Associations between longitudinal changes in weight, cognitive abilities, and dementia risk

Anna Dahl, filosofie doktor i gerontologi.

More than 60% of the European adult population is overweight or obese, including persons aged 65 and above. Present cohorts of older adults are heavier and have been heavier over a longer period of time than previous cohorts. It is alarming since overweight is associated with chronic health conditions, functional limitations, and mortality. An increasing body of evidence shows the adverse effect of being overweight also extends to brain functioning. Being overweight in midlife has been associated with an increased risk of both cognitive decline (independent of dementia), and dementia. However, the association is not clear cut, in late life is overweight both associated with better and worse cognitive abilities, and with an increased or decreased risk of dementia. So far, most research has focused on current weight in relation to late life brain health. But current weight is only a snapshot. It does not tell the story of past weight and changes in weight. This might be especially ill-timed in late life, as there is a selection bias for people who have survived until old age, and diseases common in late life might cause weight changes. Hence, I propose that the implications of overweight on late life brain health only can be understood from a life course perspective. Existing population-based studies that originate from the Swedish Twin Registries, SATSA, OCTO-Twin, and Gender, containing data ranging over fifty years and including 2061 persons, will be used to study the association between weight trajectories over the life span to cognitive abilities and dementia in late life. Causal pathways between overweight and brain health in late life will be elucidated by adding genes and life style factors into the models. A special focus will be given to those persons who gain and lose weight several times over the life span, i.e. weight cyclers. This proposed project gives a unique opportunity to achieve a holistic view on weight and brain health over the life span and it is hypothesize that weight trajectories will be an important indication of brain
health in late life both in clinical practice and in research.

This project is funded by the Swedish Council of Working Life and Social Research (FAS, 2010-0704) and is a co-operation between the Institute of Gerontology, School of Health and Welfare in Jönköping and the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet.