Hereinafter, the Lothian Birth Cohort 1936 will be called the LBC1936. Ethics permission for the study protocol was obtained from the Multi-Centre Research Ethics Committee for Scotland (MREC/01/0/56) and from Lothian Research Ethics Committee (LREC/2003/2/29). The research was carried out in compliance with the Helsinki Declaration. All subjects gave written, informed consent. On behalf of the LBC1936 research team, and with the permission of, and under the management of the Director of Public Health for Lothian, the Lothian Health Board identified potential participants using the Community Health Index (CHI). This is a list of individuals in a given area who are registered with a general medical practitioner (GP). At any time, the CHI is not fully correct. Inaccuracies are due to the time necessary to update deaths or movements into and out of an area. The Lothian Health Board was requested by us to identify all individuals listed on the Lothian CHI who were born in 1936; that is, individuals who might have taken part in the Scottish Mental Survey of 1947. At the start of the study, 3810 people born in 1936 were identified on the Lothian CHI.
