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Exposure to trauma does not necessarily guarantee that someone will develop Post-Traumatic Stress Disorder (PTSD), but experiencing a traumatic event does initiate the stress response in the brain.  Repeated exposure to trauma increases the effects on the brain and body.


The Biological Basis of PTSD


Evidence suggests that there are a number of physiological differences found in individuals with PTSD compared with individuals without the disorder. The autonomic nervous system of individuals with PTSD has been found to be more reactive. Biological differences show up in several body systems, including endocrinal (hormonal) systems and the nervous system (e.g., the brain).


There are clear hormonal differences that have been found, including abnormalities in the levels of stress hormones such as cortisol, epinephrine, and norepinephrine. These hormones are responsible for preparing our response to threat. These hormonal abnormalities are thought to explain why individuals with PTSD are kept in a constant heightened state of readiness for threat despite not encountering actual danger.


Brain differences have also been found in those suffering from PTSD. These include a smaller sized hippocampus, a brain structure responsible for processing memories and learning; an over reactive amygdala, a structure involved in the body’s fear reactions; and an under reactive prefrontal cortex, a brain area that inhibits amygdala activation. It is believed that these differences help to explain why the trauma memories of individuals with PTSD are so intrusive, and are experienced so intensely, sometimes feeling as if the trauma were happening again. These neurobiological differences are also thought to account for the excessive fear reactions that are set off very easily by a host of things experienced that are not really dangerous.

Three Main Kinds of PTSD Symptoms

There are 3 main kinds of PTSD symptoms: re-experiencing, avoidance, and arousal symptoms.

  • Re-experiencing Symptoms. Trauma survivors commonly continue re-experiencing or reliving their traumas in a number of the following ways:

    • Having upsetting memories such as images, thoughts, and perceptions about the trauma

    • Experiencing bad dreams and nightmares about the event

    • Feeling as if it the trauma were happening again ("Flashbacks"

    • Getting emotionally upset when reminded of the trauma (by something the person sees, hears, feels, smells, or tastes)

    • Reacting physically (e.g., sweating, heart racing, trouble breathing) when reminded of the trauma

  • Avoidance Symptoms. Ways of avoiding thoughts, feelings, and sensations associated with the trauma can include:

    • Avoiding trauma-related thoughts, feelings, or conversations

    • Avoiding places, activities, or people that might be reminders of the trauma

    • Trouble remembering important parts of what happened during the trauma

    • Losing interest or not participating in things you used to enjoy doing

    • Feeling detached or cutoff from other people

    • "Shutting down" emotionally or feeling emotionally numb (e.g., trouble having loving feelings for those close to you).

    • Feeling as if your future will be cut short

  • Arousal Symptoms. Trauma survivors often feel very anxious and fearful. This may show up as the following symptoms:

    • Trouble falling or staying asleep

    • Experiencing irritability or outbursts of anger

    • Problems concentrating or focusing on tasks

    • Feeling agitated and constantly on the lookout for danger (i.e., hypervigilant)

    • Feeling jumpy or getting very startled by loud noises or someone coming up on you from behind when you don't expect it

Because they have these upsetting feelings, trauma survivors often act as if they are in danger again when they get stressed or reminded of their trauma. They might get overly concerned about keeping safe in situations that really aren't very dangerous. For example, a person living in a good neighborhood might still feel that he has to have an alarm system, double locks on the door, a locked fence, and a guard dog. Because traumatized people often feel like they are in danger even when they aren't, they may be overly aggressive, lashing out to protect themselves when there is no need. For example, a person who was attacked might be quick to yell at or hit someone who seems to be threatening. This happens because, when threatened, people have a natural physical "fight or flight" reaction that prepares them to respond to them danger.

Although re-experiencing symptoms are unpleasant, they are a sign that body and mind are actively struggling to cope with the traumatic experience. These symptoms are automatic, learned responses to trauma reminders: trauma has become associated with lots of things so that they remind the person of the trauma and bring up feelings that they are in danger again.


Because re-experiencing the trauma and feeling as if you are in constant danger are so upsetting, it makes sense that trauma survivors want to avoid things that remind them of the trauma. Sometimes they are aware of this and avoid trauma reminders on purpose and sometimes they do it without realizing what they are doing.


