The Lothian Birth Cohorts of 1921 and 1936 are follow-up studies of the Scottish Mental Surveys of 1932 and 1947. The surveys had, respectively, tested the intelligence of almost every child born in 1921 or 1936 and attending school in Scotland in the month of June in those years. Therefore, tracing, recruiting and re-testing people who had taken part in the Surveys offered a rare opportunity to examine the distribution and causes of cognitive ageing across most of the human life course. The studies described here were initially set up to study determinants of non-pathological cognitive ageing: the ageing of cognitive functions largely in the normal range and not dementia or other pathological cognitive disorders.

Find out more about the studies in ’Cohort profile: The Lothian Birth Cohorts of 1921 and 1936’, published in the International Journal of Epidemiology.

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Dr Michael Mosley and Dr Hannah Fry hosted a special BBC Two Horizon show on intelligence, featuring Professor Ian Deary, Dr Simon Cox and some of our Lothian Birth Cohorts participants as well as former LBC team member, Professor Alan Gow of Heriot Watt University and the radiographers at Edinburgh Imaging.

The show demonstrated a range of tests with volunteers in the studio and presented the results of the Great British Intelligence Test.

The programme showcased the Lothian Birth Cohorts with the project’s unique history and contribution to intelligence research. Professor Deary reviewed the key insights into successful cognitive ageing.

Our neuroscientist, Dr Simon Cox, explained that superior thinking skills are only weakly related to overall brain size, and other aspects, such as the state of the white and grey matters are also important.

The programme reiterated the key LBC findings that healthy cognitive ageing is related positively to regular physical and mental activity but negatively to well-known factors such as diabetes, high blood pressure and smoking.