Association between thyroid function and psychotic symptoms in adolescents with major depressive disorder: A large sample sized cross-sectional study in China.

Backgrounds: Thyroid function was associated with depression and psychotic symptoms; however, little research has focused on its role in coexisting psychotic symptoms in adolescents with depressive disorder. This study aimed to explore the association between thyroid function and psychotic symptoms among depression adolescents. Methods: A total of 679 adolescent patients (aged 12-18) diagnosed as depressive disorder were recruited. Their socio-demographic, clinical data and thyroid function parameters were collected. The severity of psychotic symptoms was measured according to the assessment measure in DSM-5. Based on the severity of psychotic symptoms, patients were distributed into psychotic depression (PD) and non-psychotic depression (NPD) subgroups, respectively. Results: The prevalence rate of PD was 52.7% among adolescents with depressive disorder in this study. PD patients were younger (p < 0.01), with more female (p < 0.001) and non-Han nationality (p < 0.01), and presented serum FT4 level decrease (p < 0.01). PD patients displayed a higher rate of abnormal thyroid relevant parameters (p < 0.05). 35.2% of PD patients presented at least one abnormal parameter among all five parameters tested (TSH, TT3, FT3, TT4, and FT4), compared to 27.4% among NPD patients. Further logistic regression analysis indicated that increased serum FT4 level was a protective effect of PD with an adjusted odds ratio (OR) of 0.615. We did not find a statistically significant difference in the family history of mental disorders, serum TSH, TT3, FT3, and TT4 levels. Conclusions: Our results suggested a high prevalence of PD among depression adolescents, associated with younger age, female, non-Han nationality, and decreased serum FT4 level. We recommend that adolescents with depressive disorder regularly screen their serum FT4 levels for better clinical outcomes.