CHRNA7 and major depressive disorder: For example, clinical studies suggest that abnormalities in cholinergic signaling are associated with major depressive disorder, whereas nonclinical studies have implicated both β2 subunit-containing (β2) and α7 nAChRs in anxiety- and depression-like behaviors (Perera et al., 2007; Mineur et al., 2013; Yu et al., 2014; Mineur et al., 2016).