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| | #REDIRECT:[[Amnesia classification#Dissociative or Functional or Psychogenic Amnesia]] |
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| {{Infobox_Disease
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| | Name = Psychogenic amnesia/functional amnesia/dissociative amnesia
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| | ICD10 = {{ICD10|F|44|0|f|40}}
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| | ICD9 = {{ICD9|300.1}}
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| | MedlinePlus = 003257
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| '''Psychogenic amnesia''', also known as '''functional''' or '''dissociative amnesia''', is a disorder characterized by abnormal memory functioning in the absence of structural brain damage or a known neurobiological cause; severe cases are very rare.<ref name = Brandt>{{cite journal |author=Brandt J, Van Gorp WG |title=Functional ("psychogenic") amnesia |journal=Semin Neurol |volume=26 |issue=3 |pages=331–40 |year=2006 |pmid=16791779 |doi=10.1055/s-2006-945519}}</ref> It is defined by the presence of [[retrograde amnesia]] or the inability to retrieve stored memories and events leading up to the onset of amnesia and an absence of [[anterograde amnesia]] or the inability to form new long term memories.<ref name = Markowitsch>{{cite journal |author=Markowitsch HJ |title=Psychogenic amnesia |journal=Neuroimage |volume=20 Suppl 1 |issue= |pages=S132–8 |year=2003 |pmid=14597306 |doi=}}</ref><ref name = Yasuno>{{cite journal |author=Yasuno F, Nishikawa T, Nakagawa Y, ''et al'' |title=Functional anatomical study of psychogenic amnesia |journal=Psychiatry Res |volume=99 |issue=1 |pages=43–57 |year=2000 |pmid=10891648 |doi=}}</ref><ref name = Ross>{{cite journal |author=Mackenzie Ross S |title=Profound retrograde amnesia following mild head injury: organic or functional? |journal=Cortex |volume=36 |issue=4 |pages=521–37 |year=2000 |pmid=11059453 |doi=}}</ref> In most cases, patients lose their autobiographical memory and personal identity even though they are able to learn new information and perform everyday functions normally. Other times, there may be a loss of basic semantic knowledge and procedural skills such as reading and writing.<ref name = Serra>{{cite journal |author=Serra L, Fadda L, Buccione I, Caltagirone C, Carlesimo GA |title=Psychogenic and organic amnesia: a multidimensional assessment of clinical, neuroradiological, neuropsychological and psychopathological features |journal=Behav Neurol |volume=18 |issue=1 |pages=53–64 |year=2007 |pmid=17297220 |doi=}}</ref>
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| There are two types of psychogenic amnesia, global and situation-specific.<ref name = Serra/><ref name = Kopelman>{{cite journal |author=Kopelman MD |title=Disorders of memory |journal=Brain |volume=125 |issue=Pt 10 |pages=2152–90 |year=2002 |pmid=12244076 |doi=|url = http://brain.oxfordjournals.org/cgi/content/full/125/10/2152 | accessdate = 2008-04-05}}</ref> Global amnesia, also known as [[fugue state]], refers to a sudden loss of personal identity that lasts a few hours to days.<ref name = Ross/> This is preceded by severe stress and/or depressed mood. Fugue state is very rare, and usually resolves over time, often helped by therapy.<ref name="myers"/> Situation-specific amnesia is a type of dissociative amnesia occurs as a result of a severely stressful event, as in [[post-traumatic stress disorder]]. Dissociative amnesia is due to psychological rather than physiological causes and can sometimes be helped by therapy.<ref name="myers">{{cite web | url = http://www.memorylossonline.com/glossary/psychogenicamnesia.html | title = Memory Loss & The Brain | publisher = [[Rutgers University]] | accessdate = 2007-12-05 | last = Myers | first = Catherine E. | year = 2006 }}</ref>
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| == Memory and the brain ==
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| {{main|Memory}}
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| There are three types of memory – sensory, short-term, and long-term memory. Sensory memory lasts up to hundreds of milliseconds and short-term memory lasts from seconds to minutes while anything else longer than short-term memory is considered to be a long-term memory.<ref name = Markowitsch/><ref name = Reinhold/>
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| The information obtained from the [[peripheral nervous system]] (PNS) is processed in four stages - encoding, consolidating, storage, and retrieval.<ref name = Markowitsch/> During encoding, the limbic system is responsible for bottlenecking or filtering information obtained from the PNS. According to the type of information given, the duration of consolidating stage varies drastically. Majority of consolidated information gets stored in the cerebral cortical networks where the limbic system record episodic-autobiographical events. These stored episodic and semantic memories can be obtained by triggering the uncinate fascicle that interconnects the regions of the temporofrontal junction area.
