Systemic inflammation mediated the association between body roundness index and depression among adults: a nationwide...

Depression is a major public health issue worldwide. We aimed to investigate the relationship between a novel abdominal obesity index (Body Roundness Index, BRI) and depression, and the potential mediating role of the systemic immune inflammatory index (SII) in this relationship.

This study used data from the National Health and Nutrition Examination Survey (NHANES, 2005-2018) in the US, and enrolled 32,616 participants. Assessment data included adult BRI, depression, and SII. Multivariate logistic regression, Spearman correlation, mediation analysis, and sensitivity analysis were performed.

Among all participants, 16,397 (50.3 %) were female, with a median age (IQR) of 47 [31,63]. Among them, 2724 (8.4 %) subjects reported depressive symptoms. Compared with the non-depressed group, the depressed group showed higher BRI levels and higher SII levels (all P < 0.001). In the fully adjusted model, we observed a positive association between BRI and depression (OR = 1.17, 95 % CI = 1.11-1.24), and positive association between SII (OR = 1.07, 95 % CI = 1.02-1.13) and depression. In addition, SII can partially mediate the effect of BRI on adult depression, and the mediating effect accounts for 2.55 % of the total effect, which were validated in males, aged <60 years, non-White population or different educational groups.

Systemic inflammation can partially mediate the relationship between abdominal obesity and depression. These findings contribute to understanding potential associations and pathways of depressive symptoms in adults and shed light for early and precise prevention strategies.