Psychogenic Amnesia: When Memory Complaints Are Medically Unexplained Gavin C
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Advances in psychiatric treatment (2009), vol. 15, 152–158 doi: 10.1192/apt.bp.105.001586 ARTICLE Psychogenic amnesia: when memory complaints are medically unexplained Gavin C. M. McKay & Michael D. Kopelman Gavin C. M. McKay was a Specialist loss, which we refer to here as ‘psychogenic’ amnesia SUMMARY Registrar in Neuropsychiatry at (i.e. loss not due to identifiable brain disease). the Memory Disorders Clinic at St The focus of this article is the assessment and management Thomas’ Hospital. He has obtained his of medically unexplained (‘psychogenic’) amnesia, which we certificate of completion of training classify here as global or situation specific. Other psychiatric Why ‘psychogenic’? and is now a locum consultant in causes for memory disorder and neurological conditions that general adult psychiatry, maintaining A number of terms have been used to describe a special interest in neuropsychiatry. could cause diagnostic confusion are briefly reviewed, as medically unexplained amnesia, including ‘hysterical’, Michael D. Kopelman is Professor are forensic aspects of memory complaints. Finally, brain ‘psychogenic’, ‘dissociative’ and ‘functional’. Each of Neuropsychiatry at the Institute and physiological mechanisms potentially associated with requires the exclusion of an underlying neurological of Psychiatry, King’s College London, psychogenic amnesia are discussed. and Consultant Neuropsychiatrist cause and the identification of a precipitating stress with the South London and Maudsley DeclaratiON OF INTEREST that has resulted in amnesia. Unfor tunately, the NHS Foundation Trust, based at the None. presence of amnesia may make it difficult to identify Neuropsychiatry and Memory Disorders the stress until either informants have come forward Clinic at St Thomas’ Hospital, London. or the amnesia itself has resolved. Professor Kopelman has published Amnesia (Fig. 1) has been defined as ‘an abnormal widely on many aspects of memory Both DSM–IV (American Psychiatric Association, disorders (including the amnesic mental state in which memory and learning are 2000) and ICD–10 (World Health Organization, syndrome, Alzheimer’s and semantic affected out of all proportion to other cognitive 1992) favour the term ‘dissociative’ amnesia. Some dementia, confabulation, psychogenic functions in an otherwise alert and responsive have argued strongly for ‘functional’ amnesia as a amnesia, amnesia for offences, and patient’ (Victor 1971). Memory impairment can false confessions), as well as calculation description more acceptable to patients (Stone 2005). disorders, sleep disorder, post-traumatic affect the learning of new material (anterograde Others prefer ‘medically unexplained amnesia’. We stress disorder and neuroimaging. amnesia), owing to impairments in the encoding, favour ‘psychogenic’ amnesia, because it points to Correspondence Dr Gavin McKay, storage or retrieval stages. It can also affect the underlying psychological processes without assuming Mascalls Park, Mascalls Lane, recall of previously acquired memories (retrograde Brentwood, Essex CM14 5HQ, UK. that any particular psychological mechanism is Email: [email protected] amnesia), which might involve personal experiences involved (a difficulty with ‘dissociative’ amnesia). (episodic memory), general information (semantic Also, it does not specify whether the memory loss is memory) or perceptuomotor skills (procedural produced (partly or entirely) consciously (‘factitious’ memory). Psychological factors can cause both or ‘exaggerated’ amnesia) or purely unconsciously anterograde and retrograde memory loss (or a (‘hysterical’ amnesia). The term ‘functional’ amnesia combination of the two). has the problem that the amnesia could in many respects be considered dysfunctional. However, Types of psychogenic amnesia regardless of the term used, the question remains, Psychologically based amnesia includes the at what point, in cases of doubt, should the clinician persistent anterograde memory impairment present assume that a psychological stressor or a marker of in mental disorders such as depression, which in an neuropathology or brain pathology is the primary extreme form can lead to depressive pseudodementia. cause of the symptoms? A subsidiary to this is, Alternatively, it can cause transient or discrete does the amnesia have both psychological and episodes of retrograde and/or anterograde memory neurological contributions to its aetiology? Amnesia/memory loss Organic (neurological) amnesia Psychogenic amnesia Transient global Persistent amnesia Global psychogenic amnesia Situation-specific psychogenic amnesia amnesia (e.g. Korsakoff syndrome) Psychogenic fugue Psychogenic focal Multiple personality Amnesia for offence Amnesia arising Amnesia for (transient) retrograde amnesia disorder (0ffender or victim, in post-traumatic memories of childhood (persistent) (DSM–IV dissociative e.g. rape) stress disorder sexual abuse identity disorder) Fig 1 A partial classification of amnesia. 