BDNF and psychotic disorder: However, advances in the investigation of the neural basis of CT in early psychosis have focused on brain regions and neurochemical substrates implicated in the regulation of the HPA axis and, hence, emotional reactivity, suggesting that a history of CT is linked to aberrant cortisol levels, lower Brain Derived Neurotrophic Factor (BDNF), higher interleukin-6 (IL-6) levels, and lower amygdala and/or hippocampus volume [16].