Best practice portal:
Treatment options for cannabis users

This page refers to the current evidence on the effectiveness of the available treatment options for cannabis users. Information on the methodology used and the definition of terms can be found on the methodology page.

Date of last update: 03.12.2012.     Next update: March 2013.

Effects of available treatments for cannabis users

Summary:Despite the increase in the number of treatment demands only a few studies have assessed the effectiveness of interventions for cannabis users. Multidimensional family therapy has proven to be effective in reducing use and retain patients in treatment, especially in high-severity patients.

Beneficial

Multidimensional family therapy (MDFT) vs. individual psychotherapy (IP) on retention in treatment and to reduce use

MDFT was compared to IP in one study (INCANT study- N= 450, Rigter et al., 2012 – in press, cited in EMCDDA 2013 - in press) and was found to be more effective in:

• reducing the frequency of cannabis consumption in the high-severity MDFT group more than the corresponding IP group across assessments points (differential slope coefficient on treatment=3.8 [95% CI=1.4 to 7.6], p=0.002)
• reducing the prevalence of cannabis use disorders at 12-month follow-up. Namely, 38% of MDFT adolescents met the criteria for cannabis dependence and 33% for cannabis abuse, with 18% no longer having a cannabis disorder. In IP, the corresponding numbers were 52%, 22%, and 15% (differential slope coefficient on treatment=0.9 [95 % CI=0.2 to 1.7], p=0.015). 
• decreasing the number of dependence symptoms from baseline to 12-month follow-up. The 12-month symptoms average was 2.4 for MDFT (SD=2.0) and 3.0 for IP (SD=2.0). The drop in symptoms was larger in MDFT than in IP (differential slope coefficient on treatment=0.27 [95 % CI=0.13 to 0.41], p<0.001).
• retaining patients in treatment. A higher proportion (90%) of MDFT patients completed therapy in comparison to IP (48%) (OR=9.8 [95 % CI=5.7 to 16.7], p<0.001). 

Likely to be beneficial

Cognitive behavioural therapy in individual sessions

Cognitive behavioural therapy (nine session or more) in individual sessions proved to be more effective than brief motivational therapy (in a systematic review including a study with 450 patients) in reducing cannabis use and symptoms of dependence (Denis et al., 2006)

Multidimensional family therapy (MDFT) vs cognitive behavioral therapy (CBT) to reduce use

MDFT was compared to CBT in one study and was found to be more effective (Liddle 2008 cited in EMCDDA 2013 - in press) in:

• reducing cannabis use (measured as number of days of use in previous 30) in the MDFT group (- 58.7%) than in the CBT group (- 46,1%) at the 12-month follow-up. However, both treatments showed statistically significant decreases across time in 30-day frequency of cannabis use (p=.001) and there were no significant differences between MDFT and CBT.

Multidimensional family therapy (MDFT) vs. individual psychotherapy (IP) to reduce the number of cannabis consumption days

MDFT was compared to IP in one study (INCANT study- N= 450, Rigter et al., 2012 – in press, cited in EMCDDA 2013 - in press) and was found effective in:

• reducing the number of cannabis consumption days across assessments. At 12-month follow-up, the mean number of consumption days had decreased by 43% (35 days) in MDFT and by 31% in IP (differential slope coefficient on treatment=1.6 [95 % CI=-0.2 to 3.3], p=0.07).

Psychotherapies in individual or group sessions

Psychotherapies (cognitive behavioural (CBT), motivational enhancement) in individual or group sessions have been found (in a systematic review of five trials involving 1 297 cannabis dependent patients) to be effective in reducing cannabis use (Denis et al., 2006).

Trade-off between benefits and harms

Voucher-based incentives

Voucher-based incentives associated with effective psychotherapeutic interventions were found to be likely to enhance treatment acceptability (defined as the number of participants who attended more than one therapy session). However, they were not effective in improving rates of treatment completion (defined as attending at least one session and giving one urine specimen) in a systematic review including two studies with 125 patients (Denis et al., 2006).

