And this can be in the form of intrusive remembering or dreams in which the person re-experiences the trauma. Or, even a terrible state of mind in which the person is suddenly thrown back and believes they are actually reliving the trauma. That's the cluster related to re-experiencing the trauma. The next cluster has to do with things that avoid the trauma. People will try to avoid thoughts or activities that remind them of the trauma.
Avoidance is very important.
They may try to avoid conversation or activity, or people and places associated with the trauma. And, also, some people are not able to remember certain aspects of the trauma. People suffering from PTSD often show markedly diminished interest in significant activities, feelings of detachment, their emotional range is constricted, and many people show a sense as if their future is foreshortened. Then the last cluster of features of PTSD has to do with physiology and that relates to increased arousal. Also, in this aspect of increased arousal, some people have outbursts of anger and irritability.