BDNF and major depressive disorder: Other clinical variables, such as the length of treatment of MDD (ρ = −0.062; p = 0.656), the number of depressive episodes (ρ = 0.059; p = 0.673), the length of the last depressive episode (ρ = −0.132; p = 0.342), the number of hospitalization (ρ = −0.115; p = 0.407), or the number of used antidepressant medications in the therapy (ρ = 0.039; p = 0.781), were also not significantly correlated (Spearman’s coefficient of correlation) with plasma BDNF concentration before BLT.