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: (1) 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 stopped 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 in 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.