Possible connections among job stress, depressive symptoms, lipid modulation and antioxidants

Background: Oxidative/antioxidative status may be related to psychological stress or pathogenesis of depression. Subjects and methods: Participants were selected from 381 female nurses working in a university hospital, and the Brief Job Stress Questionnaire was utilized to assess them. Nurses with high job stress (JS) (n = 18) and with low JS (n = 15) consented to participate in this study. Depressive symptoms were assessed by the Centre for Epidemiologic Studies Depression scale (CES-D). Cholesterols, lipid peroxidation (malondialdehyde, MDA) and antioxidants in the plasma were measured. Results: High JS participants exhibited significantly higher CES-D scores (t = 3.34, p < 0.005), and significantly lower concentrations of total cholesterol (TC), low density + very low density lipoprotein cholesterols (LDL + VLDL), α-tocopherol, and β-carotene compared with low JS participants (t = 2.69, p < 0.05; t = 3.46, p < 0.005; t = 2.96, p < 0.05; t = 2.98, p < 0.05, respectively). However, the reductions in plasma indicators were substantially weakened after controlling for lifestyle factors with the exception of LDL + VLDL and α-tocopherol. In addition, the significance of α-tocopherol concentrations appeared to depend on cholesterol levels. CES-D scores correlated positively with plasma MDA levels, the MDA / TC ratio and the MDA / LDL + VLDL ratio among the low JS group (r = 0.69, p < 0.001; r = 0.79, p < 0.001; r = 0.75, p < 0.005, respectively), whereas there were no correlations among the high JS group. After controlling for lifestyle covariates, the relationship between CES-D scores and the MDA / LDL + VLDL ratio remained significant (β = 0.95, p < 0.05) using a multiple linear regression model (F = 3.61, p < 0.05). Limitations: Sample numbers in each JS group were relatively small. Conclusions: Psychological stress may reduce the plasma levels of LDL + VLDL accompanying an α-tocopherol decrease. There appeared to be a correlation between elevated MDA and depressive symptoms in low JS participants.