION Through this process, we learnt that there are trade-offs between hosting multiple surveys in each country vs. using one integrated database. We also found that although perceived anonymity is routinely assumed to be a benefit of using digital research methodologies, there are significant limits to research participant anonymity in the current era of mass digital surveillance, especially when the target group is particularly concerned about evading law enforcement. Finally, we list a number of specific recommendations for future researchers utilising Internet-mediated approaches to researching hidden populations.

Cocaine and Crack in Amsterdam: Diverging Subcultures

Recreational cocaine use spread rapidly in Amsterdam at the end of the 1970s, particularly as a “party drug” in clubs and discotheques. At the end of the 1980s, the role of cocaine as party drug was largely taken over by ecstasy. In contrast, first cocaine and then crack cocaine increased in popularity among heroin addicts and marginalized street youth, including homeless youth and young prostitutes. Today, experimental use of crack is also observed among young people from socially deprived neighborhoods, especially among ethnic minorities. This article describes, mainly on the basis of ethnographic studies among these groups, the evolving and diverging patterns of use among trendsetting party youth and their marginalized counterparts. Important differences may be observed between groups related to socio-economic background, the role cocaine plays in their lives, transmission routes, and different operating market mechanisms influenced by drug policy. For party youth, cocaine use mainly serves recreational purposes. In contrast, for problem youth, cocaine, and now especially crack, contribute to multi-problem behavior within the context of their marginalized lifestyles.

The role of peers in the initiation and continuation of ecstasy use

This study is a supplement to the Netherlands XTC Toxicity Study (NeXT), funded by grants from the Netherlands Organisation for Health Research and Development as part of its Addiction Programme. To better understand the processes of peer influence and peer selection, in a field study 106 Ecstasy users (67M/39F, average age 25.4 years) were interviewed face-to-face in Amsterdam in 2005. In the initiation of Ecstasy use, peer influence emerged as the dominating mechanism; peer selection was uncommon. In the continuation of Ecstasy use, peer influence and peer selection occurred reciprocally in a dynamic process, although peer influence made a greater relative contribution. Our study confirms that peer influence is a multidimensional process: influence was quite often reciprocal (with respondents both exerting and undergoing influence) and it could have both restraining and encouraging effects on ecstasy use. The studys limitations are noted.

Windmills in Their Minds? Drug Policy and Drug Research in the Netherlands

Contemporary Dutch drug policy is a product of many long-term political, demographic and social changes that have taken place in the Netherlands since the nations first drug law was enacted in 1919. Shifts in policy emphasis are described and explained in terms of three principles that serve as the cornerstones of the Dutch approach, these include the following: (1) a separation of the markets for hard and soft drugs; (2) normalization of the phenomenon, which means treating drug users as ordinary citizens entitled to government assistance, but also required to assume responsibility for their actions; and (3) harm reduction efforts directed at minimizing the damage done by drugs to users, communities and to the society as a whole. The changing policies regarding cannabis are utilized here as a case study to illustrate how these principles work in practice. Several contemporary issues are analyzed in terms of their influence on recent policy changes. These include drug-related nuisance, the participation of organized crime in drug markets and criticism from abroad regarding the impact of Dutch policies on other nations. The article concludes with a reconsideration of the effects of decriminalizing cannabis, contrasting the Dutch application of the expediency principle with its use in other nations.