Understanding the Root Causes of Aggression
Even when most people call trauma to the event or circumstances someone goes through, trauma is really what results from those experiences. Traumatization involves not only experiencing scary and shocking events, but also how we respond to them, how long we remain in a state of fear or shock, and the type of mental/psychological relationship we establish with the experience. If we continue to feel afraid and threatened, our nervous system has no option but to adapt by developing survival strategies.
For our nervous system, trauma is about confronting the risk of dying. If the brain perceives that you are in danger, it will activate survival strategies to help you overcome the risk or threat. One of these strategies is the well-known "fight" response, which prepares the whole body to be ready to annihilate the enemy and “stay alive.” Too much activation of that strategy modifies our perception to assume that everyone could be dangerous. A person that grows up in an environment where they are constantly threatened or abused, easily develop the belief that the world is a dangerous place and that they must always be on guard to protect themselves. This can lead to a hyper-vigilant and aggressive stance toward others.
That's why some traumatized people become aggressive or even violent, as their primary survival strategy is to fight the aggressor, even if there is no aggressor. Their nervous system becomes habituated to work on hyper-alert and with hyper-activation of the sympathetic nervous system, which becomes their "baseline". They find enemies even in their dreams, and one of the characteristics of this state is to use anger, which becomes the habitual emotion that "protects" them.
Moreover, this state and the angry responses that it generates receive aggression and angry responses in return, the brain receives the confirmation that everyone is dangerous. This reinforces the system's attempt to eliminate enemies and creates a vicious circle that does not end unless the person receives treatment which helps them becoming aware of how their system is making their life extremely difficult. Then, the work is to dissolve the habit, recover objectivity, diminish or eliminate the hyper-alertness, and find the way to feel safe without aggression.