Contribution to the CoCA Project will be in the analysis making use of the established databases, most importantly our flagship investigation, the Estonian Children Personality Behaviour and Health Study. ECPBHS (www.ecpbhs.ee) is a prospective longitudinal birth cohort study that has a very high representation of local population and very low attrition rate, and that has since its beginning, 18 years ago, included proxy reports on ADHD-like symptomatology and aggressive behaviour, and self-reports and behavioural tests for many psychological dimensions but most remarkably on impulsivity. Because the origins of the ECPBHS lie in paediatric cardiovascular research, the database is also uniquely equipped with detailed objective data on body composition, aerobic fitness, daily diet, habitual physical activity and clinical biochemistry. As young adults all participants underwent structured psychiatric interview. ECPBHS database includes four birth cohorts, and as collected in a country with rapid socioeconomic transition such data facilitate analysis of complexity of causal factors in co-morbidity. Furthermore, the ECPBHS database has recently been amended with detailed information and biosamples from the parents of the original target subjects that makes it feasible to disentangle the genetic and environmental aspects of familial aggregation.