Everyone occasionally experiences a failure in the normal automatic integration of memories, perceptions, identity, and consciousness. For example, people may drive somewhere and then realize that they do not remember many aspects of the drive because they are preoccupied with personal concerns, a program on the radio, or conversation with a passenger. Typically, such a failure, referred to as nonpathologic dissociation, does not disrupt everyday activities.
In contrast, people with a dissociative disorder may totally forget a series of normal behaviors occupying minutes, hours, days, or weeks and may sense a missing period of time in their experience. In dissociative disorders, the normal integration of consciousness, memory, perceptions, identity, emotion, body representation, motor control, and behavior is disrupted, and continuity of self is lost.
People with a dissociative disorder may experience the following:
Dissociative disorders frequently develop after overwhelming stress. Such stress may be generated by traumatic events or by intolerable inner conflict. Dissociative disorders are related to trauma and stressor-related disorders (acute stress disorder and posttraumatic stress disorder), which can include dissociative symptoms (eg, amnesia, flashbacks, numbing, depersonalization/derealization).
Recent brain research in animals and humans has begun to identify specific brain structures and function underlying dissociation. In particular, during dissociation, structures in the memory regions deep in the brain show rhythmic activity but appear disconnected from higher cortical regions responsible for thought and planning (1). Similarly, during hypnosis there is a relative disconnection of those higher control regions from a portion of the back of the brain that is involved in self-reflection (2).
1. Vesuna S, Kauvar IV, Richman E, et al: Deep posteromedial cortical rhythm in dissociation. Nature 586(7827):87-94, 2020. doi: 10.1038/s41586-020-2731-9.
2. Jiang H, White MP, Greicius MD, et al: Brain activity and functional connectivity associated with hypnosis. Cereb Cortex 27(8):4083-4093, 2017. doi: 10.1093/cercor/bhw220.