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| Emotion seems to play an important role in memory processing in structures like the cingulated gyrus, the septal nuclei, and the amygdala that is primarily involved in emotional memories.<ref name = Markowitsch /><ref name = Yang>{{cite journal |author=Yang JC, Jeong GW, Lee MS, ''et al'' |title=Functional MR imaging of psychogenic amnesia: a case report |journal=Korean J Radiol |volume=6 |issue=3 |pages=196–9 |year=2005 |pmid=16145296 |doi=}}</ref> Functional imaging of normal patients reveal that right-hemisperic amygdala and ventral prefrontal regions are activated when they were retrieving autobiographical information and events. Additionally, the hippocampal region is known to be linked to recognizing faces.
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| Researchers have found that emotional memories can be suppressed in non-mentally ill individuals via the [[prefrontal cortex]] in two stages - an initial suppression of the sensory aspects of the memory, followed by a suppression of the [[emotion]]al aspect.<ref>{{cite journal |author=Depue BE, Curran T, Banich MT |title=Prefrontal regions orchestrate suppression of emotional memories via a two-phase process |journal=Science |volume=317 |issue=5835 |pages=215–9 |year=2007 |pmid=17626877 |doi=10.1126/science.1139560}}</ref> It has also been proposed that [[glucocorticoid]]s can impair memory retrieval, though to date this has only been tested in rats.<ref>{{cite journal |author=Roozendaal B, de Quervain DJ, Schelling G, McGaugh JL |title=A systemically administered beta-adrenoceptor antagonist blocks corticosterone-induced impairment of contextual memory retrieval in rats |journal=Neurobiol Learn Mem |volume=81 |issue=2 |pages=150–4 |year=2004 |pmid=14990235 |doi=10.1016/j.nlm.2003.10.001}}</ref>
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| Traumas can interfere with several memory functions. Dr. Bessel van der Kolk divided these functional disturbances into four sets, traumatic amnesia, global memory impairment, dissociative processes and traumatic memories' sensorimotor organization. Traumatic amnesia involves the loss of remembering traumatic experiences. The younger the subject and the longer the traumatic event is, the greater the chance of significant amnesia. Global memory impairment makes it difficult for these subjects to construct an accurate account of their present and past history. Dissociation refers to memories being stored as fragments and not as unitary wholes. Not being able to integrate traumatic memories seems to be the main element which leads to PTSD. In the sensorimotor organization of traumatic memories, sensations are fragmented into different sensory components.<ref name="pmid8564271">{{cite journal |author=van der Kolk BA, Fisler R |title=Dissociation and the fragmentary nature of traumatic memories: overview and exploratory study |journal=J Trauma Stress |volume=8 |issue=4 |pages=505–25 |year=1995 |pmid=8564271 |doi= |url=http://www.trauma-pages.com/a/vanderk2.php | accessdate = 2008-03-22}}</ref>
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| == Psychogenic and organic amnesia ==
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| Clinically, psychogenic amnesia is characterized by the loss of the ability to retrieve stored memory without having damages to the brain while organic amnesia is characterized by damages to the medial or anterior temporal and/or prefrontal regions caused by [[stroke]], [[traumatic brain injury]], [[ischemia]], and [[encephalitis]].<ref name = Markowitsch/><ref name = Serra/> Some characteristics that define organic amnesia is the maintenance of personal identity, basic semantic knowledge and procedural skills as well as neuroradiological images showing cerebral damage to the cortical and/or subcortical areas known to be associated with long-term memory while some characteristics that define psychogenic amnesia is the loss of personal identity, semantic knowledge, and procedural abilities at least in the early phase of amnesia as well as damage directly affecting cerebral areas critical for memory functioning that cannot be detected in clinical history or neuroradiological exams.<ref name = Serra/>
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| ==Imaging of psychogenic amnesia==
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| Psychogenic amnesia is defined by the lack of structural damage to the brain, but upon [[Medical imaging|functional imaging]], an abnormal brain activity can be seen.<ref> {{cite journal | url = http://villamartelli.com/CCPN2006Handout1.pdf | format = pdf | accessdate = 2007-12-05 | coauthors = Martelli, MF, Nicholson, K, Zasler, ND | author = Heilbronner, R | year = 2002 | title = Brain injury and functional disorders part IV | journal = Journal of Controversial Medical Claims | volume = 9 | issue = 3 | pages = 1–7}}</ref> Tests using [[functional magnetic resonance imaging]] suggest that patients with psychogenic amnesia are unable to retrieve emotional memories normally during the amnesic period, suggesting that changes in the limbic functions are related to the symptoms of psychogenic amnesia.<ref name = Yang/> By performing a [[positron emission tomography]] activation study on psychogenic amnesic patients with [[Face perception|face recognition]], it was found that activation of the right anterior medial [[Temporal lobe|temporal region]] including the [[amygdala]] was increased in the patient whereas bilateral [[Hippocampus|hippocampal]] regions increased only in the control subjects, demonstrating again that [[Limbic system|limbic]] and limbic-[[Cortex|cortical]] functions are related to the symptoms of psychogenic amnesia.<ref name = Yasuno/>
