BackgroundConduct disorder (CD) is a complex mental disorder characterized by severe rule-breaking and aggressive behavior. While studies have shown that several therapeutic interventions are effective in treating CD symptoms, researchers call for treatments based on etiological knowledge and potential patho-mechanisms. Mentalization-based treatment (MBT) may represent such a treatment approach: Studies have shown that individuals with CD show mentalizing deficits and that mentalizing might represent a protective factor against the development of the disorder. As MBT focuses on the understanding of social behavior in terms of mental states, fostering mentalizing might help CD individuals to (re)gain an adaptive way of coping with negative emotions especially in social interactions and thus reduce aggressive behavior. For this purpose, MBT was adapted for adolescents with CD (MBT-CD). This is a protocol of a feasibility and pilot study to inform the planning of a prospective RCT. The primary aim is to estimate the feasibility of an RCT based on the acceptability of the intervention and the scientific assessments by CD individuals and their families indicated by quantitative and qualitative data, as well as based on necessary organizational resources to conduct an RCT. The secondary aim is to investigate the course of symptom severity and mentalizing skills.MethodsThe bi-center study is carried out in two outpatient settings associated with university hospitals (Heidelberg and Mainz) in Germany. Adolescents aged between 11 and 18 years with a CD or oppositional defiant disorder (ODD) diagnosis are included. Participants receive MBT-CD for 6 to 12 months. The primary outcome of the feasibility study (e.g., recruitment and adherence rates) will be descriptively analyzed. Multilevel modeling will be used to investigate secondary outcome data.DiscussionFostering the capacity to mentalize social interactions triggering non-mentalized, aggressive behavior might help CD individuals to behave more adaptively. The feasibility trial is essential for gathering information on how to properly conduct MBT-CD including appropriate scientific assessments in this patient group, in order to subsequently investigate the effectiveness of MBT-CD in an RCT.Trial registrationClinicalTrials.gov, NCT02988453. November 30, 2016Sources of monetary supportDietmar Hopp Stiftung, Heidehof StiftungRecruitment statusRecruitment complete and intervention complete, follow-up assessments ongoing (Heidelberg). Recruitment and assessments ongoing (Mainz).Primary sponsor, principal investigator, and lead investigator in HeidelbergSvenja Taubner is responsible for the design and conduct of MBT-CD intervention and feasibility and pilot study, preparation of protocol and revisions, and publication of study results.Secondary sponsor and lead investigator in MainzEsther Sobanski is responsible for the recruitment and data collection in the collaborating center MainzRecruitment countryGermanyHealth condition studiedConduct disorder, oppositional defiant disorderInterventionMentalization-based treatment for conduct disorder (MBT-CD): MBT-CD is an adaptation of MBT for Borderline Personality Disorder. This manualized psychodynamic psychotherapy focuses on increasing mentalizing, i.e., the ability to understand behavior in terms of mental states, in patients. MBT-CD includes weekly individual sessions with the patient and monthly family sessions.Key inclusion and exclusion criteriaIncluded are adolescent individuals with a diagnosis of conduct disorder or oppositional defiant disorder aged between 11 and 18 years.Study typeFeasibility and pilot study (single-group)Date of first enrollment19.01.2017Study statusThe trial is currently in the follow-up assessment phase in Heidelberg and in the recruitment and treatment phase in Mainz.Primary outcomesAcceptability of MBT-CD intervention (as indicated by recruitment rates, completion rates, drop-out rates, treatment duration, oral evaluation), acceptability of scientific assessments (as indicated by adherence, missing data, oral evaluation), and necessary organizational resources (scientific personnel, recruitment networks, MBT-CD training and supervision) to estimate feasibility of an RCTSecondary outcomesAdolescents’ symptom severity and mentalizing abilityProtocol version20.08.2020, version 1.0