Unknown effectiveness

Therapeutic communities for the treatment of drug misuse and dependency

This intervention was found difficult to assess in a systematic review of seven trials with around 5 000 patients (Smith et al., 2006).

Therapeutic communities in prison

Therapeutic communities in prison for the treatment of drug misuse proved to be better than prison in avoiding re-incarceration at 12 months. Significantly fewer inmates assigned to prison therapeutic communities were re-incarcerated at 12 months post-release, compared with prison inmates receiving no treatment or assigned to alternative services (Smith et al., 2006).

Evidence of ineffectiveness

No interventions met the criteria for this category.

References and definitions

List of references

• Denis, C., Lavie, E., Fatseas, M. and Auriacombe, M. (2006), ‘Psychotherapeutic interventions for cannabis abuse and/or dependence in outpatient settings’, Cochrane Database of Systematic Reviews, Issue 3.
• EMCDDA (2013 - in press), Multidimensional Family Therapy (MDFT) for adolescent illicit drug misusers: a systematic review, EMCDDA Thematic Paper, Faggiano, F., Molinar, R. et al (authors).Publications Office of the European Union, Luxembourg.
• Liddle H. A., Dakof G. A., Turner R. M., Henderson C. E. and Greenbaum P. E. (2008), 'Treating adolescent drug abuse: a randomized trial comparing multidimensional family therapy and cognitive behavior therapy'. Addiction 103, pp. 1660–1670.
• Rigter H., Pelc I., Tossmann A. et al. (2010), 'INCANT: a transnational randomized trial of Multidimensional Family Therapy versus treatment as usual for adolescents with cannabis use disorder', BMC Psychiatry 2010, 10:28 (doi:10.1186/1471-244X-10-28).
• Rigter, H., Henderson, C.E., Pelc, I., Tossmann, P., Phan, O., Hendriks, V., Schaub, M., Rowe, C.L. (2012 - in press), Multidimensional family therapy lowers the rate of cannabis dependence in adolescents: a randomised controlled trial in Western European outpatient settings. Drug Alcohol Depend., 2012 Nov 7, doi:pii: S0376-8716(12)00413-9. 10.1016/j.drugalcdep.2012.10.013. PMID: 23140805
• Smith, L.A., Gates, S. and Foxcroft, D. (2006) ‘Therapeutic communities for substance related disorder’, Cochrane Database of Systematic Reviews, Issue 1, Art. No. CD005338, DOI: 10.1002/14651858.CD005338.pub2.

Explanation of terms used

Below you can find definitions and further explanation for some of the terms used in this section of the Best practice portal. A more general glossary for the best practice portal is also available.

Affective-focused prevention intervention

A type of prevention intervention which aims to they aim to modify inner qualities (personality traits such as self-esteem and self-efficacy, and motivational aspects such as the intention to use drugs).

BA

Before-after (BA) study design

Beneficial

Interventions for which precise measures of the effects in favour of the type of intervention were found in systematic reviews of relevant studies. An intervention ranked as ‘beneficial’ is suitable for most patients/contexts. See the relevant module methodology page for further information.

CBA

Controlled before-after (CBA) study design. UCBA stands for Uncontrolled before-after study design.

CBT

Cognitive behavioral therapy is an individual based intervention occurring in three stages. Phase 1 is aimed at determining and prioritizing the patient’s problems and constructing the treatment contract. Phase 2 is aimed at increasing coping competence and reducing risky behaviors. Phase 3 focuses on relapse prevention. Each session is administered once per week over a period of 4-6 months with 60- to 90-minute sessions (Beck AT, Wright FW, Newman CF, Liese B. Cognitive Therapy of substance abuse. New York: Guilford Press, 1993).

CCT

Controlled clinical trials (CCT)

Cohort study

A cohort study is a type of observational study that follows a group of people (i.e. a cohort) over time. In a prospective cohort study, the cohort is formed and then followed over time. In a retrospective cohort study, data is gathered for a cohort that was formed sometime in the past.

Confidence Interval (CI)

The Confidence Interval (CI) is a measure of the precision (or uncertainty) of study results. It is the interval that most likely includes the true value of the parameter we are calculating, where 'most likely' is taken by common usage to be a 95% probability. Thus the current expression of '95 % CI'. A wide CI indicates less precise estimates of effect and vice versa.

