BDNF and depressive disorder: Training-induced increase in BDNF levels improves cognitive function (Best et al., 2015; Hákansson et al., 2017; Nilsson et al., 2020) and mood (Rethorst et al., 2009) in healthy people and people with cognitive impairment (Nascimento et al., 2015) and depression (Schuch et al., 2016; Kering et al., 2017).