BDNF and depressive disorder: In our study, we observed the serum BDNF levels in depressed patients to be 4.08±2.48 ng/ml, which were significantly lower than those in the control group (5.42±2.14 ng/ml, p†<0.01) which align with prior research done by Karege et al. [19] who reported a negative correlation between BDNF levels and depression severity.