Association between lipid parameters and severity of depressive symptoms in patients with first-diagnosed drug-free major depressive disorder

Abstract

Abstract Objective The association between lipid biomarkers and the severity of depressive symptoms remains uncertain in patients with major depressive disorder (MDD), as previous findings have been debatable. The objective of this research was to examine the correlation between lipid parameters and the severity of depressive symptoms in patients with first-diagnosed drug-free (FDDF) MDD in Chinese. Methods From 2016 to 2018, a total of 1718 individuals diagnosed with FDDF MDD were recruited. Detailed sociodemographic details and anthropometric measurements were gathered from each patient. An assessment of anxiety and depressive symptoms was conducted using the Hamilton Anxiety Scale (HAMA) and the 17-item Hamilton Rating Scale for Depression (HAMD-17), respectively. Furthermore, thyroxine hormones, fasting blood glucose (FBG) levels, and lipid profiles were ascertained using blood samples taken by a trained clinician. Univariate and multivariate linear regression analyses were then employed to ascertain if there was an association between patient lipid profiles and depressive symptom severity. Additionally, a two-segmental linear regression analysis was used to investigate threshold effects. Results Subsequent to adjusting for covariates, multivariate linear regression analysis unequivocally demonstrated a positive correlation between total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-c), but not high-density lipoprotein cholesterol (HDL-c), and the manifestation of depressive symptoms in patients with FDDF MDD. Intriguingly, the relationship between TC, TG, LDL-c, and depressive symptoms exhibited a non-linear pattern. By employing a two-segmental linear regression model, distinct inflection points at 6.17 mmol/l for TC, 1.80 mmol/l for TG, and 4.12 mmol/l for LDL-c were unveiled. At values higher than each inflection point, we observed a positive association between TC, TG, LDL-c, and depressive symptoms (all P < 0.05). However, this relationship between lipids and depressive symptoms appears to plateau at values higher than each inflection point (all P > 0.05). Notably, the correlation between HDL-c and depressive symptoms, on the other hand, appeared to exhibit a "U"-shaped pattern, where 1.10 mmol/l was found to be optimal. Conclusion Our investigation shed light on the intricacies regarding the association between lipid markers (TC, TG, LDL-c, and HDL-c) and the severity of depressive symptoms in patients with FDDF MDD, thereby offering valuable insights into the underlying mechanisms involved.