152 Advances in psychiatric treatment (2009), vol. 15, 152–158 doi: 10.1192/apt.bp.105.001586 Psychogenic amnesia Types of global psychogenic amnesia of this syndrome. The first is following a typical fugue with wandering and loss of personal identity, Psychogenic fugue when disproportionate retrograde amnesia persists. This is a syndrome of sudden onset, involving loss of The other is after a minor brain insult such as mild all autobiographical memories, including personal concussion in a predisposed person. These cases identity. It is usually associated with a period of are often difficult to manage, both because of the wandering, for which there is a gap in continuous coexistence of minor organic, psychological factors memories on recovery. Fugue states usually last a and the possibility of financial compensation for matter of hours or days. There is anecdotal evidence injuries, and because the underlying stressors are that they are more common in wartime, particularly often not obvious on initial inquiry. In both types in soldiers about to return to the front. Psychogenic of aetiology abnormal illness behaviour may arise fugue is classified in DSM–IV as dissociative fugue. and be reinforced by the gains derived from the emotional and practical support of family, friends, Case 1 Psychogenic fugue helping professions and the welfare system. A 40-year-old woman ‘came round’ on the London Underground. She had approached a staff member, Case 2 Psychogenic focal retrograde amnesia telling them that she had no recollection of who she was or what she was doing. The only clues to her ‘I put things in boxes, I choose to put them in the identity were a bag with a few clothes and a letter back of my mind. I’ve always done that’. These are the that turned out to be addressed to someone else. Staff words, during treatment, of a 62-year-old man who contacted the police, who took her to an accident and collapsed at work with a transient right-sided weak- emergency department. After being medically cleared ness and a complete loss of autobiographical memory. she was admitted to a psychiatric unit. Initially, she On admission, he was disoriented in time and place appeared depressed but this resolved with no medica- as well as person, and there was a mild loss of power tion. In an effort to trace her identity a picture was in the right arm and leg with an equivocally up-going shown on national television, with no responses. An right plantar response. A computed tomography (CT) amytal interview was tried, again with no success. She scan was normal but a magnetic resonance imaging was eventually discharged from hospital and the retro- (MRI) brain scan showed evidence of a few pinpoint grade memory loss persisted. One year later, relatives regions of altered signal bilaterally, consistent with a in the USA sent a missing person poster to the UK history of previously diagnosed hyperlipidaemia and police and she was traced. It emerged that, following diabetes. However, the physicians attending this man a marital crisis in the context of an unstable marriage, felt confident that his memory loss was entirely dis- she had disappeared from her home and taken a flight proportionate to his neurological signs, which rapidly to the UK. She had a history of depression. resolved. The patient did not recognise his wife, and After obtaining a clear history from the family he could not remember the names and ages of his a second amytal interview was attempted and she children. He claimed to have relearned this (personal did recover most of her retrograde memory function semantic) knowledge about his life and that ‘each day (Kopelman 1994). I remember more of the day before’. On formal tests, he showed severe and extensive autobiographical Three main factors may predispose to psychogenic memory loss, with intact anterograde memory. When fugue: first seen, he and his family were angry at any sugges- tion that there might be a psychological component •• precipitating stress such as emotional, relationship, to his memory loss. However, during the succeeding marital or financial problems weeks, his wife provided information about his dif- •• depressed mood, sometimes with suicidal ficult childhood and subsequent emotional problems. thoughts The initial onset had occurred after the patient had been confronted about ‘moonlighting’ in two employ- •• a history of a transient organic amnesia: some ments and his dismissal from both. After being seen on studies report that more than half of affected a regular basis for several weeks, he was