The original Lothian Birth Cohorts of 1921 (LBC1921) and 1936 (LBC1936) were designed as follow-up studies to the Scottish Mental Surveys of 1932 (SMS1932) and 1947 (SMS1947), respectively. The SMS1932 took place simultaneously across schools in Scotland on the 1st of June, 1932, and used the Moray House Test (No. 12 MHT) of general intelligence. Almost every child attending school and born in 1921 (N = 87, 498) was tested. The same MHT was administered to almost every child born in 1936 and attending school on the 4th of June, 1947 for the SMS1947 (N = 70, 805). Decades later, participants of both Surveys, mostly living in Edinburgh and the surrounding area (the Lothians) in older age, were invited to participate in the Lothian Birth Cohort (LBC) studies. Between 1999 and 2001, 550 of the SMS1932 were recruited to Wave 1 of the LBC1921 study, at a mean age of 79 years. Between 2004 and 2007, 1, 091 members of SMS1947 were recruited to Wave 1 of the LBC1936 study, at a mean age of 70 years. Both cohorts re-sat the MHT at initial follow-up. In addition, a large amount of other cognitive, psychosocial, lifestyle, medical, biomarker, genetic, brain imaging and other data were collected.

The LBC studies set out principally to examine the nature and determinants of non-pathological cognitive ageing from childhood to older age, and within in older age. However, in recent years the scope of the studies has extended to identifying more risk and protective factors that have the potential to be interventions to reduce the risk of cognitive loss in later life. At each visit, participants submit a wide range of data, leading to a database of thousands of data points for every single participant, including cognitive, lifestyle, social and psychological, genetic and epigenetic, health and physical fitness, biological, and brain and vascular imaging data.