A person who dissociates is, essentially, ‘cutting off from reality’, either deliberately by means such as drugs and alcohol, or due to a subconscious survival mechanism.
The survival mechanism of dissociation kicks in to protect the central organizing ego from breaking from reality and disintegrating into psychosis.
Hence, fragmented dissociated parts of the personality carry the traumatic experience and memory, while other dissociated parts function in daily life. Consequentially, profound symptoms of depersonalization and dissociation linked to C-PTSD manifest (Herman JL. Trauma and Recovery. New York: BasicBooks; 1997)
Dissociative disorders are conditions that involve disruptions or breakdowns of memory, awareness, identity, or perception. In the context of severe chronic abuse, the reliance on disassociation is adaptive, as it succeeds in reducing unbearable distress, and warding off the threat of psychological annihilation.
The dissociative disorders a survivor of chronic trauma presents with vary and are inclusive of dissociative identity disorder (formerly known as multiple personality disorder), dissociative amnesia, dissociative fugue, and depersonalization disorder.
Identity confusion is also deemed a by-product of dissociation and is linked to fugue states when the traumatized person loses memory of their past and concomitantly, a tangible sense of their personal identity (Van der Hart O et al, J Traum Stress 2005;18(5):413–423).