Dissociative Amnesia. This disorder is characterised by the presence of at least one episode in which a patient is incapable of recalling important personal data: a condition which generally follows traumatic or stressful events. The incapacity is too extensive to be explained as a normal episode of forgetfulness and does not present during the course of evolution of a different disturbance such as the Dissociative Fugue or Post-Traumatic Stress Disorder (see Anxiety Disorders). In order for it to be diagnosed it must not have been caused by the use of substances, by a general medical condition or by neurological disorders. Moreover, it must be the cause of significant distress and generate disorder in the individual’s social or occupational activities or other important areas of life. Most often the amnesia is related to all events that occurred within a certain time interval. More rarely, amnesia may present in the form of (1):
It should be noted that that during an episode of Dissociative Amnesia the behaviour of the individual will generally be normal, except for a sense of disorientation which the condition may cause and which may result in the person wandering about with no particular goal or destination in mind. The patient will not be able to recognise persons that he or she would normally know but will maintain intact all of his/her cognitive skills e.g., reading and writing), and previously acquired cultural and social knowledge. Usually, the amnesia ends quite suddenly, with a rapidity resembling that of its onset, and patients recover their memory completely. Relapse is a rare event.
Dissociative Fugue. A Dissociative Fugue occurs with an unexpected and sudden abandonment of the place where the individual normally resides, together with an incapacity to recall one’s past. In this disorder the loss of memory is more extensive than in the previous case. The patient presents confusion concerning his or her identity and may assume a new one, starting a new life in the true sense, with drastic changes in many areas (new name, new job, different social contacts and so on). The other diagnostic criteria are the same as those which apply for Dissociative Amnesia. Episodes of Dissociative Fugue generally occur following a traumatic or stressful event or period. They are characterised by variable duration, ranging from a geographically and temporally limited move to a more substantial abandonment of the individual’s habitual place of residence (and this is the case in which a new identity is assumed). The recovery of memory is generally complete, although the time of recovery will vary quite considerably and the incapacity of the subject to recall events occurring during the fugue will be permanent.
Depersonalization Disorder. In this disturbance a person presents a serious alteration of the perception or experience of the self. The disorder implies a recurring experience of feeling outside of oneself, as if one were an external observer of one’s own mental processes and body functions. These experiences cause significant distress and a general impairment of the patient’s existence. It may occur that patients perceive themselves as a mechanism, as if they and others were robots or automatons or they may have the impression they are living in a dream world, quite separate from day-to-day reality. Reality testing (see glossary) in any case remains intact: a condition that does not present in the case of schizophrenics, whose sufferance in relation to such experiences is more intense and complete. The peculiarity of this disorder with respect to other dissociative conditions is the absence of amnesia.
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(1) Coons, P.M., & Milstein, V. (1992). Psychogenic amnesia: A clinical investigation of 25 cases. Dissociation: Progress in the Dissociative Disorders, 5, 73-79.
(2) Ross, C.A., Miller, S.D., Reagor, P., Bjornson, L., & Fraser G.A. (1990). Structured interview data on 102 cases of multiple personality from four centers. American journal of Psychiatry, 147, 596-600.