Participants are members of the Dunedin Multidisciplinary Health and Development Study. Study members (N = 1037; 91% of eligible births; 52% male) were all individuals born between April 1972 and March 1973 in Dunedin, New Zealand, who were eligible for the longitudinal study based on residence in the province at age 3 years. The cohort represents the full range of socioeconomic status in the general population of New Zealand's South Island and is primarily white. Study members have been followed up repeatedly over their lives, with over 96% retention, and have given written informed consent before participating. The Otago Ethics Committee approved each phase of the study.
