Association between serum apolipoprotein B and depression: A cross-sectional and Mendelian randomization analysis study

Background: Depression is a pervasive mental illness that has a significant impact on public health globally. This study aimed to identify risk factors for depression and elucidate their causal relationships. Methods: Using data from the National Health and Nutrition Examination Survey (NHANES) and Genome-Wide Association Studies (GWAS). Serum ApoB was log-transformed and further divided into 4 groups. Multifactorial logistic regression analysis was used to assess the relationship between serum ApoB and depression. Subgroup analyses and interaction tests were used to observe the stability of the association between them. Smooth curve fitting was used to investigate nonlinear correlations. The causal effect of serum ApoB on depression was assessed using Mendelian randomization (MR) analysis. Results: A total of 6531 participated in the study. After adjusting for all covariates, serum ApoB levels were positively associated with depression after adjustment for all covariates (OR = 1.40, 95 % CI = 1.06-1.84; P = 0.0176). Unfortunately, there was no significant causal relationship between serum ApoB and depression (OR = 0.9985,95 % CI = 0.9962-1.0008; P = 0.1923). Sensitivity analysis verified the reliability of the results. Conclusions: Serum ApoB was positively associated with an increased risk of depression, but MR analysis did not show a genetic causal relationship between ApoB and depression. Based on the results of the current study, no indication maintaining high levels of ApoB contributes to the management of depression. Limitations: The main limitation of this study is the inconsistency of the cross-sectional study and the MR population.