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INCA - Intervention and Neuropsychology in Cannabis Abuse

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified April 2007 by University Hospital, Bonn.
Recruitment status was:  Recruiting
German Federal Ministry of Education and Research
Information provided by:
University Hospital, Bonn Identifier:
First received: January 18, 2006
Last updated: April 19, 2007
Last verified: April 2007
INCA (Intervention and Neuropsychology of Cannabis Abuse) is a study combining two research goals. One is to study efficacy of a short intervention the ‘Problem Profile Intervention’, which utilizes individual feedback from a ‘substance problem check-up’. Subjects will randomly receive the ‘Problem Profile Intervention’ or the WHO Brief Intervention, a brief intervention, which has been shown to be efficacious. Currently efficiency studies are under way. The WHO Brief Intervention has been translated into German by our group. In contrast to most other cannabis intervention studies the current study is focussed on cannabis abusers not so much cannabis-dependent subjects. A total of 160 subjects are to be recruited. Half of them will randomly receive either the Problem Profile Intervention or the WHO Brief Intervention (active control). A total of 25% of subjects from each group will be placed on a 3 months waiting list before receiving the intervention (inactive control). Intervention outcome will be assessed three months, six month and 12 months after the intervention. We hypothesize cannabis use to be reduced by 25% by the 'Problem Profile Intervention'. The second aim of the study is to study mechanism of substance abuse. Initial results from own studies and data from other groups point to executive cognitive functions as a subtle but important factor that can be compromised in cannabis users (Verdejo-Garcia et al., 2004; Garavan and Stout, 2005). Using an fMRI-study, we intend to examine a subgroup of our subjects on a specific aspect of executive functioning that has recently received major interest in drug research: Decision-making capability, or risk-taking behaviour, respectively (e.g. Ernst and Paulus, 2005).

Condition Intervention
Marijuana Abuse Behavioral: 'Problem Profile Intervention' vs. WHO-Brief Intervention

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Targeted Interventions in Cannabis Abuse: Focus on Decision Making (INCA)

Resource links provided by NLM:

Further study details as provided by University Hospital, Bonn:

Primary Outcome Measures:
  • Cannabis consumption,
  • motivational change

Secondary Outcome Measures:
  • ASSIST-Score

Estimated Enrollment: 160
Study Start Date: July 2005
Estimated Study Completion Date: October 2007

Ages Eligible for Study:   16 Years to 36 Years   (Child, Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • ASSIST-Score for cannabis consume ≥ 4 ≤ 26
  • german mother tongue (or comparable level)

Exclusion Criteria:

  • major current psychiatric disorder (e.g. psychosis)
  • addiction to other illegal drugs or alcohol
  • recent or current intravenous drug use
  • CNS-affecting medication
  • current psychotherapy, other treatment for substance use disorder

exclusion criteria for fMRI-part:

  • left-handedness
  • medication (birth control pill, thyroid gland hormones possible)
  • internistic illnesses (hypertension, diabetes, diseases of lungs)
  • metallic implants (cardiac pacemaker, ferromagnetic object implanted through surgical intervention or accident, large-area tattoos)
  • history of serious trauma
  • claustrophobia
  • gestation
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00279604

Contact: Christian G Schuetz, MD MPH +49 228 287 9664 christian.schü

Friedrich-Wilhelms-University, Department of Psychiatry Recruiting
Bonn, NRW, Germany, 53105
Contact: Christian G Schütz, MD MPH    +49 228 2879664    christian.schü   
Principal Investigator: Christian G Schütz, MD MPH         
University of Essen, Department of Psychiatry and Psychotherapy Recruiting
Essen, NRW, Germany, 45147
Contact: Norbert Scherbaum, MD    +49 201 7227 180   
Principal Investigator: Norbert Scherbaum, MD         
Sponsors and Collaborators
University Hospital, Bonn
German Federal Ministry of Education and Research
Principal Investigator: Christian G Schuetz, MD MPH University of Bonn, Department of Psychiatry
  More Information Identifier: NCT00279604     History of Changes
Other Study ID Numbers: 01EB0432
Study First Received: January 18, 2006
Last Updated: April 19, 2007

Additional relevant MeSH terms:
Marijuana Abuse
Substance-Related Disorders
Chemically-Induced Disorders
Mental Disorders processed this record on September 21, 2017