BDNF and major depressive disorder: Moreover, the 5-HTTLPR ss and the BDNF Met–Met genotypes, both of which had been implicated in major depressive disorder, were also associated with the presence of depression two weeks following stroke (Kim et al., 2012a) as well as with poor prognostic outcomes and worsened physical disability and cognitive functions two weeks and one year after stroke (Kim et al., 2012c).