To understand what causes PTSD we need to understand PTSD and the Brain. As humans, we are born with built-in alarms systems to alert us to danger so we can either “fight or flee.” That alarm system, which is commonly called the “limbic system” or the “arousal system”, is vital to our survival.
When activated by stress, the alarm system prepares you to fight off an attack or to flee (escape), which means your heart rate and breathing rate increase, muscles tense, adrenaline rushes, etc. Our alarm system does not know time or location; it only recognizes danger and the feeling of threat. It simply fires up and keeps you in an aroused state so that you can be prepared in the face of perceived or imminent threat.
When the danger is over, the alarm system is supposed to shut down, allowing the body to relax and return to normal. However, traumatic events can impair the functioning of the alarm system so that you cannot tell when the danger is over and your alarm system does not shut down properly. You continue to feel as if the danger is ever present, which promotes a state of chronic hyper-arousal.
When you were deployed, your alarm system was constantly on, alerting you to the fact that you were always in a state of danger. It over generalizes so that it does not miss any threats to your survival.
But here is where this treatment focus begins. Your alarm system worked perfectly well when you were deployed because you actually were in danger all the time, and needed to be alert all the time. But now that you are home, your alarm system has stayed on even when there is no actual threat of danger.
PTSD and the Brain
Two brain structures that play an important role in PTSD are the amygdala and the hippocampus.
The amygdala activates the body’s alarm system (the fight or flight response). When the brain perceives a threat, the amygdala becomes active and sends messages to the rest of the body to prepare for danger. The amygdala also processed emotional memories.
The hippocampus is responsible for processing information about your life and experiences and storing it away in long term memory for later use. Under normal circumstances, these regions communicate with one another and with the rest of the brain in a smooth fashion.
However, traumatic stress disrupts the communication between these different areas. The logical, rational parts of your brain cannot get the message through to the amygdala that the danger is over and it’s okay to relax.
The hippocampus cannot take the emotional information processed by the amygdala and store it away as a long term memory. So your memories of trauma stay with you all the time and you continue to feel as if you are in constant danger.
The prefrontal cortex is the part of our brain that allows us to think, plan and make decisions.