Avoiding thinking about trauma or avoiding treatment for trauma-related problems may keep a person from feeling upset in the short run. But avoiding treatment of PTSD prevents progress on coping with trauma so that people's trauma symptoms don't go away.

Other Problems That Can Go Along with PTSD

  • Depression: can happen when a person has losses connected with the trauma situation or when a person avoids other people and becomes isolated or gives up activities they enjoyed before the trauma

  • Despair and hopelessness: can happen when a person is afraid that he or she will never feel better again.

  • Loss of important beliefs: can happen when a traumatic event makes a person lose faith that the world is a good and safe place.

  • Aggressive behavior toward oneself or others: can happen due to frustration over the inability to control PTSD symptoms (feeling that PTSD symptoms "run your life"). It can also happen when other things that occurred at the time of trauma made the person angry (the unfairness of the situation). Because angry feelings keep people away, they also stop a person from having positive connections and getting help. Anger and aggression can cause job problems, marital and relationship problems, and loss of friendships

  • Self-blame, guilt, and shame: can happen when PTSD symptoms make it hard to fulfill current responsibilities. It can also happen when people fall into the common trap of second-guessing what they did or didn't do at the time of a trauma (“Monday-morning quarterbacking”). Many people blame themselves when trying to make sense of their experience. This is usually completely unfair. At best, it fails to take into account the other reasons why the events occurred. Self-blame causes a lot of distress and can prevent a person from reaching out for help. Society sometimes takes a "blame-the-victim" attitude, and this too is wrong.

  • Problems in relationships with people: can happen because people who have been through traumas often have a hard time feeling close to people or trusting others. This may be especially likely to happen when the trauma was caused or worsened by other people (as opposed to an accident or natural disaster).

  • Feeling detached or disconnected from others: can happen when a person has difficulty in feeling or expressing positive feelings. After traumas, people can get wrapped up in their problems or feel emotionally numb and then stop putting energy into their relationships with friends and family. It can also be hard to relate to the ordinary activities of daily life, which now seem unimportant.

  • Getting into arguments and fights with people: can happen because of the angry or aggressive feelings that are common after a trauma. Some trauma survivors feel like their temper is a lot quicker than it was before the trauma (as if they have a hair trigger). Also, a person's avoidance of social situations (such as family gatherings) may annoy family members.

  • Less or no interest or participation in things the person used to like to do: can happen because of depression following a trauma. Spending less time doing enjoyable things and being with people means a person has less of a chance to feel good and have pleasant interactions.

  • Social isolation: can happen because of social withdrawal and a lack of trust in others. This often leads to loss of caring support, friendship, and intimacy, and grows fears, worries, loneliness, and depression.

  • Problems with identity: can happen when PTSD symptoms change important things in a person's life, like relationships or whether they can do their work well. It can also happen when other things that occurred at the time of trauma make a person confused about their own identity. For instance a person who thinks of himself as unselfish might think he acted selfishly by saving himself during a disaster when others did not make it. This might make him question whether he is really who he thought he was.

  • Feeling permanently damaged: can happen when trauma symptoms don't go away and a person doesn't think they will get any better.

  • Problems with self-esteem: can happen because PTSD symptoms make it hard for a person to feel good about him or herself. Sometimes, because of things they did or didn't do at the time of trauma, survivors feel, understandably but unfairly, that they are responsible, bad, worthless, stupid, incompetent, evil, and so on.

  • Alcohol and/or drug abuse: can happen when a person wants to avoid bad feelings that come with PTSD symptoms. This is a common unhelpful way some survivors attempt to cope with upsetting trauma symptoms, but it actually leads to more problems.


All of these reactions and difficulties are common for people who experience PTSD or related stress reactions. It is important to be able to recognize these difficulties, and get treatment in order to prevent them from becoming larger problems.


Information gathered from Understanding and Coping with PTSD. Prepared by Veterans Healthcare Administration, National Center for PTSD ( Updated January 2011


Take a listen to this podcast with Bessel van der Kolk from March 9, 2017.  Human memory is a sensory experience, says psychiatrist Bessel van der Kolk. Through his longtime research and innovation in trauma treatment, he shares what he's learning about how bodywork like yoga or eye movement therapy can restore a sense of goodness and safety. What he's learning speaks to a resilience we can all cultivate in the face of the overwhelming events — which, after all, make up the drama of culture, of news, and of life.

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