The correlation between lifestyle, social and mental activities, and increased brain function in older age is well established. So too is the ‘cognitive reserve’ hypothesis which suggests that educational experiences have an enhancement mechanism on cognitive decline and brain pathology in old age. This study proposes to conduct multiple individual analyses to investigate associations between lifestyle activities, physical fitness, social engagement, biomedical measures, mental health on the longitudinal outcome of later life cognition in the population cohort, ELSA. The aim of this study is to gain a clearer understanding of the predictors of ‘successful’ cognitive ageing and cognitive decline using an existing population cohort with a wide range of variables across multiple categories and which includes multiple longitudinal waves of data. The team of researchers working on this project contribute a range of expertise including advanced mathematical and statistical modelling, and cognitive neuropsychology with specific experience in cognitive ageing.