Substance use though typically initiated in adolescence is heterogeneous. There are likely to be different patterns or trajectories of substance use which have implications for research on aetiology, prevention, and later outcomes. Specific trajectories of substance use may have different aetiological pathways and maybe more likely to lead to poor adolescent and adult outcomes, which maybe missed if average "values" of substance use are used. Research, therefore, into this area needs to identify the common types of substance use trajectory in order then to test and explore specific hypotheses on aetiology, or on who may benefit or needs to be targeted by prevention activities and the type of intervention that maybe effective, and then to carry these forward into determining their impact on adult substance dependence and other outcomes.

The Avon Longitudinal Study of Parents and Children (ALSPAC) is the largest birth cohort with detailed biological and behavioural data from before birth through till late adolescence in the world. ALSPAC is organised as a resource for the whole scientific community and provides the most detailed phenotypic, genotypic and environmental assessments of parents and their children across the life course of any comparable study available to scientists studying early life influences on health (www.alspac.bris.ac.uk). Approximately 14,000 children along with their parents were recruited to ALSPAC between 1991 and 1992. Since this time these participants have been assessed regularly, mainly through questionnaires and clinics. Since the age of ten years these assessments have included measurement of self-reported substance use (tobacco, alcohol, cannabis and other illicit drugs) and since the age of 15 years these self-reports have been augmented by hair-based toxicology. The current assessment sweep at age 17 years is due to be completed in 2010. Approximately 10,000 ALSPAC participants have DNA stored to allow genotyping, and for 2,000 information from a full genome wide scan is available. Existing ALSPAC support will allow the collection and preliminary processing of data on adolescent substance use at 17, and the drug testing of hair specimens collected at 15 and the future clinic at 17. The current application is for the statistical support necessary to consolidate these data and create an accessible research resource for future secondary analyses by researchers with an interest in drug use and dependence. The value of this resource will be demonstrated through the analysis and identification of trajectories of substance use to age 17, a preliminary genome wide association study in relation to these trajectories, and the identification of key risk and protective factors collected in ALSPAC that are relevant to different hypotheses and their bivariate association with the drug use trajectories. The project has the following aims:

1.) To identify different trajectories of adolescent substance use - both drug specific (i.e. alcohol, tobacco, and cannabis) and an overarching analysis of any adolescent substance use.

2.) To compare and validate self-reported data on selected substances with toxicological evidence based on hair analysis (cannabis, amphetamines, ecstasy, opiates, benzodiazepines, ketamine, methaphetamine) and urinalysis (cotinine)

3.) To create an accessible database of self-reported substance use amongst ALSPAC participants from ages ten to 17 years, including specific trajectories of substance use, and hair analysis.

4.) To compare case participants exhibiting the above phenotypes with study controls in a subset of approximately 2000 study members in whom whole genome scan data are available in order to identify genetic loci of possible influence on trajectories of adolescent substance use in order to inform more detailed genetic investigations.

5.) To identify, collate, and make available information on key predictors, mediating factors, and confounders of substance use collected in ALSPAC including measures of:- social position, family adversity, parental and prenatal substance use, impulsivity (conduct problems and antisocial behaviour), subjective response, peer substance use, depression and anxiety, educational performance, life events, sexual maturation, and neighbourhood.

6.) To provide bivariate analyses of these factors on substance use trajectories in order to support researchers and research clusters test specific hypotheses on causal pathways determining adolescent substance use.