I think PTSD is complex whether a person has had one trauma or a thousand traumas. Intensity of the trauma can make a single trauma as complex as one having had several traumas over a lifetime. Myself, I am almost 40 and for about 30 years of my life I lived with trauma in the form of abuse of one sort or another. Perhaps the difference lies in the type of damage done to the brain and the area of the brain in which the damage occurs. Those such as myself learn adaptive skills in childhood to survive that as adults become maladaptive because they are taken to extreme and they are not in line developmentally with a person's chronological age. For example, hypervigelence and mind reading. This kept me alive as a child but as an adult it has caused me many struggles with being overly self conscious, and egocentric in my thought processes. I am very slowly and arduously learning different skills to combat these learned responces, which in effect are brain damage due to trauma.