BDNF and Behcet disease: Most studies [44,56,57,58,59,60] have investigated BDNF serum levels during a depressive episode, while Tramontina et al. (2009) [40], Machado-Vieira et al. (2007) [61], and Oliveira et al. (2009) [59] have included BD patients in a manic phase; only Piccinni et al. (2014) [60] have included 19 mixed state patients, while Tunca et al. (2014) [62] and Yoshimura et al. (2006) [63] included both manic and depressive episodes.