Reduced BDNF expression has been implicated in anxiety and depression-like behaviours [41, 52]; therefore, hypermethylation of the Bdnf gene alongside reduced Bdnf mRNA expression in the prefrontal cortex (PFC) of rats exposed to abuse (67) suggests early stress may play a role in the development of anxiety and depression disorders. This evidence concerns the gene BDNF and depressive symptom measurement.