WordNet

(existentialism) a loss of personal identity; a feeling of being an anonymous cog in an impersonal social machine (同)depersonalisation
emotional dissociative disorder in which there is loss of contact with your own personal reality accompanied by feelings of unreality and strangeness (同)depersonalisation, depersonalization_disorder, depersonalisation disorder, depersonalization_neurosis, depersonalisation neurosis
representing a human being as a physical thing deprived of personal qualities or individuality; "according to Marx, treating labor as a commodity exemplified the reification of the individual" (同)depersonalisation, reification

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/10/06 17:19:58」(JST)

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Derealization (sometimes abbreviated as DR) is an alteration in the perception or experience of the external world so that it seems unreal. Other symptoms include feeling as though one's environment is lacking in spontaneity, emotional coloring and depth.^[1] It is a dissociative symptom of many conditions, such as psychiatric and neurological disorders, and not a standalone disorder. It is also a transient side effect of acute drug intoxication, sleep deprivation, and stress.^{[citation needed]}

Derealization is a subjective experience of unreality of the outside world, while depersonalization is unreality in one's sense of self. Although most authors currently regard derealization (surroundings) and depersonalization (self) as independent constructs, many do not want to separate derealization from depersonalization.^[2] The main reason for this is nosological, because these symptoms often co-occur, but there is another, more philosophical reason: the idea that the phenomenological experience of self, others, and world is one continuous whole. Thus, feelings of unreality may blend in and the person may puzzle over deciding whether it is the self or the world that feels unreal to them.

Chronic derealization may be caused by occipital–temporal dysfunction.^[3] These symptoms are common in the population, with a lifetime prevalence of up to 5% and 31–66% at the time of a traumatic event.^[4]

Description

The detachment of derealization can be described as an immaterial substance that separates a person from the outside world, such as a sensory fog, pane of glass, or veil. Individuals may complain that what they see lacks vividness and emotional coloring. Emotional response to visual recognition of loved ones may be significantly reduced. Feelings of déjà vu or jamais vu are common. Familiar places may look alien, bizarre, and surreal. The world as perceived by the individual may feel like it is going through a dolly zoom effect. Such perceptual abnormalities may also extend to the senses of hearing, taste, and smell. Because degree of familiarity is itself among one's sensory and psychological data when experiencing a place, the process of derealization, by blocking identification with one's surroundings, itself contributes to the difference between one's perception of one's surroundings under derealization and what one's perception would be in the absence of derealization. For this reason, the more familiar a place normally seems, the more unfamiliar it seems when a person is experiencing derealization.

Frequently, derealization occurs in the context of constant worrying or 'intrusive thoughts' that one finds hard to switch off. In such cases it can build unnoticed along with the underlying anxiety attached to these disturbing thoughts, and be recognized only in the aftermath of a realization of crisis, often a panic attack, subsequently seeming difficult or impossible to ignore. This type of anxiety can be crippling to the affected and may lead to avoidant behavior. Those who experience this phenomenon may feel concern over the cause of their derealization. It is often difficult to accept that such a disturbing symptom is simply a result of anxiety, and the individual may often think that the cause must be something more serious. This can, in turn, cause more anxiety and worsen the derealization. Derealization also affects the learning process. Because the individual almost sees the events in as if in 3rd person, they cannot properly process information.

People suffering from derealization have described feeling as if the world external to them were something in a TV show or movie, or as if they were viewing it through a TV screen. This, and other similar feelings attendant to derealization, can cause a sensation of alienation and distance between the person suffering from derealization and others around them.

Causes

Derealization can accompany the neurological conditions of epilepsy (particularly temporal lobe epilepsy), migraine, and mild head injury.^[5] There is a similarity between visual hypo-emotionality, a reduced emotional response to viewed objects, and derealization. This suggests a disruption of the process by which perception becomes emotionally coloured. This qualitative change in the experiencing of perception may lead to reports of anything viewed being unreal or detached.^[3]

Derealization can also manifest as an indirect result of certain vestibular disorders such as labyrinthitis and vestibular neuronitis. This is thought to result from the experience of anxiety precipitated by the functional disparity that arises between the ability to reconcile external stimuli relative to motion and equilibrioception that are compromised by vestibular dysfunction with the internal perceptions and expectations regarding the physical environment. An alternative explanation holds that a possible effect of vestibular dysfunction includes responses in the form of the modulation of noradrenergic and serotonergic activity due to a misattribution of vestibular symptoms to the presence of imminent physical danger resulting in the experience of anxiety or panic, which subsequently generate feelings of derealization.^[6]

Cannabis,^[7] psychedelics, dissociatives, antidepressants, caffeine, nitrous oxide, and nicotine can all produce feelings resembling derealization, particularly when taken in excess. It can also result from alcohol withdrawal or benzodiazepine withdrawal.^[8]

Derealization can also be a symptom of severe sleep disorders, and mental disorders like depersonalization disorder, borderline personality disorder, bipolar disorder, schizophrenia, and anxiety disorders.^[9]

Interoceptive exposure can be used as a means to induce derealization, as well as the related phenomenon depersonalization.^[10]

