In our study, variables independently associated with history of depression were female gender (O.R. = 2.30; 95% C.I. = 1.02–5.18; p = 0.044), poorly controlled seizures (O.R. = 2.51; 95% C.I. = 1.16–5.41; p = 0.019), and low methylation profile in the promoter region of the BDNF and SLC6A4 genes (O.R. = 5.32; 95% C.I. = 1.14–25.00; p = 0.033). Here, SLC6A4 is linked to major depressive disorder.