Specific aims of this project are to:

1. Fully exploit data already collected in ALSPAC to investigate trajectories to use of cannabis and other drugs in late adolescence and early adulthood and adverse psychological, educational and social outcomes associated with these pathways.

2. Collect new data on ALSPAC children in late adolescence and early adulthood so that the resource has data on the whole of childhood - from before birth to the onset of adulthood allowing investigation of effects of exposures both cumulatively and during critical time periods, such as pregnancy, infancy, puberty and adolescence, on outcomes measured in late adolescence and around the onset of adulthood.

3. Obtain consent for and establish mechanisms of linkage between individual ALSPAC study participants and routine sources of data on educational, social and health outcomes that may be influenced by exposure to cannabis and other drugs.

The project will realise these aims through meeting the following objectives:

* Objective 1:To obtain detailed and objective measurement of frequency, quantity, route of administration, form of drug used and dependence on cannabis and other drugs through a clinic based assessment at age 17 (including collection of biological samples) and a postal questionnaire at age 19

* Objective 2: To measure psychotic like symptoms in a clinic based assessment at age 17 and a postal questionnaire at age 19.

* Objective 3: To measure involvement in antisocial and other risky behaviour, sibling drug use, social position and labour market participation through a postal questionnaire at age 19.

* Objective 4: To develop the methodology necessary to allow individual linkage to routine health and social outcome data and to extend linkage already established (with parental consent) to educational outcome data to these other data sources after obtaining individual consent at an age 17 clinic.

* Objective 5: To examine direct associations between currently established candidate polymorphisms and candidate polymorphisms that emerge during the lifetime of the project on trajectories and level of cannabis use, and to use such polymorphisms as unconfounded measures of cannabis intake to look at associations between cannabis use and related harm.

* Objective 6: To examine possible gene-environment interactions involving such genotypes in relation to the outcomes considered in this project.

* Objective 7: To use ALSPAC data already collected along with data collected as described above to clarify causal pathways to onset and progression of cannabis use, to use of other drugs and to the adverse outcomes associated with such use, attributable risks of key causal exposures and most promising targets for effective intervention.

* Objective 8: To establish a resource that will allow consideration of these questions in relation to adverse health and social outcomes apparent beyond the lifetime of the project.