BDNF and major depressive disorder: Bonferroni post hoc tests revealed a significant reduction in BDNF mRNA levels in individuals with schizophrenia (P=0.004; 15% reduction) compared with controls in layer V and a reduction in BPD (P=0.001; 18% reduction), schizophrenia (P=0.0002; 20% reduction) and MDD (P=0.01; 14% reduction) compared with controls in layer VI (Figure 3b).