Adiposity in the older population and the risk of dementia: The Rotterdam Study

IntroductionWe determined associations of total and regional adiposity with incident dementia among older adults. MethodsWithin the population-based Rotterdam Study, adiposity was measured as total, android, and gynoid fat mass using dual-energy X-ray absorptiometry in 3408 men and 4563 women, every 3 to 6 years between 2002 and 2016. Incident dementia was recorded until 2020. ResultsHigher adiposity measures were associated with a decreased risk of dementia in both sexes. After excluding the first 5 years of follow-up, only the association of gynoid fat among women remained significant (hazard ratio 0.85 [95% confidence interval 0.75-0.97] per standard deviation increase). No major differences in trajectories of adiposity measures were observed between dementia cases and dementia-free controls. DiscussionHigher total and regional fat mass related to a decreased risk of dementia. These results may be explained by reverse causality, although a protective effect of adiposity cannot be excluded. HighlightsTotal and regional adiposity were assessed using dual-energy X-ray absorptiometry scans in 7971 older adults.All adiposity measures were associated with a decreased risk of dementia.The results suggest a beneficial effect of gynoid fat on the risk of dementia in women.Reverse causation and competing risk may explain these inverse associations.