The target group was individuals who engaged in regular or daily cannabis use, and who were motivated to quit cannabis. The formal inclusion criteria was a Severity of Dependence Scale (SDS) score ≥4 and being ≥16 years old. Exclusion criteria was polydrug use where cannabis was not the predominating substance of use and psychiatric comorbidity that was perceived as too severe to handle at the community-based centers .

Lundqvist and Ericsson developed the 'Cannabis Cessation Program' (CCP, Nordic abbreviation: HAP) in Sweden in the 1990s. The method uses a combination of cognitive therapy and psychoeducation and covers the normal withdrawal period for cannabis smoking cessation (up to 8 weeks), comprising ~15 individual sessions. It describes a medical, a psychological, and a social phase, in which the participant is helped to recognize and address typical problems related to each phase, e.g., physical and psychological withdrawal problems. The overarching aim of the program is to help cannabis users to reorganize thinking patterns that developed while they were using cannabis and increase their social and psychological coping skills in relation to quitting cannabis use. The CCP manual has been translated into eight languages, e.g., Norwegian.

Days with cannabis use last 30 days

The Hopkins Symptom Checklist (HSCL) 25-item version was used to measure mental distress. Each of the 25 items was scored on a 4-point scale (1-4). An average score was computed, indicating a global severity index of mental distress (GSI), where higher scores indicated greater distress. Clinical cut-off = 1.75