Waist circumference as a mediator in the association between sarcopenia and cognitive function

Background There is a synergistic effect between sarcopenia and obesity, and they are important factors affecting cognitive function. It's essential to explore the complex relationship among the three. Objective To explore the mediating effect of waist circumference in the relationship between sarcopenia and cognitive function. Methods A total of 5577 participants aged 60 years and older from CHARLS (China Health and Retirement Longitudinal Study) were included. Cognitive function was assessed via episodic memory and mental integrity. Sarcopenia status was diagnosed according to the criteria of the AWGS 2019. General linear regression models were applied to investigate the association between WC, sarcopenia, their combined effects and cognitive function. Mediation analysis was used to access the mediating effect of WC in the relationship between sarcopenia and cognitive function. The nonlinear association between WC and cognitive function was explored by using the restricted cubic spline model. Results Among 5577 participants, the average cognitive score was 12.41. After controlling for confounding factors, participants with central obesity and severe sarcopenia had the worst cognitive scores (β = −3.22, 95%CI = −4.81, −1.61). WC mediated 16.95% of the association between sarcopenia and cognitive scores, and 9.26% of the association between severe sarcopenia and cognitive scores. The strongest positive association was found between WC and cognitive scores when WC was 96.74 cm in men. Conclusions Central obesity was associated with better cognitive function. However, central obesity accompanied by sarcopenia or severe sarcopenia was associated with lower cognitive function. There were significant differences in the mediating effect of WC between different sarcopenia status and cognitive function.