References

^ American Psychiatric Association (2004) Diagnostic and Statistical Manual of Mental Disorders DSM-IV-TR (Text Revision). American Psychiatric Association. ISBN 0-89042-024-6.
^ Radovic F., Radovic S. (2002). "Feelings of Unreality: A Conceptual and Phenomenological Analysis of the Language of Depersonalization". Philosophy, Psychiatry, & Psychology 9: 271–279. doi:10.1353/ppp.2003.0048.
^ ^a ^b Sierra M, Lopera F, Lambert MV, Phillips ML, David AS (2002). "Separating depersonalisation and derealisation: the relevance of the "lesion method"". J. Neurol. Neurosurg. Psychiatr. 72 (4): 530–2. PMC 1737835. PMID 11909918. //www.ncbi.nlm.nih.gov/pmc/articles/PMC1737835/.
^ Hunter EC, Sierra M, David AS (2004). "The epidemiology of depersonalization and derealisation. A systematic review". Social psychiatry and psychiatric epidemiology 39 (1): 9–18. doi:10.1007/s00127-004-0701-4. PMID 15022041.
^ Lambert MV, Sierra M, Phillips ML, David AS (2002). "The spectrum of organic depersonalization: a review plus four new cases". The Journal of neuropsychiatry and clinical neurosciences 14 (2): 141–54. PMID 11983788.
^ Simon, NM; Pollack MH, Tuby KS, and Stern TA. (June 1998). "Dizziness and panic disorder: a review of the association between vestibular dysfunction and anxiety". Ann Clin Psychiatry 10 (2): 75–80. doi:10.3109/10401239809147746. PMID 9669539.
^ Johnson BA (February 1990). "Psychopharmacological effects of cannabis". Br J Hosp Med 43 (2): 114–6, 118–20, 122. PMID 2178712.
^ Mintzer MZ; Stoller KB, Griffiths RR (November 1999). "A controlled study of flumazenil-precipitated withdrawal in chronic low-dose benzodiazepine users". Psychopharmacology (Berl) 147 (2): 200–9. doi:10.1007/s002130051161. PMID 10591888.
^ Simeon D, Knutelska M, Nelson D, Guralnik O (September 2003). "Feeling unreal: a depersonalization disorder update of 117 cases". J Clin Psychiatry 64 (9): 990–7. doi:10.4088/JCP.v64n0903. PMID 14628973.
^ Lickel J, Nelson E, Lickel A H, Deacon B (2008). "Interoceptive Exposure Exercises for Evoking Depersonalization and Derealization: A Pilot Study". Journal of Cognitive Psychotherapy: An International Quarterly 22: 4.

UpToDate Contents

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1. 離人症性障害：疫学、病因、臨床症状、経過、および診断 depersonalization disorder epidemiology pathogenesis clinical manifestations course and diagnosis
2. 離人症性障害の治療 treatment of depersonalization disorder
3. 解離性同一性障害：疫学、病因、臨床症状、経過、評価、および診断 dissociative identity disorder epidemiology pathogenesis clinical manifestations course assessment and diagnosis
4. 急性ストレス障害：疫学、臨床症状、および診断 acute stress disorder epidemiology clinical manifestations and diagnosis
5. 成人における転換性障害：用語、診断および鑑別診断 conversion disorder in adults terminology diagnosis and differential diagnosis

English Journal

Prevalence and correlates of depersonalization in students aged 12-18 years in Germany.

Michal M1, Duven E, Giralt S, Dreier M, Müller KW, Adler J, Beutel ME, Wölfling K.
Social psychiatry and psychiatric epidemiology.Soc Psychiatry Psychiatr Epidemiol.2014 Sep 9. [Epub ahead of print]
BACKGROUND: Depersonalization (DP) involves unpleasant experiences of detachment from one's sense of self or unreality in the environment. DP may occur in a broad range of conditions, among healthy persons due to sleep loss, drug induced, secondary to anxiety disorders or primary in depersonalizatio
PMID 25201182

Depersonalization in Patients With Persecutory Delusions.

Cernis E1, Dunn G, Startup H, Kingdon D, Wingham G, Pugh K, Cordwell J, Mander H, Freeman D.
The Journal of nervous and mental disease.J Nerv Ment Dis.2014 Sep 5. [Epub ahead of print]
Delusions are, in part, attempts to explain confusing anomalous experience. Depersonalization, a key subset of anomalous experience, has been little studied in relation to persecutory delusions. The aims of this study were to assess the presence of depersonalization in patients with persecutory delu
PMID 25198701

Prolonged depersonalization/derealization-like symptom after migraine headache: a case report.

Kakisaka Y1, Fujikawa M, Kaneko S, Nakasato N.
Neurological sciences : official journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology.Neurol Sci.2014 Sep;35(9):1483-4. doi: 10.1007/s10072-014-1799-0. Epub 2014 Apr 22.
PMID 24752392

Japanese Journal

大学生における離人体験のとらえ方--自由記述式の質問紙による研究

田中裕記,北山修
九州大学心理学研究 10, 125-131, 2009
The purpose of this study is to clarify how the undergraduate students cognize the DepersonalizationDerealization (DP/DR). DP/DR is a subjective feeling of unreality of the self and the outside world …
NAID 120002513574

フードシステム研究における「食の現実感消失」概念導入の試み--東ティモールとの「コーヒー・フェアトレード」を手がかりとして

佐藤奨平,中島正道
食品経済研究 (35), 136-148, 2007-03
NAID 40015507688

心的外傷との関連からみた精神分裂病患者の解離症状

宋建華,福島春子,胡桃澤伸,田中究
神戸大学医学部紀要 61(4), 145-177, 2001-03-31
精神分裂病患者で成育歴に心的外傷体験を持つものは少なくないが, このような患者には精神分裂病固有の症状に加え, 心的外傷に起源をもっと考えられる症状を認めることがある。著者らは, 神戸大学精神神経科外来に通院する90名の精神分裂病患者に対して, 解離症状質問票 (Dissociation Questionnaire ; DIS-Q) および解離体験尺度 (Dissociative Experien …
NAID 110004652906