Moreover, studies also suggest that exposure to violence causes disturbances in the left hemispheric function, hyperadrenergic activity in the central nervous system (CNS), stimulation of the serotonergic receptors signaling in the CNS, increase in the corticotrophin-releasing factor in the cerebrospinal fluid, and signaling of the dynorphin/κ opioid receptor in the brain, which all may increase the risk of PTSD [64,65]. This evidence concerns the gene PDYN and post-traumatic stress disorder.