BDNF and diabetes mellitus: Also, a study by Chagnon et al., 2015 on 19 women with MDD and anxiety disorder and 24 healthy controls revealed a higher DNA methylation in the BDNF gene among MDD/anxiety subjects as compared to healthy controls (mean ± SD: 2.92 ± 0.74 vs. 2.34 ± 0.42; p = 0.0026) [50], and finally, the change in the BDNF level was due to the effect of other environmental factors such as nutritional status [51–53], presence of co-morbidity such as diabetes mellitus [54], or due to the level of physical activity [55,56].