Practical interpretation

• If the RR (the relative risk) = 1, or the CI (the confidence interval) = 1, then there is no significant difference between treatment and control groups
• If the RR > 1, and the CI does not include 1, events are significantly more likely in the treatment than the control group
• If the RR < 1, and the CI does not include 1, events are significantly less likely in the treatment than the control group

CPS

Current population survey (CPS)

Cross-sectional study

A cross-sectional study is a study employing a single point of data collection for each participant or system being studied.They are usually conducted to estimate the prevalence of the outcome of interest for a given population at a given point in time.

Evidence of ineffectiveness

Interventions that gave negative results if compared with a standard intervention or no intervention, for example. See the relevant module methodology page for further information.

Additional information for prevention
For ethical reasons this category in prevention should be considered as interventions with negative and undesired (iatrogenic) effect.

IP

Individual psychotherapy is a standard individual treatment based on counseling and motivational interviewing and focused on substance use triggers and strategies for relapse prevention. It includes elements of cognitive-behavioral therapy (CBT).

ITS

Intermittent time series design (CPS)

Knowledge-focused prevention intervention

A type of prevention intervention which aims to to enhance knowledge of drugs, and drug effects, and consequences.

Likely to be beneficial

Interventions that were shown to have limited measures of effect, that are likely to be effective but for which evidence is limited. An intervention ranked as ‘likely to be beneficial’ is suitable for most contexts/patients, with some discretion. See the relevant module methodology page for further information.

Number Needed to Treat (NNT)

The Number Needed to Treat (NNT)indicates the number of patients that needs to be treated to obtain one respondent patient. Numerically the NNT is the reciprocal of the difference between the proportion of events in the experimental and the comparison group (absolute risk reduction). Taking into consideration that the ideal NNT would be 1 (the unreal situation in which every single patient succeeded) it is easily understood that a NNT value close to 3 or 4 would be very good.

Adjusted Odds Ratio (AOR)

The Adjusted Odds Ratio is a way of comparing whether the probability of a certain event is the same between two groups, yet they are calculated adjusting for or controlling for other possible contributions from other variables (tipically demographic variables) in the model. An AOR equal to 1 implies that the the event is equally probable in both groups. An AOR greater than 1 implies that the event is more likely in the first group. An AOR less than 1 implies that the event is less likely in the first group.

Odds Ratio (OR)

The Odds Ratio is a way of comparing whether the probability of a certain event is the same between two groups. Like the Relative Risk, an OR equal to 1 implies that the the event is equally probable in both groups. A OR greater than 1 implies that the event is more likely in the first group. A OR less than 1 implies that the event is less likely in the first group. In medical research, the odds ratio is commonly used for case-control studies, as odds, but not probabilities, are usually estimated. Relative risk is used in randomized controlled trials and cohort studies.

p value

A p-value is a measure of how much evidence we have against the null hypothesis. The null hypothesis represents the hypothesis of no change or no effect. The smaller the p-value, the more evidence we have against the null hypothesis thus it is more likely that our sample result is true. Traditionally, researchers will reject a null hypothesis if the p-value is less than 0.05.

RCT

Randomised controlled trial (RCT)

Relative Risk (RR)

The Relative Risk (RR) is used to compare the risk in the two different groups of people, i.e. treated and control groups to see if belonging to one group or another increases or decreases the risk of developing certain outcomes. This measure of effect will tell us the number of times an outcome is more likely (RR > 1) or less likely (RR < 1) to happen in the treatment group compared with the control group.

Practical interpretation

• If the RR (the relative risk) = 1, or the CI (the confidence interval) = 1, then there is no significant difference between treatment and control groups
• If the RR > 1, and the CI does not include 1, events are significantly more likely in the treatment than the control group
• If the RR < 1, and the CI does not include 1, events are significantly less likely in the treatment than the control group

Trade-off between benefits and harms

Interventions that obtained measures of effects in favour of the intervention, but that showed some limitations or unintended effects that need to be assessed before providing them. See the relevant module methodology page for further information.

