Participants in the first sample were members of the Dunedin Multidisciplinary Health and Development Study. Of infants born in Dunedin, New Zealand, between April 1972 and March 1973, 1037 (91% of eligible births; 52% male) participated in the first assessment at age 3. Assessments were undertaken at ages 3, 5, 7, 9, 11, 13, 15, 18, 21, 26 and most recently at age 32 when we assessed 96% of the 1015 Study members still alive in 2004–2005. Genetic data were available for 97% participants. To minimize the risk of artefacts due to population stratification, only 847 Caucasians were included. Study members gave written informed consent before participating. The Otago Ethics Committee approved each phase of the study.
