Dipl.-Psych. Roland Simon
Tel. 089 / 360804 - 40
Fax 089 / 360804 - 49
e-mail:
30.3.2004
Project:
Regular and intensive use of cannabis and related problems:
conceptual framework and data analysis in the EU member states
Final Report
CT.2003.103.P1
CONTENTS
1Introduction
1.1Background
1.2The project
1.3Implementation
2Assessment tools and instruments
2.1Assessing problem cannabis use through patterns of use
2.2Assessing problem cannabis use through clinical aspects of use
CIDI
CRAFFT
CUDIT
EuropASI
MECA
SDS
2.3Conclusions
3The substance
3.1Availability and illegal market
Availability and drug use
Perceived availability
Drug market
Other ways to assess availability
3.2Purity
Trends in purity
Effects of increased purity
4Problematic use of cannabis
4.1Antecedents of problem cannabis use
4.1.1Demographic factors
4.1.2Family background and social situation
4.1.3Use of other psychotropic substances
4.1.4Mental disorders and problems
4.2Acute Effects
4.2.1Overview
4.2.2Somatic effects
Intoxication
Mortality
Cardiovascular effects
Respiratory system
Psychomotor effects
Other somatic effects
4.2.3Mental effects
Cognition
Dysphoria, anxiety and panic disorders
Toxic psychoses
4.3Chronic Effects
4.3.1Overview
4.3.2Somatic effects
Respiratory system
Reproduction
Other somatic effects
4.3.3Mental effects
Cognition
Development
Depression and suicide
Schizophrenia
Tolerance syndrome, harmful use and addiction
Use of other psychotropic substances
4.4Secondary Effects
4.4.1Effects to unborn children
Performance and social adaptation
4.4.2Traffic accidents
4.4.3Crime
5The main conceptual elements
5.1Antecedent factors of problem cannabis use
5.2Acute effects of problem cannabis use
5.3Chronic effects of problem cannabis use
5.4Secondary effects of problem cannabis use
6Data analysis of national reports on treated problem cannabis users
in Europe
Prevalence
Treatment demand
Characteristics of problem cannabis users
Treatment needs and referrals
7Recommendations for research and methodological developments
for assessment at European level
8Bibliography
8.1Assessment
8.2Substance
8.3Problem use
TABLES
Table 1: Global scheme of different aspects of problem cannabis use as discussed
in this report
Table 2: Antecedent factors of problem cannabis use
Table 3: Overview acute effects of problem cannabis use
Table 4: Overview chronic effects of problem cannabis use
Table 5: Overview secondary effects
Table 6: Prevalence of problematic cannabis use (PCU) in Europe
Table 7: Demand for treatment for PCU in Europe
Table 8: Characteristics of PCU clients in treatment in Europe
Table 9: Treatment needs and referral for PCU clients in Europe
Table 10: Special treatment offers for PCU in Europe
1
1Introduction
1.1Background
While the early days of the cannabis discussion were dominated by very general positions in relation to use or non-use today more specific questions are discussed. A crucial question in this respect is, which negative consequences might arise from cannabis use (Strang, Witton & Hall 2000).
The lifetime prevalence of cannabis use in the adult population in the member states of the European Union is between 20 and 25%, cannabis has been used within a 12 months period by 5 to 10% of the population. For adolescents and young adults the prevalence of cannabis use during the last 12 months is about double as high (EMCDDA 2003). The frequency of use as well as patterns of use vary considerably, as surveys show (e.g. Kraus & Augustin 2001). Many people use cannabis only during a relatively short period in their lifetime and stop this habit completely afterwards (Perkonigg et al. 1999).
Whenever an intervention is planned for this group, the heterogeneity of cannabis users has to be taken into account. While experimental users of cannabis seldom experience negative consequences of the substance, intensive, regular, long term or dependant use of cannabis can much more often lead to therapeutic needs and types of treatment, which should be tailored accordingly (Steinberg et al. 2002). The subject of this overview are problems related to regular or intensive use of cannabis. The term “problem cannabis use” (PCU) indicate throughout this text, that not experimental, low frequent use of cannabis is the primary interest here, but regular, intensive use of the substance. This use might fulfil the criteria of a “dependence syndrome” (ICD-10, DSM-IV) or “harmful use” (ICD-10) re. “abuse” (DSM-IV). As there is no simple cut-off between “use” and “problem use” also research on cannabis users in general has been included. In these cases problem drug use has been defined through parameters of intensity or frequency of use.