Unknown effectiveness

Interventions for which there are not enough studies or where available studies are of low quality (with few patients or with uncertain methodological rigour), making it difficult to assess if they are effective or not. Interventions for which more research should be undertaken are also grouped in this category.

Additional information for prevention
For prevention interventions,  this  is also known as 'zero effect'.

Skill-focused prevention intervention

A type of prevention intervention which aims to enhance students’ abilities in generic skills, refusal skills and safety skills.

Standardised Mean Difference (SMD)

The Standardised Mean Difference (SMD) is the difference in means divided by a standard deviation. Note that it is not the standard error of the difference in means (a common confusion). The standardized mean difference has the important property that its value does not depend on the measurement scale. It may be useful if there are several trials assessing the same outcome, but using different scales.

z score (Standard Score)

The z-score (aka, a standard score) indicates how many standard deviations an element is from the mean of the population.

 

About cannabis use

Case definition

The Diagnostic and statistical manual, 4th edition, text revision (DSM-IV-TR) describes cannabis abuse as problem use leading to work performance difficulties and legal problems, and cannabis dependence as compulsive use leading to numerous adverse psychological and physical consequences.
In most countries, cannabis use increased during the 1990s and early 2000s, and this has resulted today in a less varied European picture. It is the most-used illicit drug in Europe, although important differences between countries still exist.

Aetiology

Cannabis use is largely concentrated among young people (aged 15–34 years), with the highest levels of last year use generally being reported among 15- to 24-year-olds. Cannabis use is generally higher among males than females, though marked differences between countries are observed.

Prevalence

Conservatively estimated, cannabis has been used at least once (lifetime prevalence) by around 74 million Europeans — over one in five of all 15- to 64-year-olds.
Considerable differences exist between countries, with national prevalence figures varying from more than 1 % to almost 40 %. Many countries report comparatively high prevalence levels of last year and last month use of cannabis. It is estimated that around 22 million Europeans have used cannabis in the last year, or on average 7 % of all 15- to 64-year-olds. National prevalence estimates of cannabis use vary widely between countries in all measures of prevalence, with countries at the upper end of the scale reporting values up to 10 times those of the lowest-prevalence countries.

Treatment

Specific treatment programmes for cannabis users provide services tailored to the needs of this group and also reduce the risk of young people mixing with more problematic and older drug users.
Services targeting cannabis users that are available in Europe include: early intervention programmes, comprehensive family-based treatment, counselling centres implementing specific concepts for young cannabis users, prevention information, brief interventions for users, young offenders and their relatives, Internet-based cannabis cessation programmes, motivational enhancement and cognitive behavioural therapy, psychosocial problem solving and motivational interviewing.

Outcomes

Treatments may not be effective in achieving all the desired outcomes, these outcomes are prioritised.

Primary outcomes

• Retention in treatment (observational studies* showed that people in treatment are less likely to take risks, and to be involved in crimes).
• Severity of dependence/abuse measured with a standardised questionnaire.
• Use of cannabis (self-reported use of cannabis with confirmation by biological analysis).
• Dropout from treatment, measured as the absolute number of participants at the end of the follow-up.

* studies such as National Treatment Outcome Research Study – NTORS, Australian Treatment Outcome Study – ATOS

Prognosis

Periodic cannabis use and intoxication can interfere with performance at school or at work and may be physically hazardous in some situations, for example driving. Individuals with cannabis dependence may use very potent cannabis and this may create problems with their performance at school and work, and lead to difficulties within their families. People with cannabis dependence can persist in its use in spite of related physical problems (e.g. chronic cough related to smoking) or psychological problems (such as a decrease in goal-oriented activities). (DSM-IV)

References

American Psychiatric Association (2000), Diagnostic and statistical manual of mental disorders, 4th edition, text revision, American Psychiatric Association, Washington, DC.

EMCDDA statistical bulletin

EMCDDA , Annual report: the state of the drugs problem in Europe, EMCDDA, Lisbon

Ongoing studies

Cannabis related ongoing studies (PDF, updated January 2011)