DOI: 10.25549/usctheses-c40-309645
title: Relationship of body mass and body mass index (BMI) to cognitive change in the BVAIT, WISH, and ELITE clinical trials

description: Background: The B Vitamin Atherosclerosis Intervention Trial (BVAIT), Women’s Isoflavone Soy Health (WISH) trial, and Early Versus Late Intervention Trial with Estradiol (ELITE) are three randomized clinical trials, which were all conducted at the Atherosclerosis Research Unit of the University of Southern California. Using data from these three random trials, we conducted this post-clinical-trial analysis, evaluating the association of body mass and body mass index (BMI) with cognitive change. ❧ Methods: Cognitive function (global cognition, verbal memory, visual memory, and executive function) of 1330 participants (1054 women, 276 men) in total was measured at the baseline and at the end of 2.5 years. Cognitive change was computed as cognitive score at end point minus cognitive score at baseline. Body weight and height were measured at baseline visit. BMI was calculated as: weight (kg) / height (m²). Data were analyzed using multivariate linear regression, stratified by gender or apolipoprotein E (ApoE) ε4 isoform carrier status, where applicable, and adjusted for baseline cognition function (only in cognitive change models), trials, age, and other demographic variables. Regression models were built separately for two independent variables (body mass and BMI), two dependent outcomes (baseline cognition function and cognitive change). Each dependent cognitive outcome was categorized into global cognition and the other three cognitive subareas. ❧ Results: Overall, global cognitive function, verbal memory, and visual memory significantly increased over 2.5 years of follow-up (p &lt; 0.001). By contrast, executive function significantly declined (p &lt; 0.05). Weight was significantly negatively associated with baseline verbal memory (p = 0.047). After stratifying by ApoE-ε4 carrier status, weight was negatively associated with baseline verbal memory in ApoE-ε4 non-carriers (p = 0.018), but not in carriers (p = 1.00). Weight was positively associated with baseline visual memory in ApoE-ε4 carriers (p = 0.029), but this association was not evident in non-carriers (p = 0.56). In the total sample population, weight was significantly positively associated with global cognitive change (p = 0.036) and verbal memory change (p = 0.019). After stratifying by gender, weight was positively related to global cognitive change (p = 0.019) and verbal memory (p &lt; 0.001) in men only, not in women (p = 0.10, 0.15, respectively). Visual memory and executive function change were not related to weight in the total sample (p = 0.57, 0.68, respectively), in men (p = 0.53, 0.89, respectively), or in women (p = 0.16, 0.32, respectively). BMI was not associated with any baseline cognition function or cognitive change, after adjustment for age, baseline cognition function (in cognitive change models), trials, and additional demographic variables. ❧ Conclusion: Weight was positively associated with cognitive change. The association was in males only, but not evident in females; No significant relation was found on BMI to baseline cognition function or cognitive change. The finding in BMI is not consistent with previous study, which demonstrated the relation between higher BMI and cognitive decline. Future analysis could be conducted on weight change and cognitive change in order to clearly understand the association between body weight and cognitive change, and its mechanism.