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

Abstract 

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.

Keywords: Cholesterols, Lipid peroxidation, Antioxidants, Psychological stress, Depressive symptoms