Patterns of cannabis use, abuse and dependence over time : incidence, progression and stability in a sample of 1228 adolescents

Aims. To present data on the incidence of cannabis use at follow-up, and its progression, stability, abuse and dependence in a representative sample of adolescents (N = 1228), aged 14-17 years at "baseline"-the outset of the study-in Munich, Germany. Design. The study employed a prospective longitudinal design using a representative population sample. The mean follow-up time was 19.7 months. The Composite International Diagnostic Interview (M-CIDI) was used to assess patterns of use, abuse and dependence according to DSM-IV criteria. Findings. (I) In our sample, 34.8% of males and 30.2% of females had tried cannabinoids at least once. (2) Of those who used cannabis repeatedly (two or four times) at baseline, 26.1% stopped using by follow-up; the majority went on to regular use in the follow-up period Similarly, only 17.7% of the regular users at the outset slopped using cannabis completely; 74.2% continued their pattern of regular use. Thus, the higher the baseline use pattern, the higher was the probability of continued or heavier use during follow-up. (3) Although the cumulative life-time incidence for DSM-IV cannabis abuse (3.5%) in this age group was low, it is noteworthy that complete diagnostic remissions were relatively rare (31.7% for dependence, 41.1% for abuse). (4) There was considerable concurrent use of other drugs. Conclusions. Cannabis use was almost as widespread in this sample of adolescents in Germany as in similar age groups ill metropolitan areas of North America. There was a relatively low spontaneous remission rate among regular and repeated users. Cannabis use in adolescence appears to be less transient than many people would believe.