1.2The project
This report is the output of a project, which was conducted with the financial support of the European Monitoring Centre on Drugs and Drug Addiction[1]. Parts of this report are based on the outcome of a recent German study on clients with primary cannabis related problems in out-patient care (“Cannabisbezogene Störungen: Umfang, Behandlungsbedarf und Behandlungsangebot [Cannabis related disorders (CareD): Prevalence, Service needs and Treatment provision][2]). This report was based on the collection of the most relevant recent publications on cannabis, in particular international reviews. This material was complemented with recent publications from the years 2000-2004 and chapter 15 from the national REITOX reports 2003 produced by the EMDDA National Focal Points in all MemberStates and some of the acceding countries.
The following main topics were formulated at the beginning of this project:
- regular, intensive or dependent use (=”problem use”) of cannabis
- risk factors for PCU
- chronic and acute problems correlated with PCU
- availability and illegal market
- potency of cannabis, THC contents
The outcome of this project should include
- Bibliography of the most relevant publications since 1995, given the above mentioned focus of interest
- List of the instruments to assess regular/intensive use of cannabis
- Framework concept of problematic use of cannabis based on the main elements from the literature
- Proposal for future developments needed in research and methodology in order to prepare a more complete and comparable European analysis on problematic cannabis use
1.3Implementation
The literature search was focused on aspects of negative consequences, patterns (frequency, duration, onset) and clinical aspects of use (diagnoses). The resulting overview is based on the reviews published more recently by Hall & Room (1995), Kleiber & Kovar (1998), Hall, Degenhardt, Lynskey (2001), Inserm (2001) and the Ministry of Public Health in Belgium 2002. In addition more recent publications were searched using the internet via scientific data bases (DIMDI, PubMed) as well as specific information providers in the field (e.g. As far as no specific search engines were available was used with the keywords „cannabis“, „marihuana“ and “marijuana”.
The EMCDDA National Focal Points have as part of their national reports for the year 2003 elaborated a special topic on cannabis. Some of the literature mentioned there has also been included here.
2Assessment tools and instruments
Problematic use of cannabis can be assessed either through a specified pattern of use, which can be observed and classified as problematic on the basis of defined cut-off points between problematic and non problematic use as done in chapter 2.1. If a system of classification is used instead, the decision between problematic and non problematic use are made on the basis of weighted parameters on patterns of use, user’s behaviour, and negative consequences or use.
2.1Assessing problem cannabis use through patterns of use
Problematic use can be defined on the basis of frequency and patterns of use. The cut-off between use and PCU can be defined through a frequency of use during different time periods (lifetime, last year, last 30 days) or the number of consumption days during these periods. Other aspects of the pattern of use (day-time, social setting, working-situation of use) have also been taken as a proxy for PCU in some cases. The EMCDDA model questionnaire includes a question on frequency of use during the last 30 days, which would offer of the elements described.
2.2Assessing problem cannabis use through clinical aspects of use
PCU can also be defined as dependent or harmful use according to existing systems of classification. Consequences of use, tolerance development, craving and other aspect besides the pattern of use are the basis of such a diagnoses. The key terms here are “harmful use” and “dependence syndrome” as defined by WHO “International Classification of Diseases”, (Dilling et al. 1999) and “abuse” and “dependence” as defined in the “Diagnostic and Statististical Manual” (version IV) by the American Psychiatric Association (APA 1994). While the concept of dependence is very similar in both systems, harmful use and abuse do not correlate very well and are partly based on different definitions and concepts. As Regier at al. (1998) pointed out, even if a diagnosis has been proved reliable and valid, there might be a need to restrict the relevant number of cases to those, which include a “medical necessity” of treatment. This might further reduce the number of cases.
