In a previous feature we reviewed the diagnosis of Post-Traumatic Stress Disorder. This diagnosis is given when someone experiences an overwhelming trauma and has symptoms which last for more than 30 days. When the stressor is extremely severe and the person experiencing it is a young child, a more severe disorder sometimes develops. A dissociative disorder occurs when traumatic material is split-off or dissociated from the remainder of consciousness.
Other articles have dealt with some of the research concerning recovered memory. It has been established that the memory of traumatic events is sometimes dissociated or repressed and recovered at a later time. Researchers are just beginning to study what is happening in the brain when this occurs. The dissociation of traumatic material can involve the mere forgetting of a traumatic event, or it can involve the splitting of the personality into different parts. A person whose personality has split into different parts, each of which can take "executive control" of the body, is said to have Dissociative Identity Disorder (DID - formerly known as Multiple Personality Disorder - MPD). This is the extreme end of the continuum of dissociation. Other people have a milder form of dissociative disorder. Some, for example, have internal parts which "talk" to each other but do not take executive control.
People with dissociative disorders usually also meet the diagnostic criteria for PTSD. One problem with the "medical model" of diagnosis is that it forces life into a set of discrete categories. Life is much more complex than this. There are many different responses to severe trauma. PTSD and dissociative disorders are overlapping categories - some people fit into both, others fit into one or the other.
Dissociative disorders are usually caused by abuse or severe trauma in early childhood. It may be that people who respond to trauma in that manner have an inherited tendency to daydream or dissociate - to go away during the trauma. Dissociating during a trauma is protective. It allows the person to escape some of the impact of the trauma. This symptom becomes a problem later in life. Dissociative people sometimes dissociate in later situations which they could easily escape from. This can leave them vulnerable to being retraumatized.