Fat, estradiol and cognitive health

Visceral adipose tissue (VAT) and estradiol seem to have conflicting roles in regard to healthy brain aging but whether they interactive to alter brain network structure is unclear. In a study in JAMA Network Open, German researchers investigated whether VAT moderates the association between age and brain network structure and looked at whether estradiol moderates the association between VAT and brain network structure. 

The cross-sectional study included 974 cognitively healthy German adults from the Health Study of the Leipzig Research Centre for Civilization Diseases (LIFE). Magnetic resonance imaging (MRI) was used to acquire data on the brains and abdomens of the participants. A 10-word verbal episodic memory test was also given to the participants and the researchers calculated a composite score based on learning, recall, and recognition. Finally, serum estradiol levels from fasting blood were also assessed. 

Two moderation analyses were performed; one analysis used VAT as the moderator variable between age and brain network structure and the other analysis used estradiol as the moderator variable between VAT and brain network structure. The study was conducted from August 1, 2011 to November 23, 2014 and the analyses were conducted from August 2017 to September 2018.

The mean age of women (n=473) in the study was 50.10 (SD=15.63) years (age range 20-78 years) and of men (n=501) was 51.24 (SD=15.67) years (age range 19-79 years). 

The authors found that VAT was associated with exacerbation of the negative association of aging with network covariance in both women (interaction term ß = -0.02; 95% bias-corrected bootstrap CI -0.03 to -0.01, P= .001) and men (interaction term ß = -0.02; 95% bias-corrected bootstrap CI -0.03 to -0.01, P< .001). They also found that estradiol level was associated with a reduction in the negative association of VAT with network covariance in women (interaction term ß = 0.63; 95% bias-corrected bootstrap CI 0.14 to 1.12, P= .001). However, this association was not significant in men. 

When the authors examined women aged 35  to 55, low estradiol levels were associated with lower memory network covariance (Cohen d= 0.61; t₈₀= 2.76; P= .007) as well as worse memory performance (Cohen d= 0.63; t₇₆= 2.76; P= .007).

The authors noted that VAT was associated with an increased risk for compromised brain network structure and cognitive impairment in both men and women; however, estradiol was only associated with reducing the negative impact of VAT in women. The study also indicated that women had the highest VAT:age ratio in midlife. These results indicate that ob/gyns need to consider adipose tissue and hormonal profiles during primary care visits from midlife women in order to support healthy cognitive aging.