The International Cannabis Need for Treatment (INCANT) Study: An Independently Conducted Multisite Clinical Trial Craig Henderson a, Henk Rigter b, Isidore Pelc c, Peter Tossmann d, Olivier Phan e, Vincent Hendriks f, Michael Schaub g, Cindy Rowe h, Howard A. Liddle h a Sam Houston State University f Parnassia Addiction Research Centre, The Hague b Erasmus, MC g Research Institute Public Health and Addiction, Zurich c Université Libre de Bruxelles h University of Miami Miller School of Medicine d Delphi-Gesellschaft für Forschung, Berlin e Centre Emergence, Paris

Acknowledgements Federal Ministries of Health of Belgium, Germany, the Netherlands, Switzerland, Mission Interministerielle de Lutte Contra la Drogue et de Toximanie (MILDT), France

Cannabis Use Patterns In Western Europe As in US, cannabis is most widely used illegal substance in Europe 3-5% of teens consume cannabis daily Availability increased remarkably during 1990s due to increase in imports as well as local production Stabilized following initial increase, but remains at historically high levels Wide range across countries in prevalence estimates. Cannabis use in previous year (Kokkevi et al., 2006): High: Czech Republic, 27.5% Low, Greece: 4.1% INCANT participants: France 18%, Belgium 17% US: 25% (Johnston et al., 2011)

Correlates of Substance Use Age of first use younger in high prevalence countries Environmental (family, peers), behavioral, and individual risks all associated with cannabis use. Older sibling/peer cannabis use Lack of parental monitoring; relationship with parents Truancy Antisocial behavior Internalizing symptoms fairly weekly correlated (Kokkevi et al., 2007)

EBP Implementation in Europe RCTs of evidence-based treatments have been implemented in several countries (e.g., Sweden, Norway, Netherlands) Evidence of effectiveness is mixed. Why have EBT trials been effective in one country but not another? –Treatment fidelity? Other cultural factors? Raises important policy question: –Does it work somewhere? vs. Will it work for us?

International Need for Cannabis Treatment (INCANT) Study Randomized controlled trial implemented in five Western European countries: (1) Belgium, (2) France, (3) Germany, (4) The Netherlands, (5) Switzerland Two treatment conditions: MDFT and Individual Psychotherapy (IP) –In France and Switzerland, IP was a psychodynamic approach –In Belgium and the Netherlands, IP was a CBT approach –In Germany, both psychodynamic and CBT approaches were used –Treatments designed to last 6 months –Two MDFT sessions prescribed per week Eligible youth between 13 and 18 years of age with a cannabis use disorder (dependence or abuse) with at least one parent willing to be involved in MDFT

Unique Features of MDFT as Implemented in INCANT First international treatment trial of MDFT Along with the Cannabis Youth Treatment study, the only independently conducted trial of MDFT MDFT developers active in training and certifying European supervisors and therapists, but trial management and conduct led by European researchers. Advance over previous EBP trials, INCANT implemented across five countries. –Much larger sample than previous trials –Cross-country heterogeneity controlled in data analyses –Vast majority of heterogeneity due to referral source (family/self vs. externally coerced)

Study Sites Belgium: Department of Psychiatry, Brugmann University Hospital, Brussels France: Centre Emergence in Paris with suburban CEDAT (Conseils Aide et Action contre le Toximanie) sub-sites in Mantes la Jolie and St Germain en Laye Germany: Therapieladen, Berlin Netherlands: Parnassia Brijder and De Jutters, The Hague Switzerland: Phénix, Geneva

Sample N=450 total, Belgium n=60, France n=101, Germany n=120, Netherlands n=109, Switzerland n=60 85% male; 40% first- or second-generation immigrants Average age 16.3 years Most lived with family (87%) and were attending school (75%) 82% met criteria for cannabis dependence, 18% with cannabis abuse, 42% had an alcohol use disorder. SUDs for drugs other than cannabis and alcohol was rare. 33% had been arrested in the previous 90 days

Outcomes and Measures Timeline Follow-Back of cannabis use (previous 90 days) Cannabis use disorders assessed by the ADI Light Total number of cannabis dependence symptoms also assessed by ADI Light

Analyses Latent growth curve (LGC) modeling used to measure change in substance problems at intake and 3, 6, and 12- month follow-up Missing data estimated with Full Information Maximum Likelihood

Treatment Retention

Cannabis Dependence Diagnoses Site by treatment interaction was not significant

Timeline Follow-Back Site by treatment interaction was not significant

Summary Across and within sites, family-based MDFT retained cases better in treatment than IP Results suggest that MDFT remitted cannabis dependence more effectively than IP MDFT decreased frequency of substance use more than IP in more severe substance users. Finding similar to Henderson et al. (2010). Treatment differences were similar across all sites.

Conclusions International dissemination of MDFT was successful Therapists mastered MDFT model, and it is rapidly being disseminated in Europe Independent trial management mitigates against investigator allegiance Future analyses will examine cross-site predictors of treatment outcome and compare results to US-based trials –Will help address questions related to contextual/cultural factors related to treatment effectiveness