Objective: To investigate how body fat mass, an established source of endogenous estrogen after menopause, influences cognitive impairment in elderly women.
Research methods and procedures: Study participants were 5607 generally healthy postmenopausal women with mean age of 63.8 years at baseline followed for an average of 7.3 years. Cognitive function assessed at follow-up using the short Blessed test was related to baseline body weight, the yearly change in weight, and follow-up measures of body fat depots assessed by DXA. Cognitive function was also related to various surrogates of lifetime estrogen exposure.
Results: Women with the worst cognitive performance (score >or= 9) at follow-up were the ones who lost the most body weight and revealed the lowest central fat mass (CFM). The association of weight loss with worse cognitive performance was apparent across all age groups except for those more than 80 years old. In the multivariate logistic model, the risk of cognitive impairment was 18% lower in women in the second quartile of CFM (p = 0.14), 32% lower in the third (p = 0.01), and 48% lower in the fourth (p < 0.001) compared with those in the first quartile. CFM showed significant correlation with the simultaneously measured serum estradiol (r = 0.25; p < 0.001). Cognitive score showed an inverse linear relationship with the duration of reproductive period and bone mineral density assessed at follow-up.
Discussion: These findings argue for a protective association of body fat mass with cognitive impairment in elderly women. This association seems to involve a more prominent exposure to endogenous estrogens.