Irisin, Brain-Derived Neurotrophic Factor (BDNF), and Redox Balance in Geriatric Dynapenia

Irisin and brain-derived neurotrophic factor (BDNF) are considered potential biomarkers for sarcopenia; however, their interplay and relationship with oxidative stress remain unclear. Therefore, the aim of this study was to assess the serum concentration of irisin and BDNF in patients over 60 years of age, as well as their relationship with dynapenia and redox homeostasis. Dynapenia was diagnosed using the Five Times Sit-to-Stand Test (5TSST). Serum levels of irisin, BDNF, total oxidative status (TOS), and total antioxidative status (TAS) were measured, and the oxidative stress index (OSI) was calculated. A total of 110 patients from a geriatric ward (72.7% women, mean age 78.2 ± 7.1 years) participated in the study. BDNF concentration was negatively associated with dynapenia, irisin, and the irisin/BDNF ratio. TOS, TAS, and OSI were negatively associated with BDNF and positively associated with irisin and dynapenia. No significant association was found between irisin and sarcopenia parameters. In regression analysis, significantly higher odds of dynapenia were observed for older age, female sex, a greater number of chronic diseases, and higher OSI values, after adjusting for TOS, BDNF, and the irisin-to-BDNF ratio. These results confirm redox imbalance as an independent predictor of sarcopenia. A lower BDNF concentration and a higher irisin-to-BDNF ratio may indicate a protective role of BDNF in the development of sarcopenia in geriatric patients; however, this finding requires further confirmation.