Condition category
Mental and Behavioural Disorders
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status

Plain English Summary

Not provided at time of registration

Trial website

Contact information



Primary contact

Dr Henk Rigter


Contact details

Viviënstraat 24
The Hague
2582 RT

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

The effectiveness of outpatient multidimensional family therapy (MDFT) compared with outpatient treatment as usual in adolescents with a cannabis use disorder and other problem behaviour: a multicentre, trans-national randomised controlled trial


INCANT (International Cannabis Need of Treatment study)

Study hypothesis

To examine if multidimensional family therapy (MDFT) is superior to treatment as usual in reducing substance abuse (notably cannabis) and other problem behaviour in adolescents. This is a multicentre trial, with sites in Brussels, Berlin, Paris, The Hague and Geneva.

Primary hypotheses:
1. Youths assigned to MDFT will diminish their use of cannabis more than youths in the treatment as usual condition between baseline and 4 follow-up assessments spaced across a 1-year follow-up period
2. Youths assigned to MDFT will be less likely to meet diagnostic criteria of cannabis disorders going from baseline to the 12 months follow-up assessment than youths treated as usual

Ethics approval

1. Belgium: Comité dÉthique Hospitalier approved on the 8th August 2006 (ref: CE2006/39)
2. France: Comité Consultatif de Protection des Personnes dans la Recherche Biomedicale approved on the 28th August 2006 (ref: 0611357)
3. Germany: Kammer für Psychologische Psychotherapeuten und Kinder- und Jugendlichenpsychotherapeuten im Land Berlin approved on the 19th September 2006
4. Netherlands: Medisch-ethische Toetsingscommissie Instellingen Geestelijke Gezondheidszorg (METiGG) approved on the 9th May 2006 (ref: 5238)
5. Switzerland: Association des Médecins du Canton de Genève et Societé Médicale Commission d’”Ethique pour la Recherche Clinique en Ambulatoire approved on the 6th February 2007 (ref: 07-02)
6. USA (Miami): Institutional Review Board of University of Miami Miller School of Medicine, Human Subjects Research Office approved on the 21st September 2006 (ref: 20060330)

Study design

Multicentre phase III(b) randomised controlled trial with an open-label, parallel group design

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Can be found at


Cannabis abuse and cannabis dependence


4 - 6 months; sessions 2 - 3 times a week. Office-based and home-based sessions with:
1. The adolescent alone
2. The parent(s) alone
3. The family = adolescent + parent(s), and
4. Representatives of other social systems (friends, school, or probation) present

Treatment as usual (TAU):
This differs between countries to reflect local practice, but is based on cognitive-behavioural therapy and it matches MDFT in duration. In France and the Netherlands, TAU has been manualised.

Intervention type



Phase II/III

Drug names

Primary outcome measure

1. MDFT reduces cannabis consumption more strongly than TAU in the 90-day periods preceding follow-up assessments points (a lower number of consumption days: TLFB = TimeLine Follow Back), the difference growing bigger over time
2. Number of urine tests indicative of cannabis use is lower in MDFT than in TAU at follow-up assessments points
3. In MDFT, youth show fewer (symptoms of) diagnoses of cannabis use disorders (as measured with the Adolescent Diagnostic Interview-Light [ADI-Light]) than in TAU at 12 months follow-up (the validated ADI-Light measures symptoms of substance use disorders). Assessment points: baseline, 12 months follow up.

Secondary outcome measures

1. MDFT reduces alcohol consumption to a greater extent than TAU, on the same measures and the same assessment points as outlined for cannabis
2. MDFT is superior to TAU in diminishing delinquent behaviour (less recidivism), as measured with the validated Adolescent and Parent Interviews, the Self-Reported Delinquency survey (SRD; lower score), lower scores on the delinquency sub-scales of Youth-Self Report (YSR) and its parent version, the Child Behaviour Checklist (CBCL). Also police and justice registration databases. Assessment points: baseline, 6 months and 12 months follow up.
3. MDFT improves family functioning more than TAU (validated Adolescent and Parent Interviews using the Family Environment Scale [FES]). Interviews: baseline, 6 months and 12 months follow-up. FES: idem, but also 9-months follow up.
4. MDFT improves the youth's performance at school or work more than TAU (validated Adolescent and Parent Interviews, school reports, truancy logs). Assessment points: baseline, 6 months and 12 months follow up.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Age of the adolescent 13 through 18 years, either sex
2. Diagnosis of cannabis use disorder
3. At least 1 parent willing to take part in the treatment programme
4. Informed consent by both adolescent and parent(s)

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Disorder requiring hospitalisation or other residential treatment
2. Intelligence Quotient (IQ) of adolescent below 70

Recruitment start date


Recruitment end date



Countries of recruitment

Belgium, France, Germany, Netherlands, Switzerland

Trial participating centre

Viviënstraat 24
The Hague
2582 RT

Sponsor information


Erasmus Medical Centre (Netherlands)

Sponsor details

c/o Dr Henk Rigter
Department of Public Health
P.O. Box 2040
3000 CA

Sponsor type




Funder type


Funder name

Federal Ministry of Health (Federaal Ministerie van Volksgezondheid) (Belgium)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

Federal Ministry of Health (Bundesministerium für Gesundheit) (Germany)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

The Inter-Departmental Mission for the Fight Against Drugs and Drug Addiction (Mission interministérielle de lutte contre la drogue et la toxicomanie [MILDT]) (France)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

Ministry of Health, Welfare and Sports (Ministerie van Volksgezondheid, Welzijn en Sport [VWS]) (Netherlands)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

Federal Office of Public Health (das Bundesamt für Gesundheit [BAG]) (Switzerland)

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

2010 protocol in:
2014 results in:
2018 results in:

Publication citations

  1. Protocol

    Rigter H, Pelc I, Tossmann P, Phan O, Grichting E, Hendriks V, Rowe C, 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.

  2. Results

    Schaub MP, Henderson CE, Pelc I, Tossmann P, Phan O, Hendriks V, Rowe C, Rigter H, Multidimensional family therapy decreases the rate of externalising behavioural disorder symptoms in cannabis abusing adolescents: outcomes of the INCANT trial., BMC Psychiatry, 2014, 14, 26, doi: 10.1186/1471-244X-14-26.

Additional files

Editorial Notes

28/08/2018: Publication reference added.