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.

Automated summary

This study examines the association between adiposity and incident dementia in older adults. It finds that higher total and regional fat mass are associated with a decreased risk of dementia. The protective effect of gynoid fat in women is particularly significant. These findings may be explained by reverse causality, but the possibility of a protective effect of adiposity cannot be ruled out.