Comparison of the associations between Life's Essential 8 and Life's Simple 7 with depression, as well as the mediating role of oxidative stress factors and inflammation: NHANES 2005–2018

Cardiovascular health (CVH) is closely associated with depression. However, Life's Essential 8 (LE8), a novel CVH measure, has not yet been clearly linked to depression. This study aims to explore the association between LE8 and depression, compare its advantages over Life's Simple 7 (LS7), and investigate the mediating effects of oxidative stress and inflammation. This study investigated cross-sectional data of adults aged 20 and above from National Health and Nutrition Examination Survey (NHANES) 2005 to 2018. The LE8 score (ranging from 0 to 100) was derived from the American Heart Association's definition, based on the unweighted average of 8 metrics, classified as low cardiovascular health (CVH) (0–49), moderate CVH (50–79), and high CVH (80–100). Similar to LE8, LS7 scores were categorized into inadequate (0–7), average (8–10), or optimal (11–14) after calculating the unweighted mean of each component. Depression was diagnosed using the Patient Health Questionnaire (PHQ-9), with a score of ≥10 defining depression. Adjusted for sociodemographic factors and other risk factors for depression, weighted logistic regression and restricted cubic spline analysis were used to explore the correlation. Receiver operating characteristic (ROC) curves were used to study the associations between CVH scores and depression. Subsequently, subgroup analysis and sensitivity analysis were conducted, followed by an exploration of the mechanisms involved. A total of 7 cycles from 2005 to 2018 contained complete data. Weighted logistic regression showed that both LS7 and LE8 were significantly associated with depression. Specifically, for LE8, after adjustment, the risk of depression decreased by 52 % for moderate CVH compared to low CVH (OR: 0.48, 95 % CI: 0.41–0.57, P < 0.0001), while the risk decreased by 80 % for high CVH (OR: 0.20, 95 % CI: 0.15–0.26, P < 0.0001, Ptrend < 0.0001). For LS7, after adjustment, compared with inadequate CVH, the risk of depression decreased by 49 % for average CVH (OR: 0.51, 95 % CI: 0.34–0.78, P = 0.002), and by 55 % for optimal CVH (OR: 0.45, 95 % CI: 0.27–0.74, P = 0.002, Ptrend < 0.0001). Area under ROC curves for predicting depression were 0.672 (95 % CI, 0.66–0.684; P < 0.001) and 0.605 (95 % CI, 0.59–0.619; P < 0.001) for LE8 and LS7 (PDeLong < 0.001), respectively. Sensitivity analysis demonstrated the robustness of the association. GGT and WBC jointly mediated 9.62 % of this association (all P < 0.001). The cross-sectional study cannot infer causality. The association between Life's Essential 8 and depression was stronger and more practical. Oxidative stress and inflammation mediate this association. Individuals with extremely poor cardiovascular health have a 7-fold increased risk of depression, highlighting the necessity of maintaining at least moderate cardiovascular health.