AIMS The aim of this proposal is to examine risk factors for developing psychosis-like symptoms (PLIKS) during late adolescence within a population-based birth cohort. Furthermore, we will examine factors affecting persistence of PLIKS throughout adolescence, and the pathways from developing PLIKS in early adolescence through to disorder (PLIKS with concurrent functional impairment) in late adolescence, focusing on both risk and protective factors that are likely to be operating along this trajectory. More specifically, the aims of this proposal are:

1) To carry out an interview-based assessment of PLIKS, along with measures of functional impairment, in order to determine the prevalence and distribution of sub-clinical PLIKS, and of PLIKS related disorder (PLIKS and concurrent functional impairment) in 17-year olds.

2) To investigate whether established risk factors for adult onset psychotic illness (maternal exposures during pregnancy, pregnancy and birth complications, social relationships during childhood and adolescence, social cognition, emotional experiences, cognitive ability, substance use, and genetic variation) alter risk of developing PLIKS at age 17, or impact upon persistence of symptoms (from assessment at age 12 through to age 17 assessment) or transition into PLIKS related disorder.

3) To further refine and increase the validity and positive predictive value of a self-rated questionnaire-based assessment of PLIKS by comparing self-reported responses to structured questions with observer ratings of PLIKS from a semi-structured interview