Post-traumatic stress disorder is a psychiatric illness that can occur in anyone who has experienced a life-threatening or violent event. The trauma can be due to war, terrorism, torture, natural disasters, violence, or rape. In PTSD the brain areas that are likely to be affected are the hippocampus (memory), amygdala (fear association), the prefrontal cortex (cognitive processing), and the ascending reticular activating system (arousal). The chemical of interest is norepinephrine, which is released during a stressful event and is part of the fight-or-flight response meant to mobilize the...