Limitation of pro- and anti-inflammatory cytokine analysis to discriminate biological stress effects in patients suffering from chronic psychological distress

Background: Research endeavors aiming to evaluate the effect of prolonged psychological distress on the immune system have been pursed over the past decades. Due to the complexity of the two systems involved, the mental and immune status, a large number of questions still remains to be addressed. Aim: In the present study, we aimed to test if chronic distress is associated with pro- and anti-inflammatory cytokine levels in a well-defined study cohort. Methods: We recruited 42 inpatients suffering from post-traumatic embitterment disorder (PTED), a condition that has been demonstrated to cause intense and persistent psychological distress. Study participants completed established questionnaires to evaluate stress perception, depression and quality of life before and after psychotherapy, aiming to improve stress coping. Venous blood samples to detect serum levels of pro-and anti-inflammatory cytokines [interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma] were obtained pre- and post-treatment. Results: The psychological assessments showed an increase of quality of life, a decrease of perceived stress and depressive symptoms, between the two groups. These findings are not associated with significant alterations of the cytokine levels before and after treatment. Conclusions: In our study, the psychological treatment of inpatients suffering from chronic psychological distress does not result in changes in cytokine levels. Further research with a broader analysis of immune markers and enhanced detection methods may be required to unveil psycho-immunological association in PTED patients.