Interactions between age, sex and visceral adipose tissue on brain ageing

Aim: To examine the associations between visceral adipose tissue (VAT) and brain structural measures at midlife and explore how these associations may be affected by age, sex and cardiometabolic factors. Methods: We used abdominal and brain magnetic resonance imaging data from a population-based cohort of people at midlife in the UK Biobank. Regression modelling was applied to study associations of VAT volume with total brain volume (TBV), grey matter volume (GMV), white matter volume, white matter hyperintensity volume (WMHV) and total hippocampal volume (THV), and whether these associations were altered by age, sex or cardiometabolic factors. Results: Complete data were available for 17 377 participants (mean age 63 years, standard deviation = 12, 53% female). Greater VAT was associated with lower TBV, GMV and THV (P <.001). We found an interaction between VAT and sex on TBV (P <.001), such that the negative association of VAT with TBV was greater in men (β = −2.89, 95% confidence interval [CI] −2.32 to −10.15) than in women (β = −1.32, 95% CI −0.49 to −3.14), with similar findings for GMV. We also found an interaction between VAT and age (but not sex) on WMHV (P <.001). The addition of other cardiometabolic factors or measures of physical activity resulted in little change to the models. Conclusions: VAT volume is associated with poorer brain health in midlife and this relationship is greatest in men and those at younger ages.