The leading theorists on the subject recognize that reactions to extreme stress can lead to one or more differing diagnosis, and that inherent in said traumatic reactions is structural dissociation of the personality. Where three types of structural dissociation have been postulated: primary structural dissociation, secondary structural dissociation and tertiary structural dissociation.
Primary structural dissociation involves simple PTSD, and dissociative amnesia, where the Emotional Personality (EP) and the Apparently Normal Personality (ANP) have become disenfranchised or fragmented. The EP "...is fixated in the trauma and associated experiences....[and the ANP]...is fixated in avoidance of the trauma, manifesting detachment, numbing, and partial or complete amnesia" (Steele, van der Hart, and Nijenhuis, n.d., para. 8).
PTSD is not only about personal protection or self preservation but in its essence a mechanism of such endeavors, thus becoming a self-perpetual entity in of itself (the EP can develop into a sub-personality, a component of Dissociative Identity Disorder [DID]). Almost as if it has become self-aware and not only will it steer one away from danger, but also away from its own demise; a seemingly serendipitous supra-intelligent guidance of the subconscious.
The EP has evolutionary roots in defensive mechanisms that propelled us through the traumatic experience(s), an inborn reactionary system that can become entrenched within the mind. The EP's success in our survival leads us to firmly identify with this part of ourselves and engages in obsessive and compulsive rumination of the defensive mechanisms and exhibits as symptomatology.
The ANP has become the mode of operation whereby the individual can engage everyday operational tasks. Such as "...attachment, energy management, reproduction and rearing of children, socialization, play, and exploration" (para. 12). To do so, the ANP’s main function is to avoid the intrusive thoughts and fear potentials.
In a constant threat environment, the evolutionary response system and the benefits of survival further encapsulates the differentiated states of mind. Secondary structural dissociation is a result of this prolonged and saturated state of being. A fluid environment demands that we engage in concerted efforts to survive, to do otherwise means death. Animalistic reflexive defense mechanisms such as the fight or flight response or submissive freezing, delve into the realm of “…complex PTSD or disorders of extreme stress (DES), trauma-induced borderline personality disorder, and dissociative disorders not otherwise specified” (para. 12).
Tertiary structural dissociation results from the complete fragmentation of the EP and the ANP. Whereby numerous ANP’s can develop to engage different aspects of a persons life, such as putting on your “work hat” to enable the separation of a traumatic existence to a work self, the social self, etc. Here we find the diagnosis of DID, where traumatic associations or triggers have inundated the individual and submerges them into a function of constantly changing identities governed by situational exchanges.