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| == Risk factors ==
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| Patients exposed to physically or emotionally traumatic events are at a higher risk for developing psychogenic amnesia because they seem to have damaged the [[neuron]]s into the in the brain.<ref name = Brandt/><ref name = Markowitsch/> Examples of individuals at greater risk of psychogenic amnesia due to traumatic events include soldiers who have experienced combat, individuals [[Sexual abuse|sexually]] and [[Physical abuse|physically abused]] during [[childhood]] and individuals who have experienced domestic violence, natural disasters, or Terrorism|terrorist acts; essentially any sufficiently severe psychological stress, internal conflict, or intolerable life situation.<ref name = Yang/> Child abuse, especially chronic child abuse starting at an early age has been related to the development of high levels of [[Dissociation (psychology)|dissociative]] symptoms, including amnesia for abuse memories. The study strongly suggested that "independent corroboration of recovered memories of abuse is often present" and that the recovery of the abuse memories generally is not associated with psychotherapy.<ref name=chu>{{cite journal |author=Chu JA, Frey LM, Ganzel BL, Matthews JA |title=Memories of childhood abuse: dissociation, amnesia, and corroboration |journal=Am J Psychiatry |volume=156 |issue=5 |pages=749–55 |year=1999 |pmid=10327909 |doi= | url = http://ajp.psychiatryonline.org/cgi/content/full/156/5/749 }}</ref>
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| == Theoretical explanations ==
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| Psychogenic amnesia is far from being completely understood and while several explanations have been proposed, none of them have been verified as the mechanism that fits all types of psychogenic amnesia. Different theories include:
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| * [[Psychoanalysis|Freudian psychology]] states that psychogenic amnesia is an act of self-preservation, an alternative to suicide.<ref name =" Brandt"/>
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| * [[Cognitive psychology|Cognitive]] point-of-view states that this disorder utilizes the body’s personal Semantics|semantic belief system to repress unwanted memories from entering the consciousness by altering [[neuropeptide]]s and [[neurotransmitter]]s released during stressful events, affecting the formation and recall of memory.<ref name = Brandt/>
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| * "Betrayal trauma theory suggests that psychogenic amnesia is an adaptive response to childhood abuse. When a parent or other powerful figure violates a fundamental ethic of human relationships, victims may need to remain unaware of the trauma not to reduce suffering but rather to promote survival. Amnesia enables the child to maintain an attachment with a figure vital to survival, development, and thriving. Analysis of evolutionary pressures, mental modules, social cognitions, and developmental needs suggests that the degree to which the most fundamental human ethics are violated can influence the nature, form, and processes of trauma and responses to trauma."<ref>{{cite journal |last=Freyd |first=J. |year=1994 |title=Betrayal Trauma: Traumatic Amnesia as an Adaptive Response to Childhood Abuse. |journal= Ethics & Behavior |volume=4 |issue=4 |pages=307–330 |url=http://www.questia.com/read/95814385 |accessdate= 2008-01-13 |doi=10.1207/s15327019eb0404_1}}</ref>
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| *Normal autobiographical memory processing is blocked by imbalance or altered release of [[stress hormone]]s such as [[glucocorticoid]]s and [[mineralocorticoid]]s in the brain.<ref name = Markowitsch/><ref name = Yang/> The regions of expanded [[limbic system]] in the [[Cerebral hemisphere|right hemisphere]] are more vulnerable to stress and trauma, affecting the body's [[opioid]]s, [[hormone]]s, and neurotransmitters such as [[norepinephrine]], [[serotonin]], and [[neuropeptide Y]].<ref name = Reinhold>{{cite journal | author = Reinhold, N | coauthors = Kuehnel, S, Brand, M & Markowitsch, HJ | title = Functional neuroimaging in memory and memory disturbances | journal = Current Medical Imaging Reviews | volume = 2 | issue = 1 | pages = 35–57 | year = 2006 | url = http://www.ingentaconnect.com/content/ben/cmir/2006/00000002/00000001/art00004 | accessdate = 2007-12-05 | doi = 10.2174/157340506775541668 }}</ref> Increased levels of glucocorticoid and mineralocorticoid receptor density may affect the anterior temporal, [[orbitofrontal cortex]], [[Hippocampus|hippocampal]], and [[amygdala]]r regions. These morphological changes may be caused by loss of regulation of [[gene expression]]s in those receptors along with inhibition of neurotrophic factors during chronic stress conditions.
