Abstract
INTRODUCTION: Psychotic depression (PD) is characterized by the co-occurrence of emotional dysfunction and psychotic symptoms such as delusions and hallucinations with poor clinical outcomes. TSH may involve in the development of PD. This study aims to explore relationship between TSH and PD. METHODS: A total of 1718 outpatients diagnosed as FEDN MDD were recruited in this study. The relationship between PD and TSH was evaluated using multivariable binary logistic regression analysis. To assess the presence of non-linear associations, a two-piecewise linear regression model was employed. Furthermore, interaction and stratified analyses were conducted with respect to sex, education, marital status, comorbid anxiety, and suicide attempt. RESULTS: Multivariable logistic regression analysis revealed that TSH was positively associated with the risk of PD after adjusting for confounders (OR = 1.26, 95% CI: 1.11 to 1.43; p < 0.05). Smoothing plots showed a nonlinear relationship between TSH and PD, with the inflection point of TSH being 4.94 mIU/L. On the right of the inflection point, for each unit increase in serum TSH level on the right side of the inflection point, the probability of PD increased substantially by 47% (OR = 1.47, 95% CI: 1.25 to 1.73, p < 0.001), while no significant association was observed on the left side of the inflection point (OR = 0.87, 95% CI: 0.67 to 1.14, p = 0.32). CONCLUSION: Our investigation showed a nonlinear TSH-PD relationship in FEDN MDD patients, thus contributing to effective intervention strategies for psychotic symptoms in depression patients.