Subjects with a mild or moderate depression (BDI II ≥ 9 points) have higher NF-L titers (r = 0.519; n = 3; mean: 10.72; 95%-CI [-0.84;22.28]) compared to subjects with no depression (BDI II < 9 points; n = 12; mean: 7.89; 95%-CI [6.39;9.38]). This evidence concerns the gene NEFL and major depressive disorder.