CIDI
An interesting development in this field is the Diagnostic Interview Schedule (DIS). It has been applied within the Epidemiological Catchment Area Study (Regier et al 1990; Regier et al. 1998) and was further developed later into the Composite International Diagnostic Interview (CIDI) (Robins et al. 1988; Wittchen et al. 1991). The instrument is available in a paper-pencil as well as in an computerised version and covers the most relevant psychiatric diagnoses including substance disorders. It can produce DSM-IV as well as ICD-10 diagnoses. The items of this instrument have been applied in the German national survey on psychoactive substances (Kraus & Augustin 2002) where they offer DSM-IV compatible diagnoses from paper pencil questionnaires filled in by the subjects.
An international WHO study on the reliability and validity of instruments measuring alcohol and drug use disorders has included the Composite International Diagnostic Interview (CIDI), and a special version of the Alcohol Use Disorder and Associated Disabilities Interview schedule-alcohol/drug-revised (AUDADIS-ADR). Overall the diagnostic concordance coefficients were very good for dependence disorders (0.7-0.9), but were somewhat lower for the abuse and harmful use categories (Ustun et al 1997). An early study on the CIDI (Wittchen et al. 1991) found good to excellent interrater agreements and kappa values.
CRAFFT
The Car Relax Alone Forget Family or Frinds Troubles (CRAFFT) is a short 5-item test to screen adolescent clinical patients on alcohol related problems as well as on frequent use of alcohol or cannabis. It offers a classification into the categories “any problem” (problem use, abuse, dependence), “any disorder” (abuse, dependence) and “dependence” and shows good psychometric results for general clinical populations (Knight et al. 2002) and in specific ethnic groups. The instrument has been applied successfully with American-Indian and Alaska-native Americans (Cummins et al. 2003).
CUDIT
Based on the items of the Alcohol Use Disorders Identification Test (AUDIT) (Saunders et al. 1993) a test has been developed for a clinical target group to screen for cannabis abuse or dependence. The Cannabis Use Disorders Identification Test (CUDIT) was found superior to the self-reported frequency of use in a group of out-patient clients with a mild to moderate alcohol dependence. The Diagnostic Interview for Generic Studies (DIGS) was used as criterion (Adamson & Sellman, 2003).
EuropASI
The EuropASI is the European adaptation of the fifth edition of the Addiction Severity Index developed by McLellan and colleges (1985), has been translated into a number of European languages. The complete version has been published by an group of experts (Kokkevi & Harters 1995). A number of instruments has been developed in different countries for the assessment of clients in clinical settings in addition to that.
Unfortunately, most of the clinical instruments are difficult to apply as part of surveys in the general population due to their size. The application of the EuropASI requires more time than available in most cases as well as skilled interviewers with a considerable degree of clinical experience.
MECA
The computerised version of NIMH Diagnostic Interview Schedule for Children Version 2.3 was used in the Methods for the Epidemiology of Child and Adolescent Mental Disorders Study (MECA) for surveys of children and adolescents in an unscreened population-based sample of 7.500 households (Lahey et al 1996). Besides demographic data and information on service needs and utilization substance use as one of several fields has been covered by the diagnostic procedures. The instrument has been described by Shaffer et al. (1996).
SDS
The Severity of Dependence Scale (SDS) has been developed as a short, easily administered scale to measure the degree of dependence on the basis of five items (Gossop et al 1995). The drug user is requested to judge different aspects of craving and loss of control in relation to the substance. The instruments has been developed and validated in five samples of heroin, cocaine and amphetamine users in London and Sidney. This instrument has been developed for a group of highly deviant drug users with frequent i.v. use of hard drugs, cut-offs have been defined for this group. The application of this instrument to primary cannabis users has been tried only recently by Kraus and collegues (publication in preparation).
2.3Conclusions
For basic analyses and trend information on problem cannabis use subgroups of cannabis users should be defined on the basis of their pattern of use. This can offer a gross estimation of the size of the problem and give some indication on trends.
