CALB1 and major depressive disorder: This is supported by studies showing reduced volumes of prefrontal cortex and hippocampus (MacQueen et al. 2008; Savitz and Drevets 2009) and decreased cortical densities of calbindin- and somatostatin-positive GABAergic interneurons in MDD patients (Rajkowska et al. 2007; Sibille et al. 2011; Luscher and Fuchs 2015).