Effectiveness of the 'Wiet-Check', the Dutch version of the Adolescent Cannabis Check-Up (ACCU), amongst adolescents aged 14-21 years with frequent cannabis use.

The aim of the project is to test the effectiveness of the The Wiet-Check, a brief intervention based on the principles of motivational interviewing. A randomized controlled trial (RCT) will be conducted among 14-21 year old frequent cannabis users.

At 3 and 12 monts post-tests, we expect adolescents in the Wiet-Check condtion to use less cannabis and to have less symptoms of misuse and dependence compared to adolescents in the control condition.

T0: Baseline measurement before randomisation and intervention;

T1: First follow-up, 3 months after baseline;

T2: Second follow-up, 12 months after baseline.



Questionnairs used:

1. 14 items on participants' cannabis use (used in previous research on cannabis use amongst adolescents in the Netherlands);

2. Cannabis Use Problems Identification Test (CUPIT);

3. Severity of Dependence Scale (SDS);

4. 9 adapted items on school from the Adolescent Cannabis Problems Questionnaire (CPQ-A);

5. 8 adapted items on work from the Adolescent Cannabis Problems Questionnaire (CPQ-A);

6. 17 items on delinquent behaviour (used in previous research amongst adolescents in the Netherlands);

7. Youth Self Report (YSR).

The Wiet-Check is a brief intervention based on the principles of motivational interviewing and consists of two sessions of 60-90 minutes each. The intervention will be delivered by trained professionals from organisations for addiction care. The first session (the assessment session) consists of a structured interview designed to assess the young person's cannabis and other substance use history, symptoms of cannabis abuse and dependece and other aspects of their cannabis use (pros and cons, expectations on increased/decreased use) and his/her life expectations. This information provides the content for a personal feedback report. In the second session (the feedback session), about a week after the first, the professional provides structured feedback and discussion of information on the young person's cannabis use compared to age-specific normative data and other topics discussed in the first session. The personal feedback report is used as a basis for the structured feedback and information. During the feedback session, the professional uses motivational interviewing strategies to elicit the participant's active and candid involvement in the session. Expressions of motivations for change are reinforced. When the participant clearly expresses a desire to change his/her cannabis use, various change options will be discussed, including self-managed change or referrals to drug treatment.



The control condition consists of one informative session of 60 minutes. During this session factual and general information on cannabis and its effects are being discussed with the participant by taking cannabis-knowledge tests.