Non-Alcoholic Fatty Liver Disease and Its Association with Depression in Korean General Population

Background: Recent studies have indicated the significant association between non-alcoholic fatty liver disease (NAFLD) and depression. However, there is ongoing debate on whether the risk for depression is actually related with the presence and severity of NAFLD. Thus, this study was conducted to investigate the association between depression and NAFLD evaluated by diverse modalities. Methods: A total of 112,797 participants from the Korean general population were enrolled. The study participants were categorized into three groups according to degree of NAFLD evaluated by ultrasonography, fatty liver index (FLI) and fibrosis-4 score (FIB-4). Depression was defined as a score of Center for Epidemiological Studies-Depression (CES-D) >= 16, and the odd ratios (ORs) and 95% confidence interval (CI) for depression (adjusted ORs [95% CI]) were assessed by multiple logistic regression analyses. Results: In the unadjusted model, the presence and severity of NAFLD was not significantly associated with depressive symptoms. However, in the fully adjusted model, ORs for depression increased in proportion to the degree of ultrasonographically detected NAFLD (mild fatty liver: 1.14 [1.06-1.22]; and moderate to severe fatty liver: 1.32 [1.17-1.48]). An association was also observed between depression and FLI (30 <= FLI < 60: 1.06 [0.98-1.15]; FLI >= 60: 1.15 [1.02-1.29]). Conclusion: The presence and severity of NAFLD is significantly associated with depressive symptoms. In addition, this association was more distinct after adjusting for covariates including age, gender and insulin resistance. This finding indicates the necessity of further study evaluating the incidental relationship of depression with NAFLD.