Post-traumatic stress disorder, also called PTSD, happens when some memory of a past traumatic event—like war or sexual assault—causes recurrent mental and physical distress.
Now the Diagnostic and Statistical Manual 5th edition or the DSM 5 categorizes PTSD as a “trauma-and-stressor-related-disorder” that happens when the symptoms of an acute stress response persist for over a month.
The main symptoms are psychological ones, for example someone might re-experience their trauma through nightmares, flashbacks, and intrusive thoughts, but these can lead to behavioral changes as well.
Somebody might start to avoid environments and situations that remind them of their trauma and feel a sense of hypervigilance where they are constantly on guard or hyperarousal where they have this exaggerated startle response to the smallest of triggers.
Not surprisingly, all of these thoughts and behaviours can lead to trouble sleeping and general irritability, which can lead to angry outbursts.
Interestingly, this pattern is different for young children who are less likely to show distress, but instead they might use play to express their memories, sometimes acting out scenes that trouble them.
Whether or not someone develops PTSD in response to trauma is determined by a number of different factors.
For example, it’s clear that interpersonal trauma, like rape or violent muggings, are more likely to result in PTSD than accidents or environmental disasters.
In addition, people that go through extreme trauma as children are more likely to develop PTSD in response to other traumas faced in their adult life.
Having said that, if someone manages to develop effective coping strategies for trauma including having a social support network, then that can help with future traumas as well.
As far as causes go, there are some clues about biological factors related to development of PTSD.