Abstract
OBJECTIVES: The scientific literature supports a link between midlife adiposity and cognitive function or decline but most studies to-date have investigated only overall adiposity, often omitting important confounders from the analyses. We investigated in a cross-time design the relationships between two different midlife adiposity markers and subsequent cognitive function, testing midlife dietary patterns as a potential confounder of the associations. DESIGN: The study was based on the «Supplémentation en Vitamines et Minéraux Antioxydants» randomized trial (SU.VI.MAX, 1994-2002) and the SU.VI.MAX 2 observational follow-up study (2007-2009). SETTING: A general-population cohort in France. PARTICIPANTS: N=2,817 individuals (1,493 men and 1,324 women) included in both the SU.VI.MAX and SU.VI.MAX 2 studies. MEASUREMENTS: The cognitive performance of 2,817 middle-aged adults participating in the SU.VI.MAX (Supplémentation en Vitamines et Minéraux Antioxydant) study was assessed in 2007-2009 using 6 neuropsychological tests. Principal component analysis was used to derive specific cognitive scores. A composite cognitive score was also computed. Body mass index (BMI) and waist circumference (WC) were measured 13 years earlier (1994). Associations between midlife adiposity and cognitive functioning were estimated through covariance analyses. RESULTS: After adjustment for obesity-related cardio-metabolic parameters, higher BMI and larger WC at midlife predicted lower executive function. For example, the adjusted mean difference (95% confidence interval) for 1 SD increase in WC was -0.48 (-0.97, 0.00). Obese participants in midlife showed an adjusted mean difference (95% confidence interval) of -1.68 (-3.15, -0.22) compared with non-obese. Further adjustment for midlife dietary patterns slightly attenuated these associations. No relationships were observed with verbal memory or global cognitive function. CONCLUSION: Midlife overall and abdominal adiposity were similarly associated with lower executive functioning scores. Dietary patterns may partly explain such a relationship, arguing for the importance of controlling for lifestyle confounders in future studies.