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Psychogenic amnesia has similarities to organic amnesia. There are islets of fragments of preserved memory within amnesic gap. Semantic knowledge, memory for skills, verbal learning are unaffected and intact in psychogenic memory. Memory retrieval may be facilitated by environmental cues.
The differentiation between organic and psychogenic amnesia is sometimes difficult. The rate and circumstances of onset, loss of personal identity, preservation of new learning is characteristic of discrete psychogenic amnesia. In persistent psychogenic amnesia, past and family history, the pattern of deficit, patient's response to deficit are differentiating factors.
In Fugue states, the onset of loss of personal episodic memory is combined with loss of sense of personal identity and a period of wandering. The episode usually resolves within a few hours or days. The patient comes out from fugue with residual amnesic gap for the period of the fugue.
Fugue states may be precipitated by stress due to marital discord, financial problems, offending, or severe stressful situations such as during war.
Fugue states are associated with depressed mood, suicide attempts, past history of head injury, past history of alcohol abuse, epilepsy, neurotic conditions, other organic disorder and tendency to lie. Suicide does not occur during fugue but there are reports that it take place as the person emerges from the fugue. A past history of organic amnesia from head injury, epilepsy or alcoholic amnesia is commonly found in people presenting with fugue states.
An offender may claim amnesia for a criminal offence, in particular in cases of homicide. Amnesia is found mainly in violent crimes, where the victim is closely related to the offender and the offence is unplanned and take place in a state of high emotional arousal. Such complaints of amnesia are also reported by offenders who are chronic alcohol abusers who commit a crime when severely intoxicated and in schizophrenic patients who commit damage when floridly psychotic.
Memory impairment is common in depression which is closely associated with deficits in attention, concentration and motivation. Depressed patients have a tendency to recall unpleasant events with ease. The increased accessibility of unpleasant memories has diurnal variations.
Psychogenic amnesia may result from faulty encoding of information at initial input and in consequence there is deficits in retrieval. The normal process of memory acquisition is impaired due to the extreme emotional arousal, the severe intoxication, florid psychosis, depressive or abnormal mood. This demonstrates the link between psychogenic amnesia and organic amnesia which is often found in earlier history of the patient.
The psychodynamic concept of repression is a phenomenon were disagreeable memories are easily forgotten. There is evidence of memory without awareness of the person as evidenced by intact emotional reactions to cues in the presence of profound amnesia.
Psychogenic amnesia may represent a state dependent phenomena where memories are retrieved if the person is brought back to the same subjective state.