LAUSR

Abstract Substance use is widespread among adolescents and several studies focused on its prevalence, sequencing of initiation and frequency. However, longitudinal patterns of substance use in adolescence, combining sequencing and frequency, are rarely studied. The objective of this study was to analyze patterns of polysubstance use in adolescence including sequencing and frequency, their stability and change, using between-individual and within-individual analyses. This was done through a prospective longitudinal study with 879 Spanish children and adolescents (9–17 years old at time 1, 10–18 at time 2) followed-up for one year. Substance use was measured with a survey using a validated self-reported questionnaire focused on the frequency of use of different substances. Latent transition analysis found three patterns of substance use including non-users, occasional users and frequent users. Non-users and frequent users were stable over time whereas around one fifth of occasional users transitioned to frequent users. Substance use started with occasional alcohol consumption and tended to progress to frequent use and illicit drugs. It is concluded that substance use starts early in life and the best predictor of future non-use is the past non-use. Prevention and intervention seem necessary throughout the adolescence, especially before the progression to frequent use that does not seem to remit spontaneously.