BDNF and major depressive disorder: Conversely, interleukin-10 (IL-10) (OR = 0.62, 95% CI: 0.46–0.83) and brain-derived neurotrophic factor (BDNF) (OR = 0.12, 95% CI: 0.05–0.29) were found to be protective factors, indicating that both anti-inflammatory signaling and neurotrophic support play critical roles in reducing the risk of depression.