Clinical features
Dissociative symptoms are part of normal experience (for example carrying out a routine task with no recollection of doing it afterwards).
Dissociative symptoms include feelings of numbness, detachment, reduced awareness of the environment (feeling dazed), fragmentation or loss of memory, depersonalisation (sense of detachment with the experience of being an outside observer of your own mental processes or body, or a sense of part of the body not belonging to the person) and derealisation (feeling disconnected from your environment with the sense that nothing is real). Other experiences include loss of memory (amnesia).
Dissociative disorders can either be primary, when there is no underlying cause or secondary when there is an underlying physical or psychiatric cause. Primary dissociative disorders are less common than secondary dissociative disorders.
Secondary dissociative disorders occur in epilepsy (for example temporal lobe epilepsy), as a response to stressful or traumatic events (for example PTSD), and in anxiety disorders and can be caused by some drugs and alcohol.
DSM IV-R (The American Psychiatric Association in the Diagnostic and Statistical Manual of Mental Disorders, revised 4th edition) identifies the following primary dissociative disorders.
Dissociative amnesia
Dissociative amnesia is the inability to recall important personal memories, usually of a stressful nature, which cannot be explained by normal forgetfulness.
Dissociative fugue
Dissociative fugue involves the person losing their memory and wandering away from their usual surroundings. When found they are often unable to remember where they have been or who they are.
Dissociative identity disorder (multiple personality disorder)
Dissociative identity disorder involves the person making a sudden “switch” from their normal personality state to another. There may be more than one additional personality state and these often contrast markedly from the person’s normal personality. When the person is in one personality state they are not usually able to recall information about their other personality states. People with dissociative identity disorder frequently have other psychiatric disorders such as schizophrenia, personality disorder, and alcohol or drug abuse. Some authorities believe this rare phenomenon is sometimes a reaction to suggestion by an authority figure, such as a psychotherapist, or it may be an over-interpretation of swings in mood state seen in bipolar affective disorders.
Depersonalisation and derealisation disorder
Depersonalisation disorder involves the feeling that external objects, parts of the body or the person’s emotions are altered in quality or unreal. People with depersonalisation disorder complain that their perceptions feel unreal, their emotions are dulled and that their actions feel mechanical. Other symptoms include déjà vu ( sense of having experienced something before) , change in the sense of the passage of time and sensory distortion affecting parts of the body (described as feeling different, for example like cotton wool). The symptoms are unpleasant. Depersonalisation refers to states affecting internal phenomenom such as body image. Derealisation refers to external perceptions.
Most people who present with symptoms suggestive of depersonalisation disorder have secondary depersonalisation disorder i.e. they have an underlying medical or psychiatric condition, for example temporal lobe epilepsy, schizophrenia, anxiety disorder, personality disorder etc.
Dissociative stupor
In dissociative stupor the person is mute and motionless and does not react to stimulation, although they are aware of their surroundings. It is necessary to rule out an underlying medical or psychiatric condition such as schizophrenia, depression, mania and organic brain disorders (for example tumours, stroke etc).
Amended May 2009
