The effectiveness of multidimensional family therapy (MDFT) versus cognitive behavioural therapy (CBT) in Dutch adolescents with a cannabis use disorder

INTERVENTION: Treatment in the control condition consists of five to six months outpatient CBT, focused on enhancing the patient's motivation to change his addictive behaviour and subsequently changing his maladaptive behaviours and cognitions by means of self control training, social and coping skills training and relapse prevention, based on the methods and treatment protocols of Miller and Rollnick (Miller and Rollnick, 1991), Kadden et al. (Kadden et al., 1992) and Monti and colleagues (Monti et al., 1989). Treatment is delivered by trained therapists who use a CBT treatment manual (De Wildt, 2002) and who are supervised during the course of the study by a highly experienced cognitive behavioral therapist. The treatment sessions are held with the individual adolescent on a weekly basis and with a duration of one hour each. In addition, a treatment session is scheduled once a month for the parents of the adolescent, with the goal to provide psycho‐education and support and to discuss treatment progress of the adolescent. Notably, these sessions with the parents are support‐oriented and not system‐oriented. Treatment in the experimental condition consists of five to six months outpatient MDFT. MDFT is a family‐based and developmentally oriented treatment for adolescent substance use disorders and related problems, targeted at the functioning of the adolescents across four life domains: the adolescent as an individual, the relationship to his parents, the relationship to other family members and the relationship to extra‐familial contexts of influence, such as school, work, anti‐social and/or drug using peer networks and the juvenile justice system. MDFT‐therapists have individual sessions with the adolescent alone and the parents alone, sessions with the family, and sessions with family members and influential extra‐familial system representatives. The MDFT sessions with adolescent, parents or family are scheduled on average twice a week, in addition to sessions or contacts CONDITION: DSM‐IV cannabis use disorder ; Mental and Behavioural Disorders ; Mental and behavioural disorders due to psychoactive substance use PRIMARY OUTCOME: Study assessments take place at baseline and at three, six, nine and 12 months (end‐point) following baseline. ; 1. Frequency of cannabis use (i.e. number of cannabis using days and number of joints smoked) in the 90 days preceding the month 12 assessment, based on the timeline follow back (TLFB) calender method. The study data are analysed using an intent‐to‐treat approach, in which all patients are included that were notified about their group allocation after randomisation.; ; Efficacy of MDFT vs CBT in terms of the primary outcome measure is analysed by means of a 2 (treatment group: MDFT vs CBT) x 2 (time: baseline vs month 12) repeated measures MANOVA, using the baseline and month 12 datasets. SECONDARY OUTCOME: 1. The percentage of treatment responders at month 12‐treatment responders are defined as participants who have at least 30% less cannabis using days in the 90 days preceding the month 12 assesment compared to baseline, provided that this reduction is not at the expense of a substantial increase (more than 6 days in the past month) in the use of other substances (i.e. alcohol (at least five glasses a day), cocaine, amphetamines and ecstasy). Adolescents are considered to be in recovery if they live in the community (as opposed to being incarcerated or in inpatient treatment) and are completely abstinent from cannabis, alcohol (at least five glasses a day) and any other substance use on each of the 90 days preceding the month 12 assessment. ; 2. The percentage of recovered adolescents at month 12; 3. The number of property and violent crimes committed in the 90 days preceding the month 12 assessment; 4. Treatment retention‐Treatment retention is defined as the number of weeks that a treatment session was attended by the adolescent.; ; In addition, we calculate the total time of therapeutic contacts spent with the adolescent, parents and other family member or relevant extra‐familial parties as an indicator of the total treatment dosage received. Adolescents are considered as treatment completers if they attended a treatment session in at least 75% of the planned number of treatment weeks. Based on a planned treatment duration of at least five months (22 weeks), this amounts to a minimum of 17 treatment weeks for both conditions. The difference in percentage of treatment responders between the study groups at month 12 is analysed in a logistic regression model, with treatment group as independent variable and treatment response as outcome variable. The same approach is used for analysing the difference in percentage of recovered adolescents at month 12. Differences in delinquent behaviour (property and violent crimes) between the study groups at month 12 are tested using the same analytical approach as described for the primary outcome measure (i.e. repeated measures MANOVA). Difference in treatment retention and in percentage of treatment completers between the study groups is tested in a multivariate linear regression and logistic regression analysis, respectively, with treatment group as independent variable. Finally, GeneraliSed Estimation Equation (GEE) is used to investigate whether the temporal course of cannabis use and delinquent behaviour differs between the adolescents in MDFT and those in CBT on each of the assessment points during the 12 months study period. INCLUSION CRITERIA: 1. A history of cannabis abuse or cannabis dependency based on Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM‐IV) in at least the year preceding the baseline assessment 2. Recent, regular use of cannabis, as indicated by self‐reported cannabis consumption: 2.1. On two or more days a week during the three months preceding the start of the study 2.2. On two or more days a week during the three months preceding the entry of a controlled environment, provided that the controlled environment directly preceded the start of the study and started not longer ago than 90 days before the start of the study 3. Age ranging from 13 to 18 years 4. At least one (step) parent or legal guardian able and willing to participate in the treatment and in the required study assessments 5. Written informed consent, by both the adolescent and his or her parent or legal guardian