Longitudinal studies of drug abuse in a fifteen-year-old population. 1. Drug career.

A representative, stratified sample from a year cohort of ninth-graders, mostly 15 years of age, examined in 1968 with a questionnaire, was followed over a decade in official registers. After 5 and 8 years, subsamples were also interviewed. During the period in question there was a polydrug abuse pattern in the area of Gothenburg, the second city in Sweden with approx. 450,000 inhabitants. The sample comprised 1,047 individuals and the whole year cohort 5,367. The estimated proportions of registered drug abusers in the cohort were 9% men and 8% women. 3% men and 5% women had drug careers for 2 years or less, 1% men and 0.2% women for 10 years or more. Those who became registered had with few exceptions stated drug use in the school questionnaire or had attended special classes or dropped out of school prematurely. After 5 years 60-80% of the registered abuse remained among the men in these groups and 30-40% among the women. According to interviews abuse remained in 70-90% of men who had admitted drug use in the school survey and in 50-60% of the women from the same groups. According to both registers and interviews intravenous abuse of central stimulants had increased among men but decreased among women. After 11 years, 20-60% of the registered abuse remained in men and 5-60% in the women.