A return to work program improves parasympathetic activity and psychiatric symptoms in workers on sick leave due to depression

People with depression have autonomic function disturbances. In Japan, workers who take leave due to depression often undergo a work-focused intervention program called the return to work (RTW) program at a mental health hospital during their leave of absence. However, its biological efficacy remains unclear. We investigated the biological efficacy of the RTW program, including changes in autonomic nervous system (ANS) activity, in workers on sick leave due to depression in Japan. The study involved 104 workers on sick leave due to major depressive disorder or bipolar disorder who underwent the RTW program for 3 months in Yokohama City University Hospital. The ANS activity of all patients was evaluated using heart rate variability at the beginning and end of the 3-month RTW program. Psychiatric symptoms were evaluated using the Montgomery-Åsberg Depression Rating Scale-Japanese (MADRS-J) and Social Adaptation Self-evaluation Scale (SASS). We followed up 3 months after the end of the program and investigated the association between the success in returning to work within 3 months after the end of the RTW program and several factors, including ANS activity, depressive symptoms, and demographic factors. Parasympathetic activity was significantly higher and depressive symptom severity was significantly lower at program end than at baseline. Logistic regression analysis showed that the change in depressive symptoms was significantly associated with success in returning to work. We suggest that the RTW program improves parasympathetic activity as well as psychiatric symptoms. ANS activity was not a predictor of a successful return to work within 3 months after the end of the program in workers on sick leave due to depression, but further studies with a larger sample size are needed.