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| *[[Stress (medicine)|Stress]] may directly affect the medial [[Temporal lobe|temporal]]/[[Diencephalon|diencephalic]] system, inhibiting the retrieval of autobiographical memories and producing a loss of personal identity. [[Negative feedback]] produced by this system may dampen the patient's emotions, giving a perplexed or 'flat' appearance.<ref name = Kopelman/>
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| == Treatments ==
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| Currently, various treatments are available for patients with psychogenic amnesia although no well-controlled studies on the effectiveness of different treatments exist.
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| *[[Psychoanalysis]] - uses dream analysis, interpretation and other psychoanalytic methods to retrieve memories; may also involve placing patients in threatening situations where they are overwhelmed with intense emotion.<ref name = Brandt/>
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| *[[Medication]] and [[relaxation technique]]s - in conjunction with [[benzodiazepine]]s and other hypnotic medications, the patient is urged to relax and attempt to recall memories.<ref name = Brandt/> With the help of psychotherapy and learning their autobiographies from family members, most patients recover their memories completely.{{Fact|date=December 2007}}
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| *It has been proposed that [[abreaction]] could be used in conjunction with [[midazolam]] to recover memories. This technique was used the World War II|second World War but is currently much less popular. The technique is thought to work either through depressing the function of the [[cerebral cortex]] and therefore making the memory more tolerable when expressed, or through relieving the strength of an emotion attached to a memory which is so intense it suppresses memory function.<ref>{{cite journal | last = Vattakatuchery | first = JJ | coauthors = Chesterman, P | journal = Journal of Forensic Psychiatry and Psychology | url = http://www.informaworld.com/smpp/432725912-4932359/content~content=a759276300~db=all~order=page | title = The use of abreaction to recover memories in psychogenic amnesia: A case report | volume = 17 | issue = 4 | pages = 647–653 | accessdate = 2007-12-05 | year = 2006 | doi = 10.1080/14789940600965938}}</ref>
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| *Some studies about psychogenic amnesia have concluded that [[psychotherapy]] is not connected to recovered memories of [[child sexual abuse]].<ref name=dissoc-9-4>{{cite journal|title=Memory recovery of childhood sexual abuse |last=Albach |first=Francine |coauthors=Peter Paul Moormann, Bob Bermond |journal=Dissociation |volume=Vol. 9, No. 4, p. 261-273 |url=http://hdl.handle.net/1794/1774 |date=Dec-1996 |accessdate=2008-01-03 |issn=0896-2863}}</ref><ref name = chu/>Data suggests that one’s amnesic recovered memory is spontaneous, and that this is triggered by abuse-related stimuli.<ref name=dissoc-9-4/>
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| == Popular culture==
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| Psychogenic amnesia is a common plot device in many films and books. Notable examples include the character of Jason Bourne, Jackie Chan in ''Who Am I?'' and Goldie Hawn in ''Overboard (1987 film)|Overboard''. | |
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| == See also ==
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| * [[Depersonalization]]
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| * [[Dissociative disorders]]
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| * [[Fugue state]]
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| == Notes ==
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| {{reflist|2}}
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| ==External links==
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| *[http://www.brown.edu/Departments/Taubman_Center/Recovmem/ Recovered Memory Project]
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| *[http://www.leadershipcouncil.org/1/tm/prev.html Summary of Research Examining the Prevalence of Full or Partial Dissociative Amnesia for Traumatic Events]
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| *[https://scholarsbank.uoregon.edu/dspace/handle/1794/1129 The official journal of the International Society for the Study of Dissociation (ISSD), published between 1988 and 1997]
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| *[http://www.sidran.org/ Sidran Institute - PTSD and Dissociation Resources for Survivors, Supporters and Professionals]
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| *[http://boundless.uoregon.edu/digcol/diss/index.html Dissociation and Trauma Archives - Full text searchable articles and case studies published in the 1800s and early 1900s.]
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| [[Category:Diseases and disorders]]
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| {{SIB}}
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| [[sr:Дисоцијативна амнезија]]
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| {{WH}}
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| {{WS}}
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