Is the serum oxytocin level altered by treatment in rheumatoid arthritis patients complicated with depression?

Objective: The objective of this study was to investigate the factors associated with depression, including serum oxytocin (OXT) levels, disease activity, activities of daily living (ADL), and quality of life (QOL), and their effects on rheumatoid arthritis (RA).

Methods: This study included 42 RA patients who received treatment with a biological agent. We measured the following variables before and after 6 months of treatment: baseline characteristics, including age, sex, disease duration, smoking, and body mass index (BMI); prednisolone and methotrexate dose; serum level of matrix metalloproteinase-3 (MMP-3); erythrocyte sedimentation rate (ESR); and C-reactive protein (CRP) level. The disease activity of RA was assessed using the Simplified Disease Activity Index (SDAI); depression was assessed using the Hamilton Depression Rating Scale (HAM-D); ADL was assessed using the Health Assessment Questionnaire; and QOL was assessed using the Short Form (SF)-36. Serum OXT levels were determined using enzyme-linked immunosorbent assay.

Results: The HAM-D score significantly correlated with the SDAI, and the mental component summary (MCS) score of SF-36. However, the serum OXT levels did not correlate with the HAM-D score. Regression analysis using the HAM-D score as the objective variable identified female sex, smoking, BMI, and all the three component scores of SF-36, but not serum OXT levels, as significant factors. Comparisons between before and after treatment showed that the HAM-D score improved from 5 to 1.5; however, the serum OXT levels did not change.

Conclusion: The variables of female sex, smoking, BMI, and QOL correlated with depression complicated with RA. However, serum OXT levels did not correlate directly.