A more exact and reliable picture of the situation has to include clinical aspects. Most of the instruments described show some short-coming. CRAFFT and CUDIT have been tested only in clinical populations, which might not be sufficient to show their validity and applicability in the general population. EuropASI has been quite successful in clinical research but might be too time consuming for epidemiological research in the population. When PCU is understood in terms of harmful use and dependence CIDI items and CIDI as an computer based instrument for data collection is a promising instrument. They have been applied in a number of studies over the last years and shown good psychometric characteristics. Also promising but less tested is the MECA, which might be a useful instrument especially for children and adolescents.
Further publications on methodological aspects of the assessment of problem cannabis use have been included in the bibliography at the end of this report.
3The substance
3.1Availability and illegal market
Availability and drug use
Availability of drugs and easy access to the substance are crucial factors for all types of psychotropic substances (Mahhadian, Newcomb & Bentler, 1986). Korf (2002) found parallels between the development of availability of cannabis on the Dutch illegal market and the level of consumption in the population. Many factors play a role in this complex system of interactions. The influence of the availability of cannabis on the development of cannabis use is shown by Coffey et al. (2000): In a sample of male pupils in Australia drug using peers and high availability of the drug at the age of 15 correlates with daily use of cannabis at the age of 18.
Availability of drugs can be measured in two ways: perceived availability offers the view of the user while the observation of the illegal market gives a more objective description of the situation. Both ways have been used and both involve certain problems to collect the information in a reliable and valid way.
Perceived availability
Information on perceived availability is part of some of the surveys conducted in EU member states. The answers offer an insight in trends and allow to compare availability for different substances. They do not give, however, an completely objective picture of the situation. Data have been published for example for Germany (Kraus & Augustin 2001). At an European level Eurobarometer (EORG 2002) offers this information. As there is often no indication, how extensive the subject’s personal experiences with purchasing drugs are, the quality of this information is difficult to judge. In some cases it might only reflect the public stereotype on cannabis in the society. Information on drug consumption should be used to check the quality of information on perceived availability.
Drug market
Another way to assess availability of cannabis starts from the drug market. As this is an illegal market, official sales figures are not available and other indicators have to be used instead. Seizures as published by the police or customs count those samples, which have NOT reached the market. They are therefore only an indirect indicator of the amount of cannabis offered or sold. The total amount cannot be calculated from that figure with an acceptable degree of exactness. However, as on the whole there is little evidence, that the effectiveness of law enforcement has changed very much during the last 10 years all over Europe, seizures can be taken as an indicator of trends at least.
The positive correlation between perceived availability and the quantity of cannabis-related seizures, which was found in Canada (Smart & Adlaf 1989) shows, that both sources correspondent quite good.
Other ways to assess availability
Calculations on the basis of production statistics – as done for example for heroin - are not helpful for cannabis, as a considerable percentage of the substance nowadays is produced in-house in Europe. The techniques applied by ONOCP to estimate the heroin production on the basis of the area of poppy cultivation cannot be used in the case of cannabis.
3.2Purity
Trends in purity
Purity of cannabis raisin and marihuana has remained rather stable for a long period of time. At the end of the 80s, Mikuriya and Aldrich (1988) pointed out, that high potency cannabis would have been available already in the 19th century and found that raisin then had about the same range of THC contents as reported by Perry for 1977: 5-15%. For marihuana the range is given as 2-5%.
Studies indicate since then an increase in THC contents in Europe< (e.g. Bundeskriminalamt 2003) as well as in the United States (ElSohly et al. 2000). An considerable increase in the THC concentration has been reported within national REITOX reports (e.g. Simon et al. 2002). Compared to Australia (Hall, Degenhardt, Lynskey 2001) the purity of marihuana is higher here and close to hashish (BKA 2001). It has been indicated, that the average purity for the bigger part of the cannabis on the market remained rather stable while an increasing number of high potent samples with an THC contents above 15% or even 25% can be found nowadays. An evaluation of French data for the years 1993 to 2000 point to this conclusion (Mura et al. 2001).
The considerable increase in the average THC content might be caused through more potent seeds, which have been cultivated over the last 20 years. In-house growing, which can provide perfect growing conditions (light, humidity, water, nutrients), a highly developed industry offering help for growing cannabis (e.g. and special journals ( e.g. Hanfblatt in Germany) and helplines for growers like help to optimise cannabis production not only in professional production.