Secondary structural dissociation involves one ANP and more than one EP. Examples of secondary structural dissociation are complex PTSD, complex forms of acute stress disorder, complex dissociative amnesia, complex somatoform disorders, some forms of trauma-relayed personality disorders, such as borderline personality disorder, and dissociative disorder not otherwise specified (DDNOS).. Secondary structural dissociation is characterized by divideness of two or more defensive subsystems. For example, there may be different EPs that are devoted to flight, fight or freeze, total submission, and so on. (Van der Hart et al., 2004). Gail, a patient of mine, does not have a personality disorder, but describes herself as a "changed person." She survived a horrific car accident that killed several others, and in which she was the driver. Someone not knowing her history might see her as a relatively normal, somewhat anxious and stiff person (ANP). It would not occur to this observer that only a year before, Gail had been a different person: fun-loving, spontaneous, flexible, and untroubled by frightening nightmares and constant anxiety. Fortunately, Gail has been willing to pay attention to her EPs; she has been able to put the process of integration in motion; and she has been able to heal. p134
The "apparently normal personality" - the alter you view as "the client"You should not assume that the adult who function in the world, or who presents to you, week after week, is the "real" person, and the other personalities are less real. The client who comes to therapy is not "the" person; there are other personalities to meet and work
It is a rare person who can cut himself off from mediate and immediate relations with others for long spaces of time without undergoing a deterioration in personality.
The primary driver to pathological dissociation is attachment disorganization in early life: when that is followed by severe and repeated trauma, then a major disorder of structural dissociation is created (Lyons-Ruth, Dutra, Schuder, & Bianchi, 2006).