Agreement between self-reported and device-measured physical activity and sedentary behaviour in older adults with different levels of cognitive function – a multi-methodological approach

In view of the current ageing population, healthy ageing is a hot topic. Physical activity (PA) and sedentary behaviour (SB) are two modifiable lifestyle factors associated with healthy ageing. Much of the evidence on PA and SB is derived from epidemiological studies using PA/SB questionnaires. It is likely that non-pathological and pathological cognitive ageing affects the ability of older adults to complete these questionnaires, introducing bias in the observed association between PA/SB and health outcomes. The aim of my PhD research is to examine if and how the agreement between self-reported and device-measured PA and SB, is related to cognitive function. I will use data from cohort studies in Belgium and Scotland, for the first time, to explore the cross-sectional and longitudinal relationships between detailed cognitive measures of cognitive function and later MCI and dementia diagnosis and agreement. Furthermore, we will develop a core outcome set to measure PA/SB in older adults in a four-stage multimethod study. Together the results of this research will fine-tune the interpretation of the association between PA/SB and health in older adults